Effect of bone marrow-derived mesenchymal stem cells on endotoxin-induced oxidation of plasma cysteine and glutathione in mice

Human umbilical cord mesenchymal stem cells protect MC3T3-E1 osteoblasts from dexamethasone-induced apoptosis via induction of the Nrf2-ARE signaling pathway

Objective

To investigate the protective effect human umbilical cord mesenchymal stem cells (hUC-MSCs) have on Dexamethasone (Dex)-induced apoptosis in osteogenesis via the Nrf2-ARE signaling pathway.

Methods

Glucocorticoid-induced osteonecrosis of the femoral head (GC-ONFH) was developed in rats through the administration of lipopolysaccharide and methylprednisolone. The incidence of femoral head necrosis, cavity notch, apoptosis of osteoblasts, and bone density were observed by HE staining, TUNEL staining, and Micro-CT. HUC-MSCs were co-cultured with mouse pre-osteoblast MC3T3-E1. The survival rate of osteoblasts was determined by CCK8, and apoptosis and ROS levels of osteoblasts were determined by flow cytometer. The viability of antioxidant enzymes SOD, GSH-Px, and CAT was analyzed by biochemistry. Nrf2 expression levels and those of its downstream proteins and apoptosis-related proteins were analyzed by Western blotting.

Results

In rats, hUC-MSCs can reduce the rates of empty bone lacuna and osteoblast apoptosis that are induced by glucocorticoids (GCs), while reducing the incidence of GC-ONFH. hUC-MSCs can significantly improve the survival rate and antioxidant SOD, GSH-Px, and CAT activity of MC3T3-E1 cells caused by Dex, and inhibit apoptosis and oxidative stress levels. In addition, hUC-MSCs can up-regulate the expression of osteoblast antioxidant protein Nrf2 and its downstream protein HO-1, NQO-1, GCLC, GCLM, and apoptosis-related protein bcl-2, while also down-regulating the expression of apoptosis-related protein bax, cleaved caspase-3, cleaved caspase-9, and cytochrome C in MC3T3-E1 cells. hUC-MSCs improve the ability of MC3T3-E1 cells to mineralize to osteogenesis. However, the promoting effects of hUC-MSCs were abolished following the blocking of the Nrf2-ARE signaling pathway for osteoblasts.

Conclusion

The results reveal that hUC-MSCs can reduce Dex-induced apoptosis in osteoblasts via the Nrf2-ARE signaling pathway.

Anti-oxidative activities and anti-ferroptosis of conditioned medium from umbilical cord mesenchymal stem cells

The therapeutic effect of MSC is closely related to its antioxidant capacity. There is no uniform standard for evaluating the antioxidant capacity of MSC. In this study, we compared the antioxidant capacity of control medium (CON) and conditioned medium (CM) from umbilical cord mesenchymal stem cells cultured for 48 h, about total antioxidant capacity, DPPH scavenging capacity, O2- and hydroxyl radical inhibiting capacity, and the detection of antioxidant enzymes including superoxide dismutase, glutathione peroxidase, and catalase, and resistance to cellular oxidative damage caused by H2O2, SNAP, erastin, and RSL3. The results showed that CM had better DPPH scavenging capacity than CON. No significant differences were observed in antioxidant enzymes. CM did not resist the oxidative damage induced by H2O2 and SNAP, but it had a strong resistance to ferroptosis induced by erastin and RSL3, indicating that CM had excellent resistance to cell lipid peroxidation. CM could improve the cell shrinkage morphology induced by ferroptosis and reduce the production of lipid ROS. qPCR experiments proved that CM improved and regulated multiple pathways of ferroptosis, including genes related to iron metabolism such as FPN, FTH1, TFRC, and IREB2, and redox regulatory genes such as GPX4, AIFM2, DHODH, and TP53, and increased the antioxidant-related transcription factors NRF2 and ATF4.

Stem/Progenitor Cells and Related Therapy in Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is a chronic lung disease commonly seen in preterm infants, and is triggered by infection, mechanical ventilation, and oxygen toxicity. Among other problems, lifelong limitations in lung function and impaired psychomotor development may result. Despite major advances in understanding the disease pathologies, successful interventions are still limited to only a few drug therapies with a restricted therapeutic benefit, and which sometimes have significant side effects. As a more promising therapeutic option, mesenchymal stem cells (MSCs) have been in focus for several years due to their anti-inflammatory effects and their secretion of growth and development promoting factors. Preclinical studies provide evidence in that MSCs have the potential to contribute to the repair of lung injuries. This review provides an overview of MSCs, and other stem/progenitor cells present in the lung, their identifying characteristics, and their differentiation potential, including cytokine/growth factor involvement. Furthermore, animal studies and clinical trials using stem cells or their secretome are reviewed. To bring MSC-based therapeutic options further to clinical use, standardized protocols are needed, and upcoming side effects must be critically evaluated. To fill these gaps of knowledge, the MSCs' behavior and the effects of their secretome have to be examined in more (pre-) clinical studies, from which only few have been designed to date.

Emerging Trends in Mesenchymal Stem Cells Applications for Cardiac Regenerative Therapy: Current Status and Advances

Irreversible myocardium infarction is one of the leading causes of cardiovascular disease (CVD) related death and its quantum is expected to grow in coming years. Pharmacological intervention has been at the forefront to ameliorate injury-related morbidity and mortality. However, its outcomes are highly skewed. As an alternative, stem cell-based tissue engineering/regenerative medicine has been explored quite extensively to regenerate the damaged myocardium. The therapeutic modality that has been most widely studied both preclinically and clinically is based on adult multipotent mesenchymal stem cells (MSC) delivered to the injured heart. However, there is debate over the mechanistic therapeutic role of MSC in generating functional beating cardiomyocytes. This review intends to emphasize the role and use of MSC in cardiac regenerative therapy (CRT). We have elucidated in detail, the various aspects related to the history and progress of MSC use in cardiac tissue engineering and its multiple strategies to drive cardiomyogenesis. We have further discussed with a focus on the various therapeutic mechanism uncovered in recent times that has a significant role in ameliorating heart-related problems. We reviewed recent and advanced technologies using MSC to develop/create tissue construct for use in cardiac regenerative therapy. Finally, we have provided the latest update on the usage of MSC in clinical trials and discussed the outcome of such studies in realizing the full potential of MSC use in clinical management of cardiac injury as a cellular therapy module.

