The Role of Stem Cell Derived Microvesicles in Cholestatic Liver Injury
The functions of the human liver are essential to life since the liver is the only organ capable of regeneration. Human liver stem cells (HLSCs) have been extensively studied for their reparative, regenerative and immunomodulatory properties. Several studies, using different animal models of diseases, showed that treatment with exogenous HLSCs ameliorates acute organ injury including hepatic disorders. The mechanisms may involve paracrine factors promoting proliferation of surviving intrinsic epithelial cells. Whil stem cell therapies have been in pre-clinical use for the treatment of liver diseases, very little s known about the stem cell derived microvesicles (MVs) and their related non-coding RNAs (ncRNAs), which can mediate genetic changes that promote the progression and recovery of liver disorders. Many ncRNAs are expressed in a tissue-specific manner that is aberrantly altered in human alcoholic liver injuries. The biological function of the majority of ncRNAs in livr diseases is undefined. In our preliminary studies, we have shown that selected ncRNA genes are altered after cholestatic liver injuries, and aberrantly expressed in human liver stem cells and their derived MVs that can modulate the response to liver injury as well as cell anti-senescence and remodeling potentials. Based on these compelling data, we propose the central hypothesis that ncRNAs in stem cell derived microvesicles contribute to the recovery of cholestatic liver injury through induction of growth and anti-senescence/anti-fibrosis of hepatobiliary tissues and cells. To test this hypothesis, we have established techniques for ncRNA gene manipulation, functional and interaction analysis, and generated stably transfected or knockdown cell lines as well as animal models of cholestatic liver injury. Our long-term objective is to identify and isolate stem cell derived microvesicles and to characterize their functional properties of tissue repair. In this application, we propose the systematic evaluation o stemness dependent ncRNAs as markers in stem cell derived MVs with the therapeutic potentials for cholestatic liver injury. We will address our central hypothesis by focusing on the following specific aims: First, we will define the functional stemness regulated ncRNAs signaling involved in tissue repair-related cellular functions in hepatobiliary cells. Second, we will identiy functional LPS/TGF-ÃŸ dependent miRNAs involved in survival and anti-senescence during cholestatic liver injury. Third, we will determine the effects of stemness related ncRNAs enriched microvesicles on accelerating the morphologic and functional recovery of cholestatic liver injury in vivo using BDL or CCl4 treatment and in Mdr2 deficient mice, the genetic mouse model of PSC. Therapeutic effects of MVs derived from stem cells with anti-miRNAs or over-expression of T-UCRs on hepatobiliary cell growth, anti- senescence and anti-fibrosis will be evaluated. The results of the proposed studies may lead to new therapeutic strategies for human cholestatic liver diseases. Meanwhile, the acquired fundamental new knowledge about stem cell derived MVs is expected to advance the general field of stem cell biology.