Mesenchymal stem cells (MSCs) give origin to the marrow stromal environment that supports hematopoiesis. These cells present a wide range of differentiation potentials and a complex relationship with hematopoietic stem cells (HSCs) and endothelial cells. In addition to bone marrow (BM), MSCs can be obtained from other sites in the adult or the fetus. We isolate MSCs from the umbilical cord (UC) veins that are morphologically and immunophenotpically similar to MSCs obtained from the BM. In culture, these cells are capable of differentiating in vitro into adipocytes, osteoblasts, and condrocytes. The gene expression profiles of BM-MSCs and of UC-MSCs were compared by serial analysis of gene expression, then validated by reverse transcription polymerase chain reaction of selected genes. The two lineages shared almost all of the first thousand most expressed transcripts, including vimentin, galectin 1, osteonectin, collagens, transgelins, annexin A2, and MMP2. Nevertheless, a set of genes related to antimicrobial activity and to osteogenesis was more expressed in BM-MSCs, whereas higher expression in UC-MSCs was observed for genes that participate in pathways related to matrix remodeling via metalloproteinases and angiogenesis. Finally, cultured endothelial cells, CD34 + HSCs, MSCs, blood leukocytes, and bulk BM clustered together, separated from seven other normal nonhematopoietic tissues, on the basis of shared expressed genes. MSCs isolated from UC veins are functionally similar to BM-MSCs, but differentially expressed genes may reflect differences related to their sites of origin: BMMSCs would be more committed to osteogenesis, whereas UC-MSCs would be more committed to angiogenesis.

ABSTRACT

Bone marrow contains a population of stem cells that can support hematopoiesis and can differentiate into different cell lines including adipocytes, osteocytes, chondrocytes, myocytes, astrocytes, and tenocytes. These cells have been denoted mesenchymal stem cells. In the present study we isolated a cell population derived from the endothelium and subendothelium of the umbilical cord vein which possesses morphological, immunophenotypical and cell differentiation characteristics similar to those of mesenchymal stem cells isolated from bone marrow. The cells were isolated from three umbilical cords after treatment of the umbilical vein lumen with collagenase. The cell population isolated consisted of adherent cells with fibroblastoid morphology which, when properly stimulated, gave origin to adipocytes and osteocytes in culture. Immunophenotypically, this cell population was found to be positive for the CD29, CD13, CD44, CD49e, CD54, CD90 and HLA-class 1 markers and negative for CD45, CD14, glycophorin A, HLA-DR, CD51/61, CD106, and CD49d. The characteristics described are the same as those presented by bone marrow mesenchymal stem cells. Taken together, these findings indicate that the umbilical cord obtained from term deliveries is an important source of mesenchymal stem cells that could be used in cell therapy protocols.

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