The anti-fibrotic effects of mesenchymal stem cells on irradiated lungs via stimulating endogenous secretion of HGF and PGE2

Short preconditioning with TGFβ of equine adipose tissue-derived mesenchymal stem cells predisposes towards an anti-fibrotic secretory phenotype: A possible tool for treatment of endometrosis in mares

Endometrosis in mares is a disease resulting from chronic inflammation characterized by peri glandular fibrosis. There is no effective treatment so far, which opens the door for exploring the use of stem cells as a candidate. Transforming growth factor beta (TGFβ) is crucial for the establishment and progression of fibrosis in mare's endometrosis. We aimed to develop regenerative approaches to treat endometrosis by using mesenchymal stem cells (MSC), for which understanding the effect of TGFβ on exogenous MSC is crucial. We isolated and characterized equine adipose MSC from six donors. Cells were pooled and exposed to 10 ng/ml of TGFβ for 0, 4, and 24 h, after which cells were analyzed for proliferation, migration, mesodermal differentiation, expression of fibrosis-related mRNAs, and prostaglandin E2 secretion. At 24 h of exposition to TGFβ, there was a progressive increase in the contraction of the monolayer, leading to nodular structures, while cell viability did not change. Exposure to TGFβ impaired adipogenic and osteogenic differentiation after 4 h of treatment, which was more marked at 24 h, represented by a decrease in Oil red and Alizarin red staining, as well as a significant drop (p < 0.05) in the expression of key gene regulators of differentiation processes (PPARG for adipose and RUNX2 for osteogenic differentiation). TGFβ increased chondrogenic differentiation as shown by the upsurge in size of the resulting 3D cell pellet and intensity of Alcian Blue staining, as well as the significant up-regulation of SOX9 expression (p < 0.05) at 4 h, which reached a maximum peak at 24 h (p < 0.01), indicative of up-regulation of glycosaminoglycan synthesis. Preconditioning MSC with TGFβ led to a significant increase (p < 0.05) in the expression of myofibroblast gene markers aSMA, COL1A1, and TGFβ at 24 h exposition time. In contrast, the expression of COL3A1 did not change with respect to the control but registered a significant downregulation compared to 4 h (p < 0.05). TGFβ also affected the expression of genes involved in PGE2 synthesis and function; COX2, PTGES, and the PGE2 receptor EP4 were all significantly upregulated early at 4 h (p < 0.05). Cells exposed to TGFβ showed a significant upregulation of PGE2 secretion at 4 h compared to untreated cells (p < 0.05); conversely, at 24 h, the PGE2 values decreased significantly compared to control cells (p < 0.05). Preconditioning MSC for 4 h led to an anti-fibrotic secretory phenotype, while a longer period (24 h) led to a pro-fibrotic one. It is tempting to propose a 4-h preconditioning of exogenous MSC with TGFβ to drive them towards an anti-fibrotic phenotype for cellular and cell-free therapies in fibrotic diseases such as endometrosis of mares.

Ameliorative Potential of Bone Marrow-Derived Mesenchymal Stem Cells Versus Prednisolone in a Rat Model of Lung Fibrosis: A Histological, Immunohistochemical, and Biochemical Study

Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease of unknown origin with limited treatment options and poor prognosis. The encouraging findings from preclinical investigations utilizing mesenchymal stem cells (MSCs) indicated that they could serve as a promising therapeutic alternative for managing chronic lung conditions, such as IPF. The objective of this study was to compare the efficiency of bone marrow-derived MSCs (BM-MSCs) versus prednisolone, the standard anti-inflammatory medication, in rats with bleomycin (BLM)-induced lung fibrosis. Four groups were created: a control group, a BLM group, a prednisolone-treated group, and a BM-MSCs-treated group. To induce lung fibrosis, 5 mg/kg of BLM was administered intratracheally. BLM significantly increased serum levels of pro-inflammatory cytokines and oxidative stress markers. The disturbed lung structure was also revealed by light and transmission electron microscopic studies. Upregulation in the immune expression of alpha-smooth muscle actin, transforming growth factor beta-1, and Bax was demonstrated. Interestingly, all findings significantly regressed on treatment with prednisolone and BM-MSCs. However, treatment with BM-MSCs showed better results than with prednisolone. In conclusion, BM-MSCs could be a promising approach for managing lung fibrosis.

Scarring and Skin Fibrosis Reversal with Regenerative Surgery and Stem Cell Therapy

Skin scarring and fibrosis affect millions of people worldwide, representing a serious clinical problem causing physical and psychological challenges for patients. Stem cell therapy and regenerative surgery represent a new area of treatment focused on promoting the body's natural ability to repair damaged tissue. Adipose-derived stem cells (ASCs) represent an optimal choice for practical regenerative medicine due to their abundance, autologous tissue origin, non-immunogenicity, and ease of access with minimal morbidity for patients. This review of the literature explores the current body of evidence around the use of ASCs-based regenerative strategies for the treatment of scarring and skin fibrosis, exploring the different surgical approaches and their application in multiple fibrotic skin conditions. Human, animal, and in vitro studies demonstrate that ASCs present potentialities in modifying scar tissue and fibrosis by suppressing extracellular matrix (ECM) synthesis and promoting the degradation of their constituents. Through softening skin fibrosis, function and overall quality of life may be considerably enhanced in different patient cohorts presenting with scar-related symptoms. The use of stem cell therapies for skin scar repair and regeneration represents a paradigm shift, offering potential alternative therapeutic avenues for fibrosis, a condition that currently lacks a cure.

Therapeutic potential of stem cells in regeneration of liver in chronic liver diseases: Current perspectives and future challenges

The deposition of extracellular matrix and hyperplasia of connective tissue characterizes chronic liver disease called hepatic fibrosis. Progression of hepatic fibrosis may lead to hepatocellular carcinoma. At this stage, only liver transplantation is a viable option. However, the number of possible liver donors is less than the number of patients needing transplantation. Consequently, alternative cell therapies based on non-stem cells (e.g., fibroblasts, chondrocytes, keratinocytes, and hepatocytes) therapy may be able to postpone hepatic disease, but they are often ineffective. Thus, novel stem cell-based therapeutics might be potentially important cutting-edge approaches for treating liver diseases and reducing patient' suffering. Several signaling pathways provide targets for stem cell interventions. These include pathways such as TGF-β, STAT3/BCL-2, NADPH oxidase, Raf/MEK/ERK, Notch, and Wnt/β-catenin. Moreover, mesenchymal stem cells (MSCs) stimulate interleukin (IL)-10, which inhibits T-cells and converts M1 macrophages into M2 macrophages, producing an anti-inflammatory environment. Furthermore, it inhibits the action of CD4+ and CD8+ T cells and reduces the activity of TNF-α and interferon cytokines by enhancing IL-4 synthesis. Consequently, the immunomodulatory and anti-inflammatory capabilities of MSCs make them an attractive therapeutic approach. Importantly, MSCs can inhibit the activation of hepatic stellate cells, causing their apoptosis and subsequent promotion of hepatocyte proliferation, thereby replacing dead hepatocytes and reducing liver fibrosis. This review discusses the multidimensional therapeutic role of stem cells as cell-based therapeutics in liver fibrosis.

Tissue fibrosis induced by radiotherapy: current understanding of the molecular mechanisms, diagnosis and therapeutic advances

Cancer remains the leading cause of death around the world. In cancer treatment, over 50% of cancer patients receive radiotherapy alone or in multimodal combinations with other therapies. One of the adverse consequences after radiation exposure is the occurrence of radiation-induced tissue fibrosis (RIF), which is characterized by the abnormal activation of myofibroblasts and the excessive accumulation of extracellular matrix. This phenotype can manifest in multiple organs, such as lung, skin, liver and kidney. In-depth studies on the mechanisms of radiation-induced fibrosis have shown that a variety of extracellular signals such as immune cells and abnormal release of cytokines, and intracellular signals such as cGAS/STING, oxidative stress response, metabolic reprogramming and proteasome pathway activation are involved in the activation of myofibroblasts. Tissue fibrosis is extremely harmful to patients' health and requires early diagnosis. In addition to traditional serum markers, histologic and imaging tests, the diagnostic potential of nuclear medicine techniques is emerging. Anti-inflammatory and antioxidant therapies are the traditional treatments for radiation-induced fibrosis. Recently, some promising therapeutic strategies have emerged, such as stem cell therapy and targeted therapies. However, incomplete knowledge of the mechanisms hinders the treatment of this disease. Here, we also highlight the potential mechanistic, diagnostic and therapeutic directions of radiation-induced fibrosis.

