A new lyophilized formulation of the conditioned medium derived from periodontal ligament stem cells as anti-inflammatory agent

The secretome of mesenchymal stem cells (MSCs) includes the bioactive molecules released in the conditioned medium (CM) such as soluble proteins, free nucleic acids, lipids and extracellular vesicles. The secretome is known to mediate some of the beneficial properties related to MSCs, such as the anti-inflammatory, anti-apoptotic and regenerative capacities. In this work we aimed to evaluate the anti-inflammatory potential of a new lyophilized formulation of the CM derived from human periodontal ligament stem cells (hPDLSCs). With this aim we treated hPDLSCs with LPS and tested the anti-inflammatory potential of lyophilized CM (LYO) through the evaluation of the wound closure, the transcriptomic profile and the immunofluorescence analysis. We found that LPS treatment increased the expression of TLR4 and of genes involved in its signalling and in p38 andNF-kB activation, increasing also the expression of cytokines and chemokines. Interestingly, LYO downregulated the expression of genes involved in TLR4, p38 and NF-kB signalling. As a consequence, also the genes encoding for cytokines and chemokines were downregulated. Immunofluorescence acquisitions confirmed the downregulation of TLR4 and NF-kB signalling with LYO treatment. These results suggested the LYO represent an efficacious formulation with anti-inflammatory potential and highlighted lyophilization as a valid method to produce stable formulation of MSCs secretome.