Assessment of the Role of Periodontal Ligament Stem Cells in Peri-implant Bone Regeneration: A Pre-clinical Study

ABSTRACT Introduction: Bone regeneration around implants is crucial for the performance of dental implants, particularly in areas where the bone is limited. Periodontal ligament stem cells (PDLSCs) are known for their considerable regenerative and osteogenic properties. This investigation is the first to evaluate PDLSC’s contribution toward peri-implant bone regeneration and assess their therapeutic role in regenerative strategies. Materials and Methods: Thirty male Sprague-Dawley rats were divided into three groups: Control (implant alone), Scaffold (implant + biphasic calcium phosphate scaffold), and PDLSC + scaffold (implant + PDLSCs on scaffold). Dental implants were placed in standardized tibial critical-size bone defects. PDLSCs were isolated from rat incisors, characterized, and expanded. After 8 weeks, tissues were analyzed via histology, histomorphometry, and micro-computed tomography (μCT) for bone-to-implant contact (BIC), new bone formation (NBF), and bone volume/total volume (BV/TV). Results: PDLSCs demonstrated characteristic mesenchymal stem cell markers (high CD73, CD90, CD105; low CD34, CD45, HLA-DR) and multipotency. μCT showed significantly higher BV/TV in the PDLSC + scaffold group (42.7 ± 4.5%) versus Scaffold (25.3 ± 3.2%) and Control (18.5 ± 2.1%) (P < 0.001). Histology revealed robust new bone formation and excellent integration in the PDLSC + scaffold group. Histomorphometry indicated significantly increased BIC (68.2 ± 5.3%) and NBF (75.6 ± 6.1%) in the PDLSC + scaffold group compared to Scaffold (BIC: 45.1 ± 4.8%; NBF: 55.4 ± 5.7%) and Control (BIC: 28.5 ± 3.9%; NBF: 35.2 ± 4.2%) groups (P < 0.001). Qualitative assessment showed mature lamellar bone and intimate bone-implant contact with PDLSCs. Conclusion: Implanting PDLSCs with a scaffold proves beneficial in implant-placed bone restoration when compared to pure scaffold approaches. This study, together with previous findings, suggests that PDLSCs may be effective in promoting cell-based therapies aimed at enhanced osseointegration in bone-deficient areas surrounding dental implants. A lot of work still stands to be done before reaching the clinical phase.