The Investigation of Hair Follicle Regeneration Utilizing Human Interfollicular Dermal and Epidermal Stem Cells

哺乳动物毛囊中的真皮乳头细胞（DPCs）具有诱导和发育毛囊的能力。从理论上讲，通过扩大DPCs并将其移植到秃顶的皮肤上，可以再生人类的头发。为了阐明组织工程毛囊中诱导发的遗传因素，我们对从成人头皮皮肤中获得的人真皮乳头细胞和真皮成纤维细胞进行了微阵列分析和RT-PCR比较。在微阵列分析中，我们发现与真皮成纤维细胞相比，tgf基因显著上调，并且它是参与头发再生的候选基因之一。RT-PCR分析显示，与真皮成纤维细胞相比，培养的真皮乳头细胞中tgf - mRNA显著且持续上调。此外，我们发现角质形成细胞分泌的可溶性因子显著上调TGF -2 mRNA。对先前报道的IFKC特异性生物标志物进行了人头皮皮肤和毛囊的免疫组织化学（IHC）检测。通过FACS分析和免疫染色研究生物标志物在培养的角质形成细胞中的表达。IHC中角蛋白15 （K15）在凸起区表达。CD34在下端表达，包括凸起区和外根鞘（ORS）。CD271 （p75神经营养因子受体）在K15阴性的下ORS中表达。所有这些基因都只在附着于基膜的最外层表达。我们检查了先前报道的两种体内模型的可重复性，包括“腔室模型”，将培养的人DPCs移植到裸鼠的硅胶腔中，以及“三明治模型”，将培养的人DPCs与大鼠足底皮肤植入裸鼠皮肤下。在可重复性方面，“三明治模型”比“室模型”和其他体内模型更适用于测试人类DPCs的诱导可行性。

Dermal papilla cells (DPCs) in the mammalian hair follicles have been shown to have an ability to induce and develop hair follicles. It is theoretically possible to regenerate human hair by expanding DPCs and transplanting them in the bald skin.We performed a microarray analysis and RT-PCR comparing human dermal papilla cells and dermal fibroblasts both obtained from adult scalp skin, in order to elucidate the genetic factors responsible for hair induction in tissue engineered hair follicles. In the microarray analysis we found that TGFs gene was significantly upregulated compared to dermal fibroblasts and that it was one of the candidate genes involving in hair regeneration. RT-PCR analysis revealed significant and sustained upregulation of TGFs mRNA in cultured dermal papilla cells compared to dermal fibroblasts. Furthermore, we found soluble factors secreted by keratinocytes significantly upregulated TGF beta-2 mRNA.Immunohistochemistry (IHC) of human scalp skin and hair follicles for the biomarkers previously reported as specific for IFKC was performed. The expression of the biomarkers in cultured keratinocytes was also investigated by FACS analysis and immunostaining. Keratin 15 (K15) was expressed in the bulge area in IHC. CD34 was expressed in the lower area, which includes the sub-bulge area and outer root sheath (ORS). CD271 (p75 neurotrophin receptor) was expressed in the lower ORS that was negative for K15. All of them were expressed only in the outermost layer adhering to the basement membrane.We examined reproducibility of two of in vivo models for trichogenesis previously reported, including 'chamber models', grafting cultured human DPCs into silicone chambers on nude mice, and 'sandwich models', implanting cultured human DPCs with rat sole skin under the skin of nude mice. 'Sandwich models' were more useful than 'chamber models' and other in vivo models for testing the inductive viability of human DPCs in terms of reproducibility.