Cell kinetics of aortic smooth muscle cells in long-term cultures prepared from rats raised under conventional and SPF conditions.

Migration and proliferation of smooth muscle cells (SMC) were studied in cultures prepared from the aorta of Wistar male rats (170-200 g b.w., 8 weeks old) raised under conventional (CC) or specific pathogen-free (SPF) conditions. In primary cultures, higher movement of cells from explants was found in CC raised donors, namely in samples cultured in serum incomplete medium. In the following subcultures (passage 3-16), the growth curves were steeper and the doubling time shorter in CC type of cultures. The faster growth of SMC population from conventional donors was found to be due to a shorter cell cycle and a higher proportion of dividing cells. As a consequence, the maximum population densities were also higher in the latter type of cultures. The differences in growth, that were dependent on raising conditions, were evident for 16 passages, i.e. 7 months after explantation of cells into culture. The data suggest that breeding conditions may affect the activation of growth of SMC in blood vessels in situ.