August 19-21, 2013, Cleveland, OH
Major Themes Discussed/Presented
Session II: Disease Models for Adult Stem Cell Therapy
Session III: Immunomodulation Using Adult Stem Cells
Session IV: Gene Therapy on Adult Stem Cells
Session V: Regenerative Medicine and Adult Stem Cells
Session VI: Tissue Engineering
Session VII: Cell Biology in the Clinical Setting
Session VIII: Clinical Trials: Cardiovascular and Pulmonary
Session IX: Clinical Trials: Immunological
Session X: Clinical Trials: Neurological Injury and Disease
Organizers: National Center for Regenerative Medicine and Case Western Reserve University (CWRU)
Directors: Frank Barry, Arnold Caplan, Robert Deans, Stanton Gerson, Michael Gilkey,
Jan Nolta, and Mahendra Rao
Authors: Michael Gilkey; Frank Barry; Alexey Bersenev; Robert Deans; Amar Desai; Stanton Gerson; Nicholas Greco; Jan Nolta; Mahendra Rao; and Arnold Caplan
Travel Grant Writers: Gregory Asatrian; Michael Bukys; Allison Bean; Erin Collins; Douglas Crowder; Mahesh Khatri; Suzanne Lababidi; Hamidreza Riazifar; Zhina Sadeghi; Christopher Smith; Madeleine Strohl; Suharika Thotakura; Krishna Vallabhaneni; Kelly Yan; and Andrea Zanetti
Research reported in this publication was supported by the National Center For Advancing Translational Sciences of the National Institutes of Health under Award Number R13TR000975. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. Additional support for this travel grant was made by National Heart, Lung, and Blood Institute (NHLBI) and National Institute of Neurological Disorders and Stroke (NINDS).
The Primary function of this summary is to capture the main results and important scientific breakthroughs discussed during the conference and see if there are broad themes relevant and important to the field to know and take into consideration.
This fourth international conference on mesenchymal stem cell, multipotent stem cell, and related stem cell therapeutic technologies represents the significant advances occurring in the field of mesenchymal stem/stromal cell biology and therapeutics. This field is on the verge of an explosion of clinical applications, biotechnology involvement, and recognition of the value of cell therapy. National and international regulators appreciate the expanse of this field and await each new clinical application. The world also awaits these advancements and the results of these carefully constructed scientific investigations.
Major Themes Discussed/Presented
- Adoption of standard nomenclature for MSC. The adoption of a uniform nomenclature was deemed of high importance for all written and oral communications. Mesenchymal stem cell (MSC) is the designation commonly applied to the plastic-adherent cells isolated from BM, adipose and other tissues, with multipotent differentiation capacity in vitro. The "stem cell" label for MSCs has scientific implications that may or may not be strictly correct, and the Mesenchymal and Tissue Stem Cell Committee of the ISCT recommends a clarification of the nomenclature for these important cells.
- Standardization assay or assays for MSC characterization. The FDA views every MSC product as a unique drug and any change in origin of the derived cell line, culture conditions under which they are expanded, isolated, and/or characterized in, or different processing methods, would differentiate the MSC product from another cell product but also carries the need for full clinical trial evaluation. Therefore, each company or institution seeking to commercialize the use of MSC must complete extensive pre-clinical and safety experiments. Therefore, to streamline the acceptance of MSC products, there is a requirement for a minimal criterion for MSC identity and quality. A panel discussion involving Arnold Caplan, Stanton Gerson, Mahendra Rao, and Paul Simmons strongly advocated the formulation and adoption of a "ruler" of minimal standard characterization criteria for MSC identity and quality to which all investigators should compare MSC preparations.
- Accelerated approval of new cellular therapies. Dr. Caplan and others believe the FDA should not treat cell-based therapies as conventional drugs, but instead follow a new paradigm. First, the cell-based therapy should enroll a traditional phase 1 safety study, then if safe, move to phase IV clinical trial to evaluate long term patient safety and efficacy. A publically accessible, but patient identity stripped, website would be created to allow for real-time tracking of patient outcomes and safety issues. This would allow for rapid translation of new cellular therapies and a robust means to track safety in identifying patient populations which should not receive these therapies due to adverse events.
As a background for several of the important themes of this meeting, several position papers have attempted to address the inconsistency between MSC nomenclature and biologic properties and to clarify the terminology. This minimal set of standard criteria is suggested to foster a more uniform characterization of MSC and facilitate the exchange of data among investigators:
Clarification of the nomenclature for MSC: The International Society for Cellular Therapy position statement. EM Horwitz, K Le Blanc, M Dominici, I Mueller, I Slaper-Cortenbach, FC Marini, RJ Deans, DS Krause and A Keating. Cytotherapy (2005) Vol. 7, No. 5, 393-395.
Minimal criteria for defining multipotent mesenchymal stromal cells. The International Society for Cellular Therapy position statement. M Dominici, K Le Blanc, I Mueller, I Slaper-Cortenbach, FC Marini, DS Krause, RJ Deans, A Keating, DJ Prockop and EM Horwitz. Cytotherapy (2006) Vol. 8, No. 4, 315-317.
Immunological characterization of multipotent mesenchymal stromal cells - The International Society for Cellular Therapy (ISCT) working proposal. Krampera M, Galipeau J, Shi Y, Tarte K, Sensebe L. Cytotherapy. 2013 Sep;15(9):1054-61.
Heterogeneous adipose tissue has emerged as an alternative tissue source for multipotent stromal/stem cells for regenerative medicine. Adipose tissue contains two distinct populations that can be used as a therapeutic intervention; the stromal vascular fraction (SVF) and culture expanded adipose-derived stem cells (ASC). SVF is freshly isolated in suspension while ASC are isolated after culture of SVF. Administration of SVF may have distinct therapeutic effects and the clinical advantage of using SVF is that it is biologically unchanged with treatment with collagenase and is autologous. Both freshly processed heterogeneous SVF and ASC have been shown to have differentiation potential and regenerative properties, and with ASC, tri-lineage potential to adipocytes, osteocytes, and chondrocytes. SVF has been shown to have therapeutic uses for cardiac disease, multiple sclerosis, wound healing, and liver regeneration. A potential clinical advantage of SVF therapy is that the cell product might be considered to be a minimally manipulated product, resulting in a product where the biological characteristics of the cells have not been changed. This group demonstrated the activity of ASC and SVF in a preclinical EAE model of multiple sclerosis in mice. They demonstrated that treatment by SVF (1 x 106 cells injected intraperitoneal) delays the onset of disease and decreased the number of animals manifesting the disease. They demonstrated in histopathological analysis that treatment with SVF maintained myelin structure in the spinal cord. In addition, they found suppression of T cells in ASC and SVF treated animals and a reduction in proinflammatory cytokines IFN-y and TNF-α in the serum of SVF and ASC treated animals. They determined that treatment after maximal damage in the model (post inflection point in EAE) that 100% of the animals respond with SVF treatment (i.e., SVF decreased inflammation and decrease the onset of symptoms more effectively than ASC if treated after initial inflammation decreases).
