Dental Pulp Cell Sheets Enhance Facial Nerve Regeneration via Local Neurotrophic Factor Delivery

Abstract

An effective strategy for sustained neurotrophic factor (NTF) delivery to sites of peripheral nerve injury (PNI) would accelerate healing and enhance functional recovery, addressing the major clinical challenges associated with the current standard of care. In this study, scaffold-free cell sheets were generated using human dental pulp stem/progenitor cells, that endogenously express high levels of NTFs, for use as bioactive NTF delivery systems. Additionally, the effect of fibroblast growth factor 2 (FGF2) on NTF expression by dental pulp cell (DPC) sheets was evaluated. In vitro analysis confirmed that DPC sheets express high levels of NTF messenger RNA (mRNA) and proteins, and the addition of FGF2 to DPC sheet culture increased total NTF production by significantly increasing the cellularity of sheets. Furthermore, the DPC sheet secretome stimulated neurite formation and extension in cultured neuronal cells, and these functional effects were further enhanced when DPC sheets were cultured with FGF2. These neuritogenic results were reversed by NTF inhibition substantiating that DPC sheets have a positive effect on neuronal cell activity through the production of NTFs. Further evaluation of DPC sheets in a rat facial nerve crush injury model in vivo established that in comparison with untreated controls, nerves treated with DPC sheets had greater axon regeneration through the injury site and superior functional recovery as quantitatively assessed by compound muscle action potential measurements. This study demonstrates the use of DPC sheets as vehicles for NTF delivery that could augment the current methods for treating PNIs to accelerate regeneration and enhance the functional outcome.

Dental-derived mesenchymal stem cell sheets: a prospective tissue engineering for regenerative medicine

“…DPSC sheets act as an NTF transmission system to promote axon extension and significantly enhance nerve regeneration. All these results suggest the optimistic outlook of DPSC sheets for the treatment of peripheral nerve injury [ 40 ]. Currently, new biomaterials, such as nerve conduits and porous scaffolds, are widely used in the treatment of peripheral nerve injury and spinal cord injury.…”

Therapeutic potential of dental pulp stem cells and their derivatives: Insights from basic research toward clinical applications

“…To date, use of DPSC sheets has been reported for the regenerative treatment of a variety of injuries, including but not limited to dental pulp diseases[ 112 ], periodontal tissue diseases[ 121 ], bone defects[ 122 ], nerve injuries[ 123 , 124 ], etc ., and all of these applications have achieved significant results. In one representative clinical study, autologous DPSC sheets from deciduous teeth were transplanted into injured young permanent teeth due to trauma.…”

“…This transplantation was able to regenerate whole dental pulp, increase the length of the root and reduce the width of the apical foramen at 12 mo after treatment[ 125 ]. Furthermore, the evaluation of DPSC sheets in a rat facial nerve crush injury model in vivo established that in comparison to untreated controls, nerves treated with dental pulp cell sheets had greater axon regeneration through the injury site and superior functional recovery as quantitatively assessed by compound muscle action potential measurements, possibly because the DPSC sheets can highly express neurotrophic factor (NTF) and continuously deliver the NTF to sites of peripheral nerve injury[ 123 ]. Moreover, bioengineered teeth using human DPSC aggregates combined with decellularized tooth matrix or avulsed teeth after traumatic dental injuries can regenerate 3D dental pulp and periodontium equipped with vasculature and innervation in both a preclinical pig model and a pilot clinical trial for treating tooth avulsion[ 126 ].…”

Potential application of dental stem cells in regenerative reconstruction of oral and maxillofacial tissues: a narrative review

“…In a pilot clinical studies with two patients with periodontal intrabone defects, the same group reported that DPSCs-IPs generated new bones to repair the periodontal defects 9 months after surgical reconstruction (99). For craniofacial nerve regeneration, implantation of DPSCsheets and DPSCs infilled in PLGA artificial nerve conduits significantly promoted crush-injured and segmental defect models of rat facial nerves, respectively (100,101). The superior laryngeal nerve (SLN) plays an essential role in swallowing.…”