Heparin-assisted cell delivery system for liver tissue regeneration

Abstract

Heparin is a negatively charged glycosaminoglycan (GAGs) and has been used as an anticoagulant in clinical. One of advantage of heparin for liver-targeted cell delivery system is the existence of heparin receptor on liver cell. However, few studies have been reported for liver-targeted cell delivery by using heparin. Therefore, in this thesis, liver-targeted cell delivery systems by using heparin were developed for liver tissue regeneration. In Chapter 2, the micro-patterned, injectable and detachable heparin-based hydrogel was prepared on polyelectrolyte (PEM) multilayer for hepatic differentiation of ADSCs and injectable liver-targeted cell delivery. The micro-patterned heparin-based hydrogel showed sustained release of growth factors because of the heparin-binding affinity of the growth factors. That properties induced hepatic differentiation of hADSCs to hepatic-like cells by using small amount of growth factors compared to the conventional 2D cell culture. Also, the micro-patterned heparin-based hydrogel on PEM multilayer was easily detached from the indium tin oxide (ITO) glass by electrochemical stimulus for 5 min. The detached hepatic-like cell micropatches could be intravenously injected into the animal. Compared to only hepatic-like cell injection group, hepatic-like cell micropatches showed enhanced cell delivery to liver and in vivo cell stability, which induced the higher serum human hepatocyte growth factor secretion level. In Chapter 3 and 4, lipid-conjugated heparin was used as a cell surface coating material. In Chapter 3, the lipid-conjugated heparin was coated on hADSCs. The lipid-conjugated heparin coated hADSCs showed enhanced liver cell regeneration in in vitro acetaminophen (APAP)-induced acute liver failure (ALF) model. Also, the lipid-conjugated heparin coated hADSCs showed therapeutic effect of in vivo APAP-induced ALF model. The injected lipid-conjugated heparin coated hADSCs showed the enhanced liver-targeted delivery, which induced faster decrease of ALF-related enzyme levels in serum, enhanced secretion of cytokine from the injected cells, and decreased inflammation in the liver. In Chapter 4, the multicellular hepatic spheroid was formed by simple shaking of the cell suspensions and the small amount of the lipid-conjugated heparin (Lip-Hep sph). The Lip-Hep sph maintained over 10 days and showed the higher hepatocyte cellular function than the hepatic spheroid formed by the conventional hanging drop method. Also, after transplantation into subcutaneous area of animal, the Lip-Hep sph showed the higher in vivo cell stability than the hanging drop, which induced the higher albumin secretion. In conclusion, this thesis showed the potential of heparin as a cell delivery material for liver tissue engineering. Heparin was used as an injectable cell micropatch, stem cell coating materials for liver-targeted cell delivery, and a material for rapid hepatic spheroid formation.