Published online Apr 26, 2022. doi: 10.4252/wjsc.v14.i4.287
Peer-review started: March 28, 2021
First decision: May 12, 2021
Revised: May 19, 2021
Accepted: April 21, 2022
Article in press: April 21, 2022
Published online: April 26, 2022
Processing time: 393 Days and 16.6 Hours
Dental Mesenchymal stem cells are progenitor populations recovered from dental and periodontal tissues easily accessible when a tooth is extracted (and usually discarded as medical waste). One of the main effects of Mesenchymal stem cells on tissue regeneration is due to their paracrine activity, mediated by their secreted substances defined as secretome or conditioned medium. Conditioned medium represents a cell-free product with wide potential applications for various diseases treatment and tissue regeneration.
Conditioned medium manufacturing suffers from variable procedures and protocols. Results presented by various studies are difficult to compare, due to the different methods of production. Moreover, there is no well-defined optimized procedure to specifically target specialized tissue in regenerative medicine.
To describe potential consensus for the standardization and optimization of manufacturing procedures, mandatory for further clinical applications. In this systematic review, we focused on conditioned medium produced from Dental Mesenchymal stem cells. We explored the current parameters and culture conditions used in the manufacturing protocols.
The bibliographic research was conducted in accordance with the PRISMA guidelines. All articles published between 2006 and 2020 investigating the effects of Dental Mesenchymal stem cells secretome on tissue regeneration were selected. We used the electronic PubMed database with these search terms: ((dental stem cells) AND ((conditioned medium) OR (secretome))) / ((dental stem cells) AND ((extravesicles) OR (exosomes))). Only publications in English were considered.
Based on the inclusion criteria, 118 articles were included in the systematic review. Conditioned medium production was considered at three levels: before recovery (cell sources), during production (culture conditions) and after production (secretome treatment). We identified key points that were often taken into account in the published experimental works.
Among all the considered key points, no consensus could be highlighted. However, some tendencies could be described: cells used were mainly from donors under 30 years of age, with cell passage between 1 and 5, at a confluence of 70% to 80%. Conditioned medium was usually collected during the first 48 h, and kept frozen at -80°C. The various microenviroenmental cues were shown many times to have a significant impact on protein content, and improved effects on specifically targeted applications: each preconditioning manipulation induced a specific protein expression profile.
Standardization of procedures is of prior importance to develop clinical-grade products. However, the protein contents of secretome is more linked to preconditioning than to specific technical methods. The challenge to overcome in the near future is to define specific preconditioning protocols to produce tissue specific conditioned medium (i.e, osteogenic environement, neuronal environment, cell incubation with inflammatory proteins…).