Effects of bone marrow-derived mesenchymal stromal cells on gene expression in human alveolar type II cells exposed to TNF-α, IL-1β, and IFN-γ

Activation of Wnt/β‑Catenin‑p130/E2F4 promotes the differentiation of bone marrow‑derived mesenchymal stem cells into type II alveolar epithelial cells through cell cycle arrest

The results of our previous study demonstrated that activation of the Wnt/β-catenin pathway increased the differentiation of mesenchymal stem cells (MSCs) into type II alveolar epithelial (AT II) cells; however, the specific mechanisms remain unclear. The present study aimed to evaluate the role of Wnt/β-catenin-p130/E2F transcription factor 4 (E2F4) in regulating the differentiation of mouse MSCs (mMSCs) into AT II cells, and to determine the specific mechanisms. mMSCs with p130 or E2F4 overexpression were constructed using lentiviral vectors. Differentiation of mMSCs into AT II cells was promoted using a modified coculture system with murine lung epithelial-12 cells incubated in small airway growth medium for 7-14 days. The differentiation efficiency was detected using immunofluorescence, western blot analysis and transmission electron microscopy. To detect the association between the canonical Wnt pathway and p130/E2F4, 4 mmol/l lithium chloride (LiCl) or 200 ng/ml Dickkopf-related protein 1 (DKK-1) was also added to the coculture system. Following differentiation, the cell cycle of mMSCs was evaluated using flow cytometry. The results of the present study demonstrated that surfactant protein C (SP-C) protein expression was higher in the p130 overexpression (MSC-p130) and E2F4 overexpression (MSC-E2F4) groups compared with the normal control mMSCs group following differentiation into AT II cells. Similar results for SP-C protein expression and lamellar body-like structures were also observed using immunofluorescence analysis and electron microscopy. Following the addition of LiCl into the coculture system for activation of the Wnt/β-catenin signaling pathway, phosphorylated (p)-p130/p130 was slightly decreased at 7 days and E2F4 was increased both at 7 and 14 days in mMSCs. Furthermore, the p-p130/p130 ratio was significantly increased at 14 days and E2F4 was decreased both at 7 and 14 days following DKK-1-mediated inhibition of the Wnt pathway. The results of the present study demonstrated that the numbers of cells in G₁ and S phases were increased following activation of the Wnt pathway and decreased following Wnt pathway inhibition. However, the number of cells in G₁ phase was increased following the differentiation of mMSCs overexpressing p130 or E2F4. Therefore, the results of the present study revealed that the canonical Wnt signaling pathway may affect the differentiation of MSCs into AT II cells via regulation of downstream p130/E2F4. The specific mechanisms may be associated with G₁ phase extension in the cell cycle of MSCs.

Dysregulated Cell Signaling in Pulmonary Emphysema

Pulmonary emphysema is characterized by the destruction of alveolar septa and irreversible airflow limitation. Cigarette smoking is the primary cause of this disease development. It induces oxidative stress and disturbs lung physiology and tissue homeostasis. Alveolar type II (ATII) cells have stem cell potential and can repair the denuded epithelium after injury; however, their dysfunction is evident in emphysema. There is no effective treatment available for this disease. Challenges in this field involve the large complexity of lung pathophysiological processes and gaps in our knowledge on the mechanisms of emphysema progression. It implicates dysregulation of various signaling pathways, including aberrant inflammatory and oxidative responses, defective antioxidant defense system, surfactant dysfunction, altered proteostasis, disrupted circadian rhythms, mitochondrial damage, increased cell senescence, apoptosis, and abnormal proliferation and differentiation. Also, genetic predispositions are involved in this disease development. Here, we comprehensively review studies regarding dysregulated cell signaling, especially in ATII cells, and their contribution to alveolar wall destruction in emphysema. Relevant preclinical and clinical interventions are also described.

Mesenchymal stem cells as living anti-inflammatory therapy for COVID-19 related acute respiratory distress syndrome

Coronavirus disease 2019 (COVID-19), a pandemic disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV2), is growing at an exponential rate worldwide. Manifestations of this disease are heterogeneous; however, advanced cases often exhibit various acute respiratory distress syndrome-like symptoms, systemic inflammatory reactions, coagulopathy, and organ involvements. A common theme in advanced COVID-19 is unrestrained immune activation, classically referred to as a “cytokine storm”, as well as deficiencies in immune regulatory mechanisms such as T regulatory cells. While mesenchymal stem cells (MSCs) themselves are objects of cytokine regulation, they can secrete cytokines to modulate immune cells by inducing anti-inflammatory regulatory Treg cells, macrophages and neutrophils; and by reducing the activation of T and B cells, dendritic and nature killer cells. Consequently, they have therapeutic potential for treating severe cases of COVID-19. Here we discuss the unique ability of MSCs, to act as a “living anti-inflammatory”, which can “rebalance” the cytokine/immune responses to restore equilibrium. We also discuss current MSC trials and present different concepts for optimization of MSC therapy in patients with COVID-19 acute respiratory distress syndrome. 

