Multiple unique aspects of liver biology make this organ an excellent paradigm for novel cell and gene therapy applications. In recent years, insights were obtained into how transplanted cells engraft and proliferate in the liver, including in the context of pre-existing disease. Also, a variety of animal models were studied to establish the basis of cell and gene therapy applications in specific disorders. Through ongoing research activity, additional mechanisms in liver repopulation have been uncovered, where manipulation of specific cell compartments and cellular processes, e.g., those aimed at extracellular matrix component receptors or soluble signals in transplanted and native cells can be exploited for enhancing cell engraftment and proliferation. Such studies demonstrate the possibility of applying biotechnology and/or bioengineering principles to organ replacement aimed at cell and gene therapy. Joining of these disciplines with research in stem cell biology, particularly in efforts concerning targeting of transplanted stem cells to given organs with achievement of lineage-specific cell differentiation and function, will be particularly important for future cell and gene therapy applications. This review offers an overview of relevant mechanisms in liver repopulation.