Functional human hepatocytes: Isolation from small liver biopsy samples and primary cultivation with liver-specific functions.

Morphologically and functionally intact human hepatocytes were isolated from small liver biopsy samples weighing about 1-2 g by initial digestion with collagenase followed by repeated digestions with trypsin. The usual yield of hepatocytes was greater than 1 x 10(7) cells per g of liver sample and cell viability, as judged by dye exclusion test, was routinely over 90%. The isolated human hepatocytes showed intact morphology under scanning electron microscope. Formation of membrane protrusions upon phalloidin addition demonstrated that the actin in isolated hepatocytes was maintained with its structural integrity. The cultured human hepatocytes retained a variety of liver-specific functions which were similarly exhibited by rat hepatocytes isolated using the same procedure. The cultured human hepatocytes exhibited a specific cytochrome P-450 related enzyme activity, and active amino acid uptake that increased upon addition of hormones like glucagon and dexamethasone. Additionally, the cultured human hepatocytes synthesized DNA actively and, human serum albumin, and was found to be responsive to modulation by growth modulating hormones, cytokines and hepatotoxic agents. Based on the profile of activity described above, the presently established conditions for isolation and culturing of human hepatocytes demonstrate that functional liver cells can be obtained from small biopsied liver samples.