Antifibrotic effect of lung-resident progenitor cells with high aldehyde dehydrogenase activity

Background

Aldehyde dehydrogenase (ALDH) is highly expressed in stem/progenitor cells in various tissues, and cell populations with high ALDH activity (ALDH^br) are associated with tissue repair. However, little is known about lung-resident ALDH^br. This study was performed to clarify the characteristics of lung-resident ALDH^br cells and to evaluate their possible use as a tool for cell therapy using a mouse model of bleomycin-induced pulmonary fibrosis.

Methods

The characteristics of lung-resident/nonhematopoietic (CD45⁻) ALDH^br cells were assessed in control C57BL/6 mice. The kinetics and the potential usage of CD45⁻/ALDH^br for cell therapy were investigated in bleomycin-induced pulmonary fibrosis. Localization of transferred CD45⁻/ALDH^br cells was determined using mCherry-expressing mice as donors. The effects of aging on ALDH expression were also assessed using aged mice.

Results

Lung CD45⁻/ALDH^br showed higher proliferative and colony-forming potential than cell populations with low ALDH activity. The CD45⁻/ALDH^br cell population, and especially its CD45⁻/ALDH^br/PDGFRα⁺ subpopulation, was significantly reduced in the lung during bleomycin-induced pulmonary fibrosis. Furthermore, mRNA expression of ALDH isoforms was significantly reduced in the fibrotic lung. When transferred in vivo into bleomycin-pretreated mice, CD45⁻/ALDH^br cells reached the site of injury, ameliorated pulmonary fibrosis, recovered the reduced expression of ALDH mRNA, and prolonged survival, which was associated with the upregulation of the retinol-metabolizing pathway and the suppression of profibrotic cytokines. The reduction in CD45⁻/ALDH^br/PDGFRα⁺ population was more remarkable in aged mice than in young mice.

Conclusions

Our results strongly suggest that the lung expression of ALDH and lung-resident CD45⁻/ALDH^br cells are involved in pulmonary fibrosis. The current study signified the possibility that CD45⁻/ALDH^br cells could find application as novel and useful cell therapy tools in pulmonary fibrosis treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02549-6.

Mesenchymal stem cell therapies for COVID-19: Current status and mechanism of action

The outbreak of COVID-19 in December 2019, has become an urgent and serious public health emergency. At present, there is no effective treatment or vaccine for COVID-19. Therefore, there is a crucial unmet need to develop a safe and effective treatment for COVID-19 patients. Mesenchymal stem cells (MSCs) are widely used in basic science and in a variety of clinical trials. MSCs are able to engraft to the damaged tissues after transplantation and promote tissue regeneration, besides MSCs able to secrete immunomodulatory factors that suppress the cytokine storms. Moreover, the contribution of MSCs to prevent cell death and inhibit tissue fibrosis is well established. In the current review article, the potential mechanisms by which MSCs contribute to the treatment of COVID-19 patients are highlighted. Also, current trials that evaluated the potential of MSC-based treatments for COVID-19 are briefly reviewed.

Cell-Based Therapeutic Approaches for Cystic Fibrosis

Cystic Fibrosis (CF) is a chronic autosomal recessive disease caused by defects in the cystic fibrosis transmembrane conductance regulator gene (CFTR). Cystic Fibrosis affects multiple organs but progressive remodeling of the airways, mucus accumulation, and chronic inflammation in the lung, result in lung disease as the major cause of morbidity and mortality. While advances in management of CF symptoms have increased the life expectancy of this devastating disease, and there is tremendous excitement about the potential of new agents targeting the CFTR molecule itself, there is still no curative treatment. With the recent advances in the identification of endogenous airway progenitor cells and in directed differentiation of pluripotent cell sources, cell-based therapeutic approaches for CF have become a plausible treatment method with the potential to ultimately cure the disease. In this review, we highlight the current state of cell therapy in the CF field focusing on the relevant autologous and allogeneic cell populations under investigation and the challenges associated with their use. In addition, we present advances in induced pluripotent stem (iPS) cell approaches and emerging new genetic engineering methods, which have the capacity to overcome the current limitations hindering cell therapy approaches.

The emerging antioxidant paradigm of mesenchymal stem cell therapy

Mesenchymal stem cells (multipotent stromal cells; MSCs) have been under investigation for the treatment of diverse diseases, with many promising outcomes achieved in animal models and clinical trials. The biological activity of MSC therapies has not been fully resolved which is critical to rationalizing their use and developing strategies to enhance treatment efficacy. Different paradigms have been constructed to explain their mechanism of action, including tissue regeneration, trophic/anti-inflammatory secretion, and immunomodulation. MSCs rarely engraft and differentiate into other cell types after in vivo administration. Furthermore, it is equivocal whether MSCs function via the secretion of many peptide/protein ligands as their therapeutic properties are observed across xenogeneic barriers, which is suggestive of mechanisms involving mediators conserved between species. Oxidative stress is concomitant with cellular injury, inflammation, and dysregulated metabolism which are involved in many pathologies. Growing evidence supports that MSCs exert antioxidant properties in a variety of animal models of disease, which may explain their cytoprotective and anti-inflammatory properties. In this review, evidence of the antioxidant effects of MSCs in in vivo and in vitro models is explored and potential mechanisms of these effects are discussed. These include direct scavenging of free radicals, promoting endogenous antioxidant defenses, immunomodulation via reactive oxygen species suppression, altering mitochondrial bioenergetics, and donating functional mitochondria to damaged cells. Modulation of the redox environment and oxidative stress by MSCs can mediate their anti-inflammatory and cytoprotective properties and may offer an explanation to the diversity in disease models treatable by MSCs and how these mechanisms may be conserved between species.

