Mesenchymal Stromal Cell Exosomes Ameliorate Experimental Bronchopulmonary Dysplasia and Restore Lung Function through Macrophage Immunomodulation

The potential therapeutic effect of human umbilical cord mesenchymal stem cell-derived exosomes in bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is a chronic lung disease of preterm infants, with its incidence rising due to improved survival rates of these infants. BPD results from a combination of prenatal and postnatal factors, such as mechanical ventilation, oxygen toxicity, and infections, all of which significantly impact the prognosis and growth of affected infants. Current treatment options for BPD are largely supportive and do not address the underlying pathology. Exosomes are cell-derived bilayer-enclosed membrane structures enclosing proteins, lipids, RNAs, growth factors, cytokines and metabolites. They have become recognized as crucial regulators of intercellular communication in various physiological and pathological processes. Previous studies have revealed the therapeutic potential of human umbilical cord mesenchymal stem cells-derived exosomes (HUCMSCs-Exos) in promoting tissue repair and regeneration. Therefore, HUCMSCs-Exos maybe a promising and effective therapeutic modality for BPD. In this review, we firstly provide a comprehensive overview of BPD, including its etiology and the mechanisms of lung injury. Then we detail the isolation, characterization, and contents of HUCMSCs-Exos, and discuss their potential mechanisms of HUCMSCs-Exos in BPD treatment. Additionally, we summarize current clinical trials and discuss the challenges in translating these findings from bench to bedside. This review aims to lay the groundwork for future clinical applications of HUCMSCs-Exos in treating BPD.

Stem cell-derived extracellular vesicles: a potential intervention for Bronchopulmonary Dysplasia

Despite advances in neonatal care, the incidence of Bronchopulmonary Dysplasia (BPD) remains high among extreme preterm infants. The pathogenesis of BPD is multifactorial, with inflammation playing a central role. There is strong evidence that stem cell therapy reduces inflammatory changes and restores normal lung morphology in animal models of hyperoxia-induced lung injury. These therapeutic effects occur without significant engraftment of the stem cells in the host lung, suggesting more of a paracrine mechanism mediated by their secretome. In addition, there are multiple concerns with stem cell therapy which may be alleviated by administering only the effective vesicles instead of the cells themselves. Extracellular vesicles (EVs) are cell-derived components secreted by most eukaryotic cells. They can deliver their bioactive cargo (mRNAs, microRNAs, proteins, growth factors) to recipient cells, which makes them a potential therapeutic vehicle in many diseases, including BPD. The following review will highlight recent studies that investigate the effectiveness of EVs derived from stem cells in preventing or repairing injury in the preterm lung, and the potential mechanisms of action that have been proposed. Current limitations will also be discussed as well as suggestions for advancing the field and easing the transition towards clinical translation in evolving or established BPD. IMPACT: Extracellular vesicles (EVs) derived from stem cells are a potential intervention for neonatal lung diseases. Their use might alleviate the safety concerns associated with stem cell therapy. This review highlights recent studies that investigate the effectiveness of stem cell-derived EVs in preclinical models of bronchopulmonary dysplasia. It adds to the existing literature by elaborating on the challenges associated with EV research. It also provides suggestions to advance the field and ease the transition towards clinical applications. Optimizing EV research could ultimately improve the quality of life of extreme preterm infants born at vulnerable stages of lung development.

Fetal origin of bronchopulmonary dysplasia: contribution of intrauterine inflammation

Bronchopulmonary dysplasia (BPD) is a common chronic lung disease in infants and the most frequent adverse outcome of premature birth, despite major efforts to minimize injury. It is thought to result from aberrant repair response triggered by either prenatal or recurrent postnatal injury to the lungs during development. Intrauterine inflammation is an important risk factor for prenatal lung injury, which is also increasingly linked to BPD. However, the specific mechanisms remain unclear. This review summarizes clinical and animal research linking intrauterine inflammation to BPD. We assess how intrauterine inflammation affects lung alveolarization and vascular development. In addition, we discuss prenatal therapeutic strategies targeting intrauterine inflammation to prevent or treat BPD.

Therapeutic potential of extracellular vesicles derived from human amniotic epithelial cells for perinatal cerebral and pulmonary injury

Lung and brain injury that occurs during the perinatal period leads to lifelong disability and is often driven and/or exacerbated by inflammation. Human amniotic epithelial cells (hAEC), which demonstrate immunomodulatory, anti-fibrotic, and regenerative capabilities, are being explored as a therapeutic candidate for perinatal injury. However, limitations regarding scalable manufacturing, storage, transport, and dose-related toxicity have impeded clinical translation. Isolated therapeutic extracellular vesicles (EVs) from stem and stem-like cells are thought to be key paracrine mediators of therapeutic efficacy. The unique characteristics of EVs suggest that they potentially circumvent the limitations of traditional cell-based therapies. However, given the novelty of EVs as a therapeutic, recommendations around ideal methods of production, isolation, storage, and delivery have not yet been created by regulatory agencies. In this concise review, we discuss the pertinence and limitations of cell-based therapeutics in perinatal medicine. We also review the preclinical evidence supporting the use of therapeutic EVs for perinatal therapy. Further, we summarize the arising considerations regarding adequate cell source, biodistribution, isolation and storage methods, and regulatory roadblocks for the development of therapeutic EVs.

Therapeutic role of extracellular vesicles from human umbilical cord mesenchymal stem cells and their wide therapeutic implications in inflammatory bowel disease and other inflammatory disorder

The chronic immune-mediated inflammatory condition known as inflammatory bowel disease (IBD) significantly affects the gastrointestinal system. While the precise etiology of IBD remains elusive, extensive research suggests that a range of pathophysiological pathways and immunopathological mechanisms may significantly contribute as potential factors. Mesenchymal stem cells (MSCs) have shown significant potential in the development of novel therapeutic approaches for various medical conditions. However, some MSCs have been found to exhibit tumorigenic characteristics, which limit their potential for medical treatments. The extracellular vesicles (EVs), paracrine factors play a crucial role in the therapeutic benefits conferred by MSCs. The EVs consist of proteins, microRNAs, and lipids, and are instrumental in facilitating intercellular communication. Due to the ease of maintenance, and decreased immunogenicity, tumorigenicity the EVs have become a new and exciting option for whole cell treatment. This review comprehensively assesses recent preclinical research on human umbilical cord mesenchymal stem cell (hUC-MSC)-derived EVs as a potential IBD therapy. It comprehensively addresses key aspects of various conditions, including diabetes, cancer, dermal injuries, neurological disorders, cardiovascular issues, liver and kidney diseases, and bone-related afflictions.

Fetal hypoplastic lungs have multilineage inflammation that is reversed by amniotic fluid stem cell extracellular vesicle treatment

Antenatal administration of extracellular vesicles from amniotic fluid stem cells (AFSC-EVs) reverses features of pulmonary hypoplasia in models of congenital diaphragmatic hernia (CDH). However, it remains unknown which lung cellular compartments and biological pathways are affected by AFSC-EV therapy. Herein, we conducted single-nucleus RNA sequencing (snRNA-seq) on rat fetal CDH lungs treated with vehicle or AFSC-EVs. We identified that intra-amniotically injected AFSC-EVs reach the fetal lung in rats with CDH, where they promote lung branching morphogenesis and epithelial cell differentiation. Moreover, snRNA-seq revealed that rat fetal CDH lungs have a multilineage inflammatory signature with macrophage enrichment, which is reversed by AFSC-EV treatment. Macrophage enrichment in CDH fetal rat lungs was confirmed by immunofluorescence, flow cytometry, and inhibition studies with GW2580. Moreover, we validated macrophage enrichment in human fetal CDH lung autopsy samples. Together, this study advances knowledge on the pathogenesis of pulmonary hypoplasia and further evidence on the value of an EV-based therapy for CDH fetuses.

Hsa_circ_0001359 in Serum Exosomes: A Promising Marker to Predict Bronchopulmonary Dysplasia in Premature Infants

Objective

This prospective study is to explore the role of specific circRNAs in predicting the development of bronchopulmonary dysplasia (BPD).

Methods

From July 1, 2021 to December 1, 2021, peripheral blood samples were collected from 62 premature infants with gestational age (GA) ≤32 weeks on the 7th, 14th, and 28th day after birth. Then, on the 28th day, the included infants were divided into the BPD group and the non-BPD group according to the definition of BPD. Serum exosomal circRNAs from peripheral blood were identified, sequenced, and compared between the BPD and non-BPD groups at different time points. Specific differentially expressed circRNAs were further verified from another 42 enrolled premature infants (GA ≤32 weeks). The classical lung biological markers in serum were also measured simultaneously.

Results

Hsa_circ_0001359 in serum exosomes showed continuous differential expression between the BPD group and the non-BPD group on the 7th, 14th, and 28th day. Compared with that, classical lung biological markers like IL-6, IL-33, KL-6, and ET-1 did not exhibit continuous differences. Moreover, the expression of hsa_circ_0001359 on day 7 had a higher predictive value in predicting BPD (area under curve:0.853, 95% CI:0.738-0.968; adjusted odds ratio:6.033, 95% CI:2.373-13.326). The calibration curve further showed the mean absolute error = 0.033, mean squared error = 0.00231, and quantile of absolute error = 0.058.

