Combined effects of systemic parathyroid hormone (1–34) and locally delivered neutral self‐assembling peptide hydrogel in the treatment of periodontal defects: An experimental in vivo investigation

Abstract Aim To evaluate in vivo combination therapy of systemic parathyroid hormone (PTH) and locally delivered neutral self‐assembling peptide (SAP) hydrogel for periodontal treatment. Materials and Methods Viability/proliferation of rat periodontal ligament cells in a neutral SAP nanofibre hydrogel (SPG‐178) was evaluated using WST‐1 assay. Periodontal defects were created mesially to the maxillary first molars in 40 Wistar rats. Defects were filled with 1.5% SPG‐178 or left unfilled. Animals received PTH (1‒34) or saline injections every 2 days. Microcomputed tomography, histological, and immunohistochemical examinations were used to evaluate healing at 2 or 4 weeks postoperative. Results At 72 hr, cells in 1.5% SPG‐178 showed increased viability/proliferation compared to cells in 0.8% SPG‐178 or untreated controls. In vivo, systemic PTH resulted in significantly greater bone volume in the Unfilled group at 2 weeks ( p = .01) and 4 weeks ( p < .0001) than in the saline control. At 4 weeks, a significantly greater bone volume was observed in the PTH/SPG‐178 ( p = .0003) and PTH/Unfilled ( p = .004) groups than in Saline/SPG‐178 group. Histologically, greater bone formation was observed in PTH/SPG‐178 at 4 weeks than in other groups. In the PTH/SPG‐178 group, increased proportions of PCNA‐, VEGF‐, and Osterix‐positive cells were observed in the treated sites. Conclusions These findings suggest that intermittent systemic PTH and locally delivered neutral SAP hydrogel enhance periodontal healing.