Dental pulp stem cells (DPSCs) were widely used as seed cells in the field of tissue engineering and regenerative medicine, including spinal cord injury (SCI) repair and other neuronal degenerative diseases, due to their easy isolation, multiple differentiation potential, low immunogenicity and low rates of rejection during transplantation. Various studies have shown that bFGF can enhance peripheral nerve regeneration after injury, and phospho-ERK (p-ERK) activation as a major mediator may be involved in this process. Previous studies also have proved that a suitable biomaterial scaffold can carry and transport the therapeutic cells effectively to the recipient area. It has showed in our earlier experiments that 3D porous chitosan scaffolds exhibited a suitable circumstance for survival and neural differentiation of DPSCs in vitro. In current study, DPSCs were cultured in chitosan scaffolds and treated with neural differentiation medium for 7 days. The neural genes and protein markers were analyzed by western blot and immunofluorescence. Meanwhile, the relevant signaling pathway involved in this process was also tested. Our study revealed that the viability of DPSCs was not influenced by co-culture with the chitosan scaffolds as well as bFGF. Compared with the control and DPSC/chitosan-scaffold groups, the levels of GFAP, S100β and β-tubulin III significantly increased in the DPSC/chitosan-scaffold + bFGF group. Thus, chitosan scaffolds were non-cytotoxic to the survival of DPSCs, and chitosan scaffolds combined with bFGF facilitated the neural differentiation of DPSCs. The transplantation of DPSCs/chitosan-scaffold + bFGF might be a secure and effective method of treating SCI and other neuronal diseases.

Periodontitis is recognized as the major cause of tooth loss in adults, posing an adverse impact on systemic health. In periodontitis, excessive production of reactive oxygen species (ROS) at the inflamed site culminates in periodontal destruction. In this study, a novel ROS-responsive drug delivery system based on polydopamine (PDA) functionalized mesoporous silica nanoparticles was developed for delivering minocycline hydrochloride (MH) to treat periodontitis. The outer PDA layer and the inner MH of the nanoparticles acted as ROS scavengers and anti-inflammatory agents, respectively. Under the synergistic action of PDA and MH, macrophages were polarized from the pro-inflammatory M1 to the anti-inflammatory M2 phenotype. The in vitro experiments provided convincing evidence that PDA could scavenge ROS effectively, and the expression of pro-inflammatory cytokines was attenuated and the secretion of anti-inflammatory cytokines was enhanced through M1 to M2 polarization of macrophages with the cooperation of MH. In addition, the results obtained from the periodontitis rat models demonstrated that the synergetic effect of PDA and MH prevented alveolar bone loss without causing any adverse effect. Taken together, the results from the present investigation provide a new strategy to remodel the inflammatory microenvironment by inducing the polarization of macrophages from M1 toward M2 state for the treatment of periodontitis.