Osteogenic Potential of Gingival Mesenchymal Stem Cells Over Failed Implants

Objectives: Dental implants are a standard treatment option for the replacement of missing teeth. While the success rate is high, complications due to peri-implantitis are a cause of concern. Regenerative strategies have been employed to treat failing implants. However, they 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. GMSCs exhibit clonogenicity, self-renewal, and multipotent differentiation capacities. 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+ (GMSCs). GMSCs were characterized following the International Society for Cellular Therapy guidelines. GMSCs were plated on 6 failed and 6 new TiUnite® implants and osteogenesis was induced. Mineralization of calcium phosphate deposits were analyzed using Alizarin Red (AR) staining after 28 days. Bone nodule morphology and deposition was analyzed using Scanning Electron Microscopy (SEM) and energy-dispersive X-ray spectroscopy (ESD). Raman spectroscopy was used to compare the quality of the bone matrix deposited by GMSCs to that of human alveolar bone.
Results: GMSCs adhered and proliferated over failed implants. Flow cytometry confirmed the expression of stem cell surface markers CD 105, CD 90, CD 73, and CD 146. AR staining, SEM and ESD after 28 days confirmed that samples induced with osteogenic media deposited “bone nodules”. Raman spectra displayedphosphate, amide III, CH₂-scissors, and amide I peaks, similar to those observed in alveolar bone.
Conclusions: GMSCs can be induced to deposit hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂) [HA], over failed Ti 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.