Dr. Kerkis discussed the isolation and in vitro expansion of cells from dental pulp as MSCs, and/or neuroepithelial stem cells (NESCs), and/or a mixed population of both which are multipotent, non-tumorigenic, and non-immunogenic. Pluripotent dental pulp MSCs are derived from ectoderm while bone marrow and adipose derived MSCs are from mesoderm so they may represent different therapeutic agents. With dental pulp, the number of MSCs decreases during aging, as measured by the in vitro CFU-F assay. The collection interval for pluripotent dental pulp MSCs are from 5-12 years. The cells do not change immunophenotypically even following cryopreservation. Substantial quantities of stem cells of an excellent quality and at early (2–5) passages are necessary for clinical use. Dr. Kerkis and her team culture generated MSCs over six months through multiple mechanical transfers into a new culture dish every 3–4 days. Their finding is of importance for the future of stem cell therapies, providing scaling-up of stem cells at early passages with minimum risk of losing their "stemness." They found that the distinguishing feature of dental pulp stem cells is their natural capacity to express neurotrophin receptor, a marker of neural crest cell and a set of neurotrophic factors. Dr. Kerkis described their results showing human bone formation in a rat critical defect model, a human cornea epithelia formation rabbit model for chemical burns, improvement in dog model of Duchenne dystrophy lacking an immunological response, and improvement of renal injury in mice by human dental pulp-derived MSC also lacking an immunologic rejection. They have reported primary results of the first clinical phase of application of immature dental pulp cells in order to treat local bone defect with subsequent placement of an implant which demonstrates the ability to be expanded for human clinical trials. Dr. Kerkis and her team suggested the development of a tooth banking industry for dental pulp tissue for the eventual use of cryopreserved dental stem cells in regenerative medicine applications.
Bruno Peault (University of California Los Angeles and University of Edinburgh): "A Natural History of Mesenchymal Stem Cells"
What is the native origin of MSCs, are there multiple stem cells, and what is fact or an artifact? Dr. Peault introduced the concept of the in vitro native identity of MSCs by culturing purified pericytes in MSC culture media. These cells proliferated and differentiated indistinguishable from MSCs. Because pericytes express MSC markers in vivo and clonal analysis demonstrated that each cultured pericyte is a multi lineage MSC like progenitor cell, Dr. Peault posits that MSCs are derived from pericytes or from cells in adventitial layer of vessels. These cells have therapeutic potential and in a mouse ischemic heart model, Dr. Peault demonstrated a therapeutic effect of pericytes on heart tissue morphology and detected significant improvements in cardiac function and anatomy. Pericytes did not differentiate to new cardiomyocytes but instead were redistributed around the blood vessels, and reduced inflammation and induced angiogenesis. Studying pericytes within the stem cell niche, Dr. Peault found that pericytes support the survival and maintenance of undifferentiated hematopoietic stem cells precursors (HSPC) showing that if they inject MSCs into SCID/NOD mice, functional HSPC are sustained. Dr. Peault's group is conducting pre-clinical studies using a combination of adventitial cells and pericytes isolated from adipose tissue with the secretory osteoinductive cytokine, NELL-1, for bone formation in a canine model as a foundation for a pre-IND meeting with the FDA.
Liisa Kuhn (University of Connecticut health center): "Recapitulation of developmental bone tissue generation by MSCs derived from human embryonic stem cells"
Dr. Kuhn discussed a method for producing osteoprogenitor cells from human embryonic stem cells that have superior capability to repair large bone defects as compared to adult MSCs. She described substantial in vivo bone formation by human embryonic stem cell (hESC) derived cells in immunodeficient mouse calvarial defects. Dr. Kuhn emphasized the advantages of not over-committing and overly pre-engineering progenitor cells to a lineage before implantation. hESC or iPSC may represent alternative sources of MSCs. Previous studies using osteoprogenitors derived from hESC for bone repair have had shortcomings. These failures may be due to culture heterogeneity or due to over-differentiation that slows cell differentiation and limits repair within the defect area. Dr. Kuhn suggested the need to balance proliferation and differentiation and the extent of commitment to a specific lineage. The question she asked is. "How far do we differentiate before implanting?" Interestingly in bone defect models, ESCs were found to stain positive within the bone defect whereas the adult MSCs were observed to stain positive on the periphery, suggesting that ESCs differentiate into bone and MSCs assume a more active paracrine role. Dr. Kuhn demonstrated in an in vivo osteogenesis assay on mouse calvarial defect 6 weeks after implantation, complete repair of the defect and hence hESC-MSCs were capable of substantial bone regeneration. Dr. Kuhn believes substantial bone repair results from these hESC-derived MSCs reinforcing an alternate tissue engineering program referred to as developmental engineering. Future experiments could determine the effect of similar growth factor containing medium that was used to derive hESC-MSCs on the biological activity of adult MSCs.
Dr. Caplan began his talk with a proposal to the FDA that cell-based therapies should not be treated as conventional drugs, but instead follow a new paradigm. First the cell-based therapy should enroll a traditional phase 1 safety study, then if safe, move to phase IV clinical trial to evaluate long term patient safety and efficacy. A publically accessible, but patient identity stripped, website would be created to allow for real-time tracking of patient outcomes. Dr. Caplan moved on to discuss the fact that MSCs are pericytes which are found on blood vessels. Upon injury these pericytes detach and become MSCs and exhibit two major functions: (1) immunomodulatory effects and (2) to establish a regenerative environment. Thus, MSCs should be renamed "medicinal signaling cells" since the term "stem" does not accurately describe the MSC role in regeneration. Dr. Caplan described several exciting models to study the role of MSCs in disease models including recently published work in his own lab where MSCs are recruited to and localized to sites of radiation injury and play a role in tissue recovery. He additionally discussed Robert Miller's work using MSCs to treat multiple sclerosis and Diego Correa's work studying MSCs ability to control metastasis into bone tissue. Dr. Caplan believes that the potential of these MSCs is enormous because of their ability to recognize tissue injury and facilitate natural regeneration.
Stanton Gerson (University Hospitals Case Medical Center – UHCMC and CWRU): "Protecting Hematopoietic Stem Cells using P140KMGMT during Glioma therapy"
Dr. Gerson's work is focused on gene therapy in hematopoietic stem cells (HSCs) and the potential for HSC protection during glioma therapy. Cells contain a natural defense against temozolomide in the form of methylguanine methyltransferase (MGMT), and patients resistant to temozolomide have demonstrated increased MGMT expression. Clinical temozolomide treatment includes the use of Benzylguanine (BG), an agent that inactivates MGMT and allows for methylating agent induced cell death. Dr. Gerson's group has studied the potential of protecting HSCs from BG/temozolomide therapy by introducing a mutant form of MGMT that is resistant to BG inactivation in HSCs. This mutant P140K MGMT would yield an HSC population resistant to the drug and allow for increased temozolomide dosing targeting the glioma. Mice with HSCs transduced with P140K MGMT were enriched after BG/temozolomide therapy and were protected after chemotherapy. They were able to visualize these transduced cells in mice in vivo and found that they form long term, persistent foci, indicating specific localization. These mouse studies led to clinical trial studies with a clinical grade EF1-α promoter lentivirus. Patients were transplanted with transduced bone marrow and treated with dose-escalating temozolomide. Early results have shown increased life expectancy in two patients and ongoing studies are being performed to determine viral insertion sites and long term safety.
