Identification of integrin heterodimers functioning on the surface of undifferentiated porcine primed embryonic stem cells.

In vitro expansion of undifferentiated porcine primed embryonic stem (ES) cells is facilitated by use of non-cellular niches that mimic three-dimensional (3D) microenvironments enclosing an inner cell mass of porcine blastocysts. Therefore, we investigated the integrin heterodimers on the surface of undifferentiated porcine primed ES cells for the purpose of developing a non-cellular niche to support in vitro maintenance of the self-renewal ability of porcine primed ES cells. Immunocytochemistry and a fluorescence immunoassay were performed to assess integrin α and β subunit levels, and attachment and antibody inhibition assays were used to evaluate the function of integrin heterodimers. The integrin α3 , α5 , α6 , α9 , αV , and β1 subunits, but not the α1 , α2 , α4 , α7 , and α8 subunits, were identified on the surface of undifferentiated porcine primed ES cells. Subsequently, significant increase of their adhesion to fibronectin, tenascin C, and vitronectin were observed and functional blocking of integrin heterodimer α5 β1 , α9 β1 , or αV β1 showed significantly inhibited adhesion to fibronectin, tenascin C, or vitronectin. No integrin α6 β1 heterodimer-mediated adhesion to laminin was detected. These results demonstrate that active α5 β1 , α9 β1 , and αV β1 integrin heterodimers are present on the surface of undifferentiated porcine primed ES cells, together with inactive integrin α3 (presumed) and α6 subunits.