Dental Pulp-Derived Mesenchymal Stem Cells Increase Axon Numbers in Mental Nerve Repair

Abstract

Aim: The mental nerve, the extended part of the inferior alveolar nerve, is often injured during dentoalveolar, orthognathic, or tumor surgery. Numerous therapeutic interventions, including surgery and pharmacotherapy, have been used to enhance the recovery of nerve injuries. Dental pulp stem cells (DPSCs) represent an easily accessible source of adult stem cells that can be isolated from the pulp of extracted teeth. This study evaluated the effect of DPSCs on the regeneration of the mental nerve injury model of rabbits.

Methods: In this presented study, DPSCs were cultured and cell characterizations were performed by using flow cytometry and immunostainings. Bilateral mental nerve injury models of rabbits were created. In the control group (n = 10), saline was applied, and in the study group (n = 10), 2 × 106 DPSCs were applied to the repaired nerve areas. After 3 weeks, animals were killed and histological examination was obtained by using Masson's trichrome staining. An unpaired Student's t test was used when comparing the groups. Differences were considered to be statistically significant at P values of less than 0.05.

Results: The DPSCs demonstrated a homogeneous population of mesenchymal stromal cells which expressed cluster of differentiation CD44, CD73, CD90, and CD105 and lack of CD34, CD45, and HLA-DR. Our finding clearly demonstrated that a lower number of cross-sectioned axons were founded in the control group (60.18 ± 2.52) compared to the study group (72.96 ± 2.43) (p = 0.00).

Conclusions: DPSCs promote mental nerve axonal regeneration. These results suggest that DPSCs provide an important accessible source of adult stem cells for mental nerve regeneration.

Keywords: Inferior alveolar nerve; Mental nerve; Mesenchymal stem cells; Peripheral nerve regeneration.

Fig. 1

White arrow indicates N. mentalis in rabbit animal model

Fig. 2

DPSCs were positive expressed CD90, CD105, CD44, CD73 however negative for CD34, CD 45 and HLA-DR according to Flow cytometry analyses; CD44 positive Texas Red (red), CD105 positive FITC (green), CD45 negative FITC according to Immunocytochemistry

Fig. 3

Light microscopic appearance of sections of nerve in experimental groups A High power photomicrograph from study group. The axons (a) appear clear and the myelin is represented by surrounding the axons (arrow; myelin sheath). The connective tissue has been stained blue. It forms a network around the myelinated axons. B In the control group showed degenerated axons (arrow) and axonal connective tissue loosing (star) between axons. Masson’s trichrome, original magnification × 100. C Graph showing quantification of experimental groups. *p < 0.05, ** p < 0.01, *** p < 0.001