ACE2 overexpressing mesenchymal stem cells alleviates COVID-19 lung injury by inhibiting pyroptosis

The wound healing of deep partial-thickness burn in Bama miniature pigs is accelerated by a higher dose of hUCMSCs

BACKGROUND

Deep partial-thickness burns have a significant impact on both the physical and mental health of patients. Our previous study demonstrated human Umbilical Cord Mesenchymal stem cells (hUCMSCs) could enhance the healing of severe burns in small animal burn models, such as rats. Furthermore, our team has developed a deep partial-thickness burn model in Bama miniature pigs, which can be utilized for assessing drug efficacy in preclinical trials for wound healing. Therefore, this study further determine the optimal dosage of hUCMSCs in future clinical practice by comparing the efficacy of low-to-high doses of hUCMSCs on deep partial-thickness burn wounds in Bama miniature pigs.

MATERIALS AND METHODS

The male Bama miniature pigs (N = 8, weight: 23-28 kg and length: 71-75 cm) were used to establish deep partial-thickness burn models, which used a continuous pressure of 1 kg and contact times of 35 s by the invented electronic burn instrument at 100℃ to prepare 10 round burn wounds with diameter of 5 cm according to our previous report. And then, 0 × 10^7, 1 × 10^7, 2 × 10^7, 5 × 10^7 and 1 × 10^8 doses of hUCMSCs were respectively injected into burn wounds of their corresponding groups. After treatment for 7, 14 and 21 days, the burned wound tissues were obtained for histological evaluation, including HE staining for histopathological changes, immunohistochemistry for neutrophil (MPO+) infiltration and microvessel (CD31+) quantity, as well as Masson staining for collagen deposition. The levels of inflammatory factors TNF-α, IL-1β, IL-10 and angiogenesis factors angiopoietin-2 (Ang-2), vascular endothelial growth factor (VEGF), as well as collagen type-I/type-III of the wound tissues were quantified by ELISA.

RESULTS

All of doses hUCMSCs can significantly increase wound healing rate and shorten healing time of the deep partial-thickness burn pigs in a dose-dependent manner. Furthermore, all of doses hUCMSCs can significantly promote epithelialization and decreased inflammatory reaction of wound, including infiltration of inflammatory cells and levels inflammatory factors. Meanwhile, the amounts of microvessel were increased in all of doses hUCMSCs group than those in the burn group. Furthermore, the collagen structure was disordered and partially necrotized, and ratios of collagen type-I and type-III were significantly decreased in burn group (4:1 in normal skin tissue), and those of all hUCMSCs groups were significantly improved in a dose-dependent manner. In a word, 1 × 10^8 dose of hUCMSCs could regenerate the deep partial-thickness burn wounds most efficaciously compared to other dosages groups and the burn group.

CONCLUSION

This regenerative cell therapy study using hUCMSCs demonstrates the best efficacy toward a high dose, that is dose of 1 × 10^8 of hUCMSCs was used as a reference therapeutic dose for treating 20 cm2 deep partial-thickness burns wound in future clinical practice.

ACE2 Alleviates Endoplasmic Reticulum Stress and Protects against Pyroptosis by Regulating Ang1-7/Mas in Ventilator-Induced Lung Injury

BACKGROUND

Ventilator-induced lung injury (VILI) is a consequence of inflammation and increased alveolar-capillary membrane permeability due to alveolar hyperdistention or elevated intrapulmonary pressure, but the precise mechanisms remain unclear. The aim of the study was to analyze the mechanism by which angiotensin converting enzyme 2 (ACE2) alleviates endoplasmic reticulum stress (ERS) and protects alveolar cells from pyroptosis in VILI by regulating angiotensin (Ang)1-7/Mas.

METHODS

VILI was induced in mice by mechanical ventilation by regulating the tidal volume. The alveolar cell line, A549, mimics VILI in vitro by cyclic stretch (CS). Ang (1-7) (100 nmol/L) was added to the medium. ERS was induced in cells by stimulating with tunicamycin (TM, 2 μg/mL). ERS was inhibited by tracheal instillation of 4-phenylbutyric acid (4-PBA) (1 mg/kg). ACE2's enzymatic function was activated or inhibited by subcutaneous injection of resorcinolnaphthalein (RES, 20 μg/kg) or MLN-4760 (20 μg/kg). pGLV-EF1a-GFP-ACE2 was instilled into the trachea to increase the protein expression of ACE2. The Ang (1-7) receptor, Mas, was antagonized by injecting A779 subcutaneously (80 μg/kg).

