Mechanistic insights into dental stem cells-derived exosomes in regenerative endodontics

Abstract

Background: Dental pulp is a richly vascularised and innervated tissue vital for tooth vitality, sensory function, and structural integrity. While conventional root canal therapy effectively treats necrotic permanent teeth, it irreversibly eliminates pulp vitality, potentially increasing the risk of secondary infections and long-term structural compromise. In response, regenerative endodontics has emerged as a biologically favourable alternative that seeks to restore the pulp-dentine complex using principles of tissue engineering.

Objectives: This review aims to explore the therapeutic potential and mechanisms of action of exosomes derived from dental stem cells (DSC-Exos), a subclass of mesenchymal stem cells (MSCs), in promoting regeneration of the pulp-dentine complex, while also addressing translational challenges and proposing an integrated regenerative framework.

Methods: A comprehensive literature search was conducted across Web of Science, PubMed, and Scopus databases using keywords associated with "stem cells," "exosomes," "extracellular vesicles," and "dental pulp regeneration." Titles and abstracts were screened, and eligible studies were selected based on predefined inclusion criteria: (a) original research or case reports focusing on DSC-Exos in regenerative endodontics, (b) in vitro and in vivo studies, and (c) clinical trials or animal studies showing pulp-like tissue development. Studies not fulfilling these criteria were excluded. A total of 67 articles were included for narrative synthesis.

Results: DSC-Exos were found to facilitate multiple regenerative functions: promoting odontoblastic differentiation and dentine mineralisation, enhancing angiogenesis, regulating inflammation, modulating immune responses, promoting cell proliferation and migration, reducing apoptosis and senescence, and supporting neuroprotection. In-vivo studies demonstrated pulp-like tissue formation, revascularisation, and functional restoration. However, heterogeneity in exosome isolation, culture conditions, donor variability, and unclear molecular pathways remain unresolved issues.

Discussion: DSC-Exos present a promising acellular, immunologically safer approach to regenerative endodontics compared to direct stem cell transplantation. Despite their potential, the lack of standardised methodologies and incomplete understanding of their molecular interaction with odontoblasts hinders clinical translation. Integration of exosomes with scaffolds, growth factors, and endogenous cues may enhance regenerative efficacy.

Conclusions: DSC-Exos represent a novel frontier in regenerative endodontics. This review proposes a triangular framework encompassing DSCs, exosomes, signalling molecules, scaffolds, and the dentine microenvironment to support a holistic and clinically translatable model for pulp-dentine complex regeneration.

Keywords: dental pulp; exosomes; regeneration; regenerative endodontics; stem cells.

FIGURE 1

Exosomes are formed through a process involving the endosomal system in which proteins, nucleic acids or lipids accumulate at the endosomal membrane. This accumulation triggers the inward budding of the late‐sorting endosomal membrane, resulting in the formation of intraluminal vesicles. These exosomes are subsequently taken up by recipient cells via mechanisms such as endocytosis, receptor–ligand interactions and fusion. Once internalized, exosomes can influence various cellular processes in pulp healing and regeneration, including immunomodulation, odontoblastic differentiation and dentine formation, cell proliferation and migration, angiogenesis, apoptosis and senescence and neuroregeneration.

FIGURE 2

(a) Matrigel analysis demonstrating the effects of DPSC‐Exos (at concentrations of 10, 20 and 30 μg/mL at 2‐, 4‐ and 8‐h timepoints) on the tube formation of endothelial cells (reprinted with permission from Li, Wu, et al., 2022); (b) Tube formation analysis showing the endothelial differentiation of SHED‐ and SHED‐Exos (reprinted with permission from Wu et al., 2021); (c) Tube formation effects of Nor‐Exos and Hypo‐Exos on HUVECs (reprinted with permission from Li, Xian, et al., 2022); (d) Dose‐dependent tube formation effects of DPSCs in fibrin gels containing increasing concentrations of exosomes, with the most extensive tubular network forming at an exosomal concentration of 200 μg/mL (reprinted with permission from Zhang, Thiebes, et al., 2020).

FIGURE 3

Mechanism of angiogenesis mediated by the DSC‐Exos. DSCs secrete exosomes that promote endothelial cell proliferation, migration and tube formation, ultimately contributing to angiogenesis (reprinted with permission from Zou et al., 2023).

FIGURE 4

Immunomodulatory effects of the DSC‐Exos. DSC‐Exos influence immune cell populations, including monocytes, macrophages, antigen‐presenting cells (APCs), regulatory T cells (Tregs) and regulatory B cells (Bregs). Through the secretion of miRNAs and cytokines, DSC‐Exos modulate immune responses, contributing to immunoregulation. The exact mechanisms of interaction with certain cell types (i.e., Bregs) remain to be elucidated.

FIGURE 5

A schematic illustrating an innovative approach to regenerative endodontic therapies, integrating three traditional (i.e., dental stem cells, signal molecules including exosomes and scaffolds) and two contemporary elements (i.e., dentine niche including exosomes and atrophic/survival factors including exosomes). The arrows represent the interactions and influences exerted on DSC within their reconstructive niches.