Dr. Harman discusses the fact that although we frequently use mouse models to study human disease states, there are many additional animal models that naturally develop diseases similar to the human form. Additionally a limitation of pre-clinical work is often the ability of the results to translate to a clinical setting. Dr. Harman believes that cell based therapies can be used to treat these animals with the findings essential for determining safety and efficacy in humans. He described studies in which dogs with medial shoulder instability were transplanted intra-articularly with adipose derived MSCs and 90 days post-treatment saw marked improvement in shoulder function and recovery. Additionally a large study involving horses with suspensory ligament desmitis were also transplanted with adipose derived MSCs and 86% of these horses returned to their prior activity levels within one year of transplant. Dr. Harman described MSC use in several other animal studies including osteoarthritis in dogs, spinal cord injury in dogs, tendinitis in horses, chronic kidney disease in cats, and tissue injury in dolphins injured during wartime. Additionally the adverse effects in almost all cases was less than 0.01%, with the effects limited to local inflammation at the injection site. As described in his recent publication, the results from these studies will benefit not only the animals with these diseases but will be used to support the safety of these therapies in human patients.
Dr. Bonfield's group studies the ability of bone marrow and MSCs to target the pulmonary component of cystic fibrosis (CF). She first described the use of bone marrow transplantation in lethally irradiated WT or CFTRnull (a mouse model of CF) mice following p. aeruginosa infection. She found that while CF bone marrow transplanted into CF mice resulted in a 0% survival rate, WT bone marrow transplanted into a CF mouse improved this survival rate to 54%. These mice were found to have decreased neutrophils compared to the other transplant groups, thus this work suggests that bone marrow transplantation may improve CF symptoms via suppression of a hyperactive immune response. Dr. Bonfield also studied the potential therapeutic effect of MSCs in CF. As MSCs have been shown to release bioactive factors to decrease inflammation, she assessed whether MSCs would attenuate the hyper inflammation and lung destruction in CF. She found that MSC therapy in CF mice resulted in improved weight gain, decreased gross lung pathology, and decreased recruitment of alveolar macrophages. She also observed decreased production of the inflammatory mediators IL6, IL8, and TNF, and this surprisingly resulted in a decreased bacterial load as well. Animals treated with MSCs demonstrated a significantly improved prognosis compared to control animals. This work suggests that bone marrow cells and MSCs may attenuate CF mortality via anti-inflammatory and anti-microbial effects.
Katarina LeBlanc spoke about the immunological properties of MSC in clinical settings. The clinical trial, assessing allogeneic MSCs in steroid-resistant Graft-Versus-Host-Disease (GvHD) is currently ongoing and GvHD patients who received MSCs showed normalization of CD4/CD8 T-cells ratio 2 months after transplant, elevation of regulatory T-cells, increase of myeloid derived suppressor cells, reduction of pro-inflammatory Th17 cells and general skewing of pro-inflammatory to anti-inflammatory. The patients subdivided to responders and non-responders. She also gave more insight to phenomenon of instant blood mediated inflammatory reaction (IBMIR), which was described by her group earlier. IBMIR is a form of acute innate immune attack, which leads to activation of complement and coagulation systems. Among 64 infusions, there were no severe IBMIR, but its degree directly correlated with MSC passage number and cell dose. For the first time she noted that stronger IBMIR was caused by placental MSCs and fibroblasts compared to bone marrow-derived MSCs. Importantly, she noted that even though, ABO matching is not necessary, you can load MSCs with ABO antigens by mixing them with AB plasma. So, she recommended washing cells with PBS + human serum albumin 10% before infusion.
Antonello Pileggi (University of Miami): "Mesenchymal Stem Cells in Solid Organ Transplantation: Results of the First Clinical Trials"
Antonello Pileggi gave an overview of clinical trials, assessing immunomodulatory properties of MSCs in solid organ transplantation. He noted, that there are 9 ongoing clinical trials registered in NCT database. Most trials are exploring allogeneic MSC in living kidney transplantation and that the first published results are encouraging.
Dr. Dennis's laboratory identified a link between MSCs, complement and osteoporosis. His research shows that bone balance could be affected by complement activity via MSCs and pre-osteoclasts. MSCs were shown to express the key components for complement signaling via the alternative pathway, and MSCs also expressed key complement receptors to the complement signaling molecules C3a and C5a. In vitro studies showed that, in MSC-dependent osteoclast formation assays, MSCs derived from complement C3 knockout (C3 KO) mice and complement receptor knockout mice showed decreased osteoclast formation compared to MSCs from wild-type mice. Dr. Dennis presented in vivo results on ovariectomized wild-type and C3 KO mice that showed that C3 KO mice were partially protected from bone loss, as shown by microCT analysis at 6 weeks post-ovariectomy. These in vivo results validated his earlier in vitro results and indicated that diminished complement signaling partially protected mice from estrogen-deficient bone loss. The long-term goal is to develop therapeutics for post-menopausal bone loss by targeting the complement pathway.
Raphael Gorodetsky (Hadassah Hebrew): "Indirect therapeutic effect of placental stromal cells as demonstrated by migration of acute radiation syndrome and enhancement of bone marrow regeneration"
Raphael Gorodetsky reported experimental data for assessing placenta-derived MSC (commercialized by Pluristem as PLX) in acute radiation syndrome (ARS). He mentioned that PLX cells have very limited tri-lineage differentiation potential, but very powerful producers of cytokines and paracrine factors. In the model of ARS, addition of PLX increased the survival of experimental mice to 91% as compared to 21% in controls (without PLX). One of the complications of PLX infusion was a severe "lung entrapment" and some animals deteriorated from treatment. To overcome this problem, they decided to perform intramuscular injections of PLX and saw the same therapeutic effects. Intramuscular administration of PLX in ARS animals rescued bone marrow cellularity and peripheral blood cell count. He indicated that the mechanism of paracrine action was explained by significant production of IL-6, G-CSF and GM-CSF in a critical period (2-14 days) post irradiation. Interestingly, PLX produced those cytokines only in ARS, but not intact animals. He also indicated that in experimental ARS, conventional MSCs have significantly decreased efficacy compared to PLX cells.
Dr. Tarantal and her colleagues utilize the monkey model for its high relevance in the study of human health and disease, and to conduct preclinical studies in support of new clinical trials. Rhesus monkeys have similar developmental features when compared to humans including anatomy, physiology, immunology, and developmental ontogeny. One series of investigations focuses on obstructive renal disease. Here, studies have focused on pathogenesis, novel ways to investigator renal precursors and progenitors, and the use of tissue engineering to rebuild kidneys damaged by disease. Several projects also focus on techniques to effectively label and track transplanted human stem and progenitor cells in the monkey (e.g., umbilical cord blood CD34+ cells, peripheral blood stem cells, differentiated human embryonic stem cells) and using bioluminescence imaging and positron emission tomography (PET) to monitor engraftment, cell fate, and long-term gene expression. The NHLBI Center for Fetal Monkey Gene Transfer for Heart, Lung, and Blood Diseases was also highlighted, with examples given of translational studies performed. Investigators funded by the NHLBI were encouraged to submit a letter of intent if they are interested in conducting a pilot study in the monkey model.
