Phenytoin at Micromolar Concentrations is an Osteogenic Agent for Human-mandible-derived Bone Cells in vitro

Abstract

The present study sought to test the hypothesis that phenytoin acts on normal human-mandible-derived bone cells to induce osteogenic effects. To test the effects of phenytoin on bone cell proliferation, we measured [3H]-thymidine incorporation into cell DNA during the final four hr of a 24-hour incubation with phenytoin. Phenytoin at micromolar concentrations significantly stimulated the [3H]-thymidine incorporation in a dose-dependent, biphasic, manner with a maximal effect at from 10 to 50 microM. We confirmed the proliferative effect of phenytoin by counting cell number. To evaluate the effects of phenytoin on osteoblastic differentiation, we determined alkaline-phosphatase specific activity and found that phenytoin at micromolar concentrations significantly increased that activity in a dose-dependent manner, with maximal stimulation at approximately 1 microM. To investigate the effects of phenytoin on mature osteoblastic activities, we measured de novo collagen synthesis and osteocalcin secretion. Mitogenic doses of phenytoin significantly increased collagen synthesis and osteocalcin secretion in a dose-dependent, biphasic, manner, with the maximal stimulatory dose at from 5 to 10 microM. In summary, phenytoin at micromolar ranges increased (a) [3H]-thymidine incorporation and cell number, (b) alkaline-phosphatase specific activity, (c) collagen synthesis, and (d) osteocalcin secretion in monolayer cultures of normal human-mandible-derived bone cells. These observations are consistent with the premise that low doses of phenytoin act on human craniofacial bone cells to stimulate cell proliferation, differentiation, and mature osteoblastic activities to stimulate bone formation.

Pronounced Palatal and Mandibular Tori Observed in Patient With Chronic Phenytoin Therapy: A Case Report

“…6,7 In vivo and in vitro studies have demonstrated that phenytoin increases osteoblast number, osteoid thickness, surface, and volume of rat bone tissues 8,9 and that it increases markers of osteogenesis for humans. 10,11 These findings indicate that phenytoin is an osteogenic agent.…”

Bone health in young women with epilepsy after one year of antiepileptic drug monotherapy

“…However, the racial composition of the phenytoin group was diverse and no racial group predominated. Phenytoin has also been reported to have direct effects on bone resorption [20][21][22] and formation, 23,24 may directly impair calcium absorption, 24 and may impair the response of osteoblasts to PTH. 22,25 Although carbamazepine has also been shown to inhibit bone formation 23 and intestinal calcium absorption, 24 it is possible that the bone loss we observed may be mediated by one or more direct effects of phenytoin on some aspect of bone and mineral metabolism that are not shared by carbamazepine, rather than by an indirect effect of phenytoin on vitamin D metabolism.…”

“…However, the racial composition of the phenytoin group was diverse and no racial group predominated. Phenytoin has also been reported to have direct effects on bone resorption [20][21][22] This study also has several important limitations. We did not include a group of women without epilepsy to serve as normal controls.…”

Modulation of Mononuclear Phagocyte Inflammatory Response by Liposome-Encapsulated Voltage Gated Sodium Channel Inhibitor Ameliorates Myocardial Ischemia/Reperfusion Injury in Rats

“…Whereas, the relative contribution of individual VGSCs to modulate monocyte/macrophage remains to be elucidated. It has been demonstrated that PHT treatment is associated with enhanced local production of vascular-endothelial growth factor (VEGF) [47], acidic fibroblast growth factor [48], platelet-derived growth factor [49] and TGF-β1 [50], which are all essential for neovascularization. Moreover, compared with Ly6C+ subset, Ly6C- monocytes selectively expressed higher levels of VEGF [43].…”