Significant expansion of the donor pool achieved by utilizing islets of variable quality in the production of allogeneic "Neo-Islets", 3-D organoids of Mesenchymal Stromal and islet cells, a novel immune-isolating biotherapy for Type I Diabetes

Novel biotherapies for Type 1 Diabetes that provide a significantly expanded donor pool and that deliver all islet hormones without requiring anti-rejection drugs are urgently needed. Scoring systems have improved islet allotransplantation outcomes, but their use may potentially result in the waste of valuable cells for novel therapies. To address these issues, we created "Neo-Islets" (NIs), islet-sized organoids, by co-culturing in ultralow adhesion flasks culture-expanded islet (ICs) and Mesenchymal Stromal Cells (MSCs) (x 24 hrs, 1:1 ratio). The MSCs exert powerful immune- and cyto-protective, anti-inflammatory, proangiogenic, and other beneficial actions in NIs. The robust in vitro expansion of all islet hormone-producing cells is coupled to their expected progressive de-differentiation mediated by serum-induced cell cycle entry and Epithelial-Mesenchymal Transition (EMT). Re-differentiation in vivo of the ICs and resumption of their physiological functions occurs by reversal of EMT and serum withdrawal-induced exit from the cell cycle. Accordingly, we reported that allogeneic, i.p.-administered NIs engraft in the omentum, increase Treg numbers and reestablish permanent normoglycemia in autoimmune diabetic NOD mice without immunosuppression. Our FDA-guided pilot study (INAD 012-0776) in insulin-dependent pet dogs showed similar responses, and both human- and canine-NIs established normoglycemia in STZ-diabetic NOD/SCID mice even though the utilized islets would be scored as unsuitable for transplantation. The present study further demonstrates that islet gene expression profiles (α, β, γ, δ) in human "non-clinical grade" islets obtained from diverse, non-diabetic human and canine donors (n = 6 each) closely correlate with population doublings, and the in vivo re-differentiation of endocrine islet cells clearly corresponds with the reestablishment of euglycemia in diabetic mice. Conclusion: human-NIs created from diverse, "non-clinical grade" donors have the potential to greatly expand patient access to this curative therapy of T1DM, facilitated by the efficient in vitro expansion of ICs that can produce ~ 270 therapeutic NI doses per donor for 70 kg recipients.

Mesenchymal Stromal Cells: Heterogeneity and Therapeutical Applications

Mesenchymal stromal cells nowadays emerge as a major player in the field of regenerative medicine and translational research. They constitute, with their derived products, the most frequently used cell type in different therapies. However, their heterogeneity, including different subpopulations, the anatomic source of isolation, and high donor-to-donor variability, constitutes a major controversial issue that affects their use in clinical applications. Furthermore, the intrinsic and extrinsic molecular mechanisms underlying their self-renewal and fate specification are still not completely elucidated. This review dissects the different heterogeneity aspects of the tissue source associated with a distinct developmental origin that need to be considered when generating homogenous products before their usage for clinical applications.

Progress in understanding and treating idiopathic pulmonary fibrosis: recent insights and emerging therapies

Idiopathic pulmonary fibrosis (IPF) is a long-lasting, continuously advancing, and irrevocable interstitial lung disorder with an obscure origin and inadequately comprehended pathological mechanisms. Despite the intricate and uncharted causes and pathways of IPF, the scholarly consensus upholds that the transformation of fibroblasts into myofibroblasts-instigated by injury to the alveolar epithelial cells-and the disproportionate accumulation of extracellular matrix (ECM) components, such as collagen, are integral to IPF's progression. The introduction of two novel anti-fibrotic medications, pirfenidone and nintedanib, have exhibited efficacy in decelerating the ongoing degradation of lung function, lessening hospitalization risk, and postponing exacerbations among IPF patients. Nonetheless, these pharmacological interventions do not present a definitive solution to IPF, positioning lung transplantation as the solitary potential curative measure in contemporary medical practice. A host of innovative therapeutic strategies are presently under rigorous scrutiny. This comprehensive review encapsulates the recent advancements in IPF research, spanning from diagnosis and etiology to pathological mechanisms, and introduces a discussion on nascent therapeutic methodologies currently in the pipeline.

Mesenchymal stem cells in lung diseases and their potential use in COVID-19 ARDS: A systematized review

COVID-19 can converge with the pro-inflammatory immunoregulatory mechanisms of chronic lung diseases. Given the disorders inherent to lung transplantation and the inexistence of other definitive therapeutic alternatives, Adipose tissue-derived Stem Cells (ASCs) presented themselves as a therapeutic hope. The purpose of this review is to assess the basis for the potential use of ASCs in lung diseases unresponsive to conventional therapy, relating to their possible use in COVID-19 ARDS. 35 studies comprised this review, 14 being narrative reviews, 19 preclinical trials and two proofs of concept. COVID-19 can converge with the pro-inflammatory immunoregulatory mechanisms of chronic lung diseases. In view of the disorders inherent to lung transplantation and the inexistence of definitive therapeutic alternatives, Adipose tissue-derived Stem Cells (ASCs) presented themselves as a therapeutic hope. Its detailed reading indicated the absence of serious adverse effects and toxicity to the administration of ASCs and suggested possible effectiveness in reducing lung damage, in addition to promoting the recovery of leukocytes and lymphocytes with its immunomodulatory and anti-apoptotic effects. The revised clinical data suggests optimism in the applicability of ASCs in other immunoinflammatory diseases and in severe COVID-19 ARDS. However, further studies are needed to develop a consensus on the methods of collection of ASCs, the ideal dosage schedule, the most effective time and route of administration, as well as on the definition of indications for the administration of ASCs in cases of COVID-19 for conducting clinical trials in near future.

TNF-α/IL-1β-licensed hADSCs alleviate cholestatic liver injury and fibrosis in mice via COX-2/PGE2 pathway

BACKGROUND

Adipose tissue-derived stem cell (ADSC) transplantation has been shown to be effective for the management of severe liver disorders. Preactivation of ADSCs enhanced their therapeutic efficacy. However, these effects have not yet been examined in relation to cholestatic liver injury.

METHODS

In the present study, a cholestatic liver injury model was established by bile duct ligation (BDL) in male C57BL/6 mice. Human ADSCs (hADSCs) with or without tumor necrosis factor-alpha (TNF-α) and interleukin-1beta (IL-1β) pretreatment were administrated into the mice via tail vein injections. The efficacy of hADSCs on BDL-induced liver injury was assessed by histological staining, real-time quantitative PCR (RT-qPCR), Western blot, and enzyme-linked immune sorbent assay (ELISA). In vitro, the effects of hADSC conditioned medium on the activation of hepatic stellate cells (HSCs) were investigated. Small interfering RNA (siRNA) was used to knock down cyclooxygenase-2 (COX-2) in hADSCs.

RESULTS

TNF-α/IL-1β preconditioning could downregulate immunogenic gene expression and enhance the engraftment efficiency of hADSCs. Compared to control hADSCs (C-hADSCs), TNF-α/IL-1β-pretreated hADSCs (P-hADSCs) significantly alleviated BDL-induced liver injury, as demonstrated by reduced hepatic cell death, attenuated infiltration of Ly6G + neutrophils, and decreased expression of pro-inflammatory cytokines TNF-α, IL-1β, C-X-C motif chemokine ligand 1 (CXCL1), and C-X-C motif chemokine ligand 2 (CXCL2). Moreover, P-hADSCs significantly delayed the development of BDL-induced liver fibrosis. In vitro, conditioned medium from P-hADSCs significantly inhibited HSC activation compared to that from C-hADSCs. Mechanistically, TNF-α/IL-1β upregulated COX-2 expression and increased prostaglandin E2 (PGE2) secretion. The blockage of COX-2 by siRNA transfection reversed the benefits of P-hADSCs for PGE2 production, HSC activation, and liver fibrosis progression.

CONCLUSION

In conclusion, our results suggest that TNF-α/IL-1β pretreatment enhances the efficacy of hADSCs in mice with cholestatic liver injury, partially through the COX-2/PGE2 pathway.

Function of stem cells in radiation-induced damage

PURPOSE

The aim of this review is to discuss previous studies on the function of stem cells in radiation-induced damage, and the factors affecting these processes, in the hope of improving our understanding of the different stem cells and the communication networks surrounding them. This is essential for the development of effective stem cell-based therapies to regenerate or replace normal tissues damaged by radiation.

CONCLUSION

In salivary glands, senescence-associated cytokines and inflammation-associated cells have a greater effect on stem cells. In the intestinal glands, Paneth cells strongly affect stem cell-mediated tissue regeneration after radiation treatment. In the pancreas, β-cells as well as protein C receptor positive (Procr) cells are expected to be key cells in the treatment of diabetes. In the bone marrow, a variety of cytokines such as CXC-chemokine ligand 12 (CXCL12) and stem cell factor (SCF), contribute to the functional recovery of hematopoietic stem cells after irradiation.

Mesenchymal stem cells in fibrotic diseases-the two sides of the same coin

Fibrosis is caused by extensive deposition of extracellular matrix (ECM) components, which play a crucial role in injury repair. Fibrosis attributes to ~45% of all deaths worldwide. The molecular pathology of different fibrotic diseases varies, and a number of bioactive factors are involved in the pathogenic process. Mesenchymal stem cells (MSCs) are a type of multipotent stem cells that have promising therapeutic effects in the treatment of different diseases. Current updates of fibrotic pathogenesis reveal that residential MSCs may differentiate into myofibroblasts which lead to the fibrosis development. However, preclinical and clinical trials with autologous or allogeneic MSCs infusion demonstrate that MSCs can relieve the fibrotic diseases by modulating inflammation, regenerating damaged tissues, remodeling the ECMs, and modulating the death of stressed cells after implantation. A variety of animal models were developed to study the mechanisms behind different fibrotic tissues and test the preclinical efficacy of MSC therapy in these diseases. Furthermore, MSCs have been used for treating liver cirrhosis and pulmonary fibrosis patients in several clinical trials, leading to satisfactory clinical efficacy without severe adverse events. This review discusses the two opposite roles of residential MSCs and external MSCs in fibrotic diseases, and summarizes the current perspective of therapeutic mechanism of MSCs in fibrosis, through both laboratory study and clinical trials.