Boro Dropulic (Lentigen): "Lentiviral vector mediated genetic modification of cells for cellular therapy"
Dr. Dropulic initially provided a historical account of the development and use of lentiviral vectors. The first lentiviral vector was described in 1991 and the first functional vector was produced in 1996. Lentiviruses provide an advantage over retroviral vectors due to the ability to infect both dividing and non-dividing cells. Also because retroviral vectors have demonstrated stem cell toxicity, the shift towards lentiviral therapy has occurred. There are currently over 60 clinical trials running using lentiviral vectors. In addition to other cell types, he proposes that MSC transduction with lentiviruses could serve such functions as to promote lineage specific differentiation, produce payload genes to be delivered at diseases site, and have significant effects in many disease and injury models. Dr. Dropulic believes that the last 10 years of clinical trial success using lentiviruses points to a future in which this therapy is a prominent clinical option due to the relative safety compared to drug development and the multi-faceted approach that they can be used for. There are undeniable challenges that must be overcome with this therapy including designing the safest vectors, determining the proper route of delivery and dosing regimen, and knowing how to commercially scale-up and manufacture large stores of virus. If these obstacles can be overcome, then lentiviral gene therapy may be a viable therapy in the near future.
Dr. Nolta expressed her interest in MSCs as a powerful cell therapy because MSCs interact with all cell types and transfer organelles, cytokines, mitochondria, RNA, and other membrane bound molecules through exosomes. She presented Dr. John Laird's critical limb ischemia clinical trial where the goal was to use MSCs to improve circulation in diseases such as diabetes where severe ischemia leads to limb amputation. In vivo imaging models have shown that injection of marrow stem cells at the site of injury results in rapid homing and localization of the cells to the sites of ischemia (within 48 hours) leading to increases in blood flow by altering the blood vessels and increasing vascular density. This was shown to be specific to stem cells and not more mature progenitor cells. Additionally the group engineered MSCs to produce VEGF which, when transplanted, resulted in dramatic increases in blood flow and significant repair of the damaged limb. The safety of this method has been shown as the VEGF production did not lead to tumor or hemangioma formation and the MSCs were found to remain localized in the ischemic niche for extended amounts of time. She then presented a clinical trial with Dr. Vicki Wheelock using MSC therapy in Huntington's disease. While there is currently no cure for Huntington's disease (HD), MSCs have shown progress in its treatment. Even non-engineered cells injected in the brains of mice have resulted in increased activity in the striatum and decreased movement disorders. Gene therapy in MSCs has produced cells secreting brain derived neurotrophic factor (BDNF) which when injected in the murine brain results in decreased overall symptoms and improved motor function. Imaging these cells has shown that they remain localized in the brain and persist at low levels long term. Overall Dr. Nolta's work has shown that the innate properties of MSCs make them very powerful tools for multiple disease models.
Khalid Shah (Massachusetts General Hospital): "Therapeutic stem cells for cancer: Clinical translation in sight"
Dr. Shah's group is developing novel MSC and neuronal stem cell (NSC) therapies as vehicles for anti-cancer therapy for the treatment of brain tumors (pathotropism). The goal of his work is to develop therapies that will specifically target brain tumor cells and prevent the proliferation of the bulk tumor and target the reliance on angiogenesis in later stage tumors. Because NSCs and MSCs injected in mouse model brains specifically migrate to tumor sites, these cells can be engineered to deliver payloads like TRAIL to induce cancer-specific apoptosis that will kill cancer cells. Studies have shown that not all cells are TRAIL sensitive and in fact approximately 50% of all tumor cells are resistant potentially due to the lack of the death domain in these cells or upregulation of anti-apoptotic genes such as BCL-2. In order to overcome this resistance, MSCs may need to be packaged with additional TRAIL sensitizers in order to fully optimize TRAIL apoptosis. Dr. Shah showed that multiple sensitizers such as silencing Bcl-2, cotreating with temozolomide, or co-treating with the HDAC inhibitor MS-275 results in glioma sensitivity to TRAIL in part by inducing expression of the intracellular death domain. They have engineered MSCs that can secrete EGFR nanobodies along with TRAIL and have demonstrated significant tumor sensitization with these combination therapies. They have also noted that surgical resection of tumors results in the remaining resected tumor behaving differently than the bulk tumor. To prevent washout of MSCs from the resection cavity, the group has combined MSCs secreting TRAIL as well as NSCs and mixed them with Hystem C gel in order to keep the cells localized to the cavity and induce apoptosis in the remaining tumor.
Johnny Huard (University of Pittsburgh): "Exhaustion of muscle progenitor cells during disease and aging: Implications for stem cell therapy"
Dr. Huard spoke on his laboratory's work utilizing skeletal muscle derived stem cells (MDSCs) in both mouse models of accelerated aging of progeria and Duchenne's muscular dystrophy (DMD). MDSCs derived from ERCC1-XPF or Zmpste24 knockout mice showed decreased proliferation and differentiation, suggesting that in these models, the exhaustion of muscle progenitor cells has decreased ability to repair musculoskeletal tissues such as skeletal muscle and bone damage. When wild-type MDSCs were injected IP into ERCC mice, they increased the lifespan of these animals dramatically, from approximately 20 days to 70 days, suggesting that decreased stem cell function may contribute to the pathology and that stem cells may be a potential treatment option in the future: neither PBS nor fibroblasts had this life lengthening effect. They suggested that the rescue mechanism includes the ability of MDSC to increase angiogenesis via paracrine factors. Additionally, Dr. Huard described work with dystrophin and utrophin double knockout mice (dKO) which show a phenotype similar to patients with DMD. These mice show similar, severe histopathological signs to DMD and a decrease in stem cell proliferation, differentiation, and resistance to stress, suggesting that dKO mice model suffer from a premature musculoskeletal aging. Parabiotic pairing of dKO mice with young wild type-mice demonstrated an improvement in the histopathological features in dKO mice with an improvement of skeletal muscle and bone healing. The circulating factor(s) responsible for the beneficial effects observed in the dKO mice after parabiotic pairing with young wild type mice is still unclear and remains under investigation.
Frank Barry (National University of Ireland): "Mesenchymal stem cell therapy: host response and mechanism"
Dr. Barry's presentation described his laboratory's work to translate MSC therapy by (1) the development of new cell-specific markers for MSC, (2) understanding the therapeutic mechanism of action and understanding the paracrine signals contributing to tissue repair, (3) understanding clonal heterogeneity in cultured cell populations, (4) controlling batch variability following expansion, and (5) understanding the mechanisms of the host immunomodulation response to transplanted MSC. In vivo studies in mice demonstrated that MSCs home specifically to an injury site and that their effects are limited to secretion of soluble factors rather than contributing directly to new tissue formation. Mechanisms of MSC recruitment involve chemotactic factors such as MCP-1 and CINC-3 which activate cell migratory responses via ROCK/Rho signaling pathways. MSCs increase the survival of cardiomyocytes under hypoxic conditions by secretion of SPARCL1, which increases expression of the anti-apoptotic gene, bcl-2. Dr. Barry also presented work on derivation of iPS cells from patients suffering from familial osteochondritis dissecans (a cartilage defect), which when differentiated into MSCs and then to chondrocytes, demonstrated an inability to secrete aggrecan. This suggests that this may contribute to the pathology seen in this disease. Dr. Barry suggested the potential to use genetically altered autologous iPS cells as a cartilage repair therapy for familial osteochondritis dissecans.
