日本研究人员在新一期美国《细胞—干细胞》杂志上报告说，动物实验证实毛根缺乏一种胶原蛋白可同时导致脱发和白发。这一研究成果将有助于开发出治疗脱发和白发的新药。
东京医科齿科大学教授西村荣美等研究人员报告说，他们发现ⅩⅦ型胶原蛋白的作用可使毛囊干细胞不会枯竭，从而防止脱发。同时，这种胶原蛋白在毛囊干细胞产生转化生长因子－β的过程中也是不可缺少的。而转化生长因子－β对色素干细胞的生成起着重要作用。
研究人员利用小鼠进行的实验证实了他们的判断。在正常情况下，毛色非白色的小鼠出生后约两年就会因衰老而出现脱毛和毛变白的现象。研究人员通过基因技术使一些小鼠体内不能产生ⅩⅦ型胶原蛋白，结果它们在半年内就明显地出现了白毛，大约10个月后，全身的毛就脱得差不多了。
在进一步的实验中，研究人员把能生成ⅩⅦ型胶原蛋白的基因植入自身不能产生这种胶原蛋白的小鼠体内，结果小鼠能够重新产生毛囊干细胞和色素干细胞，最终长出了一簇簇黑毛。
Hair Follicle Stem Cells Provide a Functional Niche for Melanocyte Stem Cells
Shintaro Tanimura, Yuko Tadokoro, Ken Inomata, Nguyen Thanh Binh, Wataru Nishie, Satoshi Yamazaki, Hiromitsu Nakauchi, Yoshio Tanaka, James R. McMillan, Daisuke Sawamura, Kim Yancey, Hiroshi Shimizu, Emi K. Nishimura
In most stem cell systems, the organization of the stem cell niche and the anchoring matrix required for stem cell maintenance are largely unknown. We report here that collagen XVII (COL17A1/BP180/BPAG2), a hemidesmosomal transmembrane collagen, is highly expressed in hair follicle stem cells (HFSCs) and is required for the maintenance not only of HFSCs but also of melanocyte stem cells (MSCs), which do not express Col17a1 but directly adhere to HFSCs. Mice lacking Col17a1 show premature hair graying and hair loss. Analysis of Col17a1-null mice revealed that COL17A1 is critical for the self-renewal of HFSCs through maintaining their quiescence and immaturity, potentially explaining the mechanism underlying hair loss in human COL17A1 deficiency. Moreover, forced expression of COL17A1 in basal keratinocytes, including HFSCs, in Col17a1-null mice rescues MSCs from premature differentiation and restores TGF-β signaling, demonstrating that HFSCs function as a critical regulatory component of the MSC niche.