Impact of sex, age and diet on the cysteine/cystine and glutathione/glutathione disulfide plasma redox couples in mice

Age, sex and diet are well-established risk factors for several diseases. In humans, each of these variables has been linked to differences in plasma redox potentials (E_h) of the glutathione/glutathione disulfide (GSH/GSSG) and cysteine/cystine (Cys/CySS) redox couples. Mice have been very useful for modeling human disease processes, but it is unknown if age, sex and diet affect redox couples in mice as they do in humans. The purpose of the present study was to examine the effects of these factors on plasma redox potentials in C57BL/6J mice. We found that age had no effect on either redox couple in either sex. Plasma E_h Cys/CySS and E_h GSH/GSSG were both more oxidized (more positive) in females than in males. A 24-hour fast negated the sex differences in both redox potentials by oxidizing both redox couples in male mice, while having no effect on E_h Cys/CySS and a smaller effect on E_h GSH/GSSG in female mice. A diet with excess sulfur amino acids reduced the plasma E_h Cys/CySS in females to a level comparable to that seen in male mice. Thus, sex-specific differences in plasma E_h Cys/CySS could be normalized by two different dietary interventions. Some of these findings are consistent with reported human studies, while others are not. Most strikingly, mice do not exhibit age-dependent oxidation of plasma redox potentials. Care must be taken when designing and interpreting mouse studies to investigate redox regulation in humans.

GC-MS based metabolomic profiling of lung tissue couple with network pharmacology revealed the possible protection mechanism of Pudilan Xiaoyan Oral Liquid in LPS-induced lung injury of mice

Pudilan Xiaoyan Oral Liquid (PDL) originated from "Pudilan" Classic Recipe of traditional Chinese medicine is one kind of anti-inflammatory Chinese patent medicine recorded in Chinese Pharmacopeia. PDL has been used clinically for treating inflammatory diseases of the respiratory tract. However, due to the complex composition of PDL, its potential anti-inflammation and the mechanism remain unknown. To identify the mechanism of the PDL in the treatment of lipopolysaccharide (LPS)-induced lung injury of mice. The mice models of lung injury were established and the changes of biochemical indices in serum and histopathology were detected to explore the effects of PDL. The approach of GC-MS metabolomics was used to find more significant metabolites, and the metabolic pathways were enriched through MetaboAnalyst. Then network analysis was applied to visualize the protein related to the important metabolites, merging into a protein-metabolite network via Cytoscape. The treatment of PDL could attenuate LPS-induced histopathological damage of lung tissues, followed by reducing pro-inflammation mediators including IL-10, TNF-a and NF-ĸB in serum. 11 potential metabolites were identified in lung tissue through metabolomics, which were significantly regulated to recover by PDL treatment. The correlated network was constructed by integrating potential metabolites and pathways. Aspartate and l-cysteine were selected as key metabolites and correlated proteins such as IL4I1 and ASPA were speculated as the potential target to treat LPS-induced lung injury using PDL. These results demonstrated that PDL might prevent the pathological process of lung injury through regulating the disturbed protein-metabolite network.

Mesenchymal stem cells alleviate hydrochloric acid-induced lung injury through suppression of inflammation, oxidative stress and apoptosis in comparison to moxifloxacin and sildenafil

Introduction

Acute lung injury (ALI) is a severe life-threatening disease causing uncontrolled pulmonary inflammation and oxidative damage. There are still no effective therapies for this disease. The aim of this study was to evaluate the protective role of mesenchymal stem cells, moxifloxacin, sildenafil or a combination of moxifloxacin and sildenafil against hydrochloric Acid (HCl) - induced ALI.

Methods

HCl or saline was injected intra-tracheally and after 2 h, moxifloxacin, sildenafil, moxifloxacin + sildenafil or mesenchymal stem cells were injected. After 7 days, rats were sacrificed for evaluation of the blood chemistry and inflammation via determination of the level of oxidative stress markers, apoptosis and the histopathological alterations by H&E.

Results

In HCl-injected rats, there were a significant increase in total white blood cells (WBCs), lymphocytes, malondialdehyde (MDA) and caspase-3 gene expression. Also, there were a significant decrease in superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH) and Hemeoxygenase-1 (HO-1) gene expression in lung tissue. On the other hand, treatment of lung injured rats with mesenchymal stem cell, moxifloxacin, sildenafil or a combination of moxifloxacin and sildenafil showed a significant decrease in WBCs and lymphocytes and ameliorated the histopathological changes. MDA level in lung tissue was only significantly lowered in rats treated with moxifloxacin alone or in combination with sildenafil or MSCs. GSH was just increased in rats treated with moxifloxacin, sildenafil or with MSCs. Antioxidant parameters and gene expression of HO-1 and caspase-3 were significantly modulated in rats treated with MSCs.

Conclusion

MSCs ameliorated the toxic effects of HCl through their ability to decrease inflammation, oxidative stress, and apoptosis in acute lung injury.