Conclusion

Hsa_circ_0001359 in serum exosomes is a promising marker for predicting BPD in preterm infants with gestational age ≤32 weeks.

The immunoregulatory property of mesenchymal stem cells in Crocin treatment by expression modulation of microRNA-155, microRNA-21, microRNA-23b, microRNA-126a, and their target inflammatory genes

Mesenchymal stem cells (MSCs) have high priority in clinical applications for treatment of immune disorders because of their immunomodulatory function. A lot of researches have currently been undertaken to enhance the stemness capacities of the cells and pick an excellent type of MSCs for clinical approaches. This study aims to assess the immunomodulatory related MicroRNAs (miRNAs) expression as well as their target genes in both adipose derived stem cells (Ad-SCs) and dental pulp derived stem cell (DP-SCs) in the presence or lack of Crocin (saffron plant's bioactive compound). For this purpose, first MSCs were extracted from adipose and dental pulp tissues, and then their mesenchymal nature was confirmed using flow cytometry and differentiation tests. Following the cell treatment with an optimal-non-toxic dose of Crocin (Obtained by MTT test), the expression of 4 selected immunomodulatory-related micro-RNAs (Mir-126, -21, -23, and-155) and their target genes (PI3K/ Akt 1 and 2/ NFKB and RELA) were assessed by RT-PCR. Our findings revealed that miRNA-23 and miRNA-126 were up-regulated in both types of cells treated with Crocin, while in the other side, miRNA-21 and miRNA-155 were down-regulated in DP-SCs and were up-regulated in Ad-SCs under treatment. Moreover, the real-time PCR results indicated that Crocin could significantly down regulate the expression of PI3K/ Akt1/ Akt2/ NFKB/ RELA genes in DP-SCs and PI3K/Akt2 genes in Ad-SCs and up regulate the expression of Akt1/ NFKB/ RELA genes in recent cells. Based on the analysis of the obtained data, the immunoregulatory effects of Crocin were higher in DP-SCs than in Ad-SCs. In conclusion, Crocin could control essential signaling pathways related to the inflammation by regulating the expression of related- miRNAs genes that play a key function in the immune regulation pathways in MSCs. Our findings can give an understanding of the mechanisms by which Crocin enhances the immunomodulatory feature of MSCs. According to the research findings, DP-SCs are probably a better immunomodulator in Crocin treatment than Ad-SCs and it may be helpful for MSCs selection in clinical applications for modulation or treatment of autoimmune disorders.

Effect of Oridonin on Experimental Animal Model of Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is a serious disease that occurs in premature and low-birth-weight infants. In recent years, the incidence of BPD has not decreased, and there is no effective treatment for it. Oridonin (Ori) is a traditional Chinese medicine with a wide range of biological activities, especially pharmacological and anti-inflammatory. It is well known that inflammation plays a key role in BPD. However, the therapeutic effect of Ori on BPD has not been studied. Therefore, in the present study, we will observe the anti-inflammatory activity of Ori in an experimental animal model of BPD. Here, we showed that Ori could significantly decrease hyperoxia-induced alveolar injury, inhibit neutrophil recruitment, myeloperoxidase concentrations, and release inflammatory factors in BPD neonatal rats. Taken together, the experimental results suggested that Ori can significantly improve BPD in neonatal rats by inhibiting inflammatory response.

PC (16:0/14:0) ameliorates hyperoxia-induced bronchopulmonary dysplasia by upregulating claudin-1 and promoting alveolar type II cell repair

Bronchopulmonary dysplasia (BPD) remains a significant challenge in neonatal care, the pathogenesis of which potentially involves altered lipid metabolism. Given the critical role of lipids in lung development and the injury response, we hypothesized that specific lipid species could serve as therapeutic agents in BPD. This study aimed to investigate the role of the lipid Phosphatidylcholine (PC) (16:0/14:0) in modulating BPD pathology and to elucidate its underlying mechanisms of action. Our approach integrated in vitro and in vivo methodologies to assess the effects of PC (16:0/14:0) on the histopathology, cellular proliferation, apoptosis, and molecular markers in lung tissue. In a hyperoxia-induced BPD rat model, we observed a reduction in alveolar number and an enlargement in alveolar size, which were ameliorated by PC (16:0/14:0) treatment. Correspondingly, in BPD cell models, PC (16:0/14:0) intervention led to increased cell viability, enhanced proliferation, reduced apoptosis, and elevated surfactant protein C (SPC) expression. RNA sequencing revealed significant gene expression differences between BPD and PC (16:0/14:0) treated groups, with a particular focus on Cldn1 (encoding claudin 1), which was significantly enriched in our analysis. Our findings suggest that PC (16:0/14:0) might protect against hyperoxia-induced alveolar type II cell damage by upregulating CLDN1 expression, potentially serving as a novel therapeutic target for BPD. This study not only advances our understanding of the role of lipids in BPD pathogenesis, but also highlights the significance of PC (16:0/14:0) in the prevention and treatment of BPD, offering new avenues for future research and therapeutic development.

Transplantation of alveolar macrophages improves the efficacy of endothelial progenitor cell therapy in mouse model of bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is a severe complication of preterm births, which develops due to exposure to supplemental oxygen and mechanical ventilation. Published studies demonstrated that the number of endothelial progenitor cells (EPC) is decreased in mouse and human BPD lungs and that adoptive transfer of EPC is an effective approach in reversing the hyperoxia-induced lung damage in mouse model of BPD. Recent advancements in macrophage biology identified the specific subtypes of circulating and resident macrophages mediating the developmental and regenerative functions in the lungs. Several studies reported the successful application of macrophage therapy in accelerating the regenerative capacity of damaged tissues and enhancing the therapeutic efficacy of other transplantable progenitor cells. In the present study, we explored the efficacy of combined cell therapy with EPC and resident alveolar macrophages (rAM) in hyperoxia-induced BPD mouse model. rAM and EPC were purified from neonatal mouse lungs and were used for adoptive transfer to the recipient neonatal mice exposed to hyperoxia. Adoptive transfer of rAM alone did not result in engraftment of donor rAM into the lung tissue but increased the mRNA level and protein concentration of proangiogenic CXCL12 chemokine in recipient mouse lungs. Depletion of rAM by chlodronate-liposomes decreased the retention of donor EPC after their transplantation into hyperoxia-injured lungs. Adoptive transfer of rAM in combination with EPC enhanced the therapeutic efficacy of EPC as evidenced by increased retention of EPC, increased capillary density, improved arterial oxygenation, and alveolarization in hyperoxia-injured lungs. Dual therapy with EPC and rAM has promise in human BPD.NEW & NOTEWORTHY Recent studies demonstrated that transplantation of lung-resident endothelial progenitor cells (EPC) is an effective therapy in mouse model of bronchopulmonary dysplasia (BPD). However, key factors regulating the efficacy of EPC are unknown. Herein, we demonstrate that transplantation of tissue-resident alveolar macrophages (rAM) increases CXCL12 expression in neonatal mouse lungs. rAM are required for retention of donor EPC in hyperoxia-injured lungs. Co-transplantation of rAM and EPC improves the efficacy of EPC therapy in mouse BPD model.

Outcomes of combined mitochondria and mesenchymal stem cells-derived exosome therapy in rat acute respiratory distress syndrome and sepsis

BACKGROUND

The treatment of acute respiratory distress syndrome (ARDS) complicated by sepsis syndrome (SS) remains challenging.

AIM

To investigate whether combined adipose-derived mesenchymal-stem-cells (ADMSCs)-derived exosome (EXAD) and exogenous mitochondria (mitoEx) protect the lung from ARDS complicated by SS.

METHODS

In vitro study, including L2 cells treated with lipopolysaccharide (LPS) and in vivo study including male-adult-SD rats categorized into groups 1 (sham-operated-control), 2 (ARDS-SS), 3 (ARDS-SS + EXAD), 4 (ARDS-SS + mitoEx), and 5 (ARDS-SS + EXAD + mitoEx), were included in the present study.

