Generation of Functioning Platelets from Mature Megakaryocytes Derived from CD34 ⁺ Umbilical Cord Blood Cells

Clinically patients with thrombocytopenia are in urgent need of platelet transfusion, thus it is necessary to produce the platelets in large scale in vitro to meet the clinical needs. In this study, we developed efficient protocol to generate functioning platelets by differentiating umbilical cord blood (CB)-derived CD34⁺ cells into mature megakaryocytes. Under our condition, up to 85% of mature megakaryocytes were generated from CB-derived CD34⁺ cells, and over 75% CD42b⁺CD62p⁺ platelets were produced. The megakaryocytes at day 12 after the differentiation had the similar gene expression pattern to natural mature megakaryocytes, and AMPK and insulin signal pathway were activated to inhibit the apoptosis and benefit platelet release. There were up to 72% of the platelets that could bind with PAC1, which is the highest rate of CB CD34⁺ cell-derived platelets to play function <i>in vitro</i> to date. The recovery of hemostasis and coagulation was similar in thrombocytopenia mice injected with CB CD34⁺ cell-derived platelets and with human blood-derived platelets, respectively, and it is the first time to demonstrate that human CB CD34⁺ cell-derived platelets were functional <i>in vivo</i>. Therefore, our findings open a new avenue to provide an <i>in vitro</i> efficient approach to generate functional platelets for clinical applications.