Stage-Specific Embryonic Antigen 4 in Wharton's Jelly–Derived Mesenchymal Stem Cells Is Not a Marker for Proliferation and Multipotency

Abstract

Umbilical cord Wharton's jelly (WJ) is a rich source of mesenchymal stem cells (MSCs) similar to bone marrow (BM) and adipose tissues. Stage-specific embryonic antigen (SSEA)4 has been reported as a stem cell marker in BM-derived MSCs, but whether SSEA4(+) cells have growth and differentiation advantages over SSEA4(-) cells remains controversial. To gain insight into the role of SSEA4, we studied SSEA4(+) cells in WJ-derived MSCs (WJ-MSCs). WJ-MSCs were collected by the explant (WJe-MSCs) or collagenase methods (WJc-MSCs) and analyzed by flow cytometry and reverse-transcription polymerase chain reaction (RT-PCR). To evaluate whether culture conditions influenced the SSEA4 expression, WJe-MSCs were cultured in the medium supplemented with different fetal bovine serum (FBS) concentrations. SSEA4 was expressed for a long-term culture. In contrast, SSEA3(+) disappeared rapidly in early passages of the culture. The incidence of SSEA4(+) and SSEA3(+) cells was similar between WJe-MSCs and WJc-MSCs at passages P0-P9, except for transient depletion of SSEA4 expression in early passages of WJe-MSCs. These were CD73(+)CD105(+) cells that express embryonic stem cell markers detected by RT-PCR. No differences in growth and differentiation ability of osteocytes and adipocytes were observed between the sorted SSEA4(+) cells and SSEA4(-) cells. Further, SSEA4 expression in WJe-MSCs was significantly correlated with FBS concentration in the culture medium. SSEA4, which may display altered expression profiles in response to culture conditions, may not be an essential marker of WJ-MSC multipotency.