RESULTS

In vitro study showed an abundance of mitoEx found in recipient-L2 cells, resulting in significantly higher mitochondrial-cytochrome-C, adenosine triphosphate and relative mitochondrial DNA levels (P < 0.001). The protein levels of inflammation [interleukin (IL)-1β/tumor necrosis factor (TNF)-α/nuclear factor-κB/toll-like receptor (TLR)-4/matrix-metalloproteinase (MMP)-9/oxidative-stress (NOX-1/NOX-2)/apoptosis (cleaved-caspase3/cleaved-poly (ADP-ribose) polymerase)] were significantly attenuated in lipopolysaccharide (LPS)-treated L2 cells with EXAD treatment than without EXAD treatment, whereas the protein expressions of cellular junctions [occluding/β-catenin/zonula occludens (ZO)-1/E-cadherin] exhibited an opposite pattern of inflammation (all P < 0.001). Animals were euthanized by 72 h post-48 h-ARDS induction, and lung tissues were harvested. By 72 h, flow cytometric analysis of bronchoalveolar lavage fluid demonstrated that the levels of inflammatory cells (Ly6G+/CD14+/CD68+/CD11b/c+/myeloperoxidase+) and albumin were lowest in group 1, highest in group 2, and significantly higher in groups 3 and 4 than in group 5 (all P < 0.0001), whereas arterial oxygen-saturation (SaO2%) displayed an opposite pattern of albumin among the groups. Histopathological findings of lung injury/fibrosis area and inflammatory/DNA-damaged markers (CD68+/γ-H2AX) displayed an identical pattern of SaO2% among the groups (all P < 0.0001). The protein expressions of inflammatory (TLR-4/MMP-9/IL-1β/TNF-α)/oxidative stress (NOX-1/NOX-2/p22phox/oxidized protein)/mitochondrial-damaged (cytosolic-cytochrome-C/dynamin-related protein 1)/autophagic (beclin-1/Atg-5/ratio of LC3B-II/LC3B-I) biomarkers exhibited a similar manner, whereas antioxidants [nuclear respiratory factor (Nrf)-1/Nrf-2]/cellular junctions (ZO-1/E-cadherin)/mitochondrial electron transport chain (complex I-V) exhibited an opposite manner of albumin among the groups (all P < 0.0001).

CONCLUSION

Combined EXAD-mitoEx therapy was better than merely one for protecting the lung against ARDS-SS induced injury.

Outcomes of combined mitochondria and mesenchymal stem cells-derived exosome therapy in rat acute respiratory distress syndrome and sepsis

BACKGROUND

The treatment of acute respiratory distress syndrome (ARDS) complicated by sepsis syndrome (SS) remains challenging.

AIM

To investigate whether combined adipose-derived mesenchymal-stem-cells (ADMSCs)-derived exosome (EX^AD) and exogenous mitochondria (mito^Ex) protect the lung from ARDS complicated by SS.

METHODS

In vitro study, including L2 cells treated with lipopolysaccharide (LPS) and in vivo study including male-adult-SD rats categorized into groups 1 (sham-operated-control), 2 (ARDS-SS), 3 (ARDS-SS + EX^AD), 4 (ARDS-SS + mito^Ex), and 5 (ARDS-SS + EX^AD + mito^Ex), were included in the present study.

RESULTS

In vitro study showed an abundance of mito^Ex found in recipient-L2 cells, resulting in significantly higher mitochondrial-cytochrome-C, adenosine triphosphate and relative mitochondrial DNA levels (P < 0.001). The protein levels of inflammation [interleukin (IL)-1β/tumor necrosis factor (TNF)-α/nuclear factor-κB/toll-like receptor (TLR)-4/matrix-metalloproteinase (MMP)-9/oxidative-stress (NOX-1/NOX-2)/apoptosis (cleaved-caspase3/cleaved-poly (ADP-ribose) polymerase)] were significantly attenuated in lipopolysaccharide (LPS)-treated L2 cells with EX^AD treatment than without EX^AD treatment, whereas the protein expressions of cellular junctions [occluding/β-catenin/zonula occludens (ZO)-1/E-cadherin] exhibited an opposite pattern of inflammation (all P < 0.001). Animals were euthanized by 72 h post-48 h-ARDS induction, and lung tissues were harvested. By 72 h, flow cytometric analysis of bronchoalveolar lavage fluid demonstrated that the levels of inflammatory cells (Ly6G+/CD14+/CD68+/CD11^b/c+/myeloperoxidase+) and albumin were lowest in group 1, highest in group 2, and significantly higher in groups 3 and 4 than in group 5 (all P < 0.0001), whereas arterial oxygen-saturation (SaO₂%) displayed an opposite pattern of albumin among the groups. Histopathological findings of lung injury/fibrosis area and inflammatory/DNA-damaged markers (CD68+/γ-H2AX) displayed an identical pattern of SaO₂% among the groups (all P < 0.0001). The protein expressions of inflammatory (TLR-4/MMP-9/IL-1β/TNF-α)/oxidative stress (NOX-1/NOX-2/p22phox/oxidized protein)/mitochondrial-damaged (cytosolic-cytochrome-C/dynamin-related protein 1)/autophagic (beclin-1/Atg-5/ratio of LC3B-II/LC3B-I) biomarkers exhibited a similar manner, whereas antioxidants [nuclear respiratory factor (Nrf)-1/Nrf-2]/cellular junctions (ZO-1/E-cadherin)/mitochondrial electron transport chain (complex I-V) exhibited an opposite manner of albumin among the groups (all P < 0.0001).

CONCLUSION

Combined EX^AD-mito^Ex therapy was better than merely one for protecting the lung against ARDS-SS induced injury.

Stem cell-based therapy for fibrotic diseases: mechanisms and pathways

Fibrosis is a pathological process, that could result in permanent scarring and impairment of the physiological function of the affected organ; this condition which is categorized under the term organ failure could affect various organs in different situations. The involvement of the major organs, such as the lungs, liver, kidney, heart, and skin, is associated with a high rate of morbidity and mortality across the world. Fibrotic disorders encompass a broad range of complications and could be traced to various illnesses and impairments; these could range from simple skin scars with beauty issues to severe rheumatologic or inflammatory disorders such as systemic sclerosis as well as idiopathic pulmonary fibrosis. Besides, the overactivation of immune responses during any inflammatory condition causing tissue damage could contribute to the pathogenic fibrotic events accompanying the healing response; for instance, the inflammation resulting from tissue engraftment could cause the formation of fibrotic scars in the grafted tissue, even in cases where the immune system deals with hard to clear infections, fibrotic scars could follow and cause severe adverse effects. A good example of such a complication is post-Covid19 lung fibrosis which could impair the life of the affected individuals with extensive lung involvement. However, effective therapies that halt or slow down the progression of fibrosis are missing in the current clinical settings. Considering the immunomodulatory and regenerative potential of distinct stem cell types, their application as an anti-fibrotic agent, capable of attenuating tissue fibrosis has been investigated by many researchers. Although the majority of the studies addressing the anti-fibrotic effects of stem cells indicated their potent capabilities, the underlying mechanisms, and pathways by which these cells could impact fibrotic processes remain poorly understood. Here, we first, review the properties of various stem cell types utilized so far as anti-fibrotic treatments and discuss the challenges and limitations associated with their applications in clinical settings; then, we will summarize the general and organ-specific mechanisms and pathways contributing to tissue fibrosis; finally, we will describe the mechanisms and pathways considered to be employed by distinct stem cell types for exerting anti-fibrotic events.

Novel insights into the potential applications of stem cells in pulmonary hypertension therapy

Pulmonary hypertension (PH) refers to a group of deadly lung diseases characterized by vascular lesions in the microvasculature and a progressive increase in pulmonary vascular resistance. The prevalence of PH has increased over time. Currently, the treatment options available for PH patients have limited efficacy, and none of them can fundamentally reverse pulmonary vascular remodeling. Stem cells represent an ideal seed with proven efficacy in clinical studies focusing on liver, cardiovascular, and nerve diseases. Since the potential therapeutic effect of mesenchymal stem cells (MSCs) on PH was first reported in 2006, many studies have demonstrated the efficacy of stem cells in PH animal models and suggested that stem cells can help slow the deterioration of lung tissue. Existing PH treatment studies basically focus on the paracrine action of stem cells, including protein regulation, exosome pathway, and cell signaling; however, the specific mechanisms have not yet been clarified. Apoptotic and afunctional pulmonary microvascular endothelial cells (PMVECs) and alveolar epithelial cells (AECs) are two fundamental promoters of PH although they have not been extensively studied by researchers. This review mainly focuses on the supportive communication and interaction between PMVECs and AECs as well as the potential restorative effect of stem cells on their injury. In the future, more studies are needed to prove these effects and explore more radical cures for PH.

Repeated intravenous doses of human umbilical cord-derived mesenchymal stromal cells for bronchopulmonary dysplasia: results of a phase 1 clinical trial with 2-year follow-up

BACKGROUND

Currently, there is a lack of effective treatments or preventive strategies for bronchopulmonary dysplasia (BPD). Pre-clinical studies with mesenchymal stromal cells (MSCs) have yielded encouraging results. The safety of administering repeated intravenous doses of umbilical cord tissue-derived mesenchymal stromal cells (UC-MSCs) has not yet been tested in extremely-low-gestational-age newborns (ELGANs).

AIMS

to test the safety and feasibility of administering three sequential intravenous doses of UC-MSCs every 7 days to ELGANs at risk of developing BPD.

METHODS

In this phase 1 clinical trial, we recruited ELGANs (birth weight ≤1250 g and ≤28 weeks in gestational age [GA]) who were on invasive mechanical ventilation (IMV) with FiO2 ≥ 0.3 at postnatal days 7-14. Three doses of 5 × 106/kg of UC-MSCs were intravenously administered at weekly intervals. Adverse effects and prematurity-related morbidities were recorded.

RESULTS

From April 2019 to July 2020, 10 patients were recruited with a mean GA of 25.2 ± 0.8 weeks and a mean birth weight of 659.8 ± 153.8 g. All patients received three intravenous UC-MSC doses. The first dose was administered at a mean of 16.6 ± 2.9 postnatal days. All patients were diagnosed with BPD. All patients were discharged from the hospital. No deaths or any serious adverse events related to the infusion of UC-MSCs were observed during administration, hospital stays or at 2-year follow-up.

