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Background In heart transplantation, donor hearts inevitably suffer from ischemia/reperfusion (I/R) injury, which leads to primary graft dysfunction and affects patients’ survival rate. Bone marrow mesenchymal stem cells (BMSCs) have been reported to attenuate myocardial I/R injury via their paracrine effects, which can be enhanced by hypoxic preconditioning. We hypothesized that the donor heart preservation with hypoxic conditioned medium (CdM) derived from BMSCs would improve post-transplant graft function. Methods Normoxic or hypoxic CdM were isolated from rat BMSCs cultured under normoxic (20% O2) or hypoxic (1% O2) condition. Donor hearts were explanted; stored in cardioplegic solution supplemented with either a medium (vehicle), normoxic CdM (N-CdM), or hypoxic CdM (H-CdM); and then heterotopically transplanted. Antibody arrays were performed to compare the differences between hypoxic and normoxic CdM. Results After heart transplantation, the donor heart preservation with normoxic CdM was associated with a shorter time to return of spontaneous contraction and left ventricular systolic diameter, lower histopathological scores, higher ejection fraction, and fractional shortening of the transplanted hearts. The cardioprotective effects may be associated with the inhibition of apoptosis and inflammation, as reflected by less TUNEL-positive cells and lower levels of plasma proinflammatory cytokines (interleukin-1β, interleukin-6, tumor necrosis factor-α) and cardiac troponin I in the N-CdM group compared with the vehicle group. These therapeutic effects can be further enhanced by hypoxic preconditioning. Antibody arrays revealed that nine proteins were significantly increased in hypoxic CdM compared with normoxic CdM. Furthermore, compared with vehicle and N-CdM groups, the protein levels of PI3K and p-Akt/Akt ratio in the transplanted hearts significantly increased in the H-CdM group. However, no significant difference was found in the phosphorylation of Smad2 and Smad3 for the donor hearts among the three groups. Conclusions Our results indicate that the cardioplegic solution-enriched with hypoxic CdM can be a novel and promising preservation solution for donor hearts.

Objective: Atrial fibroblasts are the main component of atrial fibrosis. Data in previous studies proved the implication of miRNAs in AF progression and the association of miR-205 with cancer associated-fibroblasts, while no evidence supported the implication of miR-205 in atrial fibrosis. Therefore, this study aims to explore the effect and mechanism of miR-205/P4HA3 axis on atrial fibrosis.Methods: Angiotensin II (Ang II) was used to induce atrial fibrosis model in rats, which was verified by H&E staining and Masson staining. qRT-PCR and Western blot were applied to measure the expressions of miR-205, P4HA3, collagen I, and α-SMA. The rat atrial fibroblasts were isolated and then subjected to Ang II treatment or cell transfection for determination of cell biological functions using CCK-8, BrdU assay, TUNEL staining, and cell scratch assay. qRT-PCR and Western blot was applied to analyze the expressions of miR-205, P4HA3, collagen I, α-SMA, JNK, and p-JNK in atrial fibroblasts. Dual-luciferase reporter gene assay and RNA immune-precipitation experiment was employed to verify the binding relationship between miR-205 and P4HA3.Results: Ang II induced rats had disordered arrangement of atrial muscles with uneven nuclear sizes and necrotic atrial myocytes, and increased collagen deposition, in which elevated expressions of P4HA3, collagen I, and α-SMA as well as suppressed expression level of miR-205 were found. In vitro, Ang II treatment in atrial fibroblasts with overexpression of P4HA3 facilitated cellular migration and proliferation, with the induction of JNK signaling pathway. However, these trends were reversed after transfection with miR-205 mimic. P4HA3 is a target gene of miR-205.Conclusion: The miR-205/P4HA3 axis is implicated in atrial fibrosis by inhibition of rat fibroblast proliferation and migration and the inactivation of JNK signaling pathway.