Monocytes Do Not Transdifferentiate into Proper Osteoblasts
Figure 3
Weak response of monocyte-derived cells to differentiation. (a) Alkaline phosphatase (AP) activity [μmol/min] of monocyte-derived cells in comparison to primary osteoblasts, macrophages, and osteoclasts (, ). AP activity [μM/min] normalized to cell amount determined by Alamar blue. (b) Alizarin red measurement [μmol] in monocyte-derived cells in comparison to primary osteoblasts (, ). (c) Relative expression levels of Runx2 measured by RT-PCR normalized to GAPDH and subsequently to expression in primary osteoblasts as internal control (, ). Runx2 expression significantly increases after treatment to obtain PCMOs (***). After the differentiation procedure, Runx2 expression in PCMOs decreases again (°°°) (d) relative expression levels of Osterix measured by RT-PCR normalized to GAPDH and subsequently to expression in monocytes after 6 days in culture as internal control (, ). Osterix expression significantly increases after treatment to obtain MOMPs and after 6 days culture of control monocytes (***). After the differentiation procedure, osterix expression in both cell types decreases again (°°°). Monocytes (Mo) day 1: freshly isolated monocytes; Mo, MOMP (M), and PCMO (P) day 6: cells after treatment; Mo, M, P day 20: cells after differentiation with vitamin-D-containing medium. Macrophages (Ma), osteoclasts (Oc). (***).