CONCLUSIONS

The administration of repeated intravenous infusion of UC-MSCs in ELGANs at a high risk of developing BPD was feasible and safe in the short- and mid-term follow-up.

Mesenchymal stromal cell extracellular vesicles improve lung development in mechanically ventilated preterm lambs

Novel therapies are needed for bronchopulmonary dysplasia (BPD) because no effective treatment exists. Mesenchymal stromal cell extracellular vesicles (MSC-sEVs) have therapeutic efficacy in a mouse pup neonatal hyperoxia BPD model. We tested the hypothesis that MSC-sEVs will improve lung functional and structural development in mechanically ventilated preterm lambs. Preterm lambs (∼129 days; equivalent to human lung development at ∼28 wk gestation) were exposed to antenatal steroids, surfactant, caffeine, and supported by mechanical ventilation for 6-7 days. Lambs were randomized to blinded treatment with either MSC-sEVs (human bone marrow MSC-derived; 2 × 1011 particles iv; n = 8; 4 F/4 M) or vehicle control (saline iv; 4 F/4 M) at 6 and 78 h post delivery. Physiological targets were pulse oximetry O2 saturation 90-94% ([Formula: see text] 60-90 mmHg), [Formula: see text] 45-60 mmHg (pH 7.25-7.35), and tidal volume 5-7 mL/kg. MSC-sEVs-treated preterm lambs tolerated enteral feedings compared with vehicle control preterm lambs. Differences in weight patterns were statistically significant. Respiratory severity score, oxygenation index, A-a gradient, distal airspace wall thickness, and smooth muscle thickness around terminal bronchioles and pulmonary arterioles were significantly lower for the MSC-sEVs group. S/F ratio, radial alveolar count, secondary septal volume density, alveolar capillary surface density, and protein abundance of VEGF-R2 were significantly higher for the MSC-sEVs group. MSC-sEVs improved respiratory system physiology and alveolar formation in mechanically ventilated preterm lambs. MSC-sEVs may be an effective and safe therapy for appropriate functional and structural development of the lung in preterm infants who require mechanical ventilation and are at risk of developing BPD.NEW & NOTEWORTHY This study focused on potential treatment of preterm infants at risk of developing bronchopulmonary dysplasia (BPD), for which no effective treatment exists. We tested treatment of mechanically ventilated preterm lambs with human mesenchymal stromal cell extracellular vesicles (MSC-sEVs). The results show improved respiratory gas exchange and parenchymal growth of capillaries and epithelium that are necessary for alveolar formation. Our study provides new mechanistic insight into potential efficacy of MSC-sEVs for preterm infants at risk of developing BPD.

Roles of extracellular vesicles on macrophages in inflammatory bone diseases

Inflammatory bone disease is a general term for a series of diseases caused by chronic inflammation, which leads to the destruction of bone homeostasis, that is, the osteolytic activity of osteoclasts increases, and the osteogenic activity of osteoblasts decreases, leading to osteolysis. Macrophages are innate immune cell with plasticity, and their polarization is related to inflammatory bone diseases. The dynamic balance of macrophages between the M1 phenotype and the M2 phenotype affects the occurrence and development of diseases. In recent years, an increasing number of studies have shown that extracellular vesicles existing in the extracellular environment can act on macrophages, affecting the progress of inflammatory diseases. This process is realized by influencing the physiological activity or functional activity of macrophages, inducing macrophages to secrete cytokines, and playing an anti-inflammatory or pro-inflammatory role. In addition, by modifying and editing extracellular vesicles, the potential of targeting macrophages can be used to provide new ideas for developing new drug carriers for inflammatory bone diseases.

Recent progress in neonatal hyperoxic lung injury

With the progress in neonatal intensive care, there has been an increase in the survival rates of premature infants. However, this has also led to an increased incidence of neonatal hyperoxia lung injury and bronchopulmonary dysplasia (BPD), whose pathogenesis is believed to be influenced by various prenatal and postnatal factors, although the exact mechanisms remain unclear. Recent studies suggest that multiple mechanisms might be involved in neonatal hyperoxic lung injury and BPD, with sex also possibly playing an important role, and numerous drugs have been proposed and shown promise for improving the treatment outcomes of hyperoxic lung injury. Therefore, this paper aims to analyze and summarize sex differences in neonatal hyperoxic lung injury, potential pathogenesis and treatment progress to provide new ideas for basic and clinical research in this field.

Proteomic Analysis of Umbilical Cord Mesenchymal Stem Cell-Derived Extracellular Vesicles: A Systematic Review

Numerous challenges remain within conventional cell-based therapy despite the growing trend of stem cells used to treat various life-debilitating diseases. These limitations include batch-to-batch heterogeneity, induced alloreactivity, cell survival and integration, poor scalability, and high cost of treatment, thus hindering successful translation from lab to bedside. However, recent pioneering technology has enabled the isolation and enrichment of small extracellular vesicles (EVs), canonically known as exosomes. EVs are described as a membrane-enclosed cargo of functional biomolecules not limited to lipids, nucleic acid, and proteins. Interestingly, studies have correlated the biological role of MSC-EVs to the paracrine activity of MSCs. This key evidence has led to rigorous studies on MSC-EVs as an acellular alternative. Using EVs as a therapy was proposed as a model leading to improvements through increased safety; enhanced bioavailability due to size and permeability; reduced heterogeneity by selective and quantifiable properties; and prolonged shelf-life via long-term freezing or lyophilization. Yet, the identity and potency of EVs are still relatively unknown due to various methods of preparation and to qualify the final product. This is reflected by the absence of regulatory strategies overseeing manufacturing, quality control, clinical implementation, and product registration. In this review, the authors review the various production processes and the proteomic profile of MSC-EVs.

The emerging role of extracellular vesicles in bronchopulmonary dysplasia

Extracellular vesicle (EV) biology in neonatal lung development and disease is a rapidly growing area of investigation. Although EV research in the neonatal population lags behind EV research in adult lung diseases, recent discoveries demonstrate promise in furthering our understanding of the pathophysiology of bronchopulmonary dysplasia and the potential use of EVs in the clinical setting, as both biomarkers and therapeutic agents. This review article explores some of the recent advances in this field and our evolving knowledge of the role of EVs in bronchopulmonary dysplasia.

Mesenchymal Stem Cell-Derived Exosomes Attenuate Murine Cytomegalovirus-Infected Pneumonia via NF-κB/NLRP3 Signaling Pathway

Reactivation and infection with cytomegalovirus (CMV) are frequently observed in recipients of solid organ transplants, bone marrow transplants, and individuals with HIV infection. This presents an increasing risk of allograft rejection, opportunistic infection, graft failure, and patient mortality. Among immunocompromised hosts, interstitial pneumonia is the most critical clinical manifestation of CMV infection. Recent studies have demonstrated the potential therapeutic benefits of exosomes derived from mesenchymal stem cells (MSC-exos) in preclinical models of acute lung injury, including pneumonia, ARDS, and sepsis. However, the role of MSC-exos in the pathogenesis of infectious viral diseases, such as CMV pneumonia, remains unclear. In a mouse model of murine CMV-induced pneumonia, we observed that intravenous administration of mouse MSC (mMSC)-exos reduced lung damage, decreased the hyperinflammatory response, and shifted macrophage polarization from the M1 to the M2 phenotype. Treatment with mMSC-exos also significantly reduced the infiltration of inflammatory cells and pulmonary fibrosis. Furthermore, in vitro studies revealed that mMSC-exos reversed the hyperinflammatory phenotype of bone marrow-derived macrophages infected with murine CMV. Mechanistically, mMSC-exos treatment decreased activation of the NF-κB/NLRP3 signaling pathway both in vivo and in vitro. In summary, our findings indicate that mMSC-exo treatment is effective in severe CMV pneumonia by reducing lung inflammation and fibrosis through the NF-κB/NLRP3 signaling pathway, thus providing promising therapeutic potential for clinical CMV infection.

Exosomes: efficient macrophage-related immunomodulators in chronic lung diseases

Macrophages, the predominant immune cells in the lungs, play a pivotal role in maintaining the delicate balance of the pulmonary immune microenvironment. However, in chronic inflammatory lung diseases and lung cancer, macrophage phenotypes undergo distinct transitions, with M1-predominant macrophages promoting inflammatory damage and M2-predominant macrophages fostering cancer progression. Exosomes, as critical mediators of intercellular signaling and substance exchange, participate in pathological reshaping of macrophages during development of pulmonary inflammatory diseases and lung cancer. Specifically, in inflammatory lung diseases, exosomes promote the pro-inflammatory phenotype of macrophages, suppress the anti-inflammatory phenotype, and subsequently, exosomes released by reshaped macrophages further exacerbate inflammatory damage. In cancer, exosomes promote pro-tumor tumor-associated macrophages (TAMs); inhibit anti-tumor TAMs; and exosomes released by TAMs further enhance tumor proliferation, metastasis, and resistance to chemotherapy. Simultaneously, exosomes exhibit a dual role, holding the potential to transmit immune-modulating molecules and load therapeutic agents and offering prospects for restoring immune dysregulation in macrophages during chronic inflammatory lung diseases and lung cancer. In chronic inflammatory lung diseases, this is manifested by exosomes reshaping anti-inflammatory macrophages, inhibiting pro-inflammatory macrophages, and alleviating inflammatory damage post-reshaping. In lung cancer, exosomes reshape anti-tumor macrophages, inhibit pro-tumor macrophages, and reshaped macrophages secrete exosomes that suppress lung cancer development. Looking ahead, efficient and targeted exosome-based therapies may emerge as a promising direction for treatment of pulmonary diseases.

