Relationship between microenvironment and hepatocyte function : possible application in liver cell therapy
(2014)
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- The liver has strong and robust regenerative capacity, employing different modes of regeneration according to type and extent of the injury. During liver physiological regeneration, the process of compensatory hypertrophy of the liver involves proliferation of mature hepatocytes. In many human and animal liver pathologies, hepatocyte proliferation is inhibited and adult liver progenitor cells (LPC) are activated. LPC are believed to differentiate into hepatocytes and cholangiocytes leading to functional recovery of the organ following a poorly efficient and lengthy mechanism. LPC are supported and regulated by their surrounding microenvironment so-called “LPC niche” consisting in various other types of cells, more particularly hepatic stellate cells (HSC) and extracellular matrix (ECM), which are suggested to physically interact with LPC and exert some signals on them. This Ph D thesis aims to test the hypothesis that a specific microenvironment is of importance for promotion and maintenance of hepatocyte differentiation. First, we evaluated the importance of microenvironment on LPC differentiation into mature hepatocytes using the 2-acetaminofluorene (AAF)/ partial hepatectomy (PH) rat model in which liver regeneration is needed and LPC are activated. However, with the strategy used, we had little evidence of hepatocytic differentiation of LPC. Therefore, this model could not be used to study the role of the micro-environment on LPC-aided liver regeneration. Secondly, we analyzed the effect of HSC and ECM they produce on survival and function of cryopreserved mature hepatocytes. In vitro, cryopreserved hepatocytes have poor attachment and function due to alterations during freezing and thawing processes. We showed that co-culture with HSC ameliorates maintenance of cryopreserved hepatocytes by supporting their attachment probably through production of ECM and soluble factors, and that culture-activated HSC do better than quiescent HSC. In vivo, cryopreserved hepatocytes are preferred cell candidate for liver cell therapy to replace dysfunctional or lost mature hepatocytes. The success of liver cell therapy is challenged by the poor quality of cryopreserved hepatocytes leading to low engraftment and function after transplantation. We demonstrate that addition of HSC to the hepatocyte suspension significantly improves engraftment of cryopreserved hepatocytes, at least partly by ameliorating their homing early after transplantation. Importantly, co-transplantation with HSC did not generate abnormal matrix deposition nor alter function in recipient liver. This represents a promising strategy for improving liver cell therapy using cryopreserved hepatocytes.
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Dusabineza, A. C. (2014). Relationship between microenvironment and hepatocyte function : possible application in liver cell therapy. https://hdl.handle.net/2078.5/197001