Enhanced secretion of hepatocyte growth factor in human umbilical cord mesenchymal stem cells ameliorates pulmonary fibrosis induced by bleomycin in rats

Umbilical cord mesenchymal stem cells (UCMSCs) are a reportedly promising choice in the treatment of irreversible pulmonary fibrosis and lethal interstitial lung disease with limited drug treatment options. In this study, we investigated the therapeutic efficacy of UCMSCs overexpressing hepatocyte growth factor (HGF), which is considered one of the main anti-fibrotic factors secreted by MSCs. Adenovirus vector carrying the HGF gene was transfected into UCMSCs to produce HGF-modified UCMSCs (HGF-UCMSCs). Transfection promoted the proliferation of UCMSCs and did not change the morphology, and differentiation ability, or biomarkers. Rats were injected with HGF-UCMSCs on days 7 and 11 after intratracheal administration of bleomycin (10 mg/kg). We performed an analysis of histopathology and lung function to evaluate the anti-fibrotic effect. The results showed that HGF-UCMSCs decreased the Ashcroft scores in hematoxylin and eosin-stained sections, the percentage positive area in Masson trichrome-stained sections, and the hydroxyproline level in lungs. Forced expiratory volume in the first 300 m/forced vital capacity was also improved by HGF-UCMSCs. To explore the possible therapeutic mechanism of HGF-UCMSCs, we detected inflammatory factors in the lungs and performed mRNA sequencing in UCMSCs and HGF-UCMSCs. The data indicated that inhibition of interleukin-17 in the lung may be related to the anti-fibrosis of HGF-UCMSCs, and overexpressed HGF probably played a primary role in the treatment. Collectively, our study findings suggested that the overexpression of HGF may improve the anti-fibrotic effect of UCMSCs through directly or indirectly interacting with interleukin-17-producing cells in fibrotic lungs.

Use of Mesenchymal Stem Cells in Crohn's Disease and Perianal Fistulas: A Narrative Review

Crohn's Disease (CD), which usually leads to anal fistulas among patients, is the most important inflammatory bowel disease that causes morbidity in many people around the world. This review article proposes using MSCs as a hopeful therapeutic strategy for CD and anal fistula treatment in both preclinical and clinical conditions. Finally, darvadstrocel, a cell-based medication to treat complex anal fistulas in adults, as the only European Medicines Agency (EMA)-approved product for the treatment of anal fistulas in CD is addressed. Although several common therapies, such as surgery and anti-tumor necrosis factor-alpha (TNF-α) drugs as well as a combination of these methods is used to improve this disease, however, due to the low effectiveness of these treatments, the use of new strategies with higher efficiency is still recommended. Cell therapy is among the new emerging therapeutic strategies that have attracted great attention from clinicians due to its unique capabilities. One of the most widely used cell sources administrated in cell therapy is mesenchymal stem cell (MSC). This review article will discuss preclinical and clinical studies about MSCs as a potent and promising therapeutic option in the treatment of CD and anal fistula.

Mesenchymal Stem Cells in Radiation-Induced Pulmonary Fibrosis: Future Prospects

Radiation-induced pulmonary fibrosis (RIPF) is a general and fatal side effect of radiotherapy, while the pathogenesis has not been entirely understood yet. By now, there is still no effective clinical intervention available for treatment of RIPF. Recent studies revealed mesenchymal stromal cells (MSCs) as a promising therapy treatment due to their homing and differentiation ability, paracrine effects, immunomodulatory effects, and MSCs-derived exosomes. Nevertheless, problems and challenges in applying MSCs still need to be taken seriously. Herein, we reviewed the mechanisms and challenges in the applications of MSCs in treating RIPF.

Cellular expansion of MSCs: Shifting the regenerative potential

Mesenchymal-derived stromal or progenitor cells, commonly called "MSCs," have attracted significant clinical interest for their remarkable abilities to promote tissue regeneration and reduce inflammation. Recent studies have shown that MSCs' therapeutic effects, originally attributed to the cells' direct differentiation capacity into the tissue of interest, are largely driven by the biomolecules the cells secrete, including cytokines, chemokines, growth factors, and extracellular vesicles containing miRNA. This secretome coordinates upregulation of endogenous repair and immunomodulation in the local microenvironment through crosstalk of MSCs with host tissue cells. Therapeutic applications for MSCs and their secretome-derived products often involve in vitro monolayer expansion. However, consecutive passaging of MSCs significantly alters their therapeutic potential, inducing a broad shift from a pro-regenerative to a pro-inflammatory phenotype. A consistent by-product of in vitro expansion of MSCs is the onset of replicative senescence, a state of cell arrest characterized by an increased release of proinflammatory cytokines and growth factors. However, little is known about changes in the secretome profile at different stages of in vitro expansion. Some culture conditions and bioprocessing techniques have shown promise in more effectively retaining the pro-regenerative and anti-inflammatory MSC phenotype throughout expansion. Understanding how in vitro expansion conditions influence the nature and function of MSCs, and their associated secretome, may provide key insights into the underlying mechanisms driving these alterations. Elucidating the dynamic and diverse changes in the MSC secretome at each stage of in vitro expansion is a critical next step in the development of standardized, safe, and effective MSC-based therapies.

Therapeutic effect of adipose-derived mesenchymal stem cells (AD-MSCs) compared to pirfenidone on corticosteroid resistance in a mouse model of acute exacerbation of idiopathic pulmonary fibrosis

INTRODUCTION

Acute exacerbation-idiopathic pulmonary fibrosis (AE-IPF) is a life-threatening condition. In the treatment of AE-IPF, corticosteroid medication is commonly utilized. However, there is insufficient evidence to justify its usage. Pirfenidone (PFD) has recently been discovered to be effective in the treatment of AE-IPF patients. However, regenerative therapy, such as stem cell therapy or tissue engineering, is necessary due to ineffective and limited therapies. Combining MSC transplantation with pharmacological therapy may also give additional benefits; nevertheless, its use must be proven experimentally. As a result, the goal of this study was to assess the therapeutic effects of adipose-derived mesenchymal stem cells (AD-MSCs) on corticosteroid resistance in an animal model of AE-IPF caused by bleomycin compared to PFD.

MATERIALS AND METHODS

Seventy C57BL/6J male mice were randomly divided into seven groups, control, BLM, methylprednisolone (MP), PFD, AD-MSCs, PFD +MP, and AD-MSCs +MP.

RESULTS

In terms of survival, collagen deposition, the acute lung injury score (ALI), and the Ashcroft score, AD-MSCs exceeded PFD. AD-MSCs + MP provided protection and preserved the lung's architecture in BLM-induced AE. In addition, AD-MSCs successfully decreased chemokine (CC motif) ligand-2 (CCL2) positive cells and lower pro-fibrotic and pro-inflammatory cytokines.

CONCLUSIONS

AD-MSCs enhanced histological structure, Ashcroft and ALI scores, lung collagen deposition, survival, and cytokines in an animal model of AE-IPF. As a result, we believe that AD-MSCs may be more therapeutically helpful for AE-IPF than presently available therapies, either alone or in conjunction with MP.

Advances in mesenchymal stromal cell therapy for acute lung injury/acute respiratory distress syndrome

Acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) develops rapidly and has high mortality. ALI/ARDS is mainly manifested as acute or progressive hypoxic respiratory failure. At present, there is no effective clinical intervention for the treatment of ALI/ARDS. Mesenchymal stromal cells (MSCs) show promise for ALI/ARDS treatment due to their biological characteristics, easy cultivation, low immunogenicity, and abundant sources. The therapeutic mechanisms of MSCs in diseases are related to their homing capability, multidirectional differentiation, anti-inflammatory effect, paracrine signaling, macrophage polarization, the polarization of the MSCs themselves, and MSCs-derived exosomes. In this review, we discuss the pathogenesis of ALI/ARDS along with the biological characteristics and mechanisms of MSCs in the treatment of ALI/ARDS.

Mesenchymal Stem Cell Mechanisms of Action and Clinical Effects in Osteoarthritis: A Narrative Review

With the insufficient satisfaction rates and high cost of operative treatment for osteoarthritis (OA), alternatives have been sought. Furthermore, the inability of current medications to arrest disease progression has led to rapidly growing clinical research relating to mesenchymal stem cells (MSCs). The availability and function of MSCs vary according to tissue source. The three primary sources include the placenta, bone marrow, and adipose tissue, all of which offer excellent safety profiles. The primary mechanisms of action are trophic and immunomodulatory effects, which prevent the further degradation of joints. However, the function and degree to which benefits are observed vary significantly based on the exosomes secreted by MSCs. Paracrine and autocrine mechanisms prevent cell apoptosis and tissue fibrosis, initiate angiogenesis, and stimulate mitosis via growth factors. MSCs have even been shown to exhibit antimicrobial effects. Clinical results incorporating clinical scores and objective radiological imaging have been promising, but a lack of standardization in isolating MSCs prevents their incorporation in current guidelines.

