The influences of nano-sized type I collagen molecules on hepatocyte cultures were studied on primary rat hepatocytes cultured in dish and in stir bioreactor. Rat hepatocyte morphology was assessed by light and electron microscopy. Hepatocyte viability and function was measured by MTT test and albumin secretion. The preliminary results showed that hepatocytes exhibited better viability and function after addition of higher concentration of type I collagen particles (5 x 10-2 mg/ml) into the culture medium as compared to lower concentration of collagen particles (5 x 10-4 mg/ml) and control group. The mitochondrial function of hepatocytes decreased about 50% within 72 h of isolation and progressively increased to a level similar to the initial activity after 10 days. The hepatocytes cultured with nano-sized type I collagen particles had slightly higher level of albumin secretion in static dish cultures. Hepatocytes cultured in the stir bioreactor could form cell pellets rapidly (spheroid) after addition of nano-sized type I collagen particles into the medium. Also, hepatocyte spheroids gradually increased in size to approximately 5 mm in diameter during 5-day culture. From histological and SEM observations, these spheroids contained viable and well-differentiated hepatocytes inside.
