Adult stem cells that were obtained from human hair follicles (HF-SC) exhibited high proliferation potential and expressed surface markers characteristic of mesenchymal stem cells such as CD44, CD49b, CD73, CD90 and CD105. Notably, HF-SC could differentiate towards the adipogenic, chondrogenic and osteogenic lineages suggesting that these cells are similar to mesenchymal stem cells from bone marrow. In addition, TGF-beta promoted HF-SC differentiation towards the smooth muscle cell (SMC) lineage. Differentiation towards SMCs was further explored using tissue specific promoters, namely smooth muscle alpha-actin (SMa) and myosin heavy chain (MHC) promoters driving expression of a green fluorescence protein variant (ZsGreen) or red fluorescence protein (RFP), respectively. Using flow cytometry we found that the expression level of ZsGreen or RFP decreased significantly by bFGF and increased by TGF-beta. In addition, bFGF was found to maintain the potential of HF-SC for multilineage differentiation even after long time in culture.

We also prepared tissue engineered blood vessel constructs (TEV) using smooth muscle cells (SMC) derived from HF-SC and designated as HF-SMC. Notably, TEVs from HF-SMC exhibited receptor and non-receptor medicated contractility in response to vasoactive agonists such as KCl, endothelin and the thromboxane mimetic, U46619. In conclusion, HF-SC exhibit high proliferation ability and multilineage differentiation potential and therefore, they provide an easily accessible source of stem cells for tissue engineering and regenerative medicine.