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Hard to heal bone fractures could benefit from CD34+ stem cell treatment

A new study appearing in STEM CELLS Translational Medicine (SCTM) demonstrates the potential of a subset of stem cell called CD34+ in treating hard to heal bone fractures.

While most patients recover from broken bones with little or no complication, up to 10 percent experience fractures that won’t heal. This can lead to a number of debilitating side effects, from infection to bone loss, and it can require extensive treatment involving multiple operations and prolonged hospitalization as well as long-term disability.

Regenerating broken bone using stem cells could offer an answer. Adult human peripheral blood CD34+ cells have been shown to contain an abundance of a type of stem cell called endothelial progenitor cells (EPCs) as well as hematopoietic stem cells, which give rise to all types of blood cells. As such, they could be good candidates for this therapy.

However, while other types of stem cells had been tested for their bone regeneration potential, the ability of CD34+ to do so had never been reported on before the phase I/II clinical study was published in the current SCTM. It was conducted by researchers at Kobe University Graduate School of Medicine, led by Tomoyuki Matsumoto, M.D., and Ryosuke Kuroda, M.D., members of the university’s department of orthopedic surgery and its Institute of Biomedical Research and Innovation (IBRI).

The study was designed to evaluate the safety, feasibility and efficacy of autologous and G-CSF-mobilized CD34+ cells in patients with non-healing breaks, breaks that had not healed in nine months, in their legs. (G-CSF is a drug that releases stem cells from the bone marrow into the blood.) Seven patients were treated with the stem cells after receiving bone grafts.

“Bone union was successfully achieved in every case, confirmed as early as 16.4 weeks on average after treatment,” Dr. Kuroda said.

Dr. Matsumoto added, “Neither deaths nor life-threatening adverse events were observed during the one year follow-up after the cell therapy. These results suggest feasibility, safety and potential effectiveness of CD34+ cell therapy in patients with nonunion.”

Atsuhiko Kawamoto, MD, Ph.D., a collaborator in IBRI, said, "Our team has been conducting translational research of CD34+ cell-based vascular regeneration therapy mainly in cardiovascular diseases. This promising outcome in bone fracture opens a new gate of the bone marrow-derived stem cell application to other fields of medicine."

Although the study documents a relatively small number of patients, the results suggest the feasibility, safety and potential effectiveness of CD34+ cell therapy in patients with non-healing breaks,” said Anthony Atala, M.D., editor of STEM CELLS Translational Medicine and director of the Wake Forest Institute for Regenerative Medicine.