Epigenetic modifications in the development of bronchopulmonary dysplasia: a review

While perinatal medicine advancements have bolstered survival outcomes for premature infants, bronchopulmonary dysplasia (BPD) continues to threaten their long-term health. Gene-environment interactions, mediated by epigenetic modifications such as DNA methylation, histone modification, and non-coding RNA regulation, take center stage in BPD pathogenesis. Recent discoveries link methylation variations across biological pathways with BPD. Also, the potential reversibility of histone modifications fuels new treatment avenues. The review also highlights the promise of utilizing mesenchymal stem cells and their exosomes as BPD therapies, given their ability to modulate non-coding RNA, opening novel research and intervention possibilities. IMPACT: The complexity and universality of epigenetic modifications in the occurrence and development of bronchopulmonary dysplasia were thoroughly discussed. Both molecular and cellular mechanisms contribute to the diverse nature of epigenetic changes, suggesting the need for deeper biochemical techniques to explore these molecular alterations. The utilization of innovative cell-specific drug delivery methods like exosomes and extracellular vesicles holds promise in achieving precise epigenetic regulation.

Human lens epithelial-secreted exosomes attenuate ocular angiogenesis via inhibiting microglial activation

The lens is an avascular tissue, where epithelial cells (LECs) are the primary living cells. The role of LECs-derived exosomes (LEC-exos) is largely unknown. In our study, we determined the anti-angiogenic role of LEC-exos, manifested as regressed retinal neovascularization (NV) using the oxygen-induced retinopathy (OIR), and reduced choroidal NV size and pathological vascular leakage using the laser-induced choroidal neovascularization (laser-induced CNV). Furthermore, the activation and accumulation of microglia were also restricted by LEC-exos. Based on Luminex multiplex assays, the expressions of chemokines such as SCYB16/CXCL16, MCP-1/CCL2, I-TAC/CXCL11, and MIP 3beta/CCL19 were decreased after treatment with LEC-exos. Transwell assays showed that LEC-exos restricted the migration of the mouse microglia cell line (BV2 cells). After incubation with LEC-exos-treated BV2 cells, human umbilical vein endothelial cells (hUVECs) were collected for further evaluation using tube formation, Transwell assays, and 5-ethynyl-2'-deoxyuridine (EDU) assays. Using in vitro experiments, the pro-angiogenic effect of microglia was restricted by LEC-exos. Hence, it was investigated that LEC-exos attenuated ocular NV, which might attribute to the inhibition of microglial activation and accumulation.

Human milk exosome-derived circDNAJB6 improves bronchopulmonary dysplasia model by promoting DNAJB6 gene transcription

To verify the protective effect of circDNAJB6 on Bronchopulmonary dysplasia (BPD) cell and animal models and to explore the possible mechanism of its protective effect. The function of circDNAJB6 was investigated at the cell and animal levels. Nuclear and Cytoplasmic RNA extraction kits and fluorescence in situ hybridization (FISH) were used to explore the distribution of circDNAJB6 in cells, and the potential mechanism of circDNAJB6 was verified by q-PCR, luciferase assays and rescue experiments.CircDNAJB6 is abundant in breast milk exosomes. Overexpression of circDNAJB6 can ameliorate damage in BPD models caused by hyperoxia exposure in vivo and in vitro. Mechanistically, circDNAJB6 can target the downstream DNAJB6 gene and promote the transcription of DNAJB6, exertive a protective effect on the experimental BPD model. Our results showed that circDNAJB6 alleviated damage and inhibited the proliferation of alveolar epithelial cells in the BPD model by promoting transcription of parent gene DNAJB6. Human milk exosome-derived circDNAJB6 provides new directions for preventing and treating BPD.

Mesenchymal Stem Cell-Derived Exosomes Promote Recovery of The Facial Nerve Injury through Regulating Macrophage M1 and M2 Polarization by Targeting the P38 MAPK/NF-Κb Pathway

Facial nerve (FN) injury seriously affects human social viability and causes a heavy economic and social burden. Although mesenchymal stem cell-derived exosomes (MSC-Exos) promise therapeutic benefits for injury repair, there has been no evaluation of the impact of MSC-Exos administration on FN repair. Herein, we explore the function of MSC-Exos in the immunomodulation of macrophages and their effects in repairing FN injury. An ultracentrifugation technique was used to separate exosomes from the MSC supernatant. Administrating MSC-Exos to SD rats via local injection after FN injury promoted axon regeneration and myelination and alleviated local and systemic inflammation. MSC-Exos facilitated M2 polarization and reduced the M1-M2 polarization ratio. miRNA sequencing of MSC-Exos and previous literature showed that the MAPK/NF-κb pathway was a downstream target of macrophage polarization. We confirmed this hypothesis both in vivo and in vitro. Our findings show that MSC-Exos are a potential candidate for treating FN injury because they may have superior benefits for FN injury recovery and can decrease inflammation by controlling the heterogeneity of macrophages, which is regulated by the p38 MAPK/NF-κb pathway.

Mesenchymal stem cell-derived exosomes: Characteristics and applications in disease pathology and management

Mesenchymal stem cells (MSCs) possess a role in tissue regeneration and homeostasis because of inherent immunomodulatory capacity and the production of factors that encourage healing. There is substantial evidence that MSCs' therapeutic efficacy is primarily determined by their paracrine function including in cancers. Extracellular vesicles (EVs) are basic paracrine effectors of MSCs that reside in numerous bodily fluids and cell homogenates and play an important role in bidirectional communication. MSC-derived EVs (MSC-EVs) offer a wide range of potential therapeutic uses that exceed cell treatment, while maintaining protocell function and having less immunogenicity. We describe characteristics and isolation methods of MSC-EVs, and focus on their therapeutic potential describing its roles in tissue repair, anti-fibrosis, and cancer with an emphasis on the molecular mechanism and immune modulation and clinical trials. We also explain current understanding and challenges in the clinical applications of MSC-EVs as a cell free therapy.

Effectiveness of extracellular vesicles derived from hiPSCs in repairing hyperoxia-induced injury in a fetal murine lung explant model

BACKGROUND

Despite advances in neonatal care, the incidence of Bronchopulmonary Dysplasia (BPD) remains high among preterm infants. Human induced pluripotent stem cells (hiPSCs) have shown promise in repairing injury in animal BPD models. Evidence suggests they exert their effects via paracrine mechanisms. We aim herein to assess the effectiveness of extracellular vesicles (EVs) derived from hiPSCs and their alveolar progenies (diPSCs) in attenuating hyperoxic injury in a preterm lung explant model.

METHODS

Murine lung lobes were harvested on embryonic day 17.5 and maintained in air-liquid interface. Following exposure to 95% O2 for 24 h, media was supplemented with 5 × 106 particles/mL of EVs isolated from hiPSCs or diPSCs by size-exclusion chromatography. On day 3, explants were assessed using Hematoxylin-Eosin staining with mean linear intercept (MLI) measurements, immunohistochemistry, VEGFa and antioxidant gene expression. Statistical analysis was conducted using one-way ANOVA and Multiple Comparison Test. EV proteomic profiling was performed, and annotations focused on alveolarization and angiogenesis signaling pathways, as well as anti-inflammatory, anti-oxidant, and regenerative pathways.

RESULTS

Exposure of fetal lung explants to hyperoxia induced airspace enlargement, increased MLI, upregulation of anti-oxidants Prdx5 and Nfe2l2 with decreased VEGFa expression. Treatment with hiPSC-EVs improved parenchymal histologic changes. No overt changes in vasculature structure were observed on immunohistochemistry in our in vitro model. However, VEGFa and anti-oxidant genes were upregulated with diPSC-EVs, suggesting a pro-angiogenic and cytoprotective potential. EV proteomic analysis provided new insights in regard to potential pathways influencing lung regeneration.

CONCLUSION

This proof-of-concept in vitro study reveals a potential role for hiPSC- and diPSC-EVs in attenuating lung changes associated with prematurity and oxygen exposure. Our findings pave the way for a novel cell free approach to prevent and/or treat BPD, and ultimately reduce the global burden of the disease.

