[Cellular transplantation--orthotopic liver transplantation alternative]

Abstract

Hepatocyte transplantation is a promising treatment for several liver diseases and can also be used as a "bridge" to liver transplantation in cases of liver failure. It was known that human fetal liver multipotent progenitor cells are capable of differentiating into liver and mesenchymal cell lineages. Hepatoblast and ductal plate/bile duct cells development from common precursor mainly occurs during the second trimester. Functional differentiation of hepatocytes in adults resembles this phenomenon. Mesenchymal stem cells migrate from bone marrow to injured sites of liver under influence of hepatocyte growth factor and chemokine signal (CXCR3 and CXCR4 stimulation). Further, small, extraportal, hepatic parenchymal cells represent hepatic stem cells, canals of Hering, and/or ductal plate remnants. Human hepatic progenitor cells (HPCs) have been shown to coexpress the hematopoietic stem cell (HSC) markers - CD117, CD34 and also CD90. Taking together these observations confirm that cell-replacement may be useful tool in hepatic injury therapy. Low expression of MHC class II in liver and secretion MHC I by hepatocytes are source of immune tolerance and allow for HLA-nonidentical transplantation. Currently, one of the major limiting factors for clinical application is the insufficient access to suitable liver cell preparations.