First characterization of small hepatocytes from human liver as possible source in liver regeneration

Severe hepatic dysfunction in humans is caused by various diseases such as persistent hepatitis, cirrhosis or liver tumours. Currently, the absence of donors leads to a high mortality rate. Cell based therapies may be a possible alternative to stabilize patients who are waiting for an adequate liver. However, one limitation of cell-based therapies is the availability of functional human hepatocytes. So far, only limited approaches exist to stimulate the proliferation of functional human hepatocytes in vitro, using cytokines which are known to play a key role in liver regeneration. Besides several methods to overcome this cell limitation, the use of hepatic precursor cells may be a real alternative. In the adult human liver, two candidates of progenitor cells have been identified: oval cells and small hepatocytes (SH cells). We describe here, for the first time, the isolation and characterization of human SH cells. SH cells are isolated by a Percoll based multistep centrifugation technique and cultured in a serum free medium. The cells can be maintained for up to two months without losing their ability to proliferate. First results have shown that a better proliferation is achieved when human foreskin fibroblasts are used as a feeder layer rather than collagen coated surfaces. First characterizations were done by immunofluorescence staining and PCR. SH cells possess close relationships to adult hepatocytes. Like adult human hepatocytes they are positive for albumin, transferrin as well as cytokeratin 18. Additionally, SH cells do not express α Fetoprotein, which indicates that these cells are not tumor- or stem cell like. Also, the marker CD90, which is not expressed at detectable levels, indicates a distance from stem cells.

Further characterization of SH cells may help to determine the relationship between small hepatocytes, oval cells and adult hepatocytes. This will, consequently, reveal the future potential use of SH cells in the regeneration of damaged livers.

Liver regeneration - Small hepatocytes - cell based therapy