Di 2-ethyl hexyl phthalate affects differentiation and matrix mineralization of rat calvarial osteoblasts - in vitro

Di-2-ethyl hexyl phthalate (DEHP), an industrial plasticizer and a ubiquitous environmental contaminant, is an established endocrine disruptor (ED). Increasing evidences indicate that some EDs interfere with osteoblast differentiation and function. In the present study, we investigated the effects of DEHP on the expression of cell cycle proteins, differentiation markers, Runx2 and its co-activator TAZ in osteoblasts derived from neonatal rat calvaria. A significant decrease in protein levels of cyclin D1 and CDK-2 was found at high dosage of DEHP (100 μM) after 24 h treatment. DEHP treatment caused a significant decrease in ALP mRNA. While DEHP treatment significantly decreased the TAZ at mRNA and protein levels, it decreased only the Runx2protein levels. Histochemical localization of ALP, collagen and mineralized nodules studied from cells treated with DEHP (10 and 100 μM) for 21 days revealed a drastic decrease in collagen, ALP and mineralization. In conclusion, DEHP affected differentiation of neonatal rat calvarial osteoblasts and mineralization of matrix secreted by these cells.

► Phthalates are known as endocrine disruptors, which interfere with rat osteoblast cellular functions. ► Primary rat calvarial osteoblasts exposed to DEHP for a short term (2 days) decreased cell viability and cell proliferation. ► While long term treatment (21 days) drastically affected mineralization of matrix secreted by calvarial osteoblasts.