The monoclonal antibody SH-2, raised against human mesenchymal stem cells,recognizes an epitope on endoglin (CD105)

Mesenchymal stem cells are multipotent cells resident in the bone marrow th roughout adulthood which have the capacity to differentiate into cartilage, bone, fat, muscle, and tendon. A number of monoclonal antibodies raised ag ainst human MSCs have been shown to react with surface antigens on these ce lls in vitro. A protein of molecular mass 92 kDa was immunoprecipitated usi ng the SH-2 monoclonal antibody. This was purified and identified by peptid e sequencing analysis and mass spectrometry as endoglin (CD105), the TGF-be ta receptor III present on endothelial cells, syncytiotrophoblasts, macroph ages, and connective tissue stromal cells. Endoglin on MSCs potentially pla ys a role in TGF-beta signalling in the control of chondrogenic differentia tion of MSCs and also in mediating interactions between MSCs and haematopoi etic cells in the bone marrow microenvironment. (C) 1999 Academic Press.