The effect of human adipose-derived stem cells on lipopolysaccharide-induced acute respiratory distress syndrome in mice

Background

Acute respiratory distress syndrome (ARDS) is a type of acute respiratory failure in critically ill patients. Recently, several treatment modalities have been proposed for ARDS, but it still has a high mortality rate. In general, the role of mesenchymal stem cells (MSCs) in controlling inflammatory responses has been studied in various immune-associated diseases in humans and animals. However, only a few studies reported adipose-derived stem cells (ASCs), which are easier to isolate, are currently emerging as an attractive treatment option in ARDS. Therefore, in this study, we investigated the therapeutic effects of human ASCs and the regulation of inflammatory responses in an ARDS mouse model.

Methods

In the ARDS model, lipopolysaccharide (LPS) (5 mg/kg) was administered via the intra tracheal injection method. The mice were divided into the following four groups: (I) saline + medium; (II) saline + ASCs (2×10⁵); (III) LPS + medium; (IV) LPS + ASCs. The ARDS observation time was divided into short and long term. LPS administration increased the concentration of proinflammatory cytokines, which was a consistent systemic inflammatory response.

Results

LPS/ASC group showed less neutrophil infiltration and less alveolar hemorrhage or congestion than did the LPS group. The lung injury scores of the LPS/ASC group were lower than those of the LPS group (3.8±0.9 vs. 6.8±1.1; P=0.03) at day 2. Compared to the LPS group, LPS/ASC group showed reduced collagen deposition around the vessels and fibrosis accompanied by alveolar septal or interstitial thickening and lower MPO levels than did the LPS group (453.2±26.2 vs. 670.2±65.9 pg/mL; P<0.01) at day 7.

Conclusions

ASC therapy can inhibit neutrophil recruitment, which shows trend of reducing short term lung injury (day 2) and affecting fibrosis in long term (day 7). Further studies are warranted to understand the mechanism and improve the therapeutic effect of ASCs.

α-Lipoic acid and amlodipine/perindopril combination potentiate the therapeutic effect of mesenchymal stem cells on isoproterenol induced cardiac injury in rats

Cardiac injury is a dangerous disease and become a greater issue in the forthcoming decades. The ultimate goal is to prevent the progression of heart failure and apoptotic processes. Cardiac tissue may regenerate itself but to certain extent depending on the number of resident stem cells that is limited. Thus, research had been focused on bone marrow derived stem cells (BM-MSCs) as a promising therapy in different types of tissues, including the heart. This study is designed not only to assess the therapeutic effect of BM-MSCs but also to improve their therapeutic effect in combination with antioxidant α-lipoic acid (ALA) and antihypertensive therapeutic drug form (AP) against isoproterenol-induced cardiac injury and compared with that of BM-MSCs alone. Cardiac injury was induced in 70 male rats by Isoproterenol (ISO was injected s.c. for four consecutive days). Experimental animals were divided into six ISO-treated groups beside a control non treated one. The six ISO-treated groups were divided into: ISO group, ISO+BM-MSCs group, ISO+ALA group, ISO+AP group, ISO+ALA+AP group and ISO+ALA+AP+BM-MSCs group, the last five groups were treated with the examined materials after one week of ISO injection. Isoproterenol significantly increased serum CK-MB, LDH activities, Troponin1 and TNF-α. Oxidative stress is evidenced by the increased MDA, NO and Caspase-3 activity associated with significant reduction of GSH content and SOD activity in cardiac tissue. Furthermore, mRNA expression of NFκB and iNOS were significantly up regulated and eNOS mRNA expression was down regulated. Administration of BM-MSCs, ALA and AP alone significantly mitigated the induced cardiac injury. Concomitant administration of ALA and AP after BM-MSCs induced a more pronounced improving effect on cardiac functions. In conclusion, the concomitant administration of ALA and AP after BM-MSCs infusion increases the cellular antioxidant levels of cardiac tissue that improves the repairing function of BM-MSCs.

Bone Marrow Mesenchymal Stem Cells Combat Lipopolysaccharide-Induced Sepsis in Rats via Amendment of P38-MAPK Signaling Cascade

Sepsis is a systemic inflammatory disorder which often occurs during extremely stressful conditions such as trauma, burn, shock, and infection. This study investigated the curative effects of bone marrow-derived mesenchymal stem cells (BM-MSCs) against hepatic, renal, and pulmonary responses caused by a single administration of lipopolysaccharide (LPS) (10 mg/kg, i.p) in rats. Treatment with BM-MSCs (5 × 10⁵ in 0.1 ml PBS, i.p.) 3 h after LPS antagonized the LPS-induced increment of the liver enzymes (ALT, AST) and kidney functions (BUN, sCr). BM-MSCs decreased tissue levels of P38-MAPK, NF-κB, STAT-3, TNF-α, IL-1β, iNOS, Bax together with elevation of the anti-inflammatory cytokine IL-10 and the anti-apoptotic biomarker Bcl-2. Meanwhile, rats exhibited marked reduction of the broncho-alveolar lavage fluid levels of TNF-α, IL-1β, and IFN-γ. Interestingly, BM-MSCs normalized both broncho-alveolar lavage fluid (BALF) neutrophils count and lung wet/dry ratios. Briefly, these findings may provide a preclinical platform for the management of LPS-induced sepsis using BM-MSCs via their ameliorative anti-inflammatory, anti-oxidant, and anti-apoptotic potentials.

