颌突外胚间充质干细胞(EMSCs)的体外分离及鉴定

外胚间充质(ectomesenchyme)是一种胚胎发育早期颅面部出现的多能性结构(multipotentstructure),大多数颅面部结构和组织均由其衍生而来,这提示外胚间充质中存在一种干细胞,即外胚间充质干细胞(ectomesenchymalstemcells,EMSCs)。为了分离和鉴定EMSCs,对E125的SD大鼠颌突组织细胞进行了流式细胞学分析,发现其中的外胚间充质细胞表达多种神经谱系和中胚层谱系的标志,包括p75、CD57和nestin等。根据此特点,采用磁细胞分离技术对p75+的颌突外胚间充质细胞进行了分离和克隆培养。克隆分析表明,单个p75+细胞经过10～14d培养,可以形成由两种或两种以上细胞组成的多潜能性克隆(multipotentclone),提示该群外胚间充质细胞具有多潜能性。同时,亚克隆分析表明,多潜能性子克隆中的单个p75+细胞具有再次形成多潜能性克隆的能力,说明这些细胞在体外具有自我更新的能力。这些结果提示,p75+细胞同时具有多潜能性和自我更新能力,因此是外胚间充质干细胞。该干细胞的分离对于口腔颅面部的起源和发育研究无疑具有重要意义。此外,该干细胞的高度可塑性也预示它可以作为一种新的种子细胞,为组织工程皮肤、肌肉、软骨的研究提供新思路。

Isolation and Identification of Ectomesenchymal Stem Cells

In mammalian, most of craniofacial structures are developed from ectomesenchyme, which is composed of post-migrated neural crest cells. Evidence has showed that in mass culture ecotomesenchymal cells are multipotent. However, whether stem cells exist in ectomesenchyme is unknown. It showed that both neural lineage and mesenchymal lineage markers (such as: p75, CD57, nestin and S-100) expressed in mandibular processes. p75 population from ectomesecnchymal cells was then selected and cultured in clone density to access their prosperity. After 14d culture, clone analysis showed that single founders could produce more than two types of derivatives, which include myofibroblasts, oestoblasts, Schwann cells, or mealnoblasts, suggesting such cells are multipotent. Multipotent founders also have capacity to self-renew as revealed by subcloning experiments. Therefore, p75 population are stem cells. These findings firstly demonstrated the existence of ectomesenchymal stem cells in vitro, and gave the profile of its lineage differentiation. The findings also suggested that p75 was a valuable specific marker for isolation and enrichment of ectomesenchymal stem cells. These results were thought important for further study and application of ectomesenchymal stem cells.