Transient activation of c-MYC expression is critical for efficient platelet generation from human induced pluripotent stem cells

Abstract

A specific kinetic pattern of c-MYC expression is essential for optimal generation of functional platelets from human induced pluripotent stem cells.

In vitro generation of platelets through direct conversion: first report in My Knowledge (iMK)

“…To examine whether iMKderived platelets are functional, ex vivo thrombus formation under flow condition was also tested, and functionality was confirmed [3]. As demonstrated in previous papers [8,10], it should be proved in the future that iMK-derived platelets circulate in NOG mice and are able to form thrombus in vivo.…”

“…On the other hand, iPSC-or ESCmediated generation of platelets in humans has been demonstrated by Eto and colleagues [7,8]. They revealed that a transient activation of c-Myc during megakaryopoiesis is critical for efficient platelet production from human iPSCs [8] (Figure 1); that is, reactivation of c-Myc after reprogramming should be followed by reduction of c-Myc expression for further maturation.…”

“…They revealed that a transient activation of c-Myc during megakaryopoiesis is critical for efficient platelet production from human iPSCs [8] (Figure 1); that is, reactivation of c-Myc after reprogramming should be followed by reduction of c-Myc expression for further maturation. In contrast, sustained and excessive c-Myc expression in MKs was accompanied by increased p14 (ARF) and p16 (INK4A) expression, and decreased GATA1 and NF-E2 expression, eventually leading to MK senescence and apoptosis, as well as impaired production of functional platelets [8]. It took approximately 2 months to obtain MKs by reprogramming HDFs into iPSCs and then by differentiating iPSCs into MKs.…”

“…Although HDFs are easy to expand once direct conversion is initiated, the number of transfected cells is limited. Eto and colleagues generated 200-300 iPS clones from 10 5 HDFs, and 1 × 10 5 cultured iPSCs produced approximately 17 × 10 5 MKs [8]. Although it is difficult to precisely compare reprogramming efficiency between the iMK study and the iPSC study, the number of platelets per MK was similarly low in both cases, which may reflect the inefficiencies of producing human platelets via in vitro protocols.…”

“…i) Direct conversion (iMK) method: three factors (p45MF-E2, Maf G, and Maf K) are required for direct conversion into iMK, which takes only 2 weeks [3]. ii) iPSCmediated method: transient activation of c-Myc in iPSCs is required for efficient MK induction [8]. If megakaryocyte progenitor cells are immortalized (designated as MKCLs), MKCLs are valuable sources for MK production [9].…”