In vitro study of multicellular hepatocyte spheroids formed in microcapsules.

To make highly differentiated encapsulated hepatocytes, we formed hepatocyte spheroids in microcapsules in cultures. Hepatocytes isolated from rats were encapsulated in alginate-poly-L-lysine artificial cells and cultured under different medium conditions. When high molecular weight poly-L-lysine was used to make the capsule membrane, the hepatocytes aggregated and formed spheroids inside microcapsules within 48 hs. We studied the viability and function of encapsulated hepatocyte spheroids; free hepatocyte spheroids; nonaggregated encapsulated hepatocytes; and free hepatocyte monolayers. Cell viability and protein-producing ability were monitored for up to 30 days. Hepatocyte spheroids in the encapsulated or free form remained viable and continued to secrete proteins throughout the 30 days of observation. The viability and function of nonaggregated hepatocytes in the encapsulated or free form declined rapidly. These results suggest that the tridimensional structure of the spheroids may be important in maintaining the viability and function of encapsulated hepatocytes.