FGF20对毛囊干细胞调控及促进毛囊再生作用机制研究

Hair loss, caused by androgenetic alopecia or wounds, is a common clinical condition and severely affects patients' quality of life. Hair follicle regeneration is a challenging task in regenerative medicine. Despite of our current knowledge in hair follicle stem cells, more studies are needed to understand the molecular regulations of their regenerative capacity. Many recent trials demonstrated the decisive effects of FGF20 in the development of hair follicles. Our preliminary studies also confirmed that FGF20 enhanced the growth of cultured hair follicles, promoted wound induced hair morphogenesis, and up-regulated gene expression in Wnt singaling pathway. These data suggested FGF20 plays an important role in hair follicle morphogenesis and growth, however, the exact mechanisms by which FGF20 regulates hair regeneration in adults remain unknown. We plan to use ex vivo hair follicles culture model, wound induced hair morphogenesis model, Fgfr knock-out mice wound model, and Patch Assay hair follicle organogenesis model to study the regulatory effect of FGF20 on hair follicle stem/progenitor cells and regeneration. Especially, we focus on the mechanisms of FGF20/Fgfr/Wnt signalling pathway. This project will help to elucidate the role of FGF20 in hair follicle regeneration, and lead to potential clinical applications of FGF20 for the treatment of hair loss.

雄激素性脱发、创伤后瘢痕性脱发等脱发问题亟待解决，但组织工程皮肤中毛囊再生问题尚未解决，如何有效调节毛囊干细胞增殖分化并促进毛囊再生值得研究。近期有研究发现FGF20在毛发发育中起决定性作用。我们前期也发现FGF20可促进培养毛囊生长，明显促进创伤诱导毛囊再生并上调Wnt信号通路表达水平，但FGF20调节毛囊生长/再生的具体作用机制尚不清楚。本项目拟采用毛囊器官离体培养模型、创伤诱导毛囊再生模型、敲除Fgfr转基因动物的创伤诱导毛囊再生模型、Patch Assay在体毛囊再生模型等，从不同角度不同水平探究FGF20对毛囊干细胞/毛囊前体细胞增殖分化调节作用、促进毛囊生长作用和诱导毛囊再生作用，尤其探究FGF20作用受体及FGF20/Fgfr/Wnt信号通路在其作用机制。本项目有望获得有效促进毛囊生长/再生药物，为解决毛囊再生这一组织工程问题奠定基础，为脱发临床治疗提供新思路。

雄激素性脱发、斑秃等各种原因引起的脱发不仅影响外观，对患者心理也有负面影响，严重影响患者生活质量。筛选有效促进毛发生长和再生的药物并用于临床值得深入研究。近来成纤维细胞生长因子（fibroblast growth factors, FGFs）尤其是FGF9亚家族（FGF9、FGF16、FGF20）对毛发的发育、生物学行为的调控受到重视。我们前期工作中已经检测了多种生长因子对毛发生长调节作用，包括EGF、aFGF、bFGF、FGF10等，发现FGF20具有调节毛发生长/再生的潜在作用。但FGF20对毛发的具体调节作用及机制有待进一步研究。. 通过毛囊器官离体培养模型，我们证实FGF20通过上调毛囊基质细胞增殖能力和激活Wnt信号通路提高毛囊生长速度。采用皮内注射FGF20动物模型，通过大体观察和组织病理证实FGF20能促进毛囊由静止期向生长期的周期转变。流式细胞检测发现FGF20处理组毛囊干细胞（CD34+CD49f+）数量和增殖能力明显上调，提示FGF20通过促进毛囊干细胞增殖分化调节毛囊周期转变。PCR Array实验检测发现FGF20可以调节Wnt信号通路相关基因表达，尤其Wnt5a、Fzd4、Lrp5 、Lef1、Tcf1、β-catenin等表达水平差异明显。进一步通过qPCR、免疫组织化学染色、免疫荧光、Western Blot等检测证实FGF20上调Wnt5a启动经典Wnt信号通路，进而调节毛囊周期转变。通过Patch Assay模型，我们首次成功构建新生小鼠表皮细胞和小鼠触须毛乳头细胞构成的嵌合毛囊。FGF20处理组形成Patch Assay囊样结构的体积和新生毛囊数量明显超过对照组，证实FGF20能提高新生小鼠表皮细胞和小鼠触须毛乳头细胞混合细胞再生毛囊的能力。综合上述，本研究证实了FGF20对毛囊生长/再生的调节作用及机制，为FGF20进一步临床试验和应用奠定基础，FGF20有望转化到临床成为促进毛囊生长/再生药物。