The purpose of this study was to observe the ultrastructure of human umbilical cord mesenchymal stem cells (hUCMSC). hUCMSC from full-term newborn umbilical cord were isolated and cultured by collagenase digestion, and then subcultured, amplificated, and cell morphology was observed by microscopy. The immunophenotype and trilineage differentiation potential of hUCMSCs at passage 3 were analyzed. Transmission electron microscopy and scanning electron microscopy were used to observe the ultrastructure of hUCMSC. The results indicated that appearance of hUCMSC was spindle-shaped and polygonal, and nuclei were observed. hUCMSC expressed immunophenotype CD44, CD73, CD105, did not express CD34, CD45, CD31 and human leukocyte antigen HLA-DR. hUCMSC were capable of adipogenic, osteogenic, and cartilage differentiation; the short and thick microvilli processes were seen at the surface of hUCMSC by scanning electron microscope. Two different cell morpholigies of hUCMSC were seen under transmission electron microscope, the one was a quiescent period in which a large and round or oval nucleus only one nucleolus were seen, cytoplasmic organelles were less; the other was in a relatively active period in which one or two nuclei in the same one cell were observed, the organelles were rich, structure was clear, expansion of the mitochondria was visible. It is concluded that the cells successfully isolated and cultured from umbilical cord, which possess biological characteristics of MSC and display two different states of ultrastructure.%本研究观察脐带间充质干细胞的超微结构.用胶原酶消化法分离培养足月新生儿的人脐带间充质干细胞(hUCMSC),进行传代培养、扩增,在显微镜下观察其细胞形态.对培养至第3代的hUCMSC进行免疫表型测定,进行成脂细胞、成骨细胞和成软骨细胞诱导分化实验,并在透射电子显微镜、扫描电子显微镜下进行超微结构的观察.结果表明,hUCMSC外观呈梭形和多角形,并可见细胞核；高表达表面标志CD44,CD73,CD105,不表达CD34,CD45,CD31和HLA-DR;能够进行成脂、成骨、成软骨分化.在扫描电子显微镜下可见细胞表面有短而粗的微绒毛突起,在透射电子显微镜下可见到两种不同的细胞形态:一种处于静止期,细胞核大,圆或卵圆形,仅有1个核仁,胞质内细胞器少;另一种处于相对活跃期,同一个细胞内可以看到1个或2个细胞核,细胞器数量丰富、结构清晰,并可见扩张的线粒体.结论:从脐带中分离培养的细胞具有间充质干细胞的生物学特性,具有两种不同状态的超微结构.
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