Effects of Parathyroid Hormone on Osteoblastic Differentiation of iPS Cells

Objectives: Parathyroid hormone (PTH) has been used for the treatment of osteoporosis and studied for application in periodontal regeneration because of its anabolic effects on bone. Induced pluripotent stem cells (iPSCs) are promising as a cell source for regeneration of periodontal tissues due to their ability of proliferation and pluripotency. However, the effects of PTH on osteoblastic differentiation of iPSCs are unknown. This study aimed to investigate the effects of PTH on osteoblastic differentiation of iPSCs in vitro.
Methods: Mouse iPSCs (miPSCs) were seeded on unadhesive plate to generate embryonic body (EB). EBs were treated with 0.05% trypsin EDTA and seeded into atelocollagen sponge (ACS) in osteoblast differentiation medium (OBM). Cells were divided into three groups: control, continuous PTH exposure (PTH-C), and intermittent PTH exposure (PTH-I) groups. PTH-I were cultured in OBM+PTH for the first 6 hours and in OBM alone for the next 42 hours. These cycles were repeated. Alkaline phosphatase (ALP) staining and real-time PCR were performed for evaluation of osteoblastic differentiation.
Results: Degree of ALP staining in PTH-I group tends to be higher than the control group and lower than PTH-C group. Real-time PCR analysis showed that the Alp mRNA expression in PTH-I group was significantly increased (approximately 4-fold) compared with PTH-C group on day 12 (p < 0.05, n = 8). There was no significant difference in the expression of osteocalcin mRNA among all three groups.
Conclusions: These results suggested that intermittent administration of PTH promotes early osteoblastic differentiation of miPSCs.