Smooth muscle cells of injured rat and rabbit arteries in culture: contractile and cytoskeletal proteins

The aim of this study is to determine whether subpopulations of smooth musc le cells (SMC). as distinguished by variations in contractile and cytoskele tal proteins, appear in the neointima at different times after vascular inj ury, and/or whether subpopulations develop during serial passaging of these cells. Rat aortae and rabbit carotid arteries were injured with a 2F Fogar ty balloon catheter and cultures established from the resulting neointima a nd the media 2, 6, 12, 16 and 24 weeks later. Cultures were examined at pas sages 1-5 and subpopulations of SMC categorised by intensity of staining fo r each protein by immunohistochemistry. Two populations of SMC with differe nt staining intensities ('+ +', '+') were observed for each of the followin g proteins: alpha -SM actin, SM-myosin, desmin and vimentin. Populations wi thout these proteins were also found. Changes in the percentages of cells e xpressing these proteins were transitory, indicating that the populations w ere not limited to a particular tissue (neointima or media), time after inj ury or passage number. One exception was found in rabbit cultures where the number of desmin-expressing cells quickly decreased with both time after i njury and time in culture. Subpopulations of SMC were found at all times after injury in the media and neointima of rat and rabbit arteries, and after multiple passage of these cells. There was no pattern of development of one population suggesting tha t either no subpopulation has a proliferative or migratory advantage over o thers, or that only one population exists: that is capable of diverse pheno typic changes. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.