MSCs alleviate LPS-induced acute lung injury by inhibiting the proinflammatory function of macrophages in mouse lung organoid-macrophage model

Acute lung injury (ALI) is an inflammatory disease associated with alveolar injury, subsequent macrophage activation, inflammatory cell infiltration, and cytokine production. Mesenchymal stem cells (MSCs) are beneficial for application in the treatment of inflammatory diseases due to their immunomodulatory effects. However, the mechanisms of regulatory effects by MSCs on macrophages in ALI need more in-depth study. Lung tissues were collected from mice for mouse lung organoid construction. Alveolar macrophages (AMs) derived from bronchoalveolar lavage and interstitial macrophages (IMs) derived from lung tissue were co-cultured, with novel matrigel-spreading lung organoids to construct an in vitro model of lung organoids-immune cells. Mouse compact bone-derived MSCs were co-cultured with organoids-macrophages to confirm their therapeutic effect on acute lung injury. Changes in transcriptome expression profile were analyzed by RNA sequencing. Well-established lung organoids expressed various lung cell type-specific markers. Lung organoids grown on spreading matrigel had the property of functional cells growing outside the lumen. Lipopolysaccharide (LPS)-induced injury promoted macrophage chemotaxis toward lung organoids and enhanced the expression of inflammation-associated genes in inflammation-injured lung organoids-macrophages compared with controls. Treatment with MSCs inhibited the injury progress and reduced the levels of inflammatory components. Furthermore, through the nuclear factor-κB pathway, MSC treatment inhibited inflammatory and phenotypic transformation of AMs and modulated the antigen-presenting function of IMs, thereby affecting the inflammatory phenotype of lung organoids. Lung organoids grown by spreading matrigel facilitate the reception of external stimuli and the construction of in vitro models containing immune cells, which is a potential novel model for disease research. MSCs exert protective effects against lung injury by regulating different functions of AMs and IMs in the lung, indicating a potential mechanism for therapeutic intervention.

The phenotype and related gene expressions of macrophages in adipose tissue of T2D mice following MSCs infusion

BACKGROUND

Infusion of mesenchymal stem cells (MSCs) induces polarization of M2 macrophages in adipose tissue of type 2 diabetes (T2D) mice. Studies have shown that M2 macrophages were divided into four sub-phenotypes (M2a, M2b, M2c and M2d) with different functions, and manuscripts have also confirmed that macrophages co-cultured with MSCs were not matched with known four phenotype macrophages. Therefore, our study explored the phenotype and related gene expressions of macrophages in the adipose tissue of T2D mice with/without MSCs infusion.

METHODS

We induced a T2D mouse model by using high-fat diets and streptozotocin (STZ) injection. The mice were divided into three groups: the control group, the T2D group, and the MSCs group. MSCs were systemically injected once a week for 6 weeks. The phenotype of macrophages in adipose tissue was detected via flow cytometric analysis. We also investigated the gene expression of macrophages in different groups via SMART-RNA-sequencing and quantitative real-time reverse transcriptase polymerase chain reaction (qRT-PCR).

RESULTS

The present study found that the macrophages of adipose tissue in the MSCs group were polarized to the M2 phenotype mixed with four sub-phenotypes. Besides, M2a and M2c held a dominant position, while M2b and M2d (tumor-associated macrophages, TAMs) exhibited a decreasing trend after infusion of MSCs. Moreover, the MSCs group did not appear to express higher levels of tumor-associated, inflammation-associated, or fibrosis-associated genes in comparison to the T2D group.

CONCLUSION

The present results unveiled that the macrophage phenotype was inclined to be present in a hybridity state of four M2 sub-phenotypes and the genes related to tumor-promoting, pro-inflammation and pro-fibrosis were not increased after MSCs injection.

A Review of the Use of Extracellular Vesicles in the Treatment of Neonatal Diseases: Current State and Problems with Translation to the Clinic

Neonatal disorders, particularly those resulting from prematurity, pose a major challenge in health care and have a significant impact on infant mortality and long-term child health. The limitations of current therapeutic strategies emphasize the need for innovative treatments. New cell-free technologies utilizing extracellular vesicles (EVs) offer a compelling opportunity for neonatal therapy by harnessing the inherent regenerative capabilities of EVs. These nanoscale particles, secreted by a variety of organisms including animals, bacteria, fungi and plants, contain a repertoire of bioactive molecules with therapeutic potential. This review aims to provide a comprehensive assessment of the therapeutic effects of EVs and mechanistic insights into EVs from stem cells, biological fluids and non-animal sources, with a focus on common neonatal conditions such as hypoxic-ischemic encephalopathy, respiratory distress syndrome, bronchopulmonary dysplasia and necrotizing enterocolitis. This review summarizes evidence for the therapeutic potential of EVs, analyzes evidence of their mechanisms of action and discusses the challenges associated with the implementation of EV-based therapies in neonatal clinical practice.

Human mesenchymal stem cell secretomes: Factors affecting profiling and challenges in clinical application

The promising field of regenerative medicine is thrilling as it can repair and restore organs for various debilitating diseases. Mesenchymal stem cells are one of the main components in regenerative medicine that work through the release of secretomes. By adopting the use of the secretome in cell-free-based therapy, we may be able to address the challenges faced in cell-based therapy. As one of the components of cell-free-based therapy, secretome has the advantage of a better safety and efficacy profile than mesenchymal stem cells. However, secretome has its challenges that need to be addressed, such as its bioprocessing methods that may impact the secretome content and its mechanisms of action in clinical settings. Effective and standardization of bioprocessing protocols are important to ensure the supply and sustainability of secretomes for clinical applications. This may eventually impact its commercialization and marketability. In this review, the bioprocessing methods and their impacts on the secretome profile and treatment are discussed. This improves understanding of its fundamental aspects leading to potential clinical applications.

Pathogenesis and Physiologic Mechanisms of Neonatal Pulmonary Hypertension: Preclinical Studies

Neonatal pulmonary hypertension (PH) is a devastating disorder of the pulmonary vasculature characterized by elevated pulmonary vascular resistance and mean pulmonary arterial pressure. Occurring predominantly because of maldevelopment or maladaptation of the pulmonary vasculature, PH in neonates is associated with suboptimal short-term and long-term outcomes because its pathobiology is unclear in most circumstances, and it responds poorly to conventional pulmonary vasodilators. Understanding the pathogenesis and pathophysiology of neonatal PH can lead to novel strategies and precise therapies. The review is designed to achieve this goal by summarizing pulmonary vascular development and the pathogenesis and pathophysiology of PH associated with maladaptation, bronchopulmonary dysplasia, and congenital diaphragmatic hernia based on evidence predominantly from preclinical studies. We also discuss the pros and cons of and provide future directions for preclinical studies in neonatal PH.

Research hotspots and emerging trends in mesenchymal stem/stromal cells in bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is a prevalent lung disease in neonates that is associated with numerous complications and high mortality. The promising approach to treat BPD is the use of mesenchymal stem cells (MSCs), However, the current treatment of MSCs presents safety concerns, including occlusion of blood vessels and tumorigenicity. In this study, relevant publications from the Web of Science Core Collection were downloaded in January 2023. The acquired data were analyzed and predicted for trends and hotspots in this field using CiteSpace software. Results revealed that in recent years, the focus of co-cited references has been primarily on the clinical studies of MSCs and the application of MSCs derivatives for treating BPD models. The keywords that have gained attention are extracellular vesicles and exosomes. The United States has emerged as the most influential co-authoring country in this field. Among the co-cited journals, the American Journal of Respiratory and Critical Care Medicine holds the highest influence. Thus, this study provides trends in publications, collaboration, research interests, and hotspots, and provides clues for novel ideas and strategies in to further MSCs treatments for BPD.

Exosomes as Emerging Regulators of Immune Responses in Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disorder characterized by high blood glucose levels resulting from insulin resistance and impaired insulin secretion. Immune dysregulation-mediated chronic low-grade inflammation is a critical factor that poses a significant risk to the metabolic disorders of T2DM and its related complications. Exosomes, as small extracellular vesicles secreted by various cells, have emerged as essential regulators of intercellular communication and immune regulation. In this review, we summarize the current understanding of the role of exosomes derived from immune and nonimmune cells in modulating immune responses in T2DM by regulating immune cell functions and cytokine production. More importantly, we suggest potential strategies for the clinical applications of exosomes in T2DM management, including biomarkers for disease diagnosis and monitoring, exosome-based therapies for drug delivery vehicles, and targeted therapy for exosomes.

Implication of m6A Methylation Regulators in the Immune Microenvironment of Bronchopulmonary Dysplasia

N6-methyladenosine (m6A) regulates gene expression and governs many important biological processes. However, the function of m6A in the development of bronchopulmonary dysplasia (BPD) remains poorly characterized. Thus, the purpose of this investigation was to evaluate the effects of m6A RNA methylation regulators on the development of BPD. BPD-related transcriptome data were downloaded from the GEO database. Differentially expressed m6A methylation regulators between BPD and control group were identified. Consensus clustering was conducted for the classification of BPD and association between clusters and BPD phenotypes were explored. Analysis of differentially expressed genes (DEGs) and immune-related DEGs was performed. The GSEA, GO and KEGG analyses were used to interpret the functional enrichments. The composition of immune cell subtypes in BPD subsets was predicted by CIBERSORT analysis. Compared with the control group, expression of most m6A regulators showed significant alteration, especially for IGF2BP1/2/3. BPD was classified into 2 subsets, and cluster 1 was correlated with severe BPD. Furthermore, the results of functional enrichment analyses showed a disturbed immune-related signaling pathway. Based on CIBERSORT analysis, we found that the proportion of immune cell subsets changed between cluster 1 and cluster 2. Our study revealed the implication of m6A methylation regulators in the development of BPD, which might provide a novel insight for the diagnosis and treatment of BPD.

