Abstract 8929: Skin-Derived Precursors (SKPs) Can be Directed into Vascular Smooth Muscle Cells and Can Integrate into the Vasculature in vivo.
Background: Skin-derived precursors (SKPs) are Sox2+ multipotent, neural crest-derived stem cells that persist in adults. They self-renew in dermis and contribute to wound healing. As such, they represent an easily attainable, autologous source of stem cells for potential use in regenerative therapies and in modeling human disease. Here we instructively test the ability of rat and human SKPs to differentiate into vascular smooth muscle cells (SMC) and test their functional capacity in vivo.
Methods & Results: Signals known to (A) direct neural crest stem cells into SMCs (TGFβ-1 and -3) and (B) direct mesenchymal stem cells into SMCs (sphingosylphosphorylcholine (SPC) and S1P) were tested on rat and human SKPs. For rat SKPs, 10% FBS supplemented with SPC or S1P had no effect on SMC differentiation. However, addition of TGFβ-1 and -3 induced the formation of SMCs in ∼70% of the population. Interestingly, reduction of FBS to 0.1–2%, and plating of cells at a low density, was sufficient to induce formation of SMCs at a frequency of 95–100%, without need for additional factors. Human foreskin-derived SKPs can be differentiated serum-free with the addition of TGFβ-1 and -3, but not SPC, reaching SMC frequencies up to 80–90%. Gene expression analyses showed that the SMC markers SMα-actin, calponin and SM22α were up-regulated. The vascular SMC marker Smoothelin B was also up-regulated suggesting that these SMCs were vascular. Consistent with this, little to no telokin or SMγ-actin expression was found in differentiated SKPs, indicating that these SMC were not visceral. MRTF-A and -B were expressed highly in undifferentiated and differentiated SKPs and were also expressed at higher levels than myocardin, suggesting that these transcription factors may play a more significant role in SMC differentiation in SKPs. Finally, GFP+ SKP-derived SMCs incorporated into the vasculature in a subcutaneous matrigel angiogenesis assay, showing that these cells can generate functional vascular SMCs in vivo.
Conclusion: SKPs can be differentiated at high frequency into vascular SMCs and form functional vascular SMC in vivo. The ability to direct this phenotype in human SKPs (without serum) advances significantly the regenerative promise of this cell type.
- © 2010 by American Heart Association, Inc.