Intestinal barrier damage, systemic inflammatory response syndrome, and acute lung injury: A troublesome trio for acute pancreatitis

Severe acute pancreatitis (SAP), a serious inflammatory disease of the pancreas, can easily lead to systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndromes (MODS). Acute lung injury (ALI) is one of the most serious complications of SAP. However, the specific pathogenesis of SAP-associated ALI is not fully understood. Crosstalk and multi-mechanisms involving pancreatic necrosis, bacteremia, intestinal barrier failure, activation of inflammatory cascades and diffuse alveolar damage is the main reason for the unclear pathological mechanism of SAP-associated ALI. According to previous research on SAP-associated ALI in our laboratory and theories put forward by other scholars, we propose that the complex pattern of SAP-associated ALI is based on the "pancreas-intestine-inflammation/endotoxin-lung (P-I-I/E-L) pathway". In this review, we mainly concentrated on the specific details of the "P-I-I/E-L pathway" and the potential treatments or preventive measures for SAP-associated ALI.

Umbilical Cord-derived Mesenchymal Stem Cells for COVID-19 Patients with Acute Respiratory Distress Syndrome (ARDS)

The coronavirus SARS-CoV-2 is cause of a global pandemic of a pneumonia-like disease termed Coronavirus Disease 2019 (COVID-19). COVID-19 presents a high mortality rate, estimated at 3.4%. More than 1 out of 4 hospitalized COVID-19 patients require admission to an Intensive Care Unit (ICU) for respiratory support, and a large proportion of these ICU-COVID-19 patients, between 17% and 46%, have died. In these patients COVID-19 infection causes an inflammatory response in the lungs that can progress to inflammation with cytokine storm, Acute Lung Injury (ALI), Acute Respiratory Distress Syndrome (ARDS), thromboembolic events, disseminated intravascular coagulation, organ failure, and death. Mesenchymal Stem Cells (MSCs) are potent immunomodulatory cells that recognize sites of injury, limit effector T cell reactions, and positively modulate regulatory cell populations. MSCs also stimulate local tissue regeneration via paracrine effects inducing angiogenic, anti-fibrotic and remodeling responses. MSCs can be derived in large number from the Umbilical Cord (UC). UC-MSCs, utilized in the allogeneic setting, have demonstrated safety and efficacy in clinical trials for a number of disease conditions including inflammatory and immune-based diseases. UC-MSCs have been shown to inhibit inflammation and fibrosis in the lungs and have been utilized to treat patients with severe COVID-19 in pilot, uncontrolled clinical trials, that reported promising results. UC-MSCs processed at our facility have been authorized by the FDA for clinical trials in patients with an Alzheimer's Disease, and in patients with Type 1 Diabetes (T1D). We hypothesize that UC-MSC will also exert beneficial therapeutic effects in COVID-19 patients with cytokine storm and ARDS. We propose an early phase controlled, randomized clinical trial in COVID-19 patients with ALI/ARDS. Subjects in the treatment group will be treated with two doses of UC-MSC (l00 × 10⁶ cells). The first dose will be infused within 24 hours following study enrollment. A second dose will be administered 72 ± 6 hours after the first infusion. Subject in the control group will receive infusion of vehicle (DPBS supplemented with 1% HSA and 70 U/kg unfractionated Heparin, delivered IV) following the same timeline. Subjects will be evaluated daily during the first 6 days, then at 14, 28, 60, and 90 days following enrollment (see Schedule of Assessment for time window details). Safety will be determined by adverse events (AEs) and serious adverse events (SAEs) during the follow-up period. Efficacy will be defined by clinical outcomes, as well as a variety of pulmonary, biochemical and immunological tests. Success of the current study will provide a framework for larger controlled, randomized clinical trials and a means of accelerating a possible solution for this urgent but unmet medical need. The proposed early phase clinical trial will be performed at the University of Miami (UM), in the facilities of the Diabetes Research Institute (DRI), UHealth Intensive Care Unit (ICU) and the Clinical Translational Research Site (CTRS) at the University of Miami Miller School of Medicine and at the Jackson Memorial Hospital (JMH).

The ex vivo human lung: research value for translational science

Respiratory diseases are among the leading causes of death and disability worldwide. However, the pathogenesis of both acute and chronic lung diseases remains incompletely understood. As a result, therapeutic options for important clinical problems, including acute respiratory distress syndrome and chronic obstructive pulmonary disease, are limited. Research efforts have been held back in part by the difficulty of modeling lung injury in animals. Donor human lungs that have been rejected for transplantation offer a valuable alternative for understanding these diseases. In 2007, our group developed a simple preparation of an ex vivo-perfused single human lung. In this Review, we discuss the availability of donor human lungs for research, describe the ex vivo-perfused lung preparation, and highlight how this preparation can be used to study the mechanisms of lung injury, to isolate primary cells, and to test novel therapeutics.