A conventional means of repairing a damaged organ or tissue is to introduce cultured cells or tissues to the corresponding defect site. Three factors affecting the success of such repair include cell culturing, scaffolding and the signaling factors between the cells and scaffold. Enhanced binding of cell adhesion molecules, such as integrin, to specific molecules of the extracellular matrix (such as RGD sequences on the collagen) can generally induce cytoplasmic signal transduction cascades and activate gene expressions, subsequently achieving rapid cell proliferation and differentiation. This study investigates how type I and type II collagen nano-spheres in the culture medium influence hepatocytes and chondrocytes cultures. Experimental results indicate that hepatocytes demonstrated better viability and function after adding a higher concentration of type I collagen nano-spheres (5X10-2 mg/ml) to the culture medium than with lower concentration collagen particles (5X10-4 mg/ml) and the control group. The hepatocytes cultured with type I collagen nano-spheres also had a slightly higher level of albumin secretion in static dish cultures than that of the control group. Additionally, hepatocytes cultured in a stir bioreactor by adding type I collagen nano-spheres for 5 days formed a cell spheroid that is approximately 5 mm in diameter. In chondrocytes cultures, the chondrocytes displayed a higher secretion of glucosaminoglycan (GAG) than that of the control group (without adding collagen nano-spheres). Chondrocytes could form a large amount of spheroids rapidly with adding type II collagen nanospheres to the medium in a 1-day rotary bioreactor culture. Histological staining and SEM observations revealed that these chondrocytes still retained their original phenotype and secreted collagen around the cells. In summary, hepatocytes and chondrocytes cultured in a rotary bioreactor while adding a moderate concentration of collagen nano-spheres could rapidly form cell pellets, maintaining their in vivolike morphologies and specific functions.
