miR-155-5p inhibition rejuvenates aged mesenchymal stem cells and enhances cardioprotection following infarction.

Aging impairs the functions of human mesenchymal stem cells (MSCs), thereby severely reducing their beneficial effects on myocardial infarction (MI). MicroRNAs (miRNAs) play crucial roles in regulating the senescence of MSCs; however, the underlying mechanisms remain unclear. Here, we investigated the significance of miR-155-5p in regulating MSC senescence and whether inhibition of miR-155-5p could rejuvenate aged MSCs (AMSCs) to enhance their therapeutic efficacy for MI. Young MSCs (YMSCs) and AMSCs were isolated from young and aged donors, respectively. The cellular senescence of MSCs was evaluated by senescence-associated ß-galactosidase (SA-ß-gal) staining. Compared with YMSCs, AMSCs exhibited increased cellular senescence as evidenced by increased SA-ß-gal activity and decreased proliferative capacity and paracrine effects. The expression of miR-155-5p was much higher in both serum and MSCs from aged donors than young donors. Upregulation of miR-155-5p in YMSCs led to increased cellular senescence, whereas downregulation of miR-155-5p decreased AMSC senescence. Mechanistically, miR-155-5p inhibited mitochondrial fission and increased mitochondrial fusion in MSCs via the AMPK signaling pathway, thereby resulting in cellular senescence by repressing the expression of Cab39. These effects were partially reversed by treatment with AMPK activator or mitofusin2-specific siRNA (Mfn2-siRNA). By enhancing angiogenesis and promoting cell survival, transplantation of anti-miR-155-5p-AMSCs led to improved cardiac function in an aged mouse model of MI compared with transplantation of AMSCs. In summary, our study shows that miR-155-5p mediates MSC senescence by regulating the Cab39/AMPK signaling pathway and miR-155-5p is a novel target to rejuvenate AMSCs and enhance their cardioprotective effects.

Adipose-Derived Mesenchymal Stem Cells Isolated from Patients with Abdominal Aortic Aneurysm Exhibit Senescence Phenomena.

Mesenchymal stem cells (MSCs) have shown beneficial effects in the treatment of abdominal aortic aneurysm (AAA). Nonetheless, the biological properties of adipose-derived MSCs (ASCs) from patients with AAA (AAA-ASCs) remain unclear. This study is aimed at investigating the properties of cell phenotype and function of AAA-ASCs compared with ASCs from age-matched healthy donors (H-ASCs). H-ASCs and AAA-ASCs were studied for cell phenotype, differentiation capacity, senescence, and mitochondrial and autophagic functions. Cellular senescence was examined by senescence-associated ß-galactosidase (SA-ß-gal) staining. Mitochondrial morphology was determined by MitoTracker staining. Despite the similar surface markers of AAA-ASCs and H-ASCs, AAA-ASCs exhibited altered multidifferentiation potential. Compared with H-ASCs, AAA-ASCs displayed enhanced senescence manifested by increased SA-ß-gal activity and decreased proliferation and migration ability. Furthermore, AAA-ASCs showed increased mitochondrial fusion, reactive oxygen species (ROS) production, and decreased mitochondrial membrane potential. In addition, AAA-ASCs exhibited decreased autophagy level, upregulation of IL-6 and TNF-α secretion, and downregulation of IL-10 secretion compared with H-ASCs. Nonetheless, treatment of AAA-ASCs with rapamycin (an autophagy activator) dramatically reduced secretion of IL-6 and TNF-α and enhanced secretion of IL-10. In conclusion, our study showed that AAA-ASCs exhibit senescence phenomena and decreased cell function. Understanding the specific alterations in AAA-ASCs will help explore novel strategies to restore cell function for AAA treatment.

Inhibition of RHO Kinase by Fasudil Attenuates Ischemic Lung Injury After Cardiac Arrest in Rats.

Lung injury is a common complication after cardiac arrest (CA) and cardiopulmonary resuscitation (CPR), and Rho kinase (ROCK) may be involved in the process of this injury. In this study, we aimed to study the effects of ROCK inhibition by fasudil on lung injury induced by asphyxial CA and CPR in rats. A total of 130 rats were randomized into three groups: Sham, Control, and Fasudil intervention group. Animals in the Fasudil intervention group were intraperitoneally administered with 10 mg/kg of the drug, 1 h before inducing CA. Rats in the Control group received equivalent volume of saline and were subjected to the same experimental procedures with as the Fasudil group. Blood was collected and lungs were harvested at 3, 6, 12, 24, and 48 h after return of spontaneous circulation (ROSC) for blood gas and biochemical analysis. Fasudil significantly increased the partial pressure of oxygen and pH in arterial blood, as well as attenuated lung histological injury and lung edema after ROSC. Additionally, it significantly decreased lung inflammatory response (decreased levels of tumor necrosis factor-α and interleukin-6, and myeloperoxidase activity) and oxidative stress (decreased malonaldehyde level and increased superoxide dismutase activity) after ROSC. Using western blot analysis, we found that fasudil inhibited both isoforms ROCK1 and ROCK2, and intercellular adhesion molecule-1; nevertheless, it increased vascular endothelial cadherin protein expression after ROSC. Our study suggested that the Rho kinase signaling pathway is critical for CA-induced lung injury and fasudil has protective effects on lung injury after CA and CPR.