Clinical and Histomorphometric Evaluation of the Regenerative Potential of Gingival Mesenchymal Stem Cells in Collagen and Nano-Hydroxyapatite Scaffolds in Treatment of Periodontal Defects (Experimental Study)

Abstract

Periodontitis is an infectious disease of the periodontal tissue that can lead to tooth loss in adults. The lost periodontium, including both hard (alveolar bone and cementum) and soft (periodontal ligament [PDL]) tissues, needs to be restored to its original architecture. The complex microenvironment of the periodontal wound creates many challenges associated with the regeneration of multiple tissue types within periodontal lesions. Tissue engineering has recently provided alternative technologies to regenerate tissue defects by transplantation of appropriate cells and manipulated expression of associated genes or proteins MSCs are adult stem cells with the ability to give rise to multiple specialized cell types. MSCs have become an attractive target for use in periodontal regeneration; hence, MSCs derived from multiple tissue sources have been investigated in preclinical animal studies for the treatment and regeneration of the periodontium. GMSCs are a population of MSCs derived from human gingiva that are also capable of self-renewal, multipotent differentiation, and immunomodulation .Gingiva can easily be obtained in the clinic, and the isolation of GMSCs is simple, making GMSCs good candidates for tissue regeneration and cell-based therapy. Biomatrices play crucial roles in reconditioning the microenvironments of stem cells, providing key matrix cues for anchoring and spreading, to support self-renewal and appropriate differentiation. A surface that mimics native tissue ECM in terms of composition, topography, and rigidity is better recognizable to stem cells and more effective in driving them to differentiate into target tissues. Some recent technological advances have facilitated the development of tissue-mimicking designs of biomatrices. NHA and collagen scaffolds can be used in periodontal regeneration which similar to the bone architecture, so they became widely used in bone tissue engineering. The present study aimed to assess the regenerative power of GMSCs in chronic periodontal defects in beagle dogs by using different scaffolds for GMSCs. Eighty dogs were included in this study. Periodontal defects were induced at four sites in each dog in premolar/molar region.Within each dog, the defects were randomly treated with GMSCs with Nano-HA loaded in collagen (Group I), GMSCs loaded in collagen scaffold (Group II), Nano-HA in collagen sponge (Group III) and collagen sponge alone as a control group (Group IV). Moreover, clinical assessments including PD, clinical CAL and the depth of the bony defects were assessed at baseline and after 4weeks. Histological and histomorphometric analysis were done. Densitometry, cell number and area percentage of newly formed bone were detected using LeicaQWinPlus software. Variables were compared between groups by Wilcoxon Signed Ranks Test. The results of the present study revealed that there was statistically significant decrease in the depth of the bony defect, decrease in PD and gain in CAL in the four groups. The comparison between the four groups regarding BD, PD and CAL showed that there was no statistically significant difference (P-value =0.735, 0.220 and 0.467, respectively). While the histological cell count revealed that there was a statistically significant difference in mean cell count between the four groups (P-value < 0.001), but there was no statistically significant difference between Group I and Group III; both showed the highest mean cell counts. Group II showed lower mean cell count with non-statistically significant difference from Group I and Group III. Group IV showed the statistically significantly lowest mean cell count. Regarding the optical density There was a statistically significant difference between the four groups (P-value = 0.009). But there was no statistically significant difference between Group I and Group III; both showed the highest mean optical density. There was no statistically significant difference between Group II and Group IV; both showed the statistically significantly lowest mean optical density. There was a statistically significant difference between the four groupsin area percentage of newley formed bone (P-value < 0.001). Pair-wise comparisons between the groups revealed that Group I showed the statistically significantly highest mean area %. There was no statistically significant difference between Group II and Group III; both showed significantly lower mean area %. Group IV showed the statistically significantly lowest mean area %.