Background: It has been shown recently that human umbilical cord perivascular cells (HUCPVC) are bio-equivalent to bone marrow-derived mesenchymal stromal cells (BM-MSC) in their mesenchymal differentiation and marker expression. HUCPVC populations provide high yields of rapidly proliferating mesenchymal progenitor cells. The question we wished to address, in two independent laboratory studies, was whether HUCPVC exhibit a similar in vitro immunologic phenotype to that of BM-MSC.
Methods: HUCPVC were isolated by physical extraction of umbilical vessels followed by enzymatic digestion of the perivascular cells, and lymphocytes were obtained from heparinized human peripheral blood. Experimental evaluations were lymphocyte proliferation in HUPCVC or BM-MSC co-cultures with peripheral blood lymphocytes (PBL), mixed lymphocyte cultures (MLC) containing BM-MSC or HUCPVC, CD25 and CD45 expression in co-cultures containing HUCPVC, and finally lymphocyte proliferation in TransWell MLC with HUCPVC.
Results: Both HUCPVC and BM-MSC showed no significant increase in proliferation of lymphocytes when co-cultured. The addition of 10% HUCPVC or BM-MSC significantly reduced proliferation of PBL in one-way MLC. Upon inclusion of HUCPVC with activated T-cell lines, the expression of both CD25 and CD45 showed a significant decrease. HUCPVC were able to reduce lymphocyte cell numbers significantly when separated with a membrane insert.
Discussion: HUCPVC are not alloreactive and exhibit immunosuppression in vitro. Lymphocyte activation is significantly reduced in the presence of HUCPVC, and the immunosuppressive effect of HUCPVC is due, in part, to a soluble factor. Thus HUCPVC shows a similar immunologic phenotype to BM-MSC.