Bone marrow and adipose mesenchymal stem cells attenuate cardiac fibrosis induced by methotrexate in rats

Mesenchymal stem cells (MSCs) are an ideal adult stem cell with capacity for self-renewal and differentiation with an extensive tissue distribution. The present study evaluates the therapeutic effects of bone marrow mesenchymal stem cells (BM-MSCs) or adipose-derived mesenchymal stem cells (AD-MSCs) against the development of methotrexate (MTX)-induced cardiac fibrosis versus dexamethasone (DEX). Rats were allocated into five groups; group 1, received normal saline orally; group 2, received MTX (14 mg/kg/week for 2 weeks); groups 3 and 4, treated once with 2 × 10⁶ cells of MTX + BM-MSCs and MTX + AD-MSCs, respectively; and group 5, MTX + DEX (0.5 mg/kg, for 7 days, P.O.). MTX induced cardiac fibrosis as marked changes in oxidative biomarkers and elevation of triglyceride, cholesterol, aspartate aminotransferase, gamma-glutamyl transferase, creatine kinase, and caspase-3, as well as deposited collagen. These injurious effects were antagonized after treatment with MSCs. So, MSCs possessed antioxidant, antiapoptotic, as well antifibrotic effects, which will perhaps initiate them as notable prospective for the treatment of cardiac fibrosis.

Acute mobilization and migration of bone marrow-derived stem cells following anterior cruciate ligament rupture

OBJECTIVE

Little is known regarding acute local and systemic processes following anterior cruciate ligament (ACL) rupture. No study has elucidated whether bone marrow-derived mesenchymal stem cells (MSCs) are mobilized into circulation and recruited to the injured joint.

METHODS

In Part 1, Lewis rats were randomized to noninvasive ACL rupture (Rupture) or non-injured (Control) (n = 6/group). After 72 h, whole blood MSC concentration was assessed using flow cytometry. Synovial fluid and serum were assayed for stromal cell-derived factor (SDF)-1α and cartilage degeneration biomarkers, respectively. In Part 2, 12 additional rats were randomized and intravenously-injected with fluorescently-labeled allogenic MSCs. Cell tracking was performed using longitudinal, in vivo and ex vivo near-infrared (NIR) imaging and histology. Synovium SDF-1α and interleukin (IL)-17A immunostaining was performed. Serum was assayed for SDF-1α and 29 other cytokines.

RESULTS

In Part 1, there was a significant increase in MSC concentration and synovial fluid SDF-1α in Rupture. No differences in cartilage biomarkers were observed. In Part 2, Rupture had significantly higher NIR signal at 24, 48, and 72 h, indicating active recruitment of MSCs to the injured joint. Ex vivo cell tracking demonstrated MSC localization in the synovium and myotendinous junction (MTJ) of the quadriceps. Injured synovia exhibited increased synovitis grade and higher degree of IL-17A and SDF-1α immunostaining.

CONCLUSION

ACL rupture induced peripheral blood mobilization of MSCs and migration of intravenously-injected allogenic MSCs to the injured joint, where they localized in the synovium and quadriceps MTJ.

Differential Regulation of the Extracellular Cysteine/Cystine Redox State (EhCySS) by Lung Fibroblasts from Young and Old Mice

Aging is associated with progressive oxidation of plasma cysteine (Cys)/cystine (CySS) redox state, expressed as E_hCySS. Cultured cells condition their media to reproduce physiological E_hCySS, but it is unknown whether aged cells produce a more oxidized extracellular environment reflective of that seen in vivo. In the current study, we isolated primary lung fibroblasts from young and old female mice and measured the media E_hCySS before and after challenge with Cys or CySS. We also measured expression of genes related to redox regulation and fibroblast function. These studies revealed that old fibroblasts produced a more oxidizing extracellular E_hCySS than young fibroblasts and that old fibroblasts had a decreased capacity to recover from an oxidative challenge due to a slower rate of reduction of CySS to Cys. These defects were associated with 10-fold lower expression of the Slc7a11 subunit of the xCT cystine-glutamate transporter. Extracellular superoxide dismutase (Sod3) was the only antioxidant or thiol-disulfide regulating enzyme among 36 examined that was downregulated in old fibroblasts by more than 2-fold, but there were numerous changes in extracellular matrix components. Thus, aging fibroblasts not only contribute to remodeling of the extracellular matrix but also have a profound effect on the extracellular redox environment.

In Vivo Effects of Mesenchymal Stromal Cells in Two Patients With Severe Acute Respiratory Distress Syndrome

Mesenchymal stromal cells (MSCs) have been investigated as a treatment for various inflammatory diseases because of their immunomodulatory and reparative properties. However, many basic questions concerning their mechanisms of action after systemic infusion remain unanswered. We performed a detailed analysis of the immunomodulatory properties and proteomic profile of MSCs systemically administered to two patients with severe refractory acute respiratory distress syndrome (ARDS) on a compassionate use basis and attempted to correlate these with in vivo anti-inflammatory actions. Both patients received 2×10(6) cells per kilogram, and each subsequently improved with resolution of respiratory, hemodynamic, and multiorgan failure. In parallel, a decrease was seen in multiple pulmonary and systemic markers of inflammation, including epithelial apoptosis, alveolar-capillary fluid leakage, and proinflammatory cytokines, microRNAs, and chemokines. In vitro studies of the MSCs demonstrated a broad anti-inflammatory capacity, including suppression of T-cell responses and induction of regulatory phenotypes in T cells, monocytes, and neutrophils. Some of these in vitro potency assessments correlated with, and were relevant to, the observed in vivo actions. These experiences highlight both the mechanistic information that can be gained from clinical experience and the value of correlating in vitro potency assessments with clinical effects. The findings also suggest, but do not prove, a beneficial effect of lung protective strategies using adoptively transferred MSCs in ARDS. Appropriate randomized clinical trials are required to further assess any potential clinical efficacy and investigate the effects on in vivo inflammation.

SIGNIFICANCE

This article describes the cases of two patients with severe refractory adult respiratory syndrome (ARDS) who failed to improve after both standard life support measures, including mechanical ventilation, and additional measures, including extracorporeal ventilation (i.e., in a heart-lung machine). Unlike acute forms of ARDS (such in the current NIH-sponsored study of mesenchymal stromal cells in ARDS), recovery does not generally occur in such patients.