A highly sensitive and specific Homo1-based real-time qPCR method for quantification of human umbilical cord mesenchymal stem cells in rats

BACKGROUND

Owing to the characteristics of easier access in vitro, low immunogenicity, and high plasticity, human umbilical cord-derived mesenchymal stem cells (UC-MSCs) are considered as a promising cell-based drugs for clinical application. No internationally recognized technology exists to evaluate the pharmacokinetics and distribution of cell-based drugs in vivo.

METHODS

We determined the human-specific gene sequence, Homo1, from differential fragments Homo sapiens mitochondrion and Rattus norvegicus mitochondrion. The expression of Homo1 was utilized to determine the distribution of UC-MSCs in the normal and diabetic nephropathy (DN) rats.

RESULTS

We observed a significant correlation between the number of UC-MSCs and the expression level of Homo1. Following intravenous transplantation, the blood levels of UC-MSCs peaked at 30 min. A large amount of intravenously injected MSCs were trapped in the lungs, but the number of them decreased rapidly after 24 h. Additionally, the distribution of UC-MSCs in the kidneys of DN rats was significantly higher than that of normal rats.

CONCLUSIONS

In this study, we establish a highly sensitive and specific Homo1-based real-time quantitative PCR method to quantify the distribution of human UC-MSCs in rats. The method provides guidelines for the safety research of cells in preclinical stages.

Role of genetically engineered mesenchymal stem cell exosomes and LncRNAs in respiratory diseases treatment

The term acute respiratory disease encompasses a wide range of acute lung diseases, which in recent years have been ranked among the top three deadly diseases in the world. Since conventional treatment methods, including the use of anti-inflammatory drugs, have had no significant effect on the treatment process of these diseases, the attention of the medical community has been drawn to alternative methods. Mesenchymal stem cells (MSC) are multipotential stem/progenitor cells that have extensive immunomodulatory and anti-inflammatory properties and also play a critical role in the microenvironment of injured tissue. MSC secretomes (containing large extracellular vesicles, microvesicles, and exosomes) are a newly introduced option for cell-free therapies that can circumvent the hurdles of cell-based therapies while maintaining the therapeutic role of MSC themselves. The therapeutic capabilities of MSCs have been showed in many acute respiratory diseases, including chronic respiratory disease (CRD), novel coronavirus 2019 (COVID -19), and pneumonia. MSCs offer novel therapeutic approaches for chronic and acute lung diseases due to their anti-inflammatory and immunomodulatory properties. In this review, we summarize the current evidence on the efficacy and safety of MSC-derived products in preclinical models of lung diseases and highlight the biologically active compounds present in the MSC secretome and their mechanisms involved in anti-inflammatory activity and tissue regeneration.

Impaired receptivity of thin endometrium: therapeutic potential of mesenchymal stem cells

The endometrium is a resilient and highly dynamic tissue, undergoing cyclic renewal in preparation for embryo implantation. Cyclic endometrial regeneration depends on the intact function of several cell types, including parenchymal, endothelial, and immune cells, as well as adult stem cells that can arise from endometrial or extrauterine sources. The ability of the endometrium to undergo rapid, repeated regeneration without scarring is unique to this tissue. However, if this tissue renewal process is disrupted or dysfunctional, women may present clinically with infertility due to endometrial scarring or persistent atrophic/thin endometrium. Such disorders are rate-limiting in the treatment of female infertility and in the success of in vitro fertilization because of a dearth of treatment options specifically targeting the endometrium. A growing number of studies have explored the potential of adult stem cells, including mesenchymal stem cells (MSCs), to treat women with disorders of endometrial regeneration. MSCs are multipotent adult stem cells with capacity to differentiate into cells such as adipocytes, chondrocytes, and osteoblasts. In addition to their differentiation capacity, MSCs migrate toward injured sites where they secrete bioactive factors (e.g. cytokines, chemokines, growth factors, proteins and extracellular vesicles) to aid in tissue repair. These factors modulate biological processes critical for tissue regeneration, such as angiogenesis, cell migration and immunomodulation. The MSC secretome has therefore attracted significant attention for its therapeutic potential. In the uterus, studies utilizing rodent models and limited human trials have shown a potential benefit of MSCs and the MSC secretome in treatment of endometrial infertility. This review will explore the potential of MSCs to treat women with impaired endometrial receptivity due to a thin endometrium or endometrial scarring. We will provide context supporting leveraging MSCs for this purpose by including a review of mechanisms by which the MSC secretome promotes regeneration and repair of nonreproductive tissues.

Human Umbilical Cord Mesenchymal Stem Cell Exosome-derived miR-335-5p Alleviated Lipopolysaccharide-induced Acute Lung Injury by Regulating the m6A Level of ITGβ4 Gene

BACKGROUND

Acute lung injury (ALI) is a serious complication that may accompany severe pneumonia in children. Derived from human umbilical cord mesenchymal stem cell exosome (HucMSC-Exo) can contribute to the regeneration of damaged lung tissue. This study aims to investigate the impact of HucMSC-Exo on ALI and its potential mechanisms.

METHODS

Firstly, RT-qPCR was performed to assess the expression of miR-335-5p. Subsequently, Pearson correlation analysis was performed to examine the correlation between METTL14 and miR-335-5p, as well as the correlation between METTL14 and ITGβ4, while RNA immunoprecipitation (RIP) was used to determine the m6A modification level of ITGβ4. Additionally, molecular biology techniques were employed to evaluate the expression of glycolysis-related factors. Definitively, an LPS-induced ALI model was established to investigate the effect of miR-335-5p on mice lung tissue.

RESULTS

miR-335-5p was found to be highly expressed in HucMSC-Exo. Transfection with miR-335-5p mimics resulted in increased glucose uptake. Pearson correlation analysis revealed a negative correlation between METTL14 and miR-335-5p, as well as between METTL14 and ITGβ4. The m6A level of ITGβ4 was elevated in ALI. Overexpression of METTL14 was found to reduce the expression of ITGβ4 and glucose levels, while overexpression of ITGβ4 reversed the effects of METTL14 overexpression. In vivo, results demonstrated that miR-335-5p could improve the extent of lung tissue lesions and reduce glycolytic levels.

CONCLUSION

This study revealed the mechanism by which miR-335-5p derived from HucMSC-Exo could alleviate LPS-induced ALI by regulating the m6A modification of ITGβ4, providing a new direction for the treatment of ALI.

Emerging delivery approaches for targeted pulmonary fibrosis treatment

Pulmonary fibrosis (PF) is a progressive, and life-threatening interstitial lung disease which causes scarring in the lung parenchyma and thereby affects architecture and functioning of lung. It is an irreversible damage to lung functioning which is related to epithelial cell injury, immense accumulation of immune cells and inflammatory cytokines, and irregular recruitment of extracellular matrix. The inflammatory cytokines trigger the differentiation of fibroblasts into activated fibroblasts, also known as myofibroblasts, which further increase the production and deposition of collagen at the injury sites in the lung. Despite the significant morbidity and mortality associated with PF, there is no available treatment that efficiently and effectively treats the disease by reversing their underlying pathologies. In recent years, many therapeutic regimens, for instance, rho kinase inhibitors, Smad signaling pathway inhibitors, p38, BCL-xL/ BCL-2 and JNK pathway inhibitors, have been found to be potent and effective in treating PF, in preclinical stages. However, due to non-selectivity and non-specificity, the therapeutic molecules also result in toxicity mediated severe side effects. Hence, this review demonstrates recent advances on PF pathology, mechanism and targets related to PF, development of various drug delivery systems based on small molecules, RNAs, oligonucleotides, peptides, antibodies, exosomes, and stem cells for the treatment of PF and the progress of various therapeutic treatments in clinical trials to advance PF treatment.

Mesenchymal stem cell-derived exosomes in preeclampsia: A next-generation therapeutic tool

Preeclampsia (PE) is a major gestational disorder that causes both long- and short-term damage to both the mother and the fetus. Endometrium decidualization and the formation of the placenta are orchestrated by mesenchymal stem cells (MSCs). MSCs obtained from patients with PE exhibit an elevated rate of aging and apoptosis, which impairs the interplay between MSCs and endothelium, trophoblast, and immune cells in the placenta, accelerating the onset of PE. Preclinical and clinical evidence imply that the MSC-based therapy approach for PE is prospective. Importantly, as a novel cell-free approach, MSC-derived exosomes can improve symptoms and maternal-fetal survival in PE models by raising cell metabolism, encouraging angiogenesis balance, and regulating immune responses. Even following allogeneic administration, the likelihood of immune rejection is very limited as a result of the small quantity of exosome membrane-bound proteins. Furthermore, because exosomes do not expand, developing tumors is not probable. As a result, MSC-derived exosomes show superiority over MSCs in terms of safety. For the first time, we outline the properties of MSC-exosomes and highlight their functions and potential as a new paradigm for PE therapy in this review.

