BACKGROUND:The proliferation and differentiation of hair-folicle-generating stem cels are influenced by the joint action of their own genes and external signals. Wnt/β-catenin signaling pathway plays an important role in the development of hair folicles, but the detailed mechanisms are not yet clear. OBJECTIVE:To investigate, with interruption of keratinocyte growth factor and lithium chloride, the function and the interrelationship of Wnt/β-catenin signaling pathway with other signal factors when human hair-folicle-generating stem cels differentiate into dermal papila cels or epidermal cels. METHODS: Hair-folicle-generating stem cels were isolated from the bulge and cultivated. Then the growth curve of hair-folicle-generating stem cels was tested and formed in order to observe the cellproliferation ability cultivated at different densities (1×106/L, 1×107/L, 1×108/L, 1×109/L) at each time. Immunoflurorescene staining was performed to identify hair-folicle-generating stem cels and their differentiated cels. Lithium chloride (0, 0.5, 1.5, 10, 25 mmol/L individualy) and keratinocyte growth factor(0, 10, 25, 50, 100 μg/L individualy) were used to induce the differentiation of hair-folicle-generating stem cels. Then, we contrasted and analyzed the proliferation ability in each case, thereby investigating the most appropriate concentration of keratinocyte growth factor and lithium chloride to spur the differentiation of hair-folicle-generating stem cels. At days 3, 5, 7 and 9, we tested and compared the mRNA expressions of β-catenin, APC, GSK-3β, Axin and Lef1 from cels in control group, 10 mmol/L lithium chloride group and 10 μg/L keratinocyte growth factor group. RESULTS AND CONCLUSION:Isolating cultured hair-folicle-generating stem cels stil had a great reproductive activity and multi-lineage potential even after various times subculturein vitro. With higher lithium chloride concentration, the proliferation ability of hair-folicle-generating stem cels declined; while it increased when keratinocyte growth factor concentration increased. In K-SFM medium which contained lithium chloride, the transformation of hair-folicle-generating stem cels was obvious, showing distinct differences among groups. Especialy, the level ofβ-catenin reached the peak when lithium chloride > 10 mmol/L. However, in K-SFM medium which contained keratinocyte growth factor, hair-folicle-generating stem cels differentiated into epidermal cels and the level of β-catenin changed slightly. We found that, while spurring the differentiation of hair-folicle-generating stem cels, lithium chloride could activate Wnt/β-catenin signal pathway and inhibit GSK-3β, a vital component of degradation compound. This facilitated β-catenin expressing in the cytoplasm to translocate into the nucleus. As a result, the transcription of target gene increased. It is the most appropriate concentration to spur hair-folicle-generating stem cels differentiation when lithium chloride level is > 10 mmol/L, but the proliferation ability declines correspondingly. Keratinocyte growth factor, which can facilitate hair-folicle-generating stem cels differentiated into epidermal cels, is a key factor to accelerate proliferation ability and migration of hair-folicle-generating stem cels, re-epithelialization and healing of wound. The mechanisms of hair-folicle-generating stem cels oriented differentiation induced by lithium chloride and keratinocyte growth factor are activating Wnt/β-catenin signal pathway, inducing change of β-catenin expression, and activating the transcription of target gene related to Wnt/β-catenin signaling pathway .%背景：毛囊干细胞的增殖分化受到自身基因及外来信号的共同作用，Wnt/β-catenin信号通路在毛囊毛发发育中起重要作用，但详细机制尚未明确。 目的：探讨在角质细胞生长因子及氯化锂干预下，Wnt/β-catenin信号通路在人毛囊干细胞向毛囊乳突细胞或表皮细胞定向分化中的作用及与其他信号分子的相互关系。 方法：获取毛囊隆突区干细胞进行培养，检测其生长曲线，观察1×106 L-1、1×107 L-1、1×108 L-1和1×109 L-1培养的毛囊干细胞在不同时间点的增殖效应；使用免疫荧光染色法对毛囊干细胞及其分化细胞进行鉴定。分别以0，0.5，1.5，10，25 mmol/L氯化锂及0，10，25，50，100μg/L角质细胞生长因子诱导毛囊干细胞分化，对比各组细胞的增殖效应，探索促毛囊干细胞分化的最佳氯化锂及角质细胞生长因子浓度。使用RT-PCR检测未处理对照组、10 mmol/L氯化锂组和10μg/L角质细胞生长因子组干预后3，5，7，9 d细胞的β-catenin、APC、GSK-3β、Axin和Lef1的mRNA转录水平。 结果与结论：分离培养的毛囊干细胞在体外经多次传代后仍具有很强的增殖能力和多向分化潜能，随氯化锂浓度升高，细胞增殖效应减弱；而随角质细胞生长因子组质量浓度增高细胞增殖能力增强。含有氯化锂的K-SFM条件培养基中毛囊干细胞形态改变明显，各组间有明显差别，氯化锂>10 mmol/L时分化比例高，β-catenin表达量增高；而含有角质细胞生长因子K-SFM条件培养基中毛囊干细胞向表皮细胞分化，β-catenin变化不明显。提示氯化锂在促毛囊干细胞分化中，激活 Wnt/β-catenin 信号通路，抑制降解复合物重要成分GSK-3β的表达下降，促使β-catenin在细胞浆表达增加并转入核内，增加靶基因转录，促使毛囊干细胞向毛囊细胞方向分化。氯化锂>10 mmol/L是促毛囊干细胞分化的最佳浓度，但增殖效应减弱。角质细胞生长因子可促进毛囊干细胞向表皮分化，可促进毛囊干细胞增殖和迁移，促进创面再上皮化及创面愈合。氯化锂和角质细胞生长因子促毛囊干细胞定向分化的作用机制可能为激活Wnt/β-catenin信号通路，促使β-catenin表达改变，从而激活Wnt信号通路中Lef介导相关靶基因的转录。
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