Aging mesenchymal stem cells fail to protect because of impaired migration and antiinflammatory response

RATIONALE

Aging is characterized by functional impairment and reduced capacity to respond appropriately to environmental stimuli and injury. With age, there is an increase in the incidence and severity of chronic and acute lung diseases. However, the relationship between age and the lung's reduced ability to repair is far from established and necessitates further research in the field.

OBJECTIVES

Little is currently known about age-related phenomena in mesenchymal stem cells (MSCs). On account of their ability to protect the endothelium and the alveolar epithelium through multiple paracrine mechanisms, we looked for adverse effects that aging might cause in MSC biology. Such age-related changes might partly account for the increased susceptibility of the aging lung to injury.

MEASUREMENTS AND MAIN RESULTS

We demonstrated that old mice have more inflammation in response to acute lung injury. To investigate the causes, we compared the global gene expression of aged and young bone marrow-derived MSCs (B-MSCs). Our results revealed that the expression levels of inflammatory response genes depended on the age of the B-MSCs. We demonstrated that the age-dependent decrease in expression of several cytokine and chemokine receptors is important for the migration and activation of B-MSCs. Finally, we showed by adoptive transfer of aged B-MSCs to young endotoxemic mice that aged cells lacked the antiinflammatory protective effect of their young counterparts.

CONCLUSIONS

Taken together, the decreased expression of cytokine and chemokine receptors in aged B-MSCs compromises their protective role by perturbing the potential of B-MSCs to become activated and mobilize to the site of injury.

Human adult bone marrow-derived stem cells decrease severity of lipopolysaccharide-induced acute respiratory distress syndrome in sheep

INTRODUCTION

Acute respiratory distress syndrome (ARDS) is the most common cause of respiratory failure among critically ill subjects, sepsis and severe bacterial pneumonia being its most common causes. The only interventions that have proven beneficial are protective ventilation strategies and fluid conservation approaches. New therapies are needed to address this common clinical problem. Others and we have previously shown the beneficial effect of infusion of exogenous adult stem cells in different pre-clinical models of ARDS.

METHODS

In the present study endotoxin was infused intravenously into 14 sheep from which 6 received different doses of adult stem cells by intrabronchial delivery to evaluate the effect of stem cell therapy.

RESULTS

After administration of endotoxin, there was a rapid decline in oxygenation to hypoxemic values, indicative of severe-to-moderate ARDS. None of the animals treated with saline solution recovered to normal baseline values during the 6 hours that the animals were followed. In contrast, sheep treated with a dose of 40 million adult stem cells returned their levels of oxygen in their blood to baseline two hours after the cells were infused. Similarly, improvements in carbon dioxide (CO2) clearance, pulmonary vascular pressures and inflammation were observed and confirmed by histology and by the decrease in lung edema.

CONCLUSIONS

We concluded that instillation of adult non-hematopoietic stem cells can diminish the impact of endotoxin and accelerate recovery of oxygenation, CO2 removal and inflammation in the ovine model, making the use of adult stem cells a real alternative for future therapies for ARDS.

Thiol/redox metabolomic profiling implicates GSH dysregulation in early experimental graft versus host disease (GVHD)

Graft-versus-host disease (GVHD) is a common complication of allogeneic bone marrow transplantation (BMT). Upregulation of inflammatory cytokines precedes the clinical presentation of GVHD and predicts its severity. In this report, thiol/redox metabolomics was used to identify metabolic perturbations associated with early preclinical (Day+4) and clinical (Day+10) stages of GVHD by comparing effects in Syngeneic (Syn; major histocompatibility complex- identical) and allogeneic transplant recipients (Allo BMT) in experimental models. While most metabolic changes were similar in both groups, plasma glutathione (GSH) was significantly decreased, and GSH disulfide (GSSG) was increased after allogeneic compared to syngeneic recipient and non-transplant controls. The early oxidation of the plasma GSH/GSSG redox couple was also observed irrespective of radiation conditioning treatment and was accompanied by significant rise in hepatic protein oxidative damage and ROS generation. Despite a significant rise in oxidative stress, compensatory increase in hepatic GSH synthesis was absent following Allo BMT. Early shifts in hepatic oxidative stress and plasma GSH loss preceded a statistically significant rise in TNF-α. To identify metabolomic biomarkers of hepatic GVHD injury, plasma metabolite concentrations analyzed at Day+10 were correlated with hepatic organ injury. GSSG (oxidized GSH) and β-alanine, were positively correlated, and plasma GSH cysteinylglycine, and branched chain amino acids were inversely correlated with hepatic injury. Although changes in plasma concentrations of cysteine, cystathionine (GSH precursors) and cysteinylglycine (a GSH catabolite) were not significant by univariate analysis, principal component analysis (PCA) indicated that accumulation of these metabolites after Allo BMT contributed significantly to early GVHD in contrast to Syn BMT. In conclusion, thiol/redox metabolomic profiling implicates that early dysregulation of host hepatic GSH metabolism and oxidative stress in sub-clinical GVHD before elevated TNF-α levels is associated with GVHD pathogenesis. Future studies will probe the mechanisms for these changes and examine the potential of antioxidant intervention strategies to modulate GVHD.

Mesenchymal stromal cell injection protects against oxidative stress in Escherichia coli-induced acute lung injury in mice

BACKGROUND AIMS

Stem cells may be a promising therapy for acute respiratory distress syndrome. Recent in vivo and in vitro studies suggested that the mesenchymal stromal cells (MSCs) have anti-oxidative stress properties. We hypothesized that intravenous injection of bone marrow-derived mesenchymal stem cells (MSCs) could attenuate Escherichia coli-induced acute lung injury (ALI) in mice by controlling the oxidative stress status.