Optimization of adipose tissue-derived mesenchymal stromal cells transplantation for bone marrow repopulation following irradiation

BACKGROUND

Bone marrow (BM) suppression is one of the most common side effects of radiotherapy and the primary cause of death following exposure to irradiation. Despite concerted efforts, there is no definitive treatment method available. Recent studies have reported using mesenchymal stromal cells (MSCs), but their therapeutic effects are contested.

AIM

We administered and examined the effects of various amounts of adipose-derived MSCs (ADSCs) in mice with radiation-induced BM suppression.

METHODS

Mice were divided into three groups: Normal control group, irradiated (RT) group, and stem cell-treated group following whole-body irradiation (WBI). Mouse ADSCs (mADSCs) were transplanted into the peritoneal cavity either once or three times at 5 × 10⁵ cells/200 μL. The white blood cell count and the levels of, plasma cytokines, BM mRNA, and BM surface markers were compared between the three groups. Human BM-derived CD34⁺ hematopoietic progenitor cells were co-cultured with human ADSCs (hADSCs) or incubated in the presence of hADSCs conditioned media to investigate the effect on human cells in vitro.

RESULTS

The survival rate of mice that received one transplant of mADSCs was higher than that of mice that received three transplants. Multiple transplantations of ADSCs delayed the repopulation of BM hematopoietic stem cells. Anti-inflammatory effects and M2 polarization by intraperitoneal ADSCs might suppress erythropoiesis and induce myelopoiesis in sub-lethally RT mice.

CONCLUSION

The results suggested that an optimal amount of MSCs could improve survival rates post-WBI.

Intestinal Fibrosis in Inflammatory Bowel Disease and the Prospects of Mesenchymal Stem Cell Therapy

Intestinal fibrosis is an important complication of inflammatory bowel disease (IBD). In the course of the development of fibrosis, certain parts of the intestine become narrowed, significantly destroying the structure and function of the intestine and affecting the quality of life of patients. Chronic inflammation is an important initiating factor of fibrosis. Unfortunately, the existing anti-inflammatory drugs cannot effectively prevent and alleviate fibrosis, and there is no effective anti-fibrotic drug, which makes surgical treatment the mainstream treatment for intestinal fibrosis and stenosis. Mesenchymal stem cells (MSCs) are capable of tissue regeneration and repair through their self-differentiation, secretion of cytokines, and secretion of extracellular vesicles. MSCs have been shown to play an important therapeutic role in the fibrosis of many organs. However, the role of MSC in intestinal fibrosis largely remained unexplored. This review summarizes the mechanism of intestinal fibrosis, including the role of immune cells, TGF-β, and the gut microbiome and metabolites. Available treatment options for fibrosis, particularly, MSCs are also discussed.

Insight into the role of dermal white adipose tissue loss in dermal fibrosis

The loss of dermal white adipose tissue (dWAT) is vital to the formation of dermal fibrosis (DF), but the specific mechanism is not well understood. A few studies are reviewed to explore the role of dWAT in the formation of DF. Recent findings indicated that the adipocytes-to-myofibroblasts transition in dWAT reflects the direct contribution to the DF formation. While adipose-derived stem cells (ADSCs) contained in dWAT express antifibrotic cytokines, the loss of ADSCs leads to skin protection decreased, which indirectly exacerbates DF and tissue damage. Therefore, blocking or reversing the adipocytes-to-myofibroblasts transition or improving the survival of ADSCs in dWAT and the expression of antifibrotic cytokines may be an effective strategy for the treatment of DF.

Stem cell therapy for chronic obstructive pulmonary disease

ABSTRACT

Chronic obstructive pulmonary disease (COPD), characterized by persistent and not fully reversible airflow restrictions, is currently one of the most widespread chronic lung diseases in the world. The most common symptoms of COPD are cough, expectoration, and exertional dyspnea. Although various strategies have been developed during the last few decades, current medical treatment for COPD only focuses on the relief of symptoms, and the reversal of lung function deterioration and improvement in patient's quality of life are very limited. Consequently, development of novel effective therapeutic strategies for COPD is urgently needed. Stem cells were known to differentiate into a variety of cell types and used to regenerate lung parenchyma and airway structures. Stem cell therapy is a promising therapeutic strategy that has the potential to restore the lung function and improve the quality of life in patients with COPD. This review summarizes the current state of knowledge regarding the clinical research on the treatment of COPD with mesenchymal stem cells (MSCs) and aims to update the understanding of the role of MSCs in COPD treatment, which may be helpful for developing effective therapeutic strategies in clinical settings.

The Roles of Various Prostaglandins in Fibrosis: A Review

Organ fibrosis is a common pathological result of various chronic diseases with multiple causes. Fibrosis is characterized by the excessive deposition of extracellular matrix and eventually leads to the destruction of the tissue structure and impaired organ function. Prostaglandins are produced by arachidonic acid through cyclooxygenases and various prostaglandin-specific synthases. Prostaglandins bind to homologous receptors on adjacent tissue cells in an autocrine or paracrine manner and participate in the regulation of a series of physiological or pathological processes, including fibrosis. This review summarizes the properties, synthesis, and degradation of various prostaglandins, as well as the roles of these prostaglandins and their receptors in fibrosis in multiple models to reveal the clinical significance of prostaglandins and their receptors in the treatment of fibrosis.

Extracellular Vesicles for the Treatment of Radiation Injuries

Normal tissue injury from accidental or therapeutic exposure to high-dose radiation can cause severe acute and delayed toxicities, which result in mortality and chronic morbidity. Exposure to single high-dose radiation leads to a multi-organ failure, known as acute radiation syndrome, which is caused by radiation-induced oxidative stress and DNA damage to tissue stem cells. The radiation exposure results in acute cell loss, cell cycle arrest, senescence, and early damage to bone marrow and intestine with high mortality from sepsis. There is an urgent need for developing medical countermeasures against radiation injury for normal tissue toxicity. In this review, we discuss the potential of applying secretory extracellular vesicles derived from mesenchymal stromal/stem cells, endothelial cells, and macrophages for promoting repair and regeneration of organs after radiation injury.

Radiation-Induced Immunity and Toxicities: The Versatility of the cGAS-STING Pathway

In the past decade, radiation therapy (RT) entered the era of personalized medicine, following the striking improvements in radiation delivery and treatment planning optimization, and in the understanding of the cancer response, including the immunological response. The next challenge is to identify the optimal radiation regimen(s) to induce a clinically relevant anti-tumor immunity response. Organs at risks and the tumor microenvironment (e.g. endothelial cells, macrophages and fibroblasts) often limit the radiation regimen effects due to adverse toxicities. Here, we reviewed how RT can modulate the immune response involved in the tumor control and side effects associated with inflammatory processes. Moreover, we discussed the versatile roles of tumor microenvironment components during RT, how the innate immune sensing of RT-induced genotoxicity, through the cGAS-STING pathway, might link the anti-tumor immune response, radiation-induced necrosis and radiation-induced fibrosis, and how a better understanding of the switch between favorable and deleterious events might help to define innovative approaches to increase RT benefits in patients with cancer.

Applications and therapeutic mechanisms of action of mesenchymal stem cells in radiation-induced lung injury

Radiation-induced lung injury (RILI) is one of the most common complications associated with radiotherapy, characterized by early-stage radiation pneumonia and subsequent radiation pulmonary fibrosis. However, effective therapeutic strategies for RILI are currently lacking. Recently, an increasing number of studies reported that mesenchymal stem cells (MSCs) can enhance the regeneration of damaged tissue, modulate the inflammatory response, reduce the levels of fibrotic cytokines and reactive oxygen species, and inhibit epithelial-mesenchymal transformation. Interestingly, MSCs can also exert immunosuppressive effects, which highlights a new potential therapeutic activity of MSCs for managing RILI. Here, we reviewed the potential applications and therapeutic mechanisms of action of MSCs in RILI, which will represent a good compendium of information for researchers in this field.

Mesenchymal Stem Cells for Mitigating Radiotherapy Side Effects

Radiation therapy for cancers also damages healthy cells and causes side effects. Depending on the dosage and exposure region, radiotherapy may induce severe and irreversible injuries to various tissues or organs, especially the skin, intestine, brain, lung, liver, and heart. Therefore, promising treatment strategies to mitigate radiation injury is in pressing need. Recently, stem cell-based therapy generates great attention in clinical care. Among these, mesenchymal stem cells are extensively applied because it is easy to access and capable of mesodermal differentiation, immunomodulation, and paracrine secretion. Here, we summarize the current attempts and discuss the future perspectives about mesenchymal stem cells (MSCs) for mitigating radiotherapy side effects.

