Plasma-derived mitochondria as a minimal manipulation alternative for attenuating inflammatory immune responses

Platelet-rich plasma (PRP) has long been used to promote tissue repair through its content of cytokines, growth factors and platelet-derived mitochondria (PLT-mito). While effective, PRP often triggers an early M1-type inflammatory response that may worsen symptoms in chronic inflammatory conditions and limit its clinical utility. Harvesting functional PLT-mito usually requires platelet activation or mechanical disruption, which can exceed minimal manipulation thresholds under regulatory guidelines. In contrast, plasma-derived mitochondria (p-mito) provide an alternative, as they are naturally present in circulating plasma and can be obtained by simple centrifugation without activation or cell disruption. In this study, we compared the effects of platelets, PLT-mito, platelet releasate and p-mito on macrophage polarization and fibroblast repair assays using THP-1 and HDF models. Macrophage polarization was quantified at the RNA level by PCR of M1-associated (CD80, CD86) and M2-associated (CD163, CD206) surface-marker transcripts after each treatment. Platelets and platelet releasate predominantly induced M1-like polarization, whereas both PLT-mito and p-mito promoted an M2 phenotype. Notably, p-mito achieved M2 induction comparable to PLT-mito without requiring prior activation or manipulation. In a fibroblast scratch migration assay, p-mito enhanced cell migration and proliferation, replicating the pro-reparative effects of platelets. These findings suggest that p-mito are a functionally competent, cell-free therapeutic modality capable of modulating macrophage phenotypes without triggering early inflammatory priming. This minimally manipulated, clinically accessible mitochondrial therapeutic can be prepared and applied in a manner similar to PRP, with the potential to reduce early pro-inflammatory responses.