METHODS

Eighty mice were randomly divided into four groups: group 1 (control group) received 25 μL of saline as a vehicle; group 2 contained E coli-induced ALI mice; group 3 included mice that received MSCs before induction of ALI; group 4 included mice that received MSCs after induction of ALI. Lung samples were isolated and assayed for oxidative stress variables and histopathologic analysis. Total anti-oxidant capacity was measured in broncho-alveolar lavage.

RESULTS

Pre- and post-injury MSC injection increased survival, reduced pulmonary edema and attenuated lung injuries in ALI mice. Histologically, MSCs exhibited a considerable degree of preservation of the pulmonary alveolar architecture. An increase of anti-oxidant enzyme activities and a decrease of myeloperoxidase activity and malondialdehyde levels in the MSC recipient groups versus the ALI group were found. Furthermore, the total anti-oxidant capacity and reduced glutathione levels were significantly increased in MSCs recipient groups versus the ALI group. Weak +ve inducible nitric oxide synthase immuno-expression in groups that received MSCs was detected. Pre-injury MSC injection showed better effects than did post-injury MSC injection.

CONCLUSIONS

Systemic bone marrow-derived MSC injection was effective in modulating the oxidative stress status in E coli-induced acute lung injury in mice.

Activation of human mesenchymal stem cells impacts their therapeutic abilities in lung injury by increasing interleukin (IL)-10 and IL-1RN levels

Acute respiratory distress syndrome (ARDS) is an important cause of morbidity and mortality, with no currently effective therapies. Several preclinical studies have shown that human mesenchymal stem cells (hMSCs) have therapeutic potential for patients with ARDS because of their immunomodulatory properties. The clinical use of hMSCs has some limitations, such as the extensive manipulation required to isolate the cells from bone marrow aspirates and the heterogeneity in their anti-inflammatory effect in animal models and clinical trials. The objective of this study was to improve the protective anti-inflammatory capacity of hMSCs by evaluating the consequences of preactivating hMSCs before use in a murine model of ARDS. We injected endotoxemic mice with minimally manipulated hMSCs isolated from the bone marrow of vertebral bodies with or without prior activation with serum from ARDS patients. Minimally manipulated hMSCs were more efficient at reducing lung inflammation compared with isolated and in vitro expanded hMSCs obtained from bone marrow aspirates. Where the most important effect was observed was with the activated hMSCs, independent of their source, which resulted in increased expression of interleukin (IL)-10 and IL-1 receptor antagonist (RN), which was associated with enhancement of their protective capacity by reduction of the lung injury score, development of pulmonary edema, and accumulation of bronchoalveolar lavage inflammatory cells and cytokines compared with nonactivated cells. This study demonstrates that a low manipulation during hMSC isolation and expansion increases, together with preactivation prior to the therapeutic use of hMSCs, would ensure an appropriate immunomodulatory phenotype of the hMSCs, reducing the heterogeneity in their anti-inflammatory effect.

Adaptive redox response of mesenchymal stromal cells to stimulation with lipopolysaccharide inflammagen: mechanisms of remodeling of tissue barriers in sepsis

Acute bacterial inflammation is accompanied by excessive release of bacterial toxins and production of reactive oxygen and nitrogen species (ROS and RNS), which ultimately results in redox stress. These factors can induce damage to components of tissue barriers, including damage to ubiquitous mesenchymal stromal cells (MSCs), and thus can exacerbate the septic multiple organ dysfunctions. The mechanisms employed by MSCs in order to survive these stress conditions are still poorly understood and require clarification. In this report, we demonstrated that in vitro treatment of MSCs with lipopolysaccharide (LPS) induced inflammatory responses, which included, but not limited to, upregulation of iNOS and release of RNS and ROS. These events triggered in MSCs a cascade of responses driving adaptive remodeling and resistance to a "self-inflicted" oxidative stress. Thus, while MSCs displayed high levels of constitutively present adaptogens, for example, HSP70 and mitochondrial Sirt3, treatment with LPS induced a number of adaptive responses that included induction and nuclear translocation of redox response elements such as NFkB, TRX1, Ref1, Nrf2, FoxO3a, HO1, and activation of autophagy and mitochondrial remodeling. We propose that the above prosurvival pathways activated in MSCs in vitro could be a part of adaptive responses employed by stromal cells under septic conditions.

Mesenchymal stem cells: a promising therapy for the acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a pulmonary syndrome with growing prevalence and high mortality and morbidity that increase with age. There is no current therapy able to restore pulmonary function in ARDS patients. Preclinical models of ARDS have demonstrated that intratracheal or systemic administration of mesenchymal stem cells (MSCs) protects the lung against injury. The mechanisms responsible for the protective effects are multiple, including the secretion of multiple paracrine factors capable of modulating the immune response and restoring epithelial and endothelial integrity. Recent studies have demonstrated that MSCs can also control oxidative stress, transfer functional mitochondria to the damaged cells, and control bacterial infection by secretion of antibacterial peptides. These characteristics make MSCs promising candidates for ARDS therapy.

Lung injury in preterm neonates: the role and therapeutic potential of stem cells

Continuous improvements in perinatal care have allowed the survival of ever more premature infants, making the task of protecting the extremely immature lung from injury increasingly challenging. Premature infants at risk of developing chronic lung disease or bronchopulmonary dysplasia (BPD) are now born at the late canalicular stage of lung development, just when the airways become juxtaposed to the lung vasculature and when gas-exchange becomes possible. Readily available strategies, including improved antenatal management (education, regionalization, steroids, and antibiotics), together with exogenous surfactant and exclusive/early noninvasive ventilatory support, will likely decrease the incidence/severity of BPD over the next few years. Nonetheless, because of the extreme immaturity of the developing lung, the extent to which disruption of lung growth after prematurity and neonatal management lead to an earlier or more aggravated decline in respiratory function in later life is a matter of concern. Consequently, much more needs to be learned about the mechanisms of lung development, injury, and repair. Recent insight into stem cell biology has sparked interest for stem cells to repair damaged organs. This review summarizes the exciting potential of stem cell-based therapies for lung diseases in general and BPD in particular.

