Physical and Biological Properties of a Chitosan Hydrogel Scaffold Associated to Photobiomodulation Therapy for Dental Pulp Regeneration: An In Vitro and In Vivo Study

Abstract

Background. The regeneration of dental pulp, especially in cases of pulp death of immature teeth, is the goal of the regenerative endodontic procedures (REPs) that are based on tissue engineering principles, consisting of stem cells, growth factors, and scaffolds. Photobiomodulation therapy (PBMT) showed to improve dental pulp regeneration through cell homing approaches in preclinical studies and has been proposed as the fourth element of tissue engineering. However, when a blood clot was used as a scaffold in one of these previous studies, only 30% of success was achieved. The authors pointed out the instability of the blood clot as the regeneration shortcoming. Then, to circumvent this problem, a new scaffold was developed to be applied with the blood clot. The hypothesis of the present study was that an experimental injectable chitosan hydrogel would facilitate the three-dimensional spatial organization of endogenous stem cells in dental pulp regeneration with no interference on the positive influence of PBMT. Methods. For the in vitro analysis, stem cells from the apical papilla (SCAPs) were characterized by flow cytometry and applied in the chitosan scaffold for evaluating adhesion, migration, and proliferation. For the in vivo analysis, the chitosan scaffold was applied in a rodent orthotopic dental pulp regeneration model under the influence of PBMT (660 nm; power output of 20 mW, beam area of 0.028 cm2, and energy density of 5 J/cm2). Results. The scaffold tested in this study allowed significantly higher viability, proliferation, and migration of SCAPs in vitro when PBMT was applied, especially with the energy density of 5 J/cm2. These results were in consonance to those of the in vivo data, where pulp-like tissue formation was observed inside the root canal. Conclusion. Chitosan hydrogel when applied with a blood clot and PBMT could in the future improve previous results of dental pulp regeneration through cell homing approaches.

Pro‐angiogenic potential of a functionalized hydrogel scaffold as a secretome delivery platform: An innovative strategy for cell homing‐based dental pulp tissue engineering

“…In previous studies by our group, the chitosan hydrogel was able to act as a scaffold for regenerative endodontic procedures, having adequate physicochemical properties, allowing cell adhesion and migration through scaffold, with the advantage of having an antimicrobial effect (Caballero‐Flores et al., 2021; Moreira et al., 2021), and enabling orthotopic pulp regeneration in rats, but the results for complete and functional pulp regeneration were still unpredictable. We hypothesized that the initial colonization does not guarantee the survival of the endogenous stem cells into the root canal over time, and the growth factors present and released by the dentin walls cannot be enough to induce significant angiogenesis to maintain neo formed tissue perfusion (Moreira et al., 2021).…”

“…For the crosslinking of the hydrogel, glycerol phosphate was used as a crosslinker (0.25 ml of crosslinker to 1 ml of chitosan gel). The pre‐gel was stirred using a magnetic bar at 4°C for 10 min (Moreira et al., 2021).…”

“…Chitosan scaffold showed appropriate viscosity, swelling, degradation, and ultrastructure for application in regenerative endodontics, in addition to allowing cell adhesion and migration through scaffold. Neo‐formed pulp‐like tissue was observed; however, the results were unpredictable since full‐length pulp tissue regeneration was not achieved in all samples (Moreira et al., 2021). We hypothesized that even in the presence of trophic factors released by the dentin walls after ethylenediaminetetraacetic acid application, the amount could have been low and available very quickly, which leads to incomplete pulp regeneration.…”

“…Among the strategies investigated for pulp regeneration, we can highlight the cell homing-based approach (He et al, 2017;J. Y. Kim et al, 2010;Moreira et al, 2017Moreira et al, , 2021, which is based on the recruitment of resident stem cells by signaling molecules, which induce cell migration into a scaffold as well as proliferation and differentiation (Ahmed et al, 2021). However, there are still challenges regarding the recruitment and viability of mesenchymal stem cells (MSCs), as well as angiogenesis in an avascular environment with low oxygen tension within the root canal (Moreira et al, 2017;Zhujiang & Kim, 2016).…”

Engineering of Injectable Antibiotic-laden Fibrous Microparticles Gelatin Methacryloyl Hydrogel for Endodontic Infection Ablation

“…In light of offering a biocompatible scenario for the disinfection of contaminated root canals, biodegradable drug delivery systems (e.g., scaffolds and hydrogels) laden with antimicrobial agents have gained the attention of researchers, and several studies are currently characterizing their clinical potential [11][12][13][14]. Concerning the use of fibrous scaffolds, electrospinning is a straightforward method for synthesizing antibiotic-laden polymeric nanofibers [6,9,15,16].…”