Development of an ex vivo xenogeneic bone environment producing human platelet-like cells

The efficiency of in vitro platelet production is considerably low compared with physiological activity due to the lack of pivotal factors that are essential in vivo. We developed an ex vivo platelet production system, introducing human megakaryocytes into an isolated porcine thighbone and culturing in closed circuit. The efficiency of the ex vivo platelet production system was compared to those in vivo and in vitro. CD61(+) platelet-like cells were counted by immunostaining and flow cytometry. Results showed that 4.41 +/- 0.27 x 10(3) CD61(+) platelet-like cells were produced by 1 x 10(3) megakaryocytes in the ex vivo system, while 3.80 +/- 0.87 x 10(3) and 0.12 +/- 0.02 x 10(3) were produced in the in vivo and in vitro systems, respectively. Notably, ex vivo and in vitro production systems generated cells that responded well to thrombin stimulation and expressed functional molecules, such as CD62P. Overall, our ex vivo production system was comparable to in vivo production system and produced platelet-like cells that were functionally superior to those produced in vitro. In future, the present ex vivo production system implementing xenogeneic bone marrow would offer a promising alternative for industrial-scale production of platelet-like cells.