Mick Perez-Cruet (Beaumont Health System): "Stem cell based intervertebral disc regeneration: a possible treatment for debilitating spinal disorders"
Dr. Perez-Cruet discussed designing new technologies for minimally invasive treatment of intervertebral degenerative disc disorder using stem cell based technologies. The outstanding question asked was "Can a non-biological prosthesis (i.e., current fusion and pedicle screw based instrumentation) device be replaced with stem cell based technology to reverse disc degeneration and restore the intervertebral disc to its natural function?" The Bonebac TLIF System is a minimally invasive method for delivery of surgical site autologous bone graft enriched with autologous MSC to enhance intervertebral fusion while reducing surrounding muscle and tissue damage. His initial clinical results have shown this method to be highly effective in treating a variety of degenerative pathologies (i.e., spondylolisthesis and degenerative disc disease). Dr. Perez-Cruet proposed the use of autologous MSC to repair degenerated intervertebral discs. Using an in vivo rabbit model of degenerated disc disease, he injected chondroprogenitor MSCs and found evidence of intervertebral disc regeneration. Dr. Perez-Cruet noted the need for a mechanical device that would help restore disc and foraminal height as well as spinal canal diameter. Towards this goal, Dr. Perez-Cruet presented his proprietary technology called AnnuloTM. Annulo is a device that provides a gradual distractive force to the disc space via a pedicle screw based system. Once the disc space height is restored MSC differentiated along a chrondroprogenitor derived stem cell (new disc) line can be injected into the disc space to restore the intervertebral disc architecture and function. Currently, the Annulo concept is in development and will require clinical testing to validate. Dr. Perez-Cruet encouraged a collaborative effort to see the Annulo concept come to clinical fruition.
Steven Elliman (Orbsen Therapeutics): "The stromal cell marker CD362 enables prospective isolation of defined MSC from human tissues for therapeutic application"
Dr. Elliman presented his company's work on utilizing CD362 as a functional marker of MSC for isolation by flow cytometry. They found that this marker is expressed on MSCs in many tissues derived from a number of species including human, mouse and horse, although it is not found on MSCs from goat or pig. In comparison to MSC isolation by adhesion to tissue culture plastic, isolating MSCs using CD362+ CD271+ selection enhanced the CFU capacity. CD362+ CD271+ expression enable bone marrow selection. Isolated mouse CD362+ Sca+ cells, decrease lymphocyte proliferation. In a ventilation-induced lung injury model, the effects of PBS, fibroblasts, PA-MSC, and MSC CD362+ cells were compared. Treatment with MSC isolated by CD362 expression showed decreases in CD4+ mononuclear cell proliferation in vitro, decreased inflammation, and decreased neutrophil infiltration following ventilation-induced lung injury in vivo. This latter observation suggests the potential development of a MSC batch potency assay using an ELISA for CD362 expression.
Pawan Gupta (Stempeutics Research): "Role of allogeneic bone marrow derived mesenchymal stromal cells (Stempeucel) in osteoarthritis of knee joint – results of randomized, double blind, multicentric, placebo-controlled, dose finding, phase II study"
Dr. Gupta from Stempeutics Research presented the results of a phase II clinical trial for intra-articular injection of allogeneic bone marrow MSC into patients with osteoarthritis. Patients with grade 2-3 osteoarthritis were injected with between 25 and 150 million BM MSCs in a dose finding, multicenter trial. Adverse effects included localized pain and swelling. At the one year follow up, patients treated with low doses (25 million) of BM MSC reported decreased pain scores while there was no improvement seen with higher doses. Increased cartilage thickness (assessed by MRI) was seen at the 6 month follow up in all but the highest dose. These results suggest that BM MSC are safe and may be effective at low doses, however, it is currently unknown whether the quality of cartilage is actually improved.
Dr. Rocky Tuan (University of Pittsburgh): "Adult Stem Cells and Scaffolds for Cartilage Tissue Engineering: Technologies and Models"
The loss of cartilage and osteoarthritis represent clinical challenges for an aging quality of life especially with the intrinsically low capacity of cartilage for repair and regeneration. MSCs might provide a reservoir of therapeutic cells but a successful cell therapy must stimulate the appropriate differentiation potential of cell infusions. For success, the correct combination of scaffolding, cells, and biofactors (biological signals) must be combined. Dr. Tuan discussed a study showing that, 6 months post-treatment with MSC seeded onto polycaprolactone (PCL) nanofiber scaffolds (a FDA approved restorable biomaterial) in a bioreactor, healing of an articular cartilage defect in pigs was significantly improved over controls. This model is limited in its clinical applicability since the animal's cartilage was healthy rather than diseased as is seen in the clinical setting. Therefore, Dr. Tuan's laboratory developed an impacting device that causes injuries similar to those that cause post-traumatic osteoarthritis. Ongoing, in vivo, studies in a rabbit model suggest that treatment of cartilage after a well controlled (defined load and timing) impact injury with nanofiber scaffolds seeded with MSCs can improve healing. Dr. Tuan's group identified nanoscale biomimicking scaffolds plus MSCs which stimulate the production of collagen disks. Electrospun polymers produce collagen-like structures similar to the osteochondral junction and MSCs seeded onto these disks and incubated in a circulating bioreactor produce type II collagen in pig and rabbit animal models of osteoarthritis. Dr. Tuan's laboratory is also utilizing visible rather than UV light crosslinkable hydrogels in 3D stereolithography printing that reduce cell death during gelation and could potentially allow for arthroscopic application of the cell-seeded poly PEG diacrylate to minimize treatment invasiveness. These preparations were used to repair a critical defect and in situ generation allows for space filling of an immobilized mixture with live cells.
Antonios Mikos (Rice University): "Mesenchymal Stem Cell Co-Cultures for Tissue Engineering Applications"
Dr. Mikos discussed his laboratory's results on the optimization of techniques for co-culturing MSCs and articular chondrocytes (ACs) on polycaprolactone (PCL) microfiber scaffolds to improve the development of engineered cartilage constructs. These polymer/extracellular matrix hybrid scaffolds contain chondrogenic differentiation bioactive signaling molecules. They hypothesized that co-cultures of MSCs with differentiated chondrocytes (1:1 ratio) within an electrospun fibrous poly (ε-caprolactone) (PCL) scaffold would be able to produce a similar extracellular matrix as observed in PCL scaffolds seeded with chondrocytes alone. Co-culture improved MSC differentiation and tissue formation and the effects of the chondrocytes were found to be due to a paracrine effect rather than by direct MSC-AC contact. Further they sought to determine if acellular PCL/ECM material generated through co-culture of MSCs and chondrocytes induced chondrogenic differentiation. They show that an acellularized 1:1 co-culture generated PCL/ECM was more capable of directing chondrogenic change in MSC than the MSC monoculture generated PCL/ECM as assessed by aggrecan, collagen I, and collagen II expression. Dr. Mikos concluded chondrocyte/MSC co-culture produced PCL/ECM material with properties likely suitable for generating replacement cartilage. The suggestions for use of this material for future applications was that these could be used off-the-shelf and reseeded with patient-derived MSCs to increase the rate and quality of tissue formation while avoiding an immune response.
