Double-edged-sword effect of bisphosphonates on the osteogenic differentiation of human periodontal ligament stem cells

Mengyu Li^1,2,3,4,5,6Jiajia Wang^3,5,7Hanjin Ruan^2,3,4,5,6Zhouyang Wang^2,3,4Shaoyi Wang^3,5,8Yue He^2,3,4*Zhiyuan Zhang^2,3,4,5,6*

• ¹Shanghai Jiao Tong University, Shanghai, China
• ²Department of Oral-maxillofacial Head and Neck Oncology, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
• ³Shanghai Jiao Tong University College of Stomatology, Shanghai, China
• ⁴National Center for Stomatology, National Clinical Research Center for Oral Diseases, Shanghai, China
• ⁵Shanghai Key Laboratory of Stomatology; Shanghai Research Institute of Stomatology, Shanghai, China
• ⁶Research Unit of Oral and Maxillofacial Regenerative Medicine, Chinese Academy of Medical Sciences, Shanghai, China
• ⁷Department of Prosthodontics, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
• ⁸Department of Oral Surgery, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China

Bisphosphonates (BPs), widely used anti-resorptive agents for osteoporosis and cancer-related bone metastasis, can paradoxically contribute to medication-related osteonecrosis of the jaw (MRONJ). Our previous work showed that periodontal ligament stem cells (PDLSCs) from MRONJ patients display severely impaired osteogenesis; however, how BPs directly regulate PDLSC function remains unclear. In this study, human PDLSCs were exposed to graded concentrations of zoledronate (ZOL, 0.01–10 μM) to characterize dose-dependent effects on cell viability, apoptosis, and osteogenic differentiation. High-dose ZOL markedly reduced proliferation, induced apoptosis, and strongly inhibited osteogenesis. In contrast, low-dose ZOL promoted osteogenic differentiation in vitro, enhanced mineralization, and increased ectopic bone formation in vivo. Transcriptomic and molecular analyses revealed that ZOL activated Wnt/β-catenin and MAPK signaling, and blockade of either pathway attenuated the osteogenic enhancement. These findings demonstrate a double-edged-sword effect of BPs on PDLSCs: low-dose ZOL enhances osteogenesis through coordinated activation of Wnt/β-catenin and MAPK pathways, whereas high-dose exposure is cytotoxic and suppresses regenerative potential. The results underscore the necessity of precise BP dose control to maximize periodontal regeneration while minimizing MRONJ risk.