Linda A. Lee
Submitter: Abd Hamid Mat Sain | hamid@kb.usm.my
Dept of Surgery,School of Medical Sciences, Universiti Sains Malaysia,16150 Kbg Kerian,Kel.,Malaysia
Published August 9, 2001
I was very enthusiastic when reading the title of the paper. Despite the impressive results from conventional scientific outcome measures, organ transplantation really does have serious limitations in its routine therapeutic applications. Organs shortage is a real problem not only in a more conservative, religious societies but even in the more liberal populace of the West. Quite often, a transnational collaboration is required to share the procured organs.
The hunt for a more widely practical solution to replace organs transplantation is ongoing in all continents. Unfortunately, tissues and cellular transplantations are still at the experimental stages to say the least, if not outright disappointing at the moment. This is partly due to the fact that the cells and tissues of the diseased solid parenchymal organs like liver, pancreas and kidneys are highly heterogeneous in terms of structures and functions. Consider the liver ; it is conventional to regard the functions of the liver in two dichotomy of synthetic and excretory functions. Although this dichotomy is unsatisfactory and oversimplified in view of other functions of the liver, like metabolism of drugs and other extraneous agents, hepatocytes proper are essentially involved in synthetic processes, whereas the other component of the parenchyma, namely the ductal structures, are responsible for the excretion of the bile with the useless metabolites.
The author of the above paper has bases her enormous optimism in the potential of hepatocytes transplantation on the claim that there were documented evidence of clinical improvement (which included encephalopathy) in both animal models and human trials of hepatocytes transplantation even in ectopic locations. Hepatocyte transplantation has also been noted by the author to be used as a bridge to orthotopic liver transplantation (OLT) and she comments that in rare cases may have obviated the need for OLT altogether. I have serious reservation on the claim of this potential for hepatocyte transplantation. In my opinion, the role of the liver in maintaining homeostasis hinges significantly on its ability to eliminate various toxic products of metabolism from endogenous or exogenous substrates. This excretory function of the liver is clearly irreplaceable by just transplanting hepatocytes alone without the ductal cells which form the canaliculi and the ducts(1). With this fundamental limitation of regenerating equally important sub- structure of the liver parenchyma other than the hepatocytes, the hope that hepatocyte transplantation may become standard therapy in the near future is unfounded at the moment.
1.Mito M. 1985. The current and future aspects of liver cell transplantation. Nippon Geka Gakkai Zasshi 1985 Sep 86:993-6