Osteogenic Potential of Gingival Mesenchymal Stem Cells Over Failed Implants

Objectives: Dental implants have high success rate; however, complications due to peri-implantitis are a cause of concern. Regenerative strategies to treat failing implants are only partially effective. The goal of this study was to investigate the therapeutic potential of gingival mesenchymal stem cells (GMSCs) to treat peri-implantitis. We hypothesize that GMSCs can differentiate into osteoblasts in-vitro and deposit hydroxyapatite over failed implants from patients with peri-implantitis.
Methods: Healthy gingival tissue samples were collected from patients undergoing crown lengthening procedures. The heterogeneous gingival fibroblast population isolated from the tissue was sorted for cells expressing CD146+. Two implant surfaces were included in this study: TiUnite ® (Nobel Biocare) and SLActive ® (Straumann). GMSCs were plated on new and failed implants from patients with peri-implantitis, and osteogenesis was induced for 28 days. Calcium phosphate crystals were analyzed using Alizarin Red staining, Scanning Electron Microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Raman spectroscopy was used to compare the quality of the bone matrix deposited by GMSCs to that of human alveolar bone. A qPCR analysis was used to confirm the expression of osteoblast-related genes.
Results: GMSCs adhered and proliferated over new and failed implants. Flow cytometry confirmed the expression of stem cell surface markers. ARS staining, SEM and EDS after 28 days confirmed that samples induced with osteogenic media deposited calcium phosphate nodules. Raman spectra displayed phosphate, amide III, CH 2 -scissors, and amide I peaks, similar to those observed in alveolar bone. qPCR analysis showed an increase in expression of osteoblast-related genes.
Conclusions: GMSCs can be induced to deposit hydroxyapatite over failed implants. If HA deposition can be induced over failed dental implants, then it may be possible to re-osseointegrate failing dental implants caused by peri-implantitis in-vivo. Therefore, GMSCs may be an alternative cell-based therapy for the reconstruction of peri-implant osseous defects.