Chitosan Tubes Inoculated with Dental Pulp Stem Cells and Stem Cell Factor Enhance Facial Nerve-Vascularized Regeneration in Rabbits

Advances in the Research of Mesenchymal Stromal Cells in the Treatment of Maxillofacial Neurological Disorders and the Promotion of Facial Nerve Regeneration

Maxillofacial neurological disorders include a range of disorders affecting the cranial nerves, which can be caused by a variety of reasons, including infection, trauma, tumor, and surgical complications, resulting in severe dysfunction, and the study of new approaches for the treatment of these disorders is crucial for the restoration of sensory and motor functions of the face. In recent years, due to the excellent tissue regenerative ability of mesenchymal stromal cells (MSCs), research on MSCs and MSC-derived exosomes has been progressively deepened, bringing many new perspectives to the therapeutic strategies for many diseases. Facial nerve regeneration is a complex process involving various pathophysiological mechanisms and therapeutic strategies to restore nerve function after injury. And the rapid development of stem cell tissue engineering has greatly facilitated the research process of facial nerve regeneration. In this paper, we review the characteristics of MSCs and neural stem cells (NSCs), the roles they play in the neural microenvironment and the mechanisms that promote nerve regeneration, summarize the research progress of MSCs in the treatment of maxillofacial neurological disorders, and highlight the promising directions for future development.

Efficacy and mechanisms of concentrated growth factor on facial nerve rehabilitation in a rabbit model

Accelerated rehabilitation following facial nerve injury presents unique clinical challenges. This study evaluates the therapeutic effects of concentrated growth factor (CGF) on facial nerve recovery in a rabbit model and on RSC96 Schwann cells. Characterization of the CGF membrane (CGFM) revealed a three-dimensional fibrin network with embedded platelets, and representative growth factors, including TGF-β1, PDGF-BB, IGF-1, bFGF, and VEGF, were detected. In vivo, the Crush + CGFM group exhibited enhanced axon and myelin regeneration, increased Schwann cell proliferation, and improved facial nerve function compared to the Crush group. In vitro, CGF treatment significantly promoted the proliferation and migration of RSC96 cells and facilitated axon elongation in NG108-15 cells compared to controls. Mechanistically, CGF treatment led to a significant increase in PDGFRβ phosphorylation. Inhibition of this pathway with SU16f decreased Schwann cell activity and hindered overall nerve rehabilitation. These results underscore CGF's potential to accelerate nerve repair by promoting axon and myelin regeneration and enhancing Schwann cell biological activity, with the PDGFRβ pathway playing a crucial regulatory role. This study highlights CGF as a promising therapeutic strategy for improving facial nerve rehabilitation.

The potential role of SCF combined with DPCs in facial nerve repair

Facial nerve injuries lead to significant functional impairments and psychological distress for affected patients. Effective repair of these injuries remains a challenge. For longer nerve gaps, the regeneration outcomes after nerve grafting remain suboptimal due to limited sources and postoperative immune responses. Tissue engineering techniques are conventional methods for repairing peripheral nerve defects. This study explores the potential of dental pulp cells (DPCs) combined with stem cell factor (SCF) to enhance neurogenic differentiation and improve facial nerve regeneration. DPCs were isolated from rabbit dental pulp, the pluripotency of the cells was identified from three perspectives: osteogenic differentiation, adipogenic differentiation, and neurogenic differentiation. In vivo experiments involved injuring the buccal branch of the facial nerve in New Zealand white rabbits, followed by treatment with PBS, DPCs, SCF, or SCF + DPCs. Functional recovery was assessed over 12 weeks, with SCF + DPCs demonstrating the most significant improvement in whisker movement scores. Histomorphological evaluations revealed enhanced myelinated fiber density and axonal morphology in the SCF + DPCs group. RNA sequencing identified 608 differentially expressed genes, with enrichment in the TGF-β signaling pathway. In in vitro experiments, we demonstrated from multiple angles using Western blot analysis, Real-time quantitative polymerase chain reaction (QPCR) analysis, and immunofluorescence staining that SCF can promote the neurogenic differentiation of DPCs through the TGF-β1 signaling pathway. Our findings indicate that the combination of SCF and DPCs offers a promising strategy for enhancing facial nerve repair.

Facial nerve regeneration via body-brain crosstalk: The role of stem cells and biomaterials

The human body is a complex, integral whole, and disruptions in one organ can lead to dysfunctions in other parts of the organ network. The facial nerve, as the seventh cranial nerve, arises from the brainstem, controls facial expression muscles and plays a crucial role in brain-body communication. This vulnerable nerve can be damaged by trauma, inflammation, tumors, and congenital diseases, often impairing facial expression. Stem cells have gained significant attention for repairing peripheral nerve injuries due to their multidirectional differentiation potential. Additionally, various biomaterials have been used in tissue engineering for regeneration and repair. However, the therapeutic potential of stem cells and biomaterials in treating facial nerve injuries requires further exploration. In this review, we summarize the roles of stem cells and biomaterials in the regeneration and repair of damaged facial nerves, providing a theoretical basis for the recovery and reconstruction of body-brain crosstalk between the brain and facial expression muscles.

