[Identification of human bone marrow mesenchymal stem cells: preparation and utilization of two monoclonal antibodies against SH2, SH3].

Human mesenchymal stem cells (MSC) are one kind of adult stem cells that can self-renew and give rise to one or more mesenchymal tissues, existing in bone marrow and other tissues. Not similar to CD34 recognizing hematopoietic stem cells, no such marker can be used yet to identify MSC. To isolate and identify MSC from bone marrow, anti-SH2 and SH3 monoclonal antibodies as markers to identify MSC were used. Two monoclonal antibodies were purified from ascites of SH2 and SH3 hybridomas-inoculated mice, flow cytometry and immunohistochemistry were used to identify plastic-adherent cultured MSC. And SH2 and SH3 antigen positive cells were isolated from bone marrow mononuclear cells (BMMNC) by immunobeads covered with secondary antibodies. And anti-SH2 and CD105 McAbs were used to label MSC at the same time to clarify whether they recognize the same antigen. The results showed that about 80% of MSC were antigens SH3 and SH2 positive. The SH2 and SH3 positive-selected cells were MSC while MSC accounted for less than 1% of negative-selected cells. When cells were labeled by SH2 McAb, they could not be labeled by CD105 simutaneously. In conclusion, antigens SH2 and SH3 are specific markers to identify and isolate MSC. Anti-SH2 McAb can replace anti-CD105 McAb to identify the specific marker on MSC.