Mesenchymal stromal cells can repair radiation-induced pulmonary fibrosis via a DKK-1-mediated Wnt/β-catenin pathway

Pulmonary injury occurring after thoracic radiotherapy is a main factor limiting the curative effect of radiotherapy. Robust activation of the Wnt signalling pathway induced by ionizing radiation stress plays a critical role in epithelial-mesenchymal transition (EMT) in irradiated type II alveolar epithelial cells and in the proliferation of pulmonary fibroblasts, which contributes to the formation of fibrotic lesions in irradiated lungs. The pathogenesis of radiation-induced pulmonary fibrosis could be restricted by systemic delivery of human adipose-derived mesenchymal stromal cells (Ad-MSCs), as evidenced by the inhibitory effects of Ad-MSCs on EMT in irradiated type II alveolar epithelial cells. The purpose of this study is to observe the effects of mesenchymal stromal cells (MSCs) on repairing fibrosis caused by radiation. We used western blotting and real-time PCR to observe the expression of DKK-1 in MSCs of different origins and passages. After the successful establishment of a radiation-induced lung injury model, we investigated the potency of the supernatant from stromal cells to reduce pro-fibrotic events, including EMT and fibroblast activation. To study the mechanism, we evaluated the levels of active β-catenin, TCF4 and the target genes Snail, Twist and c-Myc. After the injection of Ad-MSCs into mice via the tail vein, proteins related to EMT, fibroblasts and Wnt/β-catenin signalling were investigated. The TGF-β and IL-10 protein concentrations in peripheral blood were measured by ELISA. Ad-MSC-derived supernatant effectively reversed the decrease in E-cadherin expression and inhibited the increase in vimentin expression induced by ionizing radiation in epithelial cells and suppressed the expression of α-SMA, a mediator of fibroblast proliferation. The canonical Wnt pathway may be activated by irradiation but the nuclear localization of active β-catenin was reduced in the presence of the supernatant from Ad-MSCs. In addition, the expression of target genes involved in EMT was downregulated. Additionally, when DKK-1 in the supernatant was neutralized, all these effects were reversed. Changes in the levels of proteins related to EMT and fibroblast activation, as well as those of active β-catenin and TCF4, were similar in vivo and in vitro. The serum level of the immunosuppressive factor IL-10 was increased after radiation and was further enhanced after Ad-MSC interference for one month. In conclusion, Ad-MSCs medium can contain DKK-1 and inhibit the induction of EMT via Wnt/β-catenin signalling in vitro and in vivo.

Human umbilical cord mesenchymal stem cell-derived extracellular vesicles ameliorate airway inflammation in a rat model of chronic obstructive pulmonary disease (COPD)

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is an incurable and debilitating chronic disease characterized by progressive airflow limitation associated with abnormal levels of tissue inflammation. Therefore, stem cell-based approaches to tackle the condition are currently a focus of regenerative therapies for COPD. Extracellular vesicles (EVs) released by all cell types are crucially involved in paracrine, extracellular communication. Recent advances in the field suggest that stem cell-derived EVs possess a therapeutic potential which is comparable to the cells of their origin.

METHODS

In this study, we assessed the potential anti-inflammatory effects of human umbilical cord mesenchymal stem cell (hUC-MSC)-derived EVs in a rat model of COPD. EVs were isolated from hUC-MSCs and characterized by the transmission electron microscope, western blotting, and nanoparticle tracking analysis. As a model of COPD, male Sprague-Dawley rats were exposed to cigarette smoke for up to 12 weeks, followed by transplantation of hUC-MSCs or application of hUC-MSC-derived EVs. Lung tissue was subjected to histological analysis using haematoxylin and eosin staining, Alcian blue-periodic acid-Schiff (AB-PAS) staining, and immunofluorescence staining. Gene expression in the lung tissue was assessed using microarray analysis. Statistical analyses were performed using GraphPad Prism 7 version 7.0 (GraphPad Software, USA). Student's t test was used to compare between 2 groups. Comparison among more than 2 groups was done using one-way analysis of variance (ANOVA). Data presented as median ± standard deviation (SD).

RESULTS

Both transplantation of hUC-MSCs and application of EVs resulted in a reduction of peribronchial and perivascular inflammation, alveolar septal thickening associated with mononuclear inflammation, and a decreased number of goblet cells. Moreover, hUC-MSCs and EVs ameliorated the loss of alveolar septa in the emphysematous lung of COPD rats and reduced the levels of NF-κB subunit p65 in the tissue. Subsequent microarray analysis revealed that both hUC-MSCs and EVs significantly regulate multiple pathways known to be associated with COPD.

CONCLUSIONS

In conclusion, we show that hUC-MSC-derived EVs effectively ameliorate by COPD-induced inflammation. Thus, EVs could serve as a new cell-free-based therapy for the treatment of COPD.

Autophagy: a promising therapeutic target for improving mesenchymal stem cell biological functions

Mesenchymal stem cells (MSCs) are considered to be a promising therapeutic material due to their capacities for self-renewal, multilineage differentiation, and immunomodulation and have attracted great attention in regenerative medicine. However, MSCs may lose their biological functions because of donor age or disease and environmental pressure before and after transplantation, which hinders the application of MSC-based therapy. As a major intracellular lysosome-dependent degradative process, autophagy plays a pivotal role in maintaining cellular homeostasis and withstanding environmental pressure and may become a potential therapeutic target for improving MSC functions. Recent studies have demonstrated that the regulation of autophagy is a promising approach for improving the biological properties of MSCs. More in-depth investigations about the role of autophagy in MSC biology are required to contribute to the clinical application of MSCs. In this review, we focus on the role of autophagy regulation by various physical and chemical factors on the biological functions of MSCs in vitro and in vivo, and provide some strategies for enhancing the therapeutic efficacy of MSCs.

Insights into the use of mesenchymal stem cells in COVID-19 mediated acute respiratory failure

The emergence of severe acute respiratory syndrome corona virus 2 (SARS-CoV-2) at the end of 2019 in Hubei province China, is now the cause of a global pandemic present in over 150 countries. COVID-19 is a respiratory illness with most subjects presenting with fever, cough and shortness of breath. In a subset of patients, COVID-19 progresses to hypoxic respiratory failure and acute respiratory distress syndrome (ARDS), both of which are mediated by widespread inflammation and a dysregulated immune response. Mesenchymal stem cells (MSCs), multipotent stromal cells that mediate immunomodulation and regeneration, could be of potential benefit to a subset of COVID-19 subjects with acute respiratory failure. In this review, we discuss key features of the current COVID-19 outbreak, and the rationale for MSC-based therapy in this setting, as well as the limitations associated with this therapeutic approach.

Radiation-induced lung toxicity - cellular and molecular mechanisms of pathogenesis, management, and literature review

Lung, breast, and esophageal cancer represent three common malignancies with high incidence and mortality worldwide. The management of these tumors critically relies on radiotherapy as a major part of multi-modality care, and treatment-related toxicities, such as radiation-induced pneumonitis and/or lung fibrosis, are important dose limiting factors with direct impact on patient outcomes and quality of life. In this review, we summarize the current understanding of radiation-induced pneumonitis and pulmonary fibrosis, present predictive factors as well as recent diagnostic and therapeutic advances. Novel candidates for molecularly targeted approaches to prevent and/or treat radiation-induced pneumonitis and pulmonary fibrosis are discussed.

Mesenchymal stem cell treatment in a critically ill COVID-19 patient: a case report

An outbreak of a new coronavirus causing severe respiratory disease (COVID-19) was first reported in China and rapidly spread worldwide. Clinical spectrum changes from asymptomatic infection to severe illness and even death, and no specific treatment is currently available. A range of antiviral, antimalarial and antibiotic agents are being used. We report a case of a COVID-19 patient that progressed to severe disease requiring intubation and intensive care. We performed mesenchymal stem cell (MSC) transplantation considering the signs showing persistent excessive immune response and deterioration despite all supportive and drug therapies. The two rounds of transplantation did not result in any severe complications and was well-tolerated. Clinical signs were improved. The use of MSC therapy may be considered for compassionate use in selected patients.

Hepatocyte Growth Factor Secreted from Human Adipose-Derived Stem Cells Inhibits Fibrosis in Hypertrophic Scar Fibroblasts

AIMS

To study the effect of Adipose-derived stem cells (ADSCs) on fibrosis of hypertrophic scar-derived fibroblasts (HSFs) and its concrete mechanism.

BACKGROUND

ADSCs have been reported to reduce collagen production and fibroblast proliferation in co-culture experiments. Conditioned medium from adipose-derived stem cells (ADSCs-CM) has successfully inhibited fibrosis by decreasing the expression of collagen type І (Col1) and α-smooth muscle actin (α-SMA) in rabbit ear scar models. Hepatocyte growth factor (HGF), the primary growth factor in ADSCs-CM, has been shown to reverse fibrosis in various fibrotic diseases.

OBJECTIVE

To test the hypothesis that ADSCs inhibit fibrosis of HSFs through the secretion of HGF.

