Comprehensive overview of COVID-19-related respiratory failure: focus on cellular interactions.

The pandemic outbreak of coronavirus disease 2019 (COVID-19) has created health challenges in all parts of the world. Understanding the entry mechanism of this virus into host cells is essential for effective treatment of COVID-19 disease. This virus can bind to various cell surface molecules or receptors, such as angiotensin-converting enzyme 2 (ACE2), to gain cell entry. Respiratory failure and pulmonary edema are the most important causes of mortality from COVID-19 infections. Cytokines, especially proinflammatory cytokines, are the main mediators of these complications. For normal respiratory function, a healthy air-blood barrier and sufficient blood flow to the lungs are required. In this review, we first discuss airway epithelial cells, airway stem cells, and the expression of COVID-19 receptors in the airway epithelium. Then, we discuss the suggested molecular mechanisms of endothelial dysfunction and blood vessel damage in COVID-19. Coagulopathy can be caused by platelet activation leading to clots, which restrict blood flow to the lungs and lead to respiratory failure. Finally, we present an overview of the effects of immune and non-immune cells and cytokines in COVID-19-related respiratory failure.

Comparison of TGF-ß3 and avocado/soybean unsaponifiable on chondrogenesis of human adipose-derived stem cells on poly (lactic-co-glycolic) acid/ hyaluronic acid hybrid scaffold.

OBJECTIVES: Avocado/soybean unsaponifible (ASU) possesses properties including chondroprotective, anticatabolic, and anabolic. The goal behind this research was to detect the effect of ASU and TGF-ß3 on the chondrogenesis of human adipose-derived stem cells (hADSCs) on poly (lactic-co-glycolic) acid (PLGA)/ hyaluronic acid (PLGA/HA) hybrid scaffold. MATERIALS AND METHODS: First hADSCs were seeded in PLGA/Hyaluronic acid scaffold and cultured in chondrogenic media. These cells were assigned into 4 groups: control, TGFß-3, ASU, and TGFß-3+ASU. The viability was assessed separately by MTT. Real-time PCR was used to quantify the expression of chondrogenic specific genes [Sox9, collagen type II (ColII), Aggrecan (AGG)] and collagen type X (ColX). Moreover, Western blotting was employed to evaluate protein expression levels of collagens type II and X. RESULTS: These findings indicated a significant increase in the proliferation and survival of hADSCs differentiated cells by ASU compared with the control group (P=0.008). Real-time PCR results revealed significant differences in the expression of AGG, SOX9, ColII, and ColX genes in the control group when compared with other groups (ASU, TGF-ß3, and TGF-ß3+ASU). ColII protein production significantly dropped in the TGF-ß3 group in comparison with the TGF-ß3+ASU group (0.000). The ColII (P=0.002) and ColX (P=0.002) protein production proved significantly higher in the TGF-ß3+ASU group compared with the ASU group. CONCLUSION: Using the synergist form TGFß-3, ASU induces chondrogenesis in hADSCs in PLGA/HA composite scaffold. This can be deduced with reduction of special markers of hyaline cartilage in comparison with ASU and decreased hypertrophic marker compared with TGF-ß3.