Fabrication of macroporous cryogels as potential hepatocyte carriers for bioartificial liver support

Two different cryogels composed of copolymer of acrylonitrile (AN) and N-vinyl-2-pyrrolidone (NVP) (poly(AN-co-NVP)) and interpenetrated polymer networks (IPN) of chitosan and poly(N-isopropylacrylamide) (poly(NiPAAm)-chitosan) were fabricated by gelation at sub-zero temperatures. The two cryogels possess an interconnected network of macropores of size 20-100 μm and efficient transport properties as determined by physiochemical analysis. Both cryogels support in vitro growth and function of fibroblasts (COS-7) and human liver hepatocarcinoma cells (HepG2). The cryogels are hemocompatible as demonstrated by low albumin adsorption and platelet adherence. Furthermore, in vivo implantation of poly(NiPAAm)-chitosan cryogel in mice shows its biocompatibility with the surrounding tissue. Primary rat hepatocytes grown on poly(NiPAAm)-chitosan cryogel for 96 h formed cellular aggregates and maintained their functions in terms of, ammonia removal, ureagenesis and drug detoxification. Cryogel-based closed continuous bioreactor systems could maintain HepG2 cells at high density for 7 days. Off-line clinical evaluation of these cryogel-based bioreactors showed the ability of immobilized cells to detoxify circulating plasma obtained from patients with acute on chronic liver failure (ACLF). Altogether, the presented data suggests cryogels as a potential bioreactor matrix for bio-artificial liver support system.