Paracrine activity of stem cells in therapy for acute lung injury and adult respiratory distress syndrome

Potential Therapeutic Role of Mesenchymal-Derived Stem Cells as an Alternative Therapy to Combat COVID-19 through Cytokines Storm

Medical health systems continue to be challenged due to newly emerging COVID-19, and there is an urgent need for alternative approaches for treatment. An increasing number of clinical observations indicate cytokine storms to be associated with COVID-19 severity and also to be a significant cause of death among COVID-19 patients. Cytokine storm involves the extensive proliferative and hyperactive activity of T and macrophage cells and the overproduction of pro-inflammatory cytokines. Stem cells are the type of cell having self-renewal properties and giving rise to differentiated cells. Currently, stem cell therapy is an exciting and promising therapeutic approach that can treat several diseases that were considered incurable in the past. It may be possible to develop novel methods to treat various diseases by identifying stem cells' growth and differentiation factors. Treatment with mesenchymal stem cells (MSCs) in medicine is anticipated to be highly effective. The present review article is organized to put forward the positive arguments and implications in support of mesenchymal stem cell therapy as an alternative therapy to cytokine storms, to combat COVID-19. Using the immunomodulatory potential of the MSCs, it is possible to fight against COVID-19 and counterbalance the cytokine storm.

Stem cell therapy for COVID-19 pneumonia

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) virus is a highly contagious microorganism, and despite substantial investigation, no progress has been achieved in treating post-COVID complications. However, the virus has made various mutations and has spread around the world. Researchers have tried different treatments to reduce the side effects of the COVID-19 symptoms. One of the most common and effective treatments now used is steroid therapy to reduce the complications of this disease. Long-term steroid therapy for chronic inflammation following COVID-19 is harmful and increases the risk of secondary infection, and effective treatment remains challenging owing to fibrosis and severe inflammation and infection. Sometimes our immune system can severely damage ourselves in disease. In the past, many researchers have conducted various studies on the immunomodulatory properties of stem cells. This property of stem cells led them to modulate the immune system of autoimmune diseases like diabetes, multiple sclerosis, and Parkinson's. Because of their immunomodulatory properties, stem cell-based therapy employing mesenchymal or hematopoietic stem cells may be a viable alternative treatment option in some patients. By priming the immune system and providing cytokines, chemokines, and growth factors, stem cells can be employed to build a long-term regenerative and protective response. This review addresses the latest trends and rapid progress in stem cell treatment for Acute Respiratory Distress Syndrome (ARDS) following COVID-19.

Non-muscle myosin II knockdown improves survival and therapeutic effects of implanted bone marrow-derived mesenchymal stem cells in lipopolysaccharide-induced acute lung injury

Background

Bone marrow-derived mesenchymal stem cells (BMSCs) have been shown to have some beneficial effects in acute lung injury (ALI), but the therapeutic effects are limited due to apoptosis or necrosis after transplantation into injured lungs. Here, we aim to explore whether Non-muscle myosin II (NM-II) knockdown could enhance BMSCs survival and improve therapeutic effects in ALI.

Methods

MSCs, isolated from rat bone marrow, were transfected with the small interfering RNA (siRNA) targeted to NM-II mRNA by a lentivirus vector. Rats were equally randomized to four groups: the control group was given normal saline via tail vein; the other three groups underwent intratracheal lipopolysaccharide (LPS) instillation followed by administration with either normal saline, BMSCs transduced with lentivirus-enhanced green fluorescent protein (eGFP) empty vector, or BMSCs transduced with lentivirus-eGFP NM-II siRNA. Hematoxylin and eosin staining was used to evaluate lung histopathologic changes and Masson trichrome staining was used to assess lung fibrosis. The myeloperoxidase activity was also tested in lung tissues. The mRNA expression of inflammatory cytokines in lung tissues was determined via quantitative reverse transcription PCR. Sex-determining region of the Y chromosome gene expression was measured by fluorescence in situ hybridization (FISH) assay. The expression of self-renewal activity and apoptosis-associated proteins were measured by Western blot.

Results

Transplantation of NM-II siRNA-modified BMSCs could improve histopathological morphology, decrease inflammatory infiltrates, down-regulate the expression levels of inflammatory cytokines, and reduce pulmonary interstitial edema. NM-II siRNA-modified BMSCs showed antifibrotic properties and alleviated the degrees of pulmonary fibrosis induced by endotoxin. In addition, NM-II knockdown BMSCs showed slightly better therapeutic effect on lung inflammation when compared with control BMSCs. The beneficial effects of NM-II siRNA-modified BMSCs may be attributed to enhanced self-renewal activity and decreased apoptosis.

Conclusions

NM-II knockdown could inhibit the apoptosis of implanted BMSCs in lung tissues and improve its self-renewal activity. NM-II siRNA-modified BMSCs have a slightly enhanced ability to attenuate lung injury after LPS challenge.

A Small-Sized Population of Human Umbilical Cord Blood-Derived Mesenchymal Stem Cells Shows High Stemness Properties and Therapeutic Benefit

Mesenchymal stem cells (MSCs) represent a promising means to promote tissue regeneration. However, the heterogeneity of MSCs impedes their use for regenerative medicine. Further investigation of this phenotype is required to develop cell therapies with improved clinical efficacy. Here, a small-sized population of human umbilical cord blood-derived MSCs (UCB-MSCs) was isolated using a filter and centrifuge system to analyze its stem cell characteristics. Consequently, this population showed higher cell growth and lower senescence. Additionally, it exhibited diverse stem cell properties including differentiation, stemness, and adhesion, as compared to those of the population before isolation. Using cell surface protein array or sorting analysis, both EGFR and CD49f were identified as markers associated with the small-sized population. Accordingly, suppression of these surface proteins abolished the superior characteristics of this population. Moreover, compared to that with large or nonisolated populations, the small-sized population showed greater therapeutic efficacy by promoting the engraftment potential of infused cells and reducing lung damage in an emphysema mouse model. Therefore, the isolation of this small-sized population of UCB-MSCs could be a simple and effective way to enhance the efficacy of cell therapy.

Therapeutic potential of mesenchymal stem cell transplantation in a nitrofen-induced congenital diaphragmatic hernia rat model

PURPOSE

The aim of this study was to evaluate the efficacy of mesenchymal stem cells (MSCs) in a nitrofen-induced congenital diaphragmatic hernia (CDH) rat model.

METHODS

Pregnant rats were exposed to nitrofen on embryonic day 9.5 (E9.5). MSCs were isolated from the enhanced green fluorescent protein (eGFP) transgenic rat lungs. The MSCs were transplanted into the nitrofen-induced E12.5 rats via the uterine vein, and the E21 lung explants were harvested. The study animals were divided into three: the control group, the nitrofen-induced left CDH (CDH group), and the MSC-treated nitrofen-induced left CDH (MSC-treated CDH group). The specimens were morphologically analyzed using HE and immunohistochemical staining with proliferating cell nuclear antigen (PCNA), surfactant protein-C (SP-C), and α-smooth muscle actin.

RESULTS

The alveolar and medial walls of the pulmonary arteries were significantly thinner in the MSC-treated CDH group than in the CDH group. The alveolar air space areas were larger, while PCNA and the SP-C positive cells were significantly higher in the MSC-treated CDH group, than in the CDH group. MSC engraftment was identified on immunohistochemical staining of the GFP in the MSC-treated CDH group.

CONCLUSIONS

MSC transplantation potentially promotes alveolar and pulmonary artery development, thereby reducing the severity of pulmonary hypoplasia.