Multipotent human hair follicle stem cells for cardiovascular tissue engineering
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Adult stem cells that were obtained from human hair follicles (hHF-SC) exhibited high proliferation potential and expressed surface markers characteristic of mesenchymal stem cells (MSC) such as CD44, CD73, and CD90. Notably, hHF-SC could differentiate towards the adipogenic, chondrogenic and osteogenic lineages suggesting that these cells are similar to mesenchymal stem cells from bone marrow. Immunohistochemistry of the hair follicle tissue confirms the isolation of MSC like cells, showing similar expression profile for the surface markers and smooth muscle alpha-actin (SMα) expression in the Outer Root Sheath (ORS). Addition of bFGF significantly increased proliferation potential of the hHF-SC. We tested the ability of the hHF-SC to compact fibrin gels. Our results show that bFGF completely blocks compaction of fibrin gels. TGF-beta is able to restore compaction partially in cells treated with bFGF, but does not show any difference in untreated cells. Immunocytochemistry confirms lack of SMá fibers in bFGF treated cells compared to untreated cells, with few cells showing fibers in cells treated with bFGF and TGF-beta. Differentiation towards SMCs was further explored using tissue specific promoters, namely SMα and myosin heavy chain (MHC) promoters driving expression of a green fluorescence protein variant (ZsGreen) or red fluorescence protein (RFP), respectively. Compaction Assay on the hHF-SMC showed that bFGF treatment showed no difference in compaction ability, suggesting the isolation of mature SMCs. In conclusion, hHF-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. Key words hair follicle, stem cell, tissue engineering, and blood vessel.