LDLR and familial hypercholesterolemia: Feng et al. found that an increased frequency of HSC, monocytes and granulocytes was observed in the peripheral blood in LDL receptor knockout (LDLr−/−) mice with higher cholesterol levels, as well as a higher number of CD34+ stem cells mobilized in hypercholesterolemia patients than in normal cholesterol patients [18, 19], indicating that hypercholesterolemia and hyper-LDL exhibited protective effects on HSC proliferation and differentiation.