METHODS

HSFs were treated with DMEM containing 0%, 10%, 50% and 100% concentration of ADSCs-CM. The effect of ADSCs-CM on the viability was determined by cell viability assay, and the collagen production in HSFs was examined by Sirius red staining. Expression and secretion of fibrosis and degradation proteins were detected separately. After measuring the concentration of HGF in ADSCs-CM, the same number of HSFs were treated with 50% ADSCs-CM or HGF. HGF activity in ADSCs-CM was neutralized with a goat anti-human HGF antibody.

RESULTS

The results demonstrated that ADSCs-CM dose-dependently decreased cell viability, expression of fibrosis molecules, and tissue inhibitor of metalloproteinases-1 (TIMP-1), and significantly increased matrix metalloproteinase-1 (MMP-1) expression in HSFs. Collagen production and the ratio of collagen type І and type III (Col1/Col3) were also suppressed by ADSCs-CM in a dose-dependent manner. When HSFs were cultured with either 50% ADSCs-CM or HGF (1 ng/ml), a similar trend was observed in gene expression and protein secretion. Adding an HGF antibody to both groups returned protein expression and secretion to basal levels but did not significantly affect the fibrosis factors in the control group.

CONCLUSION

Our findings revealed that adipose-derived stem cell-secreted HGF effectively inhibits fibrosis-related factors and regulates extracellular matrix (ECM) remodeling in hypertrophic scar fibroblasts.

Mesenchymal stem cells ameliorate myocardial fibrosis in diabetic cardiomyopathy via the secretion of prostaglandin E2

BACKGROUND

Diabetic cardiomyopathy (DCM) is a cardiac complication of long-term uncontrolled diabetes and is characterized by myocardial fibrosis and abnormal cardiac function. Mesenchymal stem cells (MSCs) are multipotent cells with immunoregulatory and secretory functions in diabetes and heart diseases. However, very few studies have focused on the effect and the underlying mechanism of MSCs on myocardial fibrosis in DCM. Therefore, we aimed to explore the therapeutic potential of MSCs in myocardial fibrosis and its underlying mechanism in vivo and in vitro.

METHODS

A DCM rat model was induced using a high-fat diet (HFD) combined with a low-dose streptozotocin (STZ) injection. After four infusions of MSCs, rat serum and heart tissues were collected, and the levels of blood glucose and lipid, cardiac structure, and function, and the degree of myocardial fibrosis including the expression levels of pro-fibrotic factor and collagen were analyzed using biochemical methods, echocardiography, histopathology, polymerase chain reaction (PCR), and enzyme-linked immunosorbent assay (ELISA). We infused prostaglandin E2 (PGE2)-deficient MSCs to DCM rats in vivo and established a system mimicking diabetic myocardial fibrosis in vitro by inducing cardiac fibroblasts with high glucose (HG) and coculturing them with MSCs or PGE2-deficient MSCs to further explore the underlying mechanism of amelioration of myocardial fibrosis by MSCs.

RESULTS

Metabolic abnormalities, myocardial fibrosis, and cardiac dysfunction in DCM rats were significantly ameliorated after treatment with MSCs. Moreover, the levels of TGF-β, collagen I, collagen III, and collagen accumulation were markedly decreased after MSC infusion compared to those in DCM hearts. However, PGE2-deficient MSCs had decreased ability to alleviate cardiac fibrosis and dysfunction. In addition, in vitro study revealed that the concentration of PGE2 in the MSC group was enhanced, while the proliferation and collagen secretion of cardiac fibroblasts were reduced after MSC treatment. However, MSCs had little effect on alleviating fibrosis when the fibroblasts were pretreated with cyclooxygenase-2 (COX-2) inhibitors, which also inhibited PGE2 secretion. This phenomenon could be reversed by adding PGE2.

CONCLUSIONS

Our results indicated that MSC infusion could ameliorate cardiac fibrosis and dysfunction in DCM rats. The underlying mechanisms might involve the function of PGE2 secreted by MSCs.

Inhibition of DNA Methyltransferase by RG108 Promotes Pluripotency-Related Character of Porcine Bone Marrow Mesenchymal Stem Cells

Mesenchymal stem/stromal cells (MSCs) have been identified in almost all adult human tissues and been used in numerous clinical trials for a variety of diseases. Studies have shown that MSCs would undergo cellular senescence when cultured over a long term, which is brought on by increased epigenetic modifications, including DNA methylation. However, the mechanism of MSCs senescence is not well studied. In this study, the effects of RG108, a DNA methyltransferase inhibitor (DNMTi), on senescence, apoptosis, and pluripotency gene expressions in porcine bone marrow (pBM)-MSCs were investigated. First, we determined the optimized dose and time of RG108 treatment in pBM-MSCs to be 10 μM for 48 hours, respectively. Under these conditions, the pluripotency genes (NANOG, POU5F1), the anti-senescence genes (TERT, bFGF), and the anti-apoptosis gene (BCL2) were increased, whereas the apoptotic gene (BAX) was decreased. RG108 protected against apoptosis when pBM-MSC induces apoptosis with H₂O₂ for 1.5 hours. We also found that RG108 significantly induced the expression of NANOG and POU5F1 by decreasing DNA methylation in gene promoter regions. These results indicate that an optimized dose of RG108 may promote the pluripotency-related character of pBM-MSCs through improving cellular anti-senescence, anti-apoptosis, and pluripotency, which provide a better cell origin for stem cell therapy.

Mesenchymal stromal cell exosomes prevent and revert experimental pulmonary fibrosis through modulation of monocyte phenotypes

Mesenchymal stromal/stem cell (MSC) therapy has shown promise in experimental models of idiopathic pulmonary fibrosis (IPF). The aim of this study was to test the therapeutic effects of extracellular vesicles produced by human BM MSCs (MEx) in a bleomycin-induced pulmonary fibrosis model and investigate mechanisms of action. Adult C57BL/6 mice were challenged with endotracheal instillation of bleomycin and treated with MEx concurrently, or for reversal models, at day 7 or 21. Experimental groups were assessed at day 7, 14, or 28. Bleomycin-challenged mice presented with severe septal thickening and prominent fibrosis, and this was effectively prevented or reversed by MEx treatment. MEx modulated lung macrophage phenotypes, shifting the proportions of lung proinflammatory/classical and nonclassical monocytes and alveolar macrophages toward the monocyte/macrophage profiles of control mice. A parallel immunomodulatory effect was demonstrated in the BM. Notably, transplantation of MEx-preconditioned BM-derived monocytes alleviated core features of pulmonary fibrosis and lung inflammation. Proteomic analysis revealed that MEx therapy promotes an immunoregulatory, antiinflammatory monocyte phenotype. We conclude that MEx prevent and revert core features of bleomycin-induced pulmonary fibrosis and that the beneficial actions of MEx may be mediated via systemic modulation of monocyte phenotypes.

Reversal of bleomycin-induced rat pulmonary fibrosis by a xenograft of human umbilical mesenchymal stem cells from Wharton's jelly

Pulmonary fibrosis (PF) is a progressive and irreversible condition with various causes, and no effective treatment has been found to rescue fibrotic lungs. Successful recovery from PF requires inhibiting inflammation, promoting collagen degradation and stimulating alveolar regeneration. Human umbilical mesenchymal stem cells (HUMSCs) not only regulate immune responses but also synthesize and release hyaluronan to improve lung regeneration. This study investigated the feasibility of HUMSC engraftment into rats with bleomycin (BLM)-induced PF to explore HUMSC therapeutic effects/outcomes.

Methods: A unique BLM-induced left-lung-dominated PF animal model was established. Rats were transplanted with low-dose (5×10⁶) or high-dose (2.5×10⁷) HUMSCs on Day 21 after BLM injection. Combinations in co-culture of pulmonary macrophages, fibroblasts, HUMSCs treated with BLM and the same conditions on alveolar epithelia versus HUMSCs were evaluated.

Results: Rats with high-dose HUMSC engraftment displayed significant recovery, including improved blood oxygen saturation levels and respiratory rates. High-dose HUMSC transplantation reversed alveolar injury, reduced cell infiltration and ameliorated collagen deposition. One month posttransplantation, HUMSCs in the rats' lungs remained viable and secreted cytokines without differentiating into alveolar or vascular epithelial cells. Moreover, HUMSCs decreased epithelial-mesenchymal transition in pulmonary inflammation, enhanced macrophage matrix-metallopeptidase-9 (MMP-9) expression for collagen degradation, and promoted toll-like receptor-4 (TLR-4) expression in the lung for alveolar regeneration. In coculture studies, HUMSCs elevated the MMP-9 level in pulmonary macrophages, released hyaluronan into the medium and stimulated the TLR-4 quantity in the alveolar epithelium.

Principal Conclusions: Transplanted HUMSCs exhibit long-term viability in rat lungs and can effectively reverse rat PF.

Use of Condensed Nanofat Combined With Fat Grafts to Treat Atrophic Scars

Importance

In addition to the physical deformity, there is often great psychological burden of facial scars for patients. In this study, we use condensed nanofat combined with fat grafts in a novel technique to improve atrophic facial scars by raising both the surface and the bottom of the affected area.

