[Ultrastructure of human umbilical cord mesenchymal stem cells]

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, amplification, 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 morphologies 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.