Original article from STEM CELLS
“Injury-Activated Transforming Growth Factor β Controls Mobilization of Mesenchymal Stem Cells for Tissue Remodeling”
Adult stem/progenitor cells are able to differentiate into many cell types and can also be recruited to a site of injury where they either repair the injured tissue or contribute to tissue remodeling (Ferrari et al, Takahashi et al,Lagasse et al, Orlic et al and Kale et al). Mesenchymal stem cells (MSCs) in peripheral blood are one such stem cell known to act in this way, and it is believed that promigratory factors released from injured tissue or surrounding inflammatory cells create a signal for their recruitment (Caplan and Correa, Krankel et al and Wojakowski et al). However the primary endogenous factors activated or released in response to injury to stimulate the mobilization of MSCs are largely unknown. Transforming growth factor beta proteins (TGFβs) are synthesized in a latent form sequestered in extracellular matrix (ECM) (Kanzaki et al and Munger et al) and perturbations in the ECM associated with phenomena such as angiogenesis, wound repair, inflammation, and cell growth (Annes et al) release active TGFβs. TGFβ1 can be released from the bone matrix to induce MSCs migration for bone remodeling (Tang et al), but less is understood about a potential role in the vasculature where shear stress and arterial injury can induce activation of TGFβ1 (Ahamed et al and Qi et al). Now, in a study in Stem Cells, researchers from the group of Xu Cao at the Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA, using two separate models of arterial damage, have found that MSCs become mobilized into peripheral blood and migrate to injured sites to participate in vascular repair and remodeling by a mechanism controlled by active TGFβ1 (Wan et al).