Galactosylated alginate-chitosan oligomer microcapsule:How to encapsulate hepatocytes? / 中国组织工程研究

ABSTRACT

BACKGROUND:A novel galactosylated alginate-chitosan oligomer microcapsule has been prepared successful y. There is no report on hepatocytes encapsulated into the microcapsule prepared with chitosan oligomer and alginate sodium. OBJECTIVE:To study the structure and properties of the previous novel galactosylated alginate-chitosan oligomer microcapsule, and then explore the morphology and function expression of the hepatocytes encapsulated. METHODS:The membrane structure and thickness of the microcapsule (containing 50%or 30%galactosylated alginate) were observed using a laser confocal microscopy. Mechanical property was determined by mechanical rupture rate. Permeability was evaluated by release profile of fluoresceine isothiocyanate-labeled human serum albumin and immunoglobulin G. The morphology of hepatocytes in the microcapsule was observed using an inverted phase contrast microscopy. Function expression of the hepatocytes included albumin secretion and urea synthesis. RESULTS AND CONCLUSION:The microcapsule had an asymmetry structure, with dense inner and loosened outer surfaces. With the increase of the galactosylated alginate, the membrane became loose, which indicated the negative charge on the alginate molecular chains was weakened after introduction of galactose, and thus electrostatic complex was affected. Mechanical property was correlated with both membrane structure and thickness. With the increase of the galactosylated alginate, the membrane structure became loose and the thickness was decreased, resulting in poor mechanical properties. The permeability was dependent mainly on the pore size of the skin layer of the membrane other than the loose sublayer. The prepared microcapsule can selectively pass through the human serum albumin and cut off immunoglobulin G, indicating skin pore size between human serum albumin and immunoglobulin G. The hepatocytes can form sphere assemble in the galactosylated alginate-chitosan oligomer microcapsule and exhibit improved albumin secretion and urea synthesis compared to the control in the alginate-chitosan oligomer microcapsule.