Re-entering the pluripotent state from blood lineage: promises and pitfalls of blood reprogramming

Blood reprogramming, in which induced pluripotent stem cells (iPSCs) are derived from haematopoietic lineages, has rapidly advanced over the past decade. Since the first report using human blood, haematopoietic cell types from various sources, such as the peripheral bone marrow and cord blood, have been successfully reprogrammed. The volume of blood required has also decreased, from around tens of millilitres to a single finger-prick drop. Besides, while early studies were limited to reprogramming methods relying on viral integration, nonintegrating reprogramming systems for blood lineages have been subsequently established. Together, these improvements have made feasible the future clinical applications of blood-derived iPSCs. Here, we review the progress in blood reprogramming from various perspectives, including the starting materials and subsequent reprogramming strategies. We also discuss the downstream applications of blood-derived iPSCs, highlighting their clinical value in terms of disease modelling and therapeutic development.