Bone Marrow Mesenchymal Stem Cell-derived Exosomal microRNA-99b-5p Promotes Cell Growth of High Glucose-treated Human Umbilical Vein Endothelial Cells by Modulating THAP Domain Containing 2 Expression

INTRODUCTION

Bone marrow mesenchymal stem cell-derived exosomes (BMSC-exos) may function as novel candidates for treating diabetic wounds due to their ability to promote angiogenesis.

MATERIALS AND METHODS

This study investigated the effects of BMSC-exos on the growth and metastasis of human umbilical vein endothelial cells (HUVECs) treated with high glucose (HG). The exosomes were separated from BMSCs and identified. The cell phenotype was detected by 3-(4,5- dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide and 5-ethynyl-2'-deoxyuridine, wound healing, and transwell assays, while the number of tubes was measured via tube formation assay.

RESULT

The RNA and protein expression levels were studied using reverse transcription-quantitative polymerase chain reaction and western blotting, whereas integration of microRNA-99b-5p (miR-99b-5p) with THAP domain containing 2 (THAP2) was confirmed via dual-luciferase reporter and RNA pull-down assays. Results of transmission electron microscopy, nanoparticle tracking analysis, and laser scanning confocal microscopy revealed that exosomes were successfully separated from BMSCs and endocytosed into the cytoplasm by HUVECs. Similarly, BMSC-exos were found to promote the growth of HG-treated HUVECs, while their growth was inhibited by suppressing miR-99b-5p. THAP2 was found to bind to miR-99b-5p, where THAP2 inhibition reversed the miR-99b-5p-induced effects on cell growth, migration, and tube numbers.

CONCLUSION

In conclusion, miR-99b-5p in BMSC-exo protects HUVECs by negatively regulating THAP2 expression.

The Role of MicroRNAs in Mesenchymal Stem Cell-Based Modulation of Pulmonary Fibrosis

Pulmonary fibrosis is a complex and multifactorial condition that involves a cascade of events, including lung injury, damage of alveolar epithelial cells (AECs), generation of immune cell-driven inflammation, and activation of fibroblasts and their differentiation into myofibroblasts, resulting in the excessive production and deposition of collagen and progressive scarring and fibrosis of the lung tissue. As lung fibrosis advances, the scarring and stiffening of lung tissue can significantly hinder the exchange of oxygen and carbon dioxide, potentially leading to respiratory failure that can be life-threatening. Anti-inflammatory and immunosuppressive drugs are used to slow down the progression of the disease, manage symptoms, and enhance the patient's quality of life. However, prolonged immunosuppression could increase the susceptibility to severe bacterial, viral, or fungal pneumonia in lung-transplant recipients. Therefore, there is an urgent need for new therapeutic agents that can effectively reduce lung inflammation and fibrosis without compromising the protective immune response in patients with severe lung fibrosis. Results obtained in recently published studies demonstrated that mesenchymal stem/stromal cell-derived microRNAs (MSC-miRNAs) could attenuate detrimental immune response in injured lungs and prevent progression of lung fibrosis. Through the post-transcriptional regulation of target mRNA, MSC-miRNAs modulate protein synthesis and affect viability, proliferation, and cytokine production in AECs, fibroblasts, and lung-infiltrated immune cells. In order to delineate molecular mechanisms responsible for beneficial effects of MSC-miRNAs in the treatment of lung fibrosis, in this review article, we summarized current knowledge related to anti-fibrotic and anti-inflammatory pathways elicited in immune cells, AECs, and myofibroblasts by MSC-miRNAs.

Potential Druggability of Mesenchymal Stem/Stromal Cell-derived Exosomes

Exosomes secreted by mesenchymal stem/stromal cells (MSC-Exos) are advantageous candidate sources for novel acellular therapy. Despite the current standards of good manufacturing practice (GMP), the deficiency of suitable quality-control methods and the difficulties in large-scale preparation largely restrict the development of therapeutic products and their clinical applications worldwide. Herein, we mainly focus on three dominating issues commonly encountered in exosomal GMP, including issues upstream of the cell culture process, downstream of the purification process, exosomes quality control, and the drug properties of exosomes and their druggability from a corporate perspective. Collectively, in this review article, we put forward the issues of preparing clinical exosome drugs for the treatment of diverse diseases and provide new references for the clinical application of GMP-grade MSC-Exos.

Advancements in engineered mesenchymal stem cell exosomes for chronic lung disease treatment

Chronic lung diseases include an array of conditions that impact airways and lung structures, leading to considerable societal burdens. Mesenchymal stem cells (MSCs) and their exosomes (MSC-exos) can be used for cell therapy and exhibit a diverse spectrum of anti-inflammatory, antifibrotic, and immunomodulatory properties. Engineered MSC-exos possesses enhanced capabilities for targeted drug delivery, resulting in more potent targeting effects. Through various engineering modifications, these exosomes can exert many biological effects, resulting in specific therapeutic outcomes for many diseases. Moreover, engineered stem cell exosomes may exhibit an increased capacity to traverse physiological barriers and infiltrate protected lesions, thereby exerting their therapeutic effects. These characteristics render them a promising therapeutic agent for chronic pulmonary diseases. This article discusses and reviews the strategies and mechanisms of engineered MSC-exos in the treatment of chronic respiratory diseases based on many studies to provide new solutions for these diseases.

Irisin alleviates hyperoxia-induced bronchopulmonary dysplasia through activation of Nrf2/HO-1 pathway

BACKGROUND

Bronchopulmonary dysplasia (BPD) is a common pulmonary injury among premature infants, which is often caused by hyperoxia exposure. Irisin is a novel hormone-like myokine derived mainly from skeletal muscles as well as adipose tissues. Many studies have indicated that Irisin exert a variety of properties against hyperoxia-induced inflammation and oxidative stress (OS). We aimed to evaluate the effects of irisin on hyperoxia-induced lung injury explore the underlying mechanisms.

METHODS

BPD model was established after exposing newborn mouse to 85% oxygen. BPD mouse received continuous intraperitoneal injection of irisin at a dose of 25 μg/kg/day. Lung tissues were collected for histological examination at 7 and 14 days after birth. The alveolarization and alveolar vascularization of each animal was assessed. Levels of oxidative stress indicators, and the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) in lung tissues were detected at 14 days after birth.

RESULTS

Hyperoxia exposure induced a markedly alveolar simplification and a disrupted alveolar angiogenesis, which was ameliorated by irisin treatment. The hyperoxia-induced increase in these oxidative stress indicators was significantly reversed by irisin treatment. The Nrf2/HO-1 pathway is inducted in the hyperoxia-induced BPD mouse model, which is further activated by irisin treatment.

CONCLUSION

Our results demonstrated the beneficial effects of irisin in reducing the OS, enhancing alveolarization, and promoting vascular development through activation of Nrf2/HO-1 axis in a hyperoxia-induced experimental model of BPD.

Mesenchymal stem cell-derived exosomes and skin photoaging: From basic research to practical application

BACKGROUND

Skin photoaging is a condition caused by long-term exposure to ultraviolet irradiation, resulting in a variety of changes in the skin, such as capillary dilation, increased or absent pigmentation, dryness, sagging, and wrinkles. Stem cells possess a remarkable antioxidant capacity and the ability to proliferate, differentiate, and migrate, and their main mode of action is through paracrine secretion, with exosomes being the primary form of secretion. Stem cell-derived exosomes contain a variety of growth factors and cytokines and may have great potential to promote skin repair and delay skin ageing.

METHODS

This review focuses on the mechanisms of UV-induced skin photoaging, the research progress of stem cell exosomes against skin photoaging, emerging application approaches and limitations in the application of exosome therapy.

RESULT

Exosomes derived from various stem cells have the potential to prevent skin photoaging.

CONCLUSION

The combination with novel materials may be a key step for their practical application, which could be an important direction for future basic research and practical applications.

Advances in neonatal cell therapies: Proceedings of the First Neonatal Cell Therapies Symposium (2022)

Despite considerable advances, there is a need to improve the outcomes of newborn infants, especially related to prematurity, encephalopathy and other conditions. In principle, cell therapies have the potential to protect, repair, or sometimes regenerate vital tissues; and improve or sustain organ function. In this review, we present highlights from the First Neonatal Cell Therapies Symposium (2022). Cells tested in preclinical and clinical studies include mesenchymal stromal cells from various sources, umbilical cord blood and cord tissue derived cells, and placental tissue and membrane derived cells. Overall, most preclinical studies suggest potential for benefit, but many of the cells tested were not adequately defined, and the optimal cell type, timing, frequency, cell dose or the most effective protocols for the targeted conditions is not known. There is as yet no clinical evidence for benefit, but several early phase clinical trials are now assessing safety in newborn babies. We discuss parental perspectives on their involvement in these trials, and lessons learnt from previous translational work of promising neonatal therapies. Finally, we make a call to the many research groups around the world working in this exciting yet complex field, to work together to make substantial and timely progress to address the knowledge gaps and move the field forward. IMPACT: Survival of preterm and sick newborn infants is improving, but they continue to be at high risk of many systemic and organ-specific complications. Cell therapies show promising results in preclinical models of various neonatal conditions and early phase clinical trials have been completed or underway. Progress on the potential utility of cell therapies for neonatal conditions, parental perspectives and translational aspects are discussed in this paper.