Dissecting hepatocyte heterogeneity in liver growth to devise liver gene therapies for pediatric patients

Objective

In vivo genetic engineering of hepatocytes may represent a definitive cure for monogenic metabolic diseases. Integration of the therapeutic transgene into the target cell genome is essential for long-term expression after a single dose early in life and can be achieved by semi-randomly integrating lentiviral vectors or site-specific genome editing. Maintenance of the genetic modification upon hepatocytes proliferation in liver growth and turnover requires targeting the cells underlying these processes. Little is known about post-natal liver growth and how different hepatocyte subsets contribute to it. Unexpectedly, we found that most hepatocytes are quiescent during liver growth, and a fraction of them generate most of the adult tissue. The overall goal of HEPAGENE is to dissect hepatocyte heterogeneity in post-natal liver maturation and unravel its implications for in vivo gene engineering, to ultimately design and develop safe, effective, and durable gene therapies to treat diseases of hepatic metabolism in pediatric patients. To achieve this goal, we will: i) characterize molecular programs of proliferating and quiescent hepatocyte subsets; ii) assess their susceptibility to lentiviral gene transfer and nuclease-mediated gene editing, in both normal mice and in a disease model of methylmalonic acidemia, a severe early-onset disease, taken as paradigmatic of inherited metabolic diseases; iii) estimate clonal dynamics of genetically modified hepatocytes in vivo in non-human primates and analyze gene signatures in human liver samples, to establish a correspondence between murine and primate’s hepatocyte subsets. We will exploit state-of-the-art organoid, single-cell and multi-omic analyses including latest-generation spatial transcriptomics. HEPAGENE will lead to improved understanding of liver biology and gene engineering of hepatocytes, paving the way for novel genomic medicine products that offer hope to children affected by otherwise incurable metabolic diseases