Graphene/ chitosan tubes inoculated with dental pulp stem cells promotes repair of facial nerve injury

Introduction: Facial nerve injury significantly impacts both the physical and psychological] wellbeing of patients. Despite advancements, there are still limitations associated with autografts transplantation. Consequently, there is an urgent need for effective artificial grafts to address these limitations and repair injuries. Recent years have witnessed the recognition of the beneficial effects of chitosan (CS) and graphene in the realm of nerve repair. Dental pulp stem cells (DPSCs) hold great promise due to their high proliferative and multi-directional differentiation capabilities. Methods: In this study, Graphene/CS (G/CST) composite tubes were synthesized and their physical, chemical and biological properties were evaluated, then DPSCs were employed as seed cells and G/CST as a scaffold to investigate their combined effect on promoting facial nerve injury repair. Results and Disscussion: The experimental results indicate that G/CST possesses favorable physical and chemical properties, along with good cyto-compatibility. making it suitable for repairing facial nerve transection injuries. Furthermore, the synergistic application of G/CST and DPSCs significantly enhanced the repair process for a 10 mm facial nerve defect in rabbits, highlighting the efficacy of graphene as a reinforcement material and DPSCs as a functional material in facial nerve injury repair. This approach offers an effective treatment strategy and introduces a novel concept for clinically managing facial nerve injuries.

Unraveling the genetic basis of the causal association between inflammatory cytokines and osteonecrosis

Background

Previous studies have reported that the occurrence and development of osteonecrosis is closely associated with immune-inflammatory responses. Mendelian randomization was performed to further assess the causal correlation between 41 inflammatory cytokines and osteonecrosis.

Methods

Two-sample Mendelian randomization utilized genetic variants for osteonecrosis from a large genome-wide association study (GWAS) with 606 cases and 209,575 controls of European ancestry. Another analysis included drug-induced osteonecrosis with 101 cases and 218,691 controls of European ancestry. Inflammatory cytokines were sourced from a GWAS abstract involving 8,293 healthy participants. The causal relationship between exposure and outcome was primarily explored using an inverse variance weighting approach. Multiple sensitivity analyses, including MR-Egger, weighted median, simple model, weighted model, and MR-PRESSO, were concurrently applied to bolster the final results.

Results

The results showed that bFGF, IL-2 and IL2-RA were clinically causally associated with the risk of osteonecrosis (OR=1.942, 95% CI=1.13-3.35, p=0.017; OR=0.688, 95% CI=0.50-0.94, p=0.021; OR=1.386, 95% CI=1.04-1.85, p = 0.026). there was a causal relationship between SCF and drug-related osteonecrosis (OR=3.356, 95% CI=1.09-10.30, p=0.034).

Conclusion

This pioneering Mendelian randomization study is the first to explore the causal link between osteonecrosis and 41 inflammatory cytokines. It conclusively establishes a causal association between osteonecrosis and bFGF, IL-2, and IL-2RA. These findings offer valuable insights into osteonecrosis pathogenesis, paving the way for effective clinical management. The study suggests bFGF, IL-2, and IL-2RA as potential therapeutic targets for osteonecrosis treatment.

How to make full use of dental pulp stem cells: an optimized cell culture method based on explant technology

Introduction

Dental pulp stem cells from humans possess self-renewal and versatile differentiation abilities. These cells, known as DPSC, are promising for tissue engineering due to their outstanding biological characteristics and ease of access without significant donor site trauma. Existing methods for isolating DPSC mainly include enzyme digestion and explant techniques. Compared with the enzymatic digestion technique, the outgrowth method is less prone to cell damage and loss during the operation, which is essential for DPSC with fewer tissue sources.

Methods

In order to maximize the amount of stem cells harvested while reducing the cost of DPSC culture, the feasibility of the optimized explant technique was evaluated in this experiment. Cell morphology, minimum cell emergence time, the total amount of cells harvested, cell survival, and proliferative and differentiation capacity of DPSC obtained with different numbers of explant attachments (A1-A5) were evaluated.

Results

There was a reduction in the survival rate of the cells in groups A2-A5, and the amount of harvested DPSC decreased in A3-A5 groups, but the DPSC harvested in groups A1-A4 had similar proliferative and differentiation abilities. However, starting from group A5, the survival rate, proliferation and differentiation ability of DPSC decreased significantly, and the adipogenic trend of the cells became more apparent, indicating that the cells had begun to enter the senescence state.

Discussion

The results of our study demonstrated that the DPSC obtained by the optimized explant method up to 4 times had reliable biological properties and is available for tissue engineering.