RESULTS

ACE2 protein levels decreased after modeling. Ang (1-7) level was decreased and Ang II was accumulated. ERS was significantly induced in VILI mice, and pyroptosis was observed in cells. When ERS was inhibited, pyroptosis under the VILI condition was significantly inhibited. Ang (1-7) alleviated ERS and pyroptosis under CS. When ERS was continuously activated, the function of Ang (1-7) in inhibiting pyroptosis was blocked. Resorcinolnaphthalein (RES) effectively promoted Ang II conversion, alleviated the Ang (1-7) level in VILI, ameliorated lung injury, and inhibited ERS and cell pyroptosis. Inhibiting ACE2's function in VILI hindered the production of Ang (1-7), promoted the accumulation of Ang II, and exacerbated ERS and pyroptosis, along with lung injury. The Mas antagonist significantly blocked the inhibitory effects of ACE2 on ERS and pyroptosis in VILI.

CONCLUSIONS

Reduced ACE2 expression in VILI is involved in ERS and pyroptosis-related injury. ACE2 can alleviate ERS in alveolar cells by catalyzing the production of Ang (1-7), thus inhibiting pyroptosis in VILI.

A Review of Potential Therapeutic Strategies for COVID-19

Coronavirus disease 2019 is a rather heterogeneous disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The ongoing pandemic is a global threat with increasing death tolls worldwide. SARS-CoV-2 belongs to lineage B β-CoV, a subgroup of Sarbecovirus. These enveloped, large, positive-sense single-stranded RNA viruses are easily spread among individuals, mainly via the respiratory system and droplets. Although the disease has been gradually controlled in many countries, once social restrictions are relaxed the virus may rebound, leading to a more severe and uncontrollable situation again, as occurred in Shanghai, China, in 2022. The current global health threat calls for the urgent development of effective therapeutic options for the treatment and prevention of SARS-CoV-2 infection. This systematic overview of possible SARS-CoV-2 therapeutic strategies from 2019 to 2022 indicates three potential targets: virus entry, virus replication, and the immune system. The information provided in this review will aid the development of more potent and specific antiviral compounds.

Pyroptotic cell death in SARS-CoV-2 infection: revealing its roles during the immunopathogenesis of COVID-19

The rapid dissemination of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19), remains a global public health emergency. The host immune response to SARS-CoV-2 plays a key role in COVID-19 pathogenesis. SARS-CoV-2 can induce aberrant and excessive immune responses, leading to cytokine storm syndrome, autoimmunity, lymphopenia, neutrophilia and dysfunction of monocytes and macrophages. Pyroptosis, a proinflammatory form of programmed cell death, acts as a host defense mechanism against infections. Pyroptosis deprives the replicative niche of SARS-CoV-2 by inducing the lysis of infected cells and exposing the virus to extracellular immune attack. Notably, SARS-CoV-2 has evolved sophisticated mechanisms to hijack this cell death mode for its own survival, propagation and shedding. SARS-CoV-2-encoded viral products act to modulate various key components in the pyroptosis pathways, including inflammasomes, caspases and gasdermins. SARS-CoV-2-induced pyroptosis contriubtes to the development of COVID-19-associated immunopathologies through leakage of intracellular contents, disruption of immune system homeostasis or exacerbation of inflammation. Therefore, pyroptosis has emerged as an important mechanism involved in COVID-19 immunopathogenesis. However, the entangled links between pyroptosis and SARS-CoV-2 pathogenesis lack systematic clarification. In this review, we briefly summarize the characteristics of SARS-CoV-2 and COVID-19-related immunopathologies. Moreover, we present an overview of the interplay between SARS-CoV-2 infection and pyroptosis and highlight recent research advances in the understanding of the mechanisms responsible for the implication of the pyroptosis pathways in COVID-19 pathogenesis, which will provide informative inspirations and new directions for further investigation and clinical practice. Finally, we discuss the potential value of pyroptosis as a therapeutic target in COVID-19. An in-depth discussion of the underlying mechanisms of COVID-19 pathogenesis will be conducive to the identification of potential therapeutic targets and the exploration of effective treatment measures aimed at conquering SARS-CoV-2-induced COVID-19.

Mesenchymal stem cells and their derived small extracellular vesicles for COVID-19 treatment

Since December 2019, the coronavirus (COVID-19) pandemic has imposed huge burdens to the whole world, seriously affecting global economic growth, and threatening people’s lives and health. At present, some therapeutic regimens are available for treatment of COVID-19 pneumonia, including antiviral therapy, immunity therapy, anticoagulant therapy, and others. Among them, injection of mesenchymal stem cells (MSCs) is currently a promising therapy. The preclinical studies and clinical trials using MSCs and small extracellular vesicles derived from MSCs (MSC-sEVs) in treating COVID-19 were summarized. Then, the molecular mechanism, feasibility, and safety of treating COVID-19 with MSCs and MSC-sEVs were also discussed.