Mesenchymal stem cell survival in the infarcted heart is enhanced by lentivirus vector-mediated heat shock protein 27 expression

Priming mesenchymal stem cells to develop "super stem cells"

The stem cell pre-treatment approaches at cellular and sub-cellular levels encompass physical manipulation of stem cells to growth factor treatment, genetic manipulation, and chemical and pharmacological treatment, each strategy having advantages and limitations. Most of these pre-treatment protocols are non-combinative. This editorial is a continuum of Li et al's published article and Wan et al's editorial focusing on the significance of pre-treatment strategies to enhance their stemness, immunoregulatory, and immunosuppressive properties. They have elaborated on the intricacies of the combinative pre-treatment protocol using pro-inflammatory cytokines and hypoxia. Applying a well-defined multi-pronged combinatorial strategy of mesenchymal stem cells (MSCs), pre-treatment based on the mechanistic understanding is expected to develop "Super MSCs", which will create a transformative shift in MSC-based therapies in clinical settings, potentially revolutionizing the field. Once optimized, the standardized protocols may be used with slight modifications to pre-treat different stem cells to develop "super stem cells" with augmented stemness, functionality, and reparability for diverse clinical applications with better outcomes.

Mesenchymal Stem Cell-Derived Exosomes and Their MicroRNAs in Heart Repair and Regeneration

Mesenchymal stem cells (MSCs) can be differentiated into cardiac, endothelial, and smooth muscle cells. Therefore, MSC-based therapeutic approaches have the potential to deal with the aftermaths of cardiac diseases. However, transplanted stem cells rarely survive in damaged myocardium, proposing that paracrine factors other than trans-differentiation may involve in heart regeneration. Apart from cytokines/growth factors, MSCs secret small, single-membrane organelles named exosomes. The MSC-secreted exosomes are enriched in lipids, proteins, nucleic acids, and microRNA (miRNA). There has been an increasing amount of data that confirmed that MSC-derived exosomes and their active molecule microRNA (miRNAs) regulate signaling pathways involved in heart repair/regeneration. In this review, we systematically present an overview of MSCs, their cardiac differentiation, and the role of MSC-derived exosomes and exosomal miRNAs in heart regeneration. In addition, biological functions regulated by MSC-derived exosomes and exosomal-derived miRNAs in the process of heart regeneration are reviewed.

Hydrogel-based cardiac repair and regeneration function in the treatment of myocardial infarction

A life-threatening illness that poses a serious threat to human health is myocardial infarction. It may result in a significant number of myocardial cells dying, dilated left ventricles, dysfunctional heart function, and ultimately cardiac failure. Based on the development of emerging biomaterials and the lack of