The metabolic activity of hepatocytes cultured on homologous acellular matrix (HAM) and transplanted into rats genetically incapable of bilirubin conjugation (Gunn rats) has been investigated. Hepatocytes from Wistar male rats were seeded on HAM and cultured for 9 days, and the proliferation rate and albumin mRNA expression were assayed daily. HAM alone or HAM plus hepatocytes (cultured for 3 days) were implanted in a subcutaneous pocket of the dorsal region of Gunn rats. No immunosuppression therapy was used. Blood samples were collected weekly and rats were sacrificed 10 weeks after surgery. Hepatocytes cultured on HAM displayed a higher proliferation rate than those cultured on plastic, and albumin mRNA expression was detected in hepatocytes seeded on HAM, but not on plastic. Serum bilirubin concentrations did not differ from baseline values in both the sham-operated control and HAM transplanted rats. On the contrary, in rats transplanted with HAM plus hepatocytes, circulating bilirubin levels decreased from week 4-7, and then plateaued until week 10. Histology did not evidence signs of rejection, but only a mild degree of inflammation around the implanted patches. It is concluded that hepatocytes seeded on HAM and transplanted into Gunn rats are able to metabolize bilirubin for at least two months, without signs of rejection even in the absence of immunosuppressive therapy.

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