Regenerative endodontics has been described as a paradigm shift in dentistry, despite its current limitation to immature teeth and reparative rather than regenerative outcomes. Cell-free treatments are favored because of regulatory issues. However, the recruitment of host-derived stem cells to the desired site remains challenging.
University of Zurich researchers investigated whether dental pulp-derived exosomes, which are extracellular vesicles that contain proteins, lipids, RNA, and DNA and thus mirror their parental cells, may be used for this purpose. The use of exosomes may present appreciable advantages over the direct use of transplanted stem cells due to a higher safety profile, easier isolation, preservation, and handling. Here they harvested exosomes from a cultured third-molar pulp cell and assessed them by transmission electron microscopy and Western blotting. Human mesenchymal stem cells (MSCs) were exposed to these exosomes to assess exosome uptake, cell migration, and proliferation. In addition, a fibrin gel (i.e., a diluted fibrin sealant), was assessed as a delivery system for the exosomes.
Confocal immunofluorescent analysis of exosome uptake using DAPI to stain the nucleus
Red dots (A,D) represent exosomes. (B,F), Alexa Fluor 488 to stain cytoskeletal actin (C,G), and BODIPY TR to stain exosomes (D,H). (A) and (E) are merged images. Labeled exosomes were isolated from the culture supernatants of dental pulp cells (DPCs). Human bone marrow‐derived mesenchymal stem cells (HBMMSCs) were cultured with labeled exosomes. The red signal was not expressed in the negative control where non‐labeled exosomes were added to the cells (E–H). Scale bar represents 20 μm
These results show that exosomes attracted MSCs, and the fibrin gel enhanced their effect. Moreover, exosomes improved the proliferation of MSCs. Therefore, the researchers propose that pulp-derived exosomes in combination with a fibrin gel could be a powerful combination for clinical translation towards improved cell-free regenerative endodontics and thus represent a new way to fill dental hard tissues.