Eben Alsberg (CWRU): "Biomaterial systems with controlled temporal and spatial signal presentation for regulating stem cell behavior and tissue engineering"
Dr. Alsberg presented a well-established technology in which human MSCs are cultured in vitro in high-density and treated repeatedly with media containing chondrogenic growth factor, chondrogenic differentiation and neocartilage formation is induced. This culture system, however, requires repeated growth factor supplementation and results in a non-uniform spatial delivery of the soluble signal through the bulk of the cell mass due to diffusional limitations. In addition, extended in vitro culture of the cell mass is required prior to potential utilization in in vivo regeneration strategies. To address these shortcomings, Dr. Alsberg described novel engineered systems of biopolymer microspheres incorporated within high-density hMSC masses that guide chondrogenic differentiation and cartilage formation through the controlled temporal and spatial delivery of growth factors. The rate and extent of chondrogenesis in vitro was regulated by the amount of growth factor used, the release profile of the growth factor and its distribution within the high cell density systems. Preliminary results indicate that these engineered constructs may have great clinical utility for the repair of cartilage defects as demonstrated using a rabbit osteochondral defect model.
Camila Favero de Oliveira (Butantan Institute in Sao Paulo, Brazil): "Preliminary clinical cases report: application of immature dental pulp cells in order to treat local bone defects with subsequent placement of the implant"
Dr. Oliveira presented two case reports where stem cells (1 x 106/0.5 ml) isolated from the deciduous teeth of the patient's grandchildren were combined with a polymer carrier and implanted in a sinus lift (oral defect) procedure. The rate and amount of bone formation was higher when dental pulp stem cells were utilized in comparison to the carrier alone and newly formed bone was found to be mature and well-vascularized. Furthermore, there were no complications found in these cases suggesting that utilization of dental pulp stem cells may be a new, safe, and effective cell source to enhance bone formation in dental applications.
Jacques Galipeau (Emory University): "Mechanistic Analysis of human Mesenchymal Stromal cells as Veto Cells in Clinical Applications"
Dr. Galipeau highlighted a few important considerations for translating MSCs in clinical trials. First, potency assays for MSC-based therapies should be developed. He said that commonly used tri-lineage potential assay cannot predict immunomodulatory function of MSCs. Immunosuppressive properties of MSCs are deployed by interferon-gamma formation and response to this cytokine can vary from donor to donor. His research demonstrated that new marker - IDO1 could be a good single predictor of immunomodulatory potency of MSCs. A second consideration is immunogenicity of MSCs. Dr. Galipeau discussed that presenting MSCs as an immunoprivileged cell population is a misconception. MSCs express MHC class 1 and also express MHC class 2 upon stimulation by interferon-gamma. Repeated infusions of allogeneic MSCs demonstrate a classical pattern of alloimmunization leading to rapid cell clearance upon rejection. The third consideration is cryopreservation. His data indicates that 25% of cryopreserved MSCs after thawing are apoptotic and the remaining 75% are "not metabolically fit." When thawed human MSCs were infused in mice, unlike fresh MSCs, no signal (human DNA) was detected in any organ. He showed that freezing severely affects cell migration and engraftment and his latest data shows that freezing is disrupting MSC actin cytoskeleton. Dr. Galipeau proposes to use fresh MSCs or "resuscitated" (in culture for a day) cryopreserved MSCs.
Dr. Sensebe discussed how we can control MSC culture and processing for clinical use. He said that if you change a process of MSC manufacturing, you can change cells completely even if the cells are derived from the same tissue source. He believes you should adapt your process to the target you want to treat. He discussed two most important variables in long-term MSC expansion - potential transformation and senescence. While there is no demonstration of malignant transformation of human MSCs in culture so far, senescence could be a real problem. He thinks that MSCs senescence is hugely underestimated, but it will affect therapeutic potency ("old cells never work!"). He also suggested that passage number, which is commonly used, was not the best way to denote MSC culture age. Rather, one should consider cell doublings as a better indicator of age. Dr. Sensebe is a coordinator of the European Consortium CASCADE, which aims to standardize GMP-grade production of MSC for clinical use. Some positions of the Consortium for assessment of MSC spontaneous transformation were recently published. Based on this position paper, Sensebe recommended to avoid a igh proliferative state (have low number of population doublings), to assess transformation by different sensitive methodologies, to assess senescence in culture, and to cryopreserve multiple samples for future tests. He discussed that European experts are coordinating efforts and trying to provide recommendations and standardize GMP-grade manufacturing of MSCs via such projects as Consortium CASCADE, STROMALab and ReBorne.
Dr. deLima presented results of Phase 1 clinical trial (done in MD Anderson Cancer Center), which assessed ex vivo expansion of cord blood in hematological malignancies. Dr. deLima discussed how they progressed from different methodologies of expansion to using MSC as an artificial niche for cord blood hematopoietic cells. Dr. deLima indicated that using off-the-shelf allogeneic MSCs for co-culture was a key success factor in cell product preparation allowing for a 30-fold expansion of CD34+ cord blood cells and logistically feasible compared to MSCs derived from related partially-matched donors. Recipients of double cord blood transplants in which one of the units was ex vivo expanded, neutrophils engrafted significantly faster than historic controls (at a medium of 15 days which is similar to the medium time observed after peripheral blood stem cell transplants). Also, platelet engraftment occurred more rapidly when compared to controls. The concept of MSC-based ex vivo cord blood expansion is now under investigation in an international, randomized clinical trial comparing double cord blood transplants (unmanipulated) versus double cord blood transplants in which one unit is expanded using the MSC platform.
Joshua Hare (University of Miami): "Cell Therapy for Chronic Ischemic Heart Disease from Concept to Clinic"
Dr. Hare presented studies on the effectiveness of MSC therapy in advanced ischemic cardiomyopathy, the POSEIDON clinical trial. The study aimed to determine whether MSCs could safely promote improved repair of cardiac structure with the additional caveat of comparing allogeneic vs. autologous bone marrow derived MSCs. Fifteen patients were treated with allogeneic MSCs and an additional 15 treated with autologous MSCs. Initial safety studies showed that only a single patient had a donor alloantibody reaction. The group proposed that the mechanism of cardiac regeneration would be the antifibrotic and pro-neoangiogenic via paracrine effects. While patients demonstrated no difference in left ventricular ejection fraction 13 months post MSC injection, they did show decreased cardiac scarring and improved left ventricular geometry. Decreased spherical density was observed as well as reduced systolic and diastolic volumes. Dr. Hare cautions that the lack of change in ejection fraction is not the only indication of improved function because all other indications suggest that both allogeneic and autologous MSC injections are beneficial for these patients. His data suggests that the mechanism of this improvement is due to proliferation of host cardiac stem cells localized to the injection site and that paracrine factors released from the MSCs also have effects on scarring at sites distal to the injection. They also observed that the vast majority of MSCs did not differentiate upon transplantation but remained localized 3 months post transplant. Thus, Dr. Hare believes that both the primary and secondary effects of MSCs have the ability to restore cardiac function in ischemic heart disease and other cardiac diseases.
