VASCULAR SMOOTH-MUSCLE CELLS OF H-2K(B)-TSA58 TRANSGENIC MICE - CHARACTERIZATION OF CELL-LINES WITH DISTINCT PROPERTIES

Background The vascular wall is composed of at least two different pop ulations of smooth muscle cells that are distinct in their structure a nd protein composition. According to the developmental stage of tissue taken for culture, the ratio between cells of epithelioid phenotype a nd spindle-shaped cells is variable. In particular, the epithelioid ce lls display characteristic features associated with immaturity. Becaus e their increased appearance can be observed in endothelial denudation , they represent a dedifferentiated, proliferative smooth muscle cell type with a repair function in vascular injury. Methods and Results To investigate this cellular heterogeneity, we established vascular smoo th muscle cell lines from H-2K(b)-tsA58 transgenic mice. Due to temper ature-sensitive expression of the SV 40 large T-antigen in cells deriv ed from this mouse strain, our smooth muscle lines were conditionally immortalized from the onset of their life in culture. Thus, we were ab le to clone cell lines representing the two different phenotypes descr ibed so far. Epithelioid cells derived from newborn animals are charac terized by their expression of cytokeratins and the development of tig ht junctional complexes, Spincle-shaped cells, which could be isolated from newborn or adult animals, corresponded in phenotype and protein expression to smooth muscle cell lines established previously. Conclus ions The special properties of vascular smooth muscle cells of the epi thelioid phenotype suggest an endothelial replacement function in the course of injury to the vascular wall.