Human umbilical cord mesenchymal stem cells reduce systemic inflammation and attenuate LPS-induced acute lung injury in rats

Background

Mesenchymal stem cells (MSCs) possess potent immunomodulatory properties and simultaneously lack the ability to illicit immune responses. Hence, MSCs have emerged as a promising candidate for cellular therapeutics for inflammatory diseases. Within the context of this study, we investigated whether human umbilical cord-derived mesenchymal stem cells (UC-MSCs) could ameliorate lipopolysaccharide- (LPS-) induced acute lung injury (ALI) in a rat model.

Methods

ALI was induced via injection of LPS. Rats were divided into three groups: (1) saline group(control), (2) LPS group, and (3) MSC + LPS group. The rats were sacrificed at 6, 24, and 48 hours after injection. Serum, bronchoalveolar lavage fluid (BALF), and lungs were collected for cytokine concentration measurements, assessment of lung injury, and histology.

Results

UC-MSCs increased survival rate and suppressed LPS-induced increase of serum concentrations of pro-inflammatory mediators TNF-α, IL-1β, and IL-6 without decreasing the level of anti-inflammatory cytokine IL-10. The MSC + LPS group exhibited significant improvements in lung inflammation, injury, edema, lung wet/dry ratio, protein concentration, and neutrophil counts in the BALF, as well as improved myeloperoxidase (MPO) activity in the lung tissue. Furthermore, UC-MSCs decreased malondialdehyde (MDA) production and increased Heme Oxygenase-1 (HO-1) protein production and activity in the lung tissue.

Conclusion

UC-MSCs noticeably increased the survival rate of rats suffering from LPS-induced lung injury and significantly reduced systemic and pulmonary inflammation. Promoting anti-inflammatory homeostasis and reducing oxidative stress might be the therapeutic basis of UC-MSCs.

Cell-based strategies to reconstitute lung function in infants with severe bronchopulmonary dysplasia

Recent advances in our understanding of stem/progenitor cells and their potential to repair damaged organs offer the possibility of cell-based treatments for neonatal lung injury. This review summarizes basic concepts of stem/progenitor cell biology and discusses the recent advances and challenges of cell-based therapies for lung diseases, with a particular focus on bronchopulmonary dysplasia (BPD), a form of chronic lung disease that primarily affects very preterm infants. Despite advances in perinatal care, BPD still remains the most common complication of extreme prematurity, and there is no specific treatment.

Lipocalin 2 deficiency dysregulates iron homeostasis and exacerbates endotoxin-induced sepsis

Various states of inflammation, including sepsis, are associated with hypoferremia, which limits iron availability to pathogens and reduces iron-mediated oxidative stress. Lipocalin 2 (Lcn2; siderocalin, 24p3) plays a central role in iron transport. Accordingly, Lcn2-deficient (Lcn2KO) mice exhibit elevated intracellular labile iron. In this study, we report that LPS induced systemic Lcn2 by 150-fold in wild-type mice at 24 h. Relative to wild-type littermates, Lcn2KO mice were markedly more sensitive to endotoxemia, exhibiting elevated indices of organ damage (transaminasemia, lactate dehydrogenase) and increased mortality. Such exacerbated endotoxemia was associated with substantially increased caspase-3 cleavage and concomitantly elevated immune cell apoptosis. Furthermore, cells from Lcn2KO mice were hyperresponsive to LPS ex vivo, exhibiting elevated cytokine secretion. Additionally, Lcn2KO mice exhibited delayed LPS-induced hypoferremia despite normal hepatic hepcidin expression and displayed decreased levels of the tissue redox state indicators cysteine and glutathione in liver and plasma. Desferroxamine, an iron chelator, significantly protects Lcn2KO mice from LPS-induced toxicity, including mortality, suggesting that Lcn2 may act as an antioxidant in vivo by regulating iron homeostasis. Thus, Lcn2-mediated regulation of labile iron protects the host against sepsis. Its small size and simple structure may make Lcn2 a deployable treatment for sepsis.

Experimental melanin-induced uveitis: experimental model of human acute anterior uveitis

Experimental melanin-protein-induced uveitis (EMIU), which is also known as experimental autoimmune anterior uveitis, was first described in 1993 by Broekhuyse et al. This experimental uveitis may be induced in certain inbred and outbred rat strains by immunization with bovine ocular melanin. The inflammation shares clinical features with human acute anterior uveitis. The duration of the first episode is approximately 1 month. Spontaneous recovery to a near normal clinical state is the rule, but multiple recurrences are common. Slit-lamp biomicroscopic examination reveals a florid anterior-chamber reaction, with formation of a retro-iridal empyema, fibrin clots and posterior synechiae. At a microscopic level, leukocytic infiltration is first observed in the anterior uvea. Although this tissue remains the site of maximum inflammation throughout an attack, in severe cases, limbitis, vitritis and choroiditis are also observed. Abrogation of EMIU occurs after treatment with anti-CD4 antibody, indicating that the uveitis is controlled by CD4-positive T cells. Several research groups have used EMIU to investigate various aspects of the pathogenesis of acute anterior uveal inflammation, including the participation of different leukocyte subsets, the expression of cell adhesion molecules, cytokines, chemokines and nitric oxide, the role of complement and the impact of apoptosis. In addition, EMIU has also been used to evaluate various biologic interventions with potential implications for the treatment of human disease.