Rat Hepatocyte Aggregate Formation on Discrete Aligned Nanofibers of Type-I Collagen-coated Poly(L-lactic Acid)

Primary hepatocytes cultured in three dimensional tissue constructs composed of multicellular aggregates maintain normal differentiated cellular function in vitro while cultured monolayers do not. Here, we report a technique to induce hepatocyte aggregate formation using type-I collagen-coated poly(L-lactic acid) (PLLA) discrete aligned nanofibers (disAFs) by providing limited cell-substrate adhesion strength and restricting cell migration to uniaxial movement. Kinetics of aggregate formation, morphology and biochemical activities of rat hepatocyte aggregates were tested over a 15 day culture period. Evidence was provided that physical cues from disAFs quickly induced the formation of aggregates. After 3 days in culture, 88.3% of free hepatocytes on disAFs were incorporated into aggregates with an average diameter of 61 +/- 18 microm. Hepatocyte aggregates formed on disAFs displayed excellent cell retention, cell activity and stable functional expression in terms of albumin secretion, urea synthesis and phase I and II (CYP1A and UGT) metabolic enzyme activity compared to monolayer culture of hepatocytes on tissue culture plastic (TCP) with type-I collagen as well as on meshes of type-I collagen-coated PLLA random nanofibers (meshRFs). These results suggest that disAFs may be a suitable method to maintain large-scale hepatic cultures with high activity for tissue engineering research and potential therapeutic applications, such as bioartificial liver devices.