Objective

To assess whether the use of condensed nanofat combined with fat grafting can be effective in treating atrophic facial scars from both an aesthetic and a functional perspective.

Design, Setting, and Participants

In this prospective case series of 20 patients with 25 atrophic facial scars, each scar was treated with condensed nanofat combined with fat grafts at the Sir Run Run Shaw Hospital, Zhejiang University, Hangzhou, Zhejiang, China. Postoperative results were evaluated by the patients themselves and by 3 senior plastic surgeon observers.

Main Outcomes and Measures

Multiple preoperative and postoperative examinations included the use of the Patient and Observer Scar Assessment Scale (POSAS) to evaluate both the functional and aesthetic aspects of the atrophic facial scars. Punch biopsy specimens were stained for the presence of melanin, elastic fibers, and cytokeratin (CK) 14 and CK19. Images were analyzed using ImageJ software, and the data were analyzed by paired sample t test.

Results

Twenty patients (6 men and 14 women; mean age, 38.25 years; age range, 21-62 years) with a total of 25 atrophic facial scars were treated between March 2014 and December 2016. The patients' mean (SD) scar assessment scores were significantly decreased postoperatively in the final examination for color, 6.40 (0.51) vs 2.40 (0.24) (P < .001); stiffness, 7.20 (0.37) vs 3.20 (0.20) (P < .001); thickness, 5.80 (0.73) vs 1.80 (0.37) (P = .001); and irregularity, 5.20 (0.49) vs 2.20 (0.37) (P = .003); and the observers' scores were also significantly decreased for pigmentation, 4.40 (0.51) vs 2.00 (0.32) (P = .004); thickness, 3.00 (0.32) vs 1.80 (0.20) (P = .03); relief, 4.40 (0.51) vs 2.40 (0.24) (P = .003); and pliability, 4.20 (0.37) vs 1.40 (0.24) (P < .001). In the final follow-up examinations, a significantly improved overall POSAS score was found among both patients, 28.80 (1.02) vs 12.20 (0.80) (P < .001), and observers, 18.00 (0.71) vs 9.20 (0.37) (P = .001). Enhancement of Fontana-Masson staining of melanin in the basal cell layer was observed postoperatively, and a significant postoperative change was detected for the mean (SD) values of average optical density from the preoperative measurement, 0.671 (0.083) vs 0.844 (0.110) (P = .01). The sebaceous glands and sweat glands that were not found in the preoperative images were seen postoperatively by immunohistochemical staining with CK14 and CK19.

Conclusions and Relevance

Our preliminary clinical and pathological results indicate that the use of condensed nanofat combined with fat grafts may be an effective approach to treating atrophic facial scars from both an aesthetic and a functional perspective.

Level of Evidence

4.

What have we learned from basic science studies on idiopathic pulmonary fibrosis?

Idiopathic pulmonary fibrosis is a fatal age-related lung disease characterised by progressive and irreversible scarring of the lung. Although the details are not fully understood, there has been tremendous progress in understanding the pathogenesis of idiopathic pulmonary fibrosis, which has led to the identification of many new potential therapeutic targets. In this review we discuss several of these advances with a focus on genetic susceptibility and cellular senescence primarily affecting epithelial cells, activation of profibrotic pathways, disease-enhancing fibrogenic cell types and the role of the remodelled extracellular matrix.

This review provides a summary of the most important findings in basic science investigations in pulmonary fibrosis and how they affect drug development and future patient management.http://bit.ly/2RjGMFZ

The Role of Mesenchymal Stem Cells in Radiation-Induced Lung Fibrosis

Radiation therapy is one of the most important treatment modalities for thoracic tumors. Despite significant advances in radiation techniques, radiation-induced lung injury (RILI) still occurs in up to 30% of patients undergoing thoracic radiotherapy, and therefore remains the main dose-limiting obstacle. RILI is a potentially lethal clinical complication of radiotherapy that has 2 main stages: an acute stage defined as radiation pneumonitis, and a late stage defined as radiation-induced lung fibrosis. Patients who develop lung fibrosis have a reduced quality of life with progressive and irreversible organ malfunction. Currently, the most effective intervention for the treatment of lung fibrosis is lung transplantation, but the lack of available lungs and transplantation-related complications severely limits the success of this procedure. Over the last few decades, advances have been reported in the use of mesenchymal stem cells (MSCs) for lung tissue repair and regeneration. MSCs not only replace damaged lung epithelial cells but also promote tissue repair through the secretion of anti-inflammatory and anti-fibrotic factors. Here, we present an overview of MSC-based therapy for radiation-induced lung fibrosis, focusing in particular on the molecular mechanisms involved and describing the most recent preclinical and clinical studies carried out in the field.

Adipose-Derived Tissue in the Treatment of Dermal Fibrosis: Antifibrotic Effects of Adipose-Derived Stem Cells

Treatment of hypertrophic scars and other fibrotic skin conditions with autologous fat injections shows promising clinical results; however, the underlying mechanisms of its antifibrotic action have not been comprehensively studied. Adipose-derived stem cells, or stromal cell-derived factors, inherent components of the transplanted fat tissue, seem to be responsible for its therapeutic effects on difficult scars. The mechanisms by which this therapeutic effect takes place are diverse and are mostly mediated by paracrine signaling, which switches on various antifibrotic molecular pathways, modulates the activity of the central profibrotic transforming growth factor β/Smad pathway, and normalizes functioning of fibroblasts and keratinocytes in the recipient site. Direct cell-to-cell communications and differentiation of cell types may also play a positive role in scar treatment, even though they have not been extensively studied in this context. A more thorough understanding of the fat tissue antifibrotic mechanisms of action will turn this treatment from an anecdotal remedy to a more controlled, timely administered technology.

NMDA receptor activation inhibits the protective effect of BM‑MSCs on bleomycin‑induced lung epithelial cell damage by inhibiting ERK signaling and the paracrine factor HGF

Endoplasmic reticulum (ER) stress in alveolar epithelial cells (AECs) is associated with the pathogenesis of pulmonary fibrosis. Bone marrow‑derived mesenchymal stromal cells (BM‑MSCs) can exert protective effects on ER‑stressed AECs via paracrine signaling. In the present study, mouse lung epithelial (MLE)‑12 cells were directly stimulated with various concentrations of bleomycin (BLM). MLE‑12 cell apoptosis was detected by flow cytometry, and Ki67 expression was detected by immunofluorescence to reflect cell proliferation. The results revealed that BLM increased the protein expression levels of X‑box binding protein 1 and immunoglobulin heavy chain‑binding protein, thus inducing ER stress, and caused cell dysfunction by inhibiting proliferation and promoting apoptosis. In addition, MSC‑derived conditioned medium (MSC‑CM) protected MLE‑12 cells from BLM‑induced injury, by reducing ER stress, promoting cell proliferation and inhibiting cell apoptosis. Our previous studies reported that N‑methyl‑D‑aspartate (NMDA) receptor activation partially inhibits the antifibrotic effect of BM‑MSCs on BLM‑induced pulmonary fibrosis through downregulating the paracrine factor hepatocyte growth factor (HGF). In the present study, the synthesis and secretion of HGF were detected by western blotting and ELISA, respectively. Results further demonstrated that NMDA inhibited the synthesis and secretion of HGF in BM‑MSCs, and NMDA‑preconditioned MSC‑CM had no protective effects on BLM‑induced injury in MLE‑12 cells. In addition, activation of the NMDA receptor decreased the phosphorylation levels of extracellular signal‑regulated kinase (ERK)1/2 in BM‑MSCs. Using Honokiol and FR180204, the activator and inhibitor of ERK1/2, respectively, it was then revealed that Honokiol partially eliminated the decrease in HGF expression, whereas FR180204 further promoted the reduction in HGF caused by NMDA. Collectively, these findings suggested that NMDA receptor activation may downregulate HGF by inhibiting ERK signaling in BM‑MSCs, thus weakening their protective effects on BLM‑induced lung epithelial cell damage.

Antifibrotic effects of 2-carba cyclic phosphatidic acid (2ccPA) in systemic sclerosis: contribution to the novel treatment

Background

Cyclic phosphatidic acid (cPA) has an inhibitory effect on the autotaxin (ATX)/lysophosphatidic acid (LPA) axis, which has been implicated to play an important role in the progression of fibrosis in systemic sclerosis (SSc). The purpose of this study is to assess the antifibrotic activity of cPA for the treatment of SSc using SSc skin fibroblasts and an animal model of bleomycin-induced skin fibrosis.

Methods

We used a chemically stable derivative of cPA (2ccPA). First, we investigated the effect of 2ccPA on extracellular matrix (ECM) expression in skin fibroblasts. Next, the effect of 2ccPA on the intracellular cAMP levels was determined to investigate the mechanisms of the antifibrotic activity of 2ccPA. Finally, we administered 2ccPA to bleomycin-induced SSc model mice to evaluate whether 2ccPA prevented the progression of skin fibrosis.

Results

2ccPA decreased ECM expression in SSc skin fibroblasts and TGF-β1-treated healthy skin fibroblasts without LPA stimulation. 2ccPA increased the intracellular cAMP levels in skin fibroblasts, suggesting that the antifibrotic effect of 2ccPA was the consequence of the increase in the intracellular cAMP levels. Administration of 2ccPA also ameliorated the progression of bleomycin-induced skin fibrosis in mice.

