The effects of young and aged, male and female megakaryocyte conditioned media on angiogenic properties of endothelial cells.

With aging, the risk of fractures and compromised healing increases. Angiogenesis plays a significant role in bone healing and is impaired with aging. We have previously shown the impact of megakaryocytes (MKs) in regulating bone healing. Notably, MKs produce factors known to promote angiogenesis. We examined the effects of conditioned media (CM) generated from MKs derived from young (3-4-month-old) and aged (22-24-month-old), male and female C57BL/6J mice on bone marrow endothelial cell (BMEC) growth and function. Female MK CM, regardless of age, caused a >65% increase in BMEC proliferation and improved vessel formation by >115%. Likewise, young male MK CM increased vessel formation by 160%. Although aged male MK CM resulted in >150% increases in the formation of vascular nodes and meshes, 62% fewer vessels formed compared to young male MK CM treatment. Aged female MK CM improved migration by over 2500%. However, aged female and male MK CM caused less wound closure. MK CM treatments also significantly altered the expression of several genes including PDGFRβ, CXCR4, and CD36 relative to controls and between ages. Further testing of mechanisms responsible for age-associated differences may allow for novel strategies to improve MK-mediated angiogenesis and bone healing, particularly within the aging population.