Stem Cell therapy for Periodontal Tissue Regeneration: An in vitro Study

Objectives: The aim of this study was to formulate an injectable scaffold based on alginate-nanohydroxypatite and to encapsulate the gingival mesenchymal stem cells (GMSC) and periodontal ligament stem cells (PDLSC) in the hydrogel beads.  

Methods: Stem cells were encapsulated using alginate hydrogel. Nano-HAp particles were used to mechanically reinforce the alginate scaffolds. The stem cell viability, proliferation and differentiation to adipogenic and osteogenic tissues were studied. To investigate the expression of both adipogenesis and ontogenesis related genes, the RNA was extracted and RT-PCR was performed. Human bone marrow mesenchymal stem cells (hBMMSC) was used as the positive control and the alginate hydrogel was used as the negative control in this study. The degradation behavior of hydrogel based on oxidized sodium alginate with different degrees of oxidation was studied in PBS at 37^oC as a function of time by monitoring the changes in weight loss. 

Results: Alginate a promising candidate as a non-toxic scaffold for GMSCs. It also has the ability to direct the differentiation of these stem cells to osteogenic and adipogenic tissues as compared to the control group (hBMMSC) in vitro. The encapsulated cells remained viable and both osteo-differentiated and adipo-differentiated after 4 weeks of culturing in the induction media with higher intensities in comparison to the control group. The density of the differentiated tissue from GMSC and PDLSC was significantly higher than the positive control group (P<0.05). Also, it was found that the degradation profile of alginate hydrogel strongly depends on the degree of oxidation showing its tunable chemistry and degradation rate. 

Conclusions: The proposed stem cell-scaffold system might be a promising approach for not only the periodontal tissue regeneration but also for treatment of the maxillofacial and skeletal defects. The presented technology might be used as a platform to enable the clinicians for soft/hard tissue generation and regeneration.