Dr. Penn and Juventas Therapeutics are working on using MSC therapies to improve recovery after myocardial infarction (MI). He stated that stem cell based recovery is a natural process that can be exploited but that it is not efficient therapeutically because of short term signaling. In particular he focused on the chemokine, SDF1, and its receptor CXCR4. Binding of SDF1 has been shown in many models to promote stem cell homing to the niche, prevent apoptosis, and induce proliferation of endogenous stem cells. SDF1 activation occurs shortly after MI while CXCR4 expression does not become induced until 48 hours post MIat a point when SDF-1 levels have already peaked and may be declining. They hypothesized that aligning the expression of SDF1/CXCR4 would improve repair and block infarction expansion. The hypothesis was initially tested with MSCs capable of secreting SDF1 in mouse models and found that MSC injection resulted in improved vascular function. This observation led to the development of multiple SDF1 plasmid vectors aimed at increasing long term levels of SDF1. JVS-100, a non-viral DNA plasmid containing the SDF1 gene, provides robust SDF1 levels for up to 21 days. JVS-100 was tested in a heart failure porcine model and subsequently in human patients with class III heart failure. They found that the patient's quality of life improved at 12 months post treatment and that more than 50% of patients improved at least 1 stage of heart failure at the 12 month time point. Although SDF1 levels remained for only 21 days, the long term paracrine effects contribute to the long term efficacy.
Daniel Weiss (University of Vermont): "Cell therapy trials in pulmonary diseases and critical illnesses"
Dr. Weiss explained that lung diseases are increasing worldwide and most such as COPD and cystic fibrosis have no cure. While a major goal of cell therapy for these diseases would be to restore the damaged lung to improve overall function, the available data to date does not support a role of any type of stem cell in replacing or repairing damaged lung tissues in situ. Ex vivo lung bioengineering is a rapidly developing area but even this is particularly challenging as the lung is a complex organ composed of over 40 different cell types. hESCs and iPS cells have not been successful in generating functional lungs and endogenous lung progenitor cells. As such, a major focus is on cell based therapies in which the anti-inflammatory effect of MSCs would yield success in acute highly inflammatory diseases and potentially in chronic inflammatory diseases as well. The mechanism of action of repair is proposed to be via secretion of anti-inflammatory paracrine mediators and antibacterial peptides, and through cell-cell contacts and interactions between MSCs and damaged tissue. In a clinical trial supported by Osiris therapeutics for patients with COPD, 65 patients were given 4 infusions of 100 million cells over 4 months and safety and efficacy were monitored. While there were no signs of pulmonary embolism or other adverse effects of infusion, there was also no change in lung function and continued respiratory failure was observed. Thus, the trial demonstrated that the therapy is safe but its effectiveness is questionable. This reiterates the question that the type of pulmonary disease in which MSCs might best be expected to have beneficial effect needs to be clarified. Dr. Weiss proposed that diseases of acute inflammation such as the acute respiratory distress syndrome, or a chronic inflammatory disease such as severe asthma may be more likely areas of success. Chronic fibrotic diseases like idiopathic pulmonary fibrosis are less likely to respond well to current MSC-based cell therapies.
Jonathan Sackner Bernstein (NeoStem): "CD34 Stem Cells: Biology's Blueprint for Optimized Interventional Cardiology"
Dr. Bernstein and NeoStem are interested in the use of CD34+ cells for interventional cardiology. In particular they are working on treating ST elevation myocardial infarction (STEMI) which is a disease that has not seen a decrease in mortality in the last 30 years. He stated that cardiac natural repair mechanisms are not activated after acute myocardial infarction and thus hypothesized that injection of bone marrow derived CD34+/CXCR4+ cells would improve perfusion and ventricular function. They found that these cells localized to the areas of damage after injection and that they greatly increased angiogenic function, potentially due to release of exosomes from these cells. These injections reduced volumes of ischemic tissues, increased ventricular function, and decreased the infarction size. Use of their CD34+ product AMR-001 resulted in favorable clinical outcomes after autologous transplant and thus Dr. Bernstein believes that CD34+ cells provide perfusion where needed, preserve ventricular function, and are a very promising therapy for a variety of cardiac diseases.
John P.S. (St. Thomas Hospital) "Bio modulation of autologous bone marrow transplant – a breakthrough in the treatment of spinal cord injury"
Dr. John presented his clinical research on autologous bone marrow transplant (AMBT) with stimulation of endogenous production of neurotransmitters as a new treatment strategy. Twenty patients with American Spinal Injury Association (ASIA) A or B traumatic paraplegics and tetraplegics of more than five years duration were grouped into two groups. Group A had multicyclic ABMT through lumbar puncture and Group B had multicyclic ABMT with stimulation of endogenous neurotransmitters using Citicholine and B6 in patient specific doses. At the end of 36 months, 3 patients in Group B started walking without support, 4 started standing without support, and the remainder had at least one grade of improvement. In Group A, one grade of improvement was noticed in 2 patients. The fractional anisotropy value in diffusion tensor magnetic resonance imaging showed significant improvement in Group B. There was improvement in bladder capacity in 3 patients, reinnervation changes in EMG in one patient and significant changes in somatosensory evoked potentials (SSEP) in one patient in group B.
Dr. LeBlanc presented results of a clinical study where engraftment of allogeneic MSCs for patients with GvHD was assessed on autopsy material. In general, engraftment of donor MSCs was extremely low and they were not able to detect donor MSC engraftment at sites of injury (for example, intestine affected by GvHD). There was no correlation between donor MSC engraftment, HLA-matching and clinical response. Her group is trying to understand the reasons for non-responsiveness. Dr. LeBlanc also said that in her institution two more trials have been initiated recently - first assessing MSCs in type 1 diabetes and the second for local injections in Phoniatrics, a voice disorder. In the diabetes trial, preliminary results showed a slight recovery in insulin response after injection of autologous MSCs. In the Phoniatrics trial, they observed very encouraging results in 4 out of 5 patients.
Elmar Burchardt (Pfizer): "Pfizer's Clinical Development Program for MultiStem in Inflammatory Bowel Disease"
Dr. Burchardt described the clinical trial design to assess MultiStem (manufactured by Athersys) in inflammatory bowel disease (IBD). The trial started in 2011 and is currently ongoing in US, Canada and 7 European countries. The Phase 2 trial is a dose escalation trial that will enroll 128 patients. He shared the challenging environment for big Pharma companies to assess the potential of cell therapy products because of differences in characterization and manufacturing, mechanism of action, pharmacokinetics/ pharmacodynamics, and logistics as compared to drugs. Pfizer assumed risk but choose to work with Athersys based on its clinical data for using MultiStem in GvHD. The proposed mechanism of action in IBD is immunomodulation. Dr. Burchardt was not able to share clinical data until official release in 2014.
