Human Placental Mesenchymal Stem Cells and Derived Extracellular Vesicles Ameliorate Lung Injury in Acute Respiratory Distress Syndrome Murine Model.

This study investigates the therapeutic potential of human placental mesenchymal stem cells (P-MSCs) and their extracellular vesicles (EVs) in a murine model of acute respiratory distress syndrome (ARDS), a condition with growing relevance due to its association with severe COVID-19. We induced ARDS-like lung injury in mice using intranasal LPS instillation and evaluated histological changes, neutrophil accumulation via immunohistochemistry, bronchoalveolar lavage fluid cell count, total protein, and cytokine concentration, as well as lung gene expression changes at three time points: 24, 72, and 168 h. We found that both P-MSCs and EV treatments reduced the histological evidence of lung injury, decreased neutrophil infiltration, and improved alveolar barrier integrity. Analyses of cytokines and gene expression revealed that both treatments accelerated inflammation resolution in lung tissue. Biodistribution studies indicated negligible cell engraftment, suggesting that intraperitoneal P-MSC therapy functions mostly through soluble factors. Overall, both P-MSC and EV therapy ameliorated LPS-induced lung injury. Notably, at the tested dose, EV therapy was more effective than P-MSCs in reducing most aspects of lung injury.

Myocardial Angiotensin-Converting Enzyme 2 Protein Expression in Ischemic Heart Failure.

The angiotensin-converting enzyme 2 (ACE2)-angiotensin-(1-7)-Mas receptor axis plays a significant role in regulating myocardial remodeling and the development of heart failure (HF), with ACE2 being the primary focus. However, contemporary understanding of the membrane-bound form of the human ACE2 protein remains insufficient. The purpose of this study was to determine the expression of ACE2 protein in different cells of the left ventricular myocardium in non-diseased hearts and at various stages of ischemic HF. A total of 103 myocardial tissue samples from the left ventricle underwent quantitative and semi-quantitative immunohistochemical analysis. Upon assessing ACE2 immunostaining in all myocardial cells through unselective digital image analysis, there was no change in the stage A HF group. Nevertheless, the expression of ACE2 membrane protein in cardiomyocytes showed a tendency to increase, while non-cardiomyocyte ACE2 expression decreased significantly (p < 0.001). In the stage B HF group, the intensity of ACE2 immunostaining continued to increase with rising cardiomyocyte ACE2 expression (p < 0.001). Non-cardiomyocyte expression, in contrast, remained similar to that observed in the stage A HF group. In the stages C/D HF group, ACE2 expression reached its highest level in cardiomyocytes (p < 0.001), while ACE2 expression in non-cardiomyocytes was the lowest (p < 0.001). These changes in ACE2 protein levels are associated with left ventricular remodeling in ischemic HF.