Priming mobilized peripheral blood mononuclear cells with the "activated platelet supernatant" enhances the efficacy of cell therapy for myocardial infarction of rats.

Aim: Various methods are used to augment the efficacy of cell therapy in myocardial infarction (MI). In this study, we used the "activated platelet supernatant (APS)" to prime autologous "granulocyte colony-stimulating factor-mobilized peripheral blood mononuclear cells ((mob) PBMCs)" and investigated the efficacy of cell-based therapy in MI.

Method: Rat (mob) PBMCs were isolated after daily subcutaneous injections of G-CSF at 100 μg/kg for 3 days. APS was isolated separately after activating rat platelets with thrombin 0.5 U/mL for 2 hours. Priming was performed with APS for 6 hours. To check the paracrine effect of primed (mob) PBMCs, we used the 36-hour culture supernatant of the primed cells. A rat MI model was used for an in vivo model.

Result: Cytokines such as IL-1β, IL-10, and TGFβ were 3.7±0.9-fold, 3.4±1.2-fold, and 1.2±0.1-fold higher in APS, respectively, compared with naïve platelet supernatant. By APS priming, (mob) PBMCs showed M2 polarization and upregulation of angiogenic molecules (i.e., TEK, IL-10, CXCL1, and CX3CR1). APS-primed (mob) PBMCs had a 2.3-fold increased adhesion ability, induced by upregulated integrins. Rat endothelial cells cultured in the 36-hour culture supernatant of APS-primed (mob) PBMCs showed a 1.6-fold augmented proliferation and capillary network formation. In vivo transplantation of APS-primed (mob) PBMCs into rat MI models showed a significant trend of reduction in fibrosis area (P=.001) and wall thinning (P=.030), which lead to improvement in cardiac function measured by echocardiography.

Conclusion: Our data reveal that APS priming can enhance the wound-healing potential of (mob) PBMCs. APS priming may be a promising method for cell-based therapy of MI.