Conclusions

Our data indicated that 2ccPA had inhibitory effects on the progression of skin fibrosis by abrogating ECM production from activated skin fibroblasts. These cells were repressed, at least in part, by increased intracellular cAMP levels. 2ccPA may be able to be used to treat fibrotic lesions in SSc.

Optimization of the adipose-derived mesenchymal stem cell delivery time for radiation-induced lung fibrosis treatment in rats

The present study attempts to identify the optimal time duration for the administration of Ad-MSCs, in order to maximize its therapeutic benefits, and compare the degree of fibrosis among three different administration time points using the RILF rat model system. Ad-MSCs were delivered to Sprague-Dawley rats through the tail vein at the following different time points after thorax irradiation: two hours, seven days, and two hours + seven days. Post Ad-MSCs transplantation and the histopathological analysis of the lungs were performed along with analysis of inflammatory cytokine levels, including interleukin (IL)-1, IL-2, IL-6, IL-10 and tumor necrosis factor-α (TNF-α). In particular, pro-fibrotic factors (TGF-β1 and α-SMA) were also evaluated in serum and lung tissues. In addition, it was also determined whether Ad-MSCs had any role in inhibiting the transition of type II alveolar epithelial cells into fibroblasts in the lungs of injured rats. The present results demonstrated that the intravenous delivery of Ad-MSCs twice at the 2-hour and 7-day (R + MSC_2h+7d group) was effective in reducing lung fibrosis for long term durations, when compared with single delivery either at the two-hour or 7-day time points. In addition, a marked anti-inflammatory effect was also observed in RILF rats in the R + MSC_2h+7d group, as indicated by the reduced serum levels of pro-inflammatory cytokines (TNF-α, IL-1 and IL-6) and increased levels of anti-inflammatory cytokines IL-10 and IL-2. Rats that were delivered twice with Ad-MSCs (R + MSC_2h+7d group) exhibited significantly reduced TGF-β1 and α-SMA levels, in contrast to rats in the R + MSC_7d or R + MSC_2h groups, after four weeks. Furthermore, it was also noted that after four weeks, Ad-MSCs increased the number of lung epithelial cells (SP-C) and inhibited the lung fibroblastic cells (α-SMA) of rats in the R + MSC_2h and R + MSC_2h+7d groups. The present study concluded that two injections of Ad-MSCs (R + MSC_2h+7d group) appear to be optimal for therapeutic efficacy and safety during RILF.

Concise Review: Therapeutic Potential of the Mesenchymal Stem Cell Derived Secretome and Extracellular Vesicles for Radiation-Induced Lung Injury: Progress and Hypotheses

Radiation-induced lung injury (RILI) is a common complication in radiotherapy of thoracic tumors and limits the therapeutic dose of radiation that can be given to effectively control tumors. RILI develops through a complex pathological process, resulting in induction and activation of various cytokines, infiltration by inflammatory cells, cytokine-induced activation of fibroblasts, and subsequent tissue remodeling by activated fibroblasts, ultimately leading to impaired lung function and respiratory failure. Increasing evidence shows that mesenchymal stem cells (MSCs) may play a main role in modulating inflammation and immune responses, promoting survival and repair of damaged resident cells and enhancing regeneration of damaged tissue through soluble paracrine factors and therapeutic extracellular vesicles. Therefore, the use of the MSC-derived secretome and exosomes holds promising potential for RILI therapy. Here, we review recent progress on the potential mechanisms of MSC therapy for RILI, with an emphasis on soluble paracrine factors of MSCs. Hypotheses on how MSC derived exosomes or MSC-released exosomal miRNAs could attenuate RILI are also proposed. Problems and translational challenges of the therapies based on the MSC-derived secretome and exosomes are further summarized and underline the need for caution on rapid clinical translation. Stem Cells Translational Medicine 2019;8:344-354.

Efficacy of bone marrow mesenchymal stem cell transplantation in animal models of pulmonary fibrosis after exposure to bleomycin: A meta-analysis

Previous studies have demonstrated that bone marrow mesenchymal stem cell (BMSC) transplantation is a promising treatment strategy for pulmonary fibrosis. Although encouraging results have been obtained using animal models of bleomycin (BLM)-induced pulmonary fibrosis, it is evident that transplantation of BMSCs at various time-points after BLM administration has produced different results in terms of treatment efficacy. To shed light on the potential utility of BMSCs for the treatment of lung disease, the present study performed a meta-analysis to estimate the efficacy of BMSCs in animal models of BLM-induced pulmonary fibrosis, and compare early transplantation (BMSCs injected on the same day after administration of BLM) with late transplantation (BMSCs injected on the 14th day after administration of BLM). Relevant studies were retrieved from the MEDLINE, PubMed, Chinese Knowledge Infrastructure and WanFang databases using a comprehensive search approach. A total of 6 studies involving 228 model rats were included. Meta-analysis indicated that early BMSC transplantation was able to prevent or reduce BLM-induced alveolitis and pulmonary fibrosis, while late BMSC transplantation was able to reduce alveolitis, but there was no significant evidence regarding improvement of pulmonary fibrosis. Although BMSC therapy was identified to be generally beneficial in rodent models of BLM-induced pulmonary fibrosis, the efficacy of early transplantation appears to be more satisfactory; overall, the efficacy of transplantation of BMSCs at the acute inflammatory phase was more effective compared with that at the chronic fibrosis stage. Of note, regarding alveolitis and pulmonary fibrosis scores after late transplantation of BMSCs, the sensitivity analysis revealed that the scores were less stable; thus, this result must be interpreted with caution. Furthermore, the quality and methodology of the included studies was comparatively low. Therefore, higher-quality and more rigorous studies are required to validate the results of the present meta-analysis in the future.

Cytokines and radiation-induced pulmonary injuries

Radiation therapy is one of the most common treatment strategies for thorax malignancies. One of the considerable limitations of this therapy is its toxicity to normal tissue. The lung is the major dose-limiting organ for radiotherapy. That is because ionizing radiation produces reactive oxygen species that induce lesions, and not only is tumor tissue damaged, but overwhelming inflammatory lung damage can occur in the alveolar epithelium and capillary endothelium. This damage may result in radiation-induced pneumonitis and/or fibrosis. While describing the lung response to irradiation generally, the main focus of this review is on cytokines and their roles and functions within the individual stages. We discuss the relationship between radiation and cytokines and their direct and indirect effects on the formation and development of radiation injuries. Although this topic has been intensively studied and discussed for years, we still do not completely understand the roles of cytokines. Experimental data on cytokine involvement are fragmented across a large number of experimental studies; hence, the need for this review of the current knowledge. Cytokines are considered not only as molecular factors involved in the signaling network in pathological processes, but also for their diagnostic potential. A concentrated effort has been made to identify the significant immune system proteins showing positive correlation between serum levels and tissue damages. Elucidating the correlations between the extent and nature of radiation-induced pulmonary injuries and the levels of one or more key cytokines that initiate and control those damages may improve the efficacy of radiotherapy in cancer treatment and ultimately the well-being of patients.

NMDA receptor activation inhibits the antifibrotic effect of BM-MSCs on bleomycin-induced pulmonary fibrosis

Endogenous glutamate (Glu) release and N-methyl-d-aspartate (NMDA) receptor (NMDAR) activation are associated with lung injury in different animal models. However, the underlying mechanism is unclear. Bone marrow-derived mesenchymal stem cells (BM-MSCs), which show potential use for immunomodulation and tissue protection, play a protective role in pulmonary fibrosis (PF) process. Here, we found the increased Glu release from the BM cells of bleomycin (BLM)-induced PF mice in vivo. BLM stimulation also increased the extracellular Glu in BM-MSCs via the antiporter system x_c⁻ in vitro. The gene expression of each subunit of NMDAR was detected in BM-MSCs. NMDAR activation inhibited the proliferation, migration, and paracrine function of BM-MSCs in vitro. BM-MSCs were derived from male C57BL/6 mice, transfected with lentiviral vectors carrying the enhanced green fluorescence protein gene, pretreated with NMDA, and transplanted into the female recipient mice that were intratracheally injected with BLM to induce PF. Transplantation of NMDA-pretreated BM-MSCs significantly aggravated PF as compared with that in the normal BM-MSCs transplantation group. The sex determination gene Y chromosome and green fluorescence protein genes of BM-MSCs were detected to observe BM-MSCs homing in the fibrotic lungs. Moreover, NMDAR activation inhibited BM-MSC migration by downregulating the stromal cell-derived factor-1/C-X-C chemokine receptor type 4 signaling axis. NMDAR activation aggravated the transforming growth factor-β1-induced extracellular matrix production in alveolar epithelial cells and fibroblasts through the paracrine effects of BM-MSCs. In summary, these findings suggested that NMDAR activation-mediated Glu excitotoxicity induced by BLM in BM-MSCs abolished the therapeutic effects of normal BM-MSCs transplantation on BLM-induced PF.