Differentiation, growth and activity of rat bone marrow stromal cells on resorbable poly(L/DL-lactide) membranes

Nonporous and porous membranes produced from poly(L/DL-lactide) 80/20% were characterized using profilometry, contact-angle measurements, infra-red spectroscopy, X-ray photoemission spectroscopy and scanning electron microscopy, and used to culture bone marrow stromal cells isolated from the rat femora. The cells were cultured for 5, 10, 15 and 20 days. Cell growth and activity was estimated from the amounts of DNA, alkaline phosphatase activity and total protein amount present in the cell lysate and cell differentiation was assessed histochemically. Cell morphology was estimated from scanning electron microscopy. The cells fully expressed osteoblastic phenotype, revealed spindle-shaped, ellipsoidal morphology, developed podia, produced an abundant fibrillar extracellular matrix and mineral noduli. The number of cells on the membranes increased with time of culturing and was higher for the porous membranes than the nonporous membranes. Osteoblastic differentiation was most significant between 5 and 10 days of culture. The total amounts of DNA, alkaline phosphatase and proteins increased with time of culturing. The surface characteristics of the porous membranes were superior to the nonporous membranes.