FIGURE 7.

Ectopic bone formation assay with BMSC. Adherent BMSC were selected from cultures of bone marrow cells harvested from wild type and genetically altered mice. Cells were absorbed into Gelfoam and surgically transplanted into immunocompromised NSG mice (Jackson Laboratory). After 8 weeks, ectopic bone ossicles formed and were analyzed by micro-CT. Ossicles formed in transplants from ΔEpoR_E mice that lack EPOR in non-hematopoietic tissue (bottom) showed similar structure to control mice (top) with a trend toward fewer trabeculae, consistent with a reduction in endogenous bone formation in ΔEpoR_E mice. Bone formation was markedly reduced with hardly any trabecular bone in ossicles in transplants from transgenic mice expressing high level of human EPO (Ruschitzka et al., 2000) (middle) compared with control mice (top), reflecting the even greater reduction of endogenous bone formation in these transgenic mice compared with ΔEpoR_E mice and control mice (modified from Suresh et al., 2019, with permissions).