Megakaryocytes and platelets from a novel human adipose tissue–derived mesenchymal stem cell line

Abstract

The clinical need for platelet transfusions is increasing; however, donor-dependent platelet transfusions are associated with practical problems, such as the limited supply and the risk of infection. Thus, we developed a manufacturing system for platelets from a donor-independent cell source: a human adipose-derived mesenchymal stromal/stem cell line (ASCL). The ASCL was obtained using an upside-down culture flask method and satisfied the minimal criteria for defining mesenchymal stem cells (MSCs) by The International Society for Cellular Therapy. The ASCL showed its proliferation capacity for ‡2 months without any abnormal karyotypes. The ASCL was cultured in megakaryocyte induction media. ASCL-derived megakaryocytes were obtained, with a peak at day 8 of culture, and ASCL-derived platelets (ASCL-PLTs) were obtained, with a peak at day 12 of culture. We observed that CD42b1 cells expressed an MSC marker (CD90) which is related to cell adhesion. Compared with peripheral platelets, ASCL-PLTs exhibit higher levels of PAC1 binding, P-selectin surface exposure, ristocetin-induced platelet aggregation, and ADP-induced platelet aggregation, as well as similar levels of fibrinogen binding and collagen-induced platelet aggregation. ASCL-PLTs have lower epinephrine-induced platelet aggregation. The pattern of in vivo kinetics after infusion into irradiated immunodeficient NOD.Cg-PrkdcscidIl2rgtm1Wjl/ SzJ mice was similar to that of platelet concentrates. ASCL-PLTs have similar characteristics to those of peripheral platelets and might have an additional function as MSCs. The establishment of the ASCL and its differentiation into ASCL-PLTs do not require gene transfer, and endogenous thrombopoietin is used for differentiation. The present protocol is a simple method that does not require feeder cells, further enhancing the clinical application of our approach.