Figure 6. Osteocyte-specific deletion of Fgf23 restores osteoblast differentiation but does not restore impaired mineralization in Dmp1^KO primary osteoblast cultures.

Bone marrow stromal cells were isolated from 12-week-old WT (n ≥ 3), Fgf23^Dmp1-cKO (n ≥ 3), Dmp1^KO (n ≥ 3), and Dmp1^KO Fgf23^Dmp1-cKO (n ≥ 4) mice, then cultured for 14 (D14) and 21 (D21) days in osteoblast differentiation medium containing 3, 7, or 10 mM of beta-glycerophosphate (bGP). Levels of (A) total DMP1 (cDMP1) and (B) total FGF23 (cFGF23) in conditioned media collected at D21. (C and D) Alkaline phosphatase (ALP) staining and quantification and (E and F) alizarin red S (ARS) staining and quantification. Values are expressed as mean ± SEM; P < 0.05 vs. bGP treatment–matched ^aWT, ^bFgf23^cKO, ^cDmp1^KO, and genotype-matched *3 mM and **7 mM within each time point. ^dP = 0.1 vs. 10 mM Dmp1^KO. Statistical tests were ANOVA test followed by Bonferroni post hoc tests.