CASIN the joint: immune aging at the stem cell level

In this issue of Blood, Leins et al use hematopoietic stem cell (HSC) transplantation from young or old mice into young Rag1(-/-) hosts to demonstrate that T-and B-cell reconstitution and acquisition of immune function is dependent on blocking the age-associated higher expression of cell division control 42 (Cdc42) in HSCs from old animals transferred to a young host. They achieved this by treating old HSCs with the specific pharmacologic Cdc42 inhibitor CASIN [2-((6-phenyl-2,3,4,9-tetrahydro-1H-carbazol-1-yl)amino)ethanol], otherwise known as Pirl1-related compound 2.(1)