A Study on Intrasplenic Transplantation of Embryonic Stem Cells

ABSTRACT

PURPOSE: The authors evaluated the morphological and proliferative properties of embryonic stem (ES) cells following intrasplenic transplantation. The results were compared with those obtained following intrasplenic transplantation of cultured hepatocytes. METHODS: ES cells of blastocysts were collected from superovulated Sprague Dawley rats. Hepatocytes were collected from the liver of 7-week old rats by perfusion of collagenase. The ES cells and hepatocytes were cultured for 6 days and transplanted into the rat spleen. The properties of the ES cells and cultured hepatocytes following transplantation were investigated by morphological methods. RESULTS: ES cells in the culture proliferated faster than hepatocytes, and differentiated to various shaped cells. Following transplantation, ES cells were distributed near the periarterial lymphatic sheath. Cultured hepatocytes gathered chiefly around the trabeculae. On PCNA stain of transplanted ES cells, positive cells appeared on day 7 and became distinct on days 10 and 14. Transplanted hepatocytes showed no PCNA positive cells on day 14. On electron microscopic examination, ES cells differentiated to hepatocyte-like structures on day 10, and became functioning hepatocytes on day 14. Transplanted hepatocytes formed bile canaliculi on day 10, although development of organelles was insufficient on day 14. CONCLUSION: ES cells proliferated faster than cultured hepatocytes. Intrasplenic ES cells proliferated at the germinal center and hepatocytes around the trabecula. ES cells differentiated to cells that had the function of hepatocytes.