Aims: To determine if mesenchymal stem cells (MSCs) can be isolated and cultured from human placenta.
Methods: Placentas were obtained at elective caesarean section from normal term pregnancies. Working from the foetal side, pieces of placenta were excised and washed in HBSS to remove excess blood. Tissue was then incubated in collagenase I and DNase I. After enzymatic digestion, a cell strainer was used to obtain a single cell suspension. The resulting cells were washed and centrifuged on a 1.073 g/ml Percoll density gradient and the interface collected. Cells were then cultured in DMEM (low glucose) with FCS. After 24 hours, non-adherent cells were removed and the remaining cells cultured until almost confluent before passage. Media was changed every 3–4 days. After two or more passages, the cells were analysed.
Results: Using this technique, placental plastic-adherent cells could be maintained in culture for long periods in a manner similar to bone marrow-derived MSC. The cells were large and exhibited an elongated, fibroblast-like morphology. In terms of phenotype, the cells were positive for CD29, CD44, CD73, CD90, CD105, CD166 and MHC class I expression, whilst negative for CD34, CD45 and MHC class II expression. The placental cells were shown to be capable of differentiating into cells of the mesenchymal lineage, namely osteocytes, chondrocytes and adipocytes and they could inhibit allogeneic T cell proliferation. However, some phenotypic differences, at both protein and mRNA level were noted between bone marrow and placental derived MSC, in particular only placental MSC showed expression of integrin VLA-4 and the chemokine receptor CXCR4.
Conclusions: The placental-derived cells exhibited characteristic MSC morphology and mesenchymal differentiation. Placental derived MSC therefore represent an alternative and more easily obtainable and abundant source of MSC than bone marrow.