5 问题与展望

目前对于毛囊干细胞的研究已取得的了很大进步，但对分离纯化及识别方法的研究仍存在着许多问题：

5.1 没有规范的分离纯化方法，分离纯化毛囊干细胞的纯度不足：目前分离纯化毛囊干细胞的技术较多，但没有公认的纯度高的分离纯化方法，应用目前常用分离纯化的方法分离毛囊干细胞的纯度大约在50%～90%之间[13]，组织块法分离的毛囊干细胞纯度较低，约在50%左右，应用差速贴壁法纯化毛囊干细胞可获得纯度为90%以上的毛囊干细胞[16]。

5.2 分离的毛囊干细胞体外传代培养几代后其增殖能力下降[13]：消化法获得的干细胞经历倍增期后,生长速度减慢,进入平台期。免疫组化染色和克隆形成率结果显示,第3 代、7代组织块法免疫组化阳性率和克隆形成率明显高于消化法,

两种方法之间差异极显著(P<0.01)。从传代次数来看,消化法第12 代细胞已出现老化现象，其原因可能是酶消化破坏了干细胞与微环境的联系,影响了干细胞的生物学特性。

5.3 标记物的选择：毛囊干细胞虽然有多种标记物，但缺乏异性。一般认为β1- 整合素阳性细胞包含了干细胞和早期TAC[36]；在毛囊生长期K19 阳性细胞不仅大量表达于毛囊隆突部，也存在于其下方的毛球部，进入退行期和静止期，随着毛球部萎缩, K19 阳性细胞消失,而毛囊外根鞘部位依然存在K19 阳性细胞。因此，只能通过联合使用标记物以提高特异性。

5.4 加入干细胞标记物相应抗体后进行传代是否会影响其增殖能力：目前，还没有关于加入毛囊干细胞相应抗体后是否影响其增殖能力的报道，但这些标记物本身是毛囊干细胞的组成成分，在细胞的增殖和分化过程中起一定作用，当我们应用其相应抗体与之结合时必将影响标记物作用的发挥，有可能会影响毛囊干细胞的体外增殖与传代的能力。随着研究的深入，相信在不久的将来定能解决上述问题，应用纯度高、增殖能力强的毛囊干细胞在特定的条件下进行分化并应用于临床。

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