Figure 5. HSCs Regulate Mesenchymal Fate Through BMPs.

Co-culture investigations were established by placing HSCs (Sca-1⁺cKit⁺CD150⁺CD41⁻CD48⁻) derived from stressed or non-stressed animals in the top chamber of a dual culture plate, and mixed BMSCs in the bottom well, in the presence or absence of neutralizing antibody to BMP-2 or BMP-6, or an IgG isotype matched control each added daily at 5 ng/ml. After 21 days the OB phenotype was examined by real-time RT-PCR for the expression of the Runx2 (an OB specific transcription factor), or the OB specific proteins bone sialoprotein (BSP) or osteocalcin (OCN). The data is presented as % change normalized to GAPDH, where the expression levels of co-cultures of BMSCs/HSCs (from the non-stressed animals) was set as the standard. *p <0.05 between HSCs derived from stressed and non-stressed animals, and ^# signifies differences between anti-BMP and IgG treated controls (p<0.05, Krusal-Wallis test, and Dunn’s multiple comparisons test). The data demonstrate that blockade of BMP-2 or BMP-6 activities modifies lineage differentiation.