MSC-derived small extracellular vesicles promote dental pulp repair by alleviating inflammation in pulpitis via AKT and p38 MAPK pathways.

BACKGROUND

Pulpitis compromises dental pulp defense and repair, and current therapies inadequately resolve inflammation. Mesenchymal stem/stromal cell (MSC)-derived small extracellular vesicles (sEVs) exhibit potent anti-inflammatory properties, yet their protective role in inflamed dental pulp and underlying mechanisms remain unclear. This study aimed to evaluate the therapeutic potential of MSC-sEVs in experimental rat pulpitis, define the contribution of sEV-associated CD73 activity, and elucidate the molecular mechanisms by which MSC-sEVs attenuate lipopolysaccharide (LPS)-induced inflammatory responses in dental pulp cells (DPCs).

METHODS

sEVs were enriched from human MSC-conditioned medium by size-based fractionation and characterized for particle size, protein concentration, and CD73/ecto-5'-nucleotidase (NT5E) activity. Rat pulpitis was induced by LPS application to Class I cavities of maxillary molars. In vitro inflammation was modeled using LPS-stimulated DPC spheroids. Inflammatory mediators were quantified by nitric oxide (NO) quantification and enzyme-linked immunosorbent assay (ELISA), while signaling pathways were examined by Western blotting and pharmacological inhibition of CD73, adenosine receptors, AKT, ERK, and p38 MAPK.

RESULTS

MSC-sEVs significantly alleviated pulpal inflammation and promoted reparative dentin formation in vivo, with efficacy comparable to mineral trioxide aggregate (MTA). In LPS-stimulated DPC spheroids, MSC-sEVs suppressed pro-inflammatory and nociceptive mediator release. Mechanistically, MSC-sEVs reduced NO, IL-6, MMP9, and NGF production through a CD73-adenosine receptor-dependent pathway involving AKT activation and p38 MAPK inhibition, but not ERK signaling.

CONCLUSIONS

MSC-sEVs promote dental pulp repair by modulating inflammation through a CD73-mediated adenosine signaling axis, highlighting their potential as a cell-free therapeutic for early pulpitis intervention.