Porous Organic Materials in Tissue Engineering: Recent Advances and Applications for Severed Facial Nerve Injury Repair

The prevalence of facial nerve injury is substantial, and the restoration of its structure and function remains a significant challenge. Autologous nerve transplantation is a common treatment for severed facial nerve injury; however, it has great limitations. Therefore, there is an urgent need for clinical repair methods that can rival it. Tissue engineering nerve conduits are usually composed of scaffolds, cells and neurofactors. Tissue engineering is regarded as a promising method for facial nerve regeneration. Among different factors, the porous nerve conduit made of organic materials, which has high porosity and biocompatibility, plays an indispensable role. This review introduces facial nerve injury and the existing treatment methods and discusses the necessity of the application of porous nerve conduit. We focus on the application of porous organic polymer materials from production technology and material classification and summarize the necessity and research progress of these in repairing severed facial nerve injury, which is relatively rare in the existing articles. This review provides a theoretical basis for further research into and clinical interventions on facial nerve injury and has certain guiding significance for the development of new materials.

The Effect of Biomaterials on Human Dental Pulp Stem Cell Neural Differentiation: A Scoping Review

Neural cells are the most important components of the nervous system and have the duty of electrical signal transmission. Damage to these cells can lead to neurological disorders. Scientists have discovered different methods, such as stem cell therapy, to heal or regenerate damaged neural cells. Dental stem cells are among the different cells used in this method. This review attempts to evaluate the effect of biomaterials mentioned in the cited papers on differentiation of human dental pulp stem cells (hDPSCs) into neural cells for use in stem cell therapy of neurological disorders. We searched international databases for articles about the effect of biomaterials on neuronal differentiation of hDPSCs. The relevant articles were screened by title, abstract, and full text, followed by selection and data extraction. Totally, we identified 731 articles and chose 18 for inclusion in the study. A total of four studies employed polymeric scaffolds, four assessed chitosan scaffolds (CS), two utilised hydrogel scaffolds, one investigation utilised decellularised extracellular matrix (ECM), and six studies applied the floating sphere technique. hDPSCs could heal nerve damage in regenerative medicine. In the third iteration of nerve conduits, scaffolds, stem cells, regulated growth factor release, and ECM proteins restore major nerve damage. hDPSCs must differentiate into neural cells or neuron-like cells to regenerate nerves. Plastic-adherent cultures, floating dentosphere cultures, CS, polymeric scaffolds, hydrogels, and ECM mimics have been used to differentiate hDPSCs. According to our findings, the floating dentosphere technique and 3D-PLAS are currently the two best techniques since they result in neuroprogenitor cells, which are the starting point of differentiation and they can turn into any desired neural cell.

Potential Application of Orofacial MSCs in Tissue Engineering Nerve Guidance for Peripheral Nerve Injury Repair

Injury to the peripheral nerve causes potential loss of sensory and motor functions, and peripheral nerve repair (PNR) remains a challenging endeavor. The current clinical methods of nerve repair, such as direct suture, autografts, and acellular nerve grafts (ANGs), exhibit their respective disadvantages like nerve tension, donor site morbidity, size mismatch, and immunogenicity. Even though commercially available nerve guidance conduits (NGCs) have demonstrated some clinical successes, the overall clinical outcome is still suboptimal, especially for nerve injuries with a large gap (≥ 3 cm) due to the lack of biologics. In the last two decades, the combination of advanced tissue engineering technologies, stem cell biology, and biomaterial science has significantly advanced the generation of a new generation of NGCs incorporated with biological factors or supportive cells, including mesenchymal stem cells (MSCs), which hold great promise to enhance peripheral nerve repair/regeneration (PNR). Orofacial MSCs are emerging as a unique source of MSCs for PNR due to their neural crest-origin and easy accessibility. In this narrative review, we have provided an update on the pathophysiology of peripheral nerve injury and the properties and biological functions of orofacial MSCs. Then we have highlighted the application of orofacial MSCs in tissue engineering nerve guidance for PNR in various preclinical models and the potential challenges and future directions in this field.

Improved Method for Dental Pulp Stem Cell Preservation and Its Underlying Cell Biological Mechanism

Dental pulp stem cells (DPSCs) are considered a valuable cell source for regenerative medicine because of their high proliferative potential, multipotency, and availability. We established a new cryopreservation method (NCM) for collecting DPSCs, in which the tissue itself is cryopreserved and DPSCs are collected after thawing. We improved the NCM and developed a new method for collecting and preserving DPSCs more efficiently. Dental pulp tissue was collected from an extracted tooth, divided into two pieces, sandwiched from above and below using cell culture inserts, and cultured. As a result, the cells in the pulp tissue migrated vertically over time and localized near the upper and lower membranes over 2-3 days. With regard to the underlying molecular mechanism, SDF1 was predominantly involved in cell migration. This improved method is valuable and enables the more efficient collection and reliable preservation of DPSCs. It has the potential to procure a large number of DPSCs stably.