Dr. Cominelli is starting a clinical trial using placenta-derived allogeneic MSC (manufactured by Celgene) for IBD patients. He discussed preclinical assessments including the mechanisms of action involving inhibition of T-cell activation, inhibition of pro-inflammatory cytokines, stimulation of anti-inflammatory cytokines, increase in the number and function of regulatory T-cells, and epithelial cell restitution.
Dr. Cohen explained that multiple sclerosis is the most common non-traumatic cause of neurologic disability in young adults. Potential therapeutic goals of MSC transplantation in MS include reduced CNS inflammation, neuroprotection, or remyelination/neuronal repair. A sizable number of human clinical trials support the safety and potential efficacy of MSC transplantation to treat divergent conditions, but the published experience in treating multiple sclerosis and other immune-related disorders is limited. Dr. Cohen described an ongoing, open-label Phase 1 safety and feasibility study of autologous MSC involving 24 participants with relapsing forms of MS (approximately equal numbers with relapsing-remitting and secondary progressive/ progressive relapsing MS) and evidence of involvement of the anterior afferent visual system. All 24 participants have been enrolled and 19 have completed follow-up. No significant safety issues have occurred, including no evidence of paradoxical disease activation. Analyses of exploratory efficacy endpoints and mechanistic studies are ongoing. Dr. Cohen described plans for a subsequent Phase 2 study and addressed issues related to cell product (e.g., use of a xeno-free defined medium, fresh versus cryopreserved cells, and autologous vs. MSCs from a non-MS donor), study design, and potential efficacy endpoints.
Charles Cox (University of Texas): "Clinical trials and tribulations using cell therapy for neurological injury"
Dr. Cox discussed their use of bone marrow derived cells in traumatic brain injury (TBI) focusing on "clinical trials and tribulations." There are few clinical trials for TBI because of two broad issues and substantial barriers for entry (1) infrastructure/operations problems - rapid presentation of patients, patient volume, a screening ratio of 100:1, follow-up issues for repeat testing, outcome testing (treatment of adults versus pediatrics, language, and insurance), and competing clinical trials; and (2) regulatory burden - access to a 24/7 operating cGMP facility and expense (cost of approximately $600,000/year), complications with the intellectual property, unanticipated costs, and funding. Dr. Cox compared the "clean" IP associated with using Athersys' MultiStem to the "tangled" IP for MSCs and multiple industry partners as a key issue limitation to conducting clinical trials. Dr. Cox explained that current rodent animal models for TBI involve a controlled cortical impact do not have significant relevance to the human injury because over 20 neuroprotective trials based on this pre-clinical model have failed. Nonetheless, BM-derived MSC and Athersys' multipotent adult progenitor cells (MAPC) have been shown to improve behavior activity, increase the apoptosis of activated microglia within the hippocampus, improve memory (water maze), and is associated with injury repair on the injury side of brain with white matter tract integration. Dr. Cox suggested several pathways forward to resolving issues with conducting clinical trials in the TBI space: requirement for a diverse funding portfolio for support, specific center investments in infrastructure and staffing requirements, seeking regulatory harmonization of reporting forms, and third party payers covering any clinical trial costs completed under IND exempt biologics or cells.
Dr. Windebank evaluated the clinical effect of adipose-derived MSC to treat amyotrophic lateral sclerosis (Lou Gehrig's disease or ALS), a fatal neurodegenerative disease that involves the loss of voluntary motor nerve cells in two studies, a safety study and a dose-escalation study. Despite super oxide dismutase and motor neuron disease animal models for ALS, none of the treatments effective in mice have translated to humans. Several explanations for these observations have been advanced: available ALS animal models do not mimic accurately human ALS, conducted clinical trials have not been sensitive in their analytical measurements, therapeutics factors do not reach the target neurons in the central nervous system, and growth factors do not cross the blood brain barrier. He proposed to evaluate the use of adipose-derived MSCs administered in the subarachnoid space by lumbar puncture to deliver neuroprotective factors to the brain. To date, no adverse effects have been observed. From this experience, Dr. Windebank is working with BrainStorm Cell Therapeutics on their Phase 2 trial, assessing NurOwn (bone marrow-derived autologous MSC) to treat 48 ALS patients. This trial would incorporate the use of growth factor enhanced bone marrow to produce neurotrophic factors. Another study being proposed would take patient-derived MSCs and genetically alter them to endogenously synthesize neurotrophic factors. BM MSCs from ALS patients are not different functionally from controls suggesting the absence of an endogenous lesion in patient-derived cells.
Dr. Mays defined Athersys' MultiStem product as an off the shelf product, devoid of tissue matching requirements or immunosuppression, and demonstrates the ability to enhance healing via multiple mechanisms via immunomodulatory but not immunosuppresive mechanisms. An angiogenic factor immunoblot assay was utilized to demonstrate the difference between MSC and MAPC with single donor cells used as a potency assay in pivotal pre-clinical safety studies. In preclinical safety studies, there was no evidence of acute toxicity. MultiStem is indicated for ulcerative colitis, GvHD, stroke, MS, TBI, acute myocardial infarction, neonatal hypoxia, and spinal cord injury. Multiple mechanisms of action are indicated. For example, in studies of cardiovascular injury, MultiStem changes infiltration of leukocytes at the site of infarction. The current treatment for stroke in 5-10% of cases involves treatment with recombinant TPA. In a mouse model of stroke, changes are observed in the brain cortex and spleen by microarray. MultiStem supports neuron survival and growth, decreases the expression of immunology related genes in the brain, decreases pro-apoptotic genes, and preserves spleen mass by promoting anti-inflammatory proteins in the spleen. Interestingly, the spleen is required for the effects of MultiStem and impacts the permeability of the blood brain barrier. Lastly, Dr. Mays explained that their communication with FDA while submitting a stroke trial IND was very positive, productive and allowed them to save time and money by not doing unnecessarily assays.
The conference directors were pleased to host 324 delegates from 21 countries and 120 different institutions at this unique, translationally-focused adult stem cell conference in Cleveland Ohio. The spectrum of over 100 high quality poster presentations spanned national and international laboratories in the field of mesenchymal stem cell biology and therapeutics as well as representation by a number of commercial entities who are refining the culture expansion methodologies, nomenclature, and characterization of mesenchymal stem cells that can be used in a variety of clinical settings. These poster sessions matched the platform presentations by topic, but included a broad array of important advances looking at specific cell sources including dental pulp, lachrymal gland, early post implant stages of characterization and adipose derived MSCs. A variety of experimental models of disease were examined including renal failure, cartilage disease, Parkinson's, endometriosis, and the important topic of cancer homing by MSCs. A variety of immunomodulation studies were presented evaluating lupus, nephritis, radiation damage, pancreatitis, and hypoxia. Most of the gene therapy studies related to improving gene transfer technology with the latest in methods described including Tal infector nuclease, RNA packaging, lentivirus, and a potential HIV resistant payload.
MSC 2015 is being planned for August 17-19, 2015.
Potential topics include:
- MSCs for making organoids
- MSCs as gene and drug delivery vehicles
- MSCs for skin structures and making other 3-D tissues
- iPSC derived MSCs
- Enhanced immunomodulation using the M2 concept including vaccine type therapy
MSC 2013 Sponsors
National Center for Regenerative Medicine thanks the sponsors for helping to make MSC 2013 a success.