Cytological examination of rat amniotic epithelial cells and cell transplantation to the liver

It is hoped that amniotic epithelial cells can be useful in cell-mediated g ene therapy. We report here an experimental cell transplantation model of a mniotic cells in rats. There is an anatomical difference between human and rodent embryos. We established a method to isolate amniotic cells that are equivalent to human amniotic epithelial cells. An amniotic membrane distinc t from the yolk sac was carefully collected and teased in saline containing deoxyribonuclease and hyaluronidase, followed by collagenase digestion. Th e cell yield was approximately 10(6) cells per pregnant female (10(5) cells per fetus), roughly in proportion to the age of fetus used, and 60% of the isolated cells were attached to the dish under culture conditions. Telomer ase activity was higher in the cells isolated from fetuses in the middle st age (day 13.5 to 15.5) than in the late stage (day 17.5 to 21.5). Adherent cells exhibited two to three times more cell division, resulting in a ninef old increase in the number of cells. Immunohistochemical analysis revealed that approximately half of the adherent cells were albumin positive and for med clusters. The senescent cells survived for 2 months without apparent mo rphological changes. The adherent cells were able to be stored in liquid ni trogen and had a viability of 70% when thawed. Gene transduction with adeno virus vector was highly effective for rat amniotic cells, Transplantation o f lacZ transfected amniotic cells into syngeneic rat liver resulted in the integration of the transplanted cells in the liver structure and the cells survived for at least 30 days.