FIG. 1.

Schematic of Mk differentiation in vivo and in 3-phase culture. Hematopoietic stem and progenitor cells (HSPCs) reside close to the endosteal bone surface in the niche. During the course of differentiation, megakaryocytic cells (Mks) are exposed to continually increasing pH and pO₂ until reaching the sinuses, where platelets are released from proplatelets aided by shear from the blood flow. Expression of CD34 decreases as Mks mature, while expression of CD41 and CD42b increases. Text above the arrows describes the niche-inspired culture system developed to optimize ex vivo Mk production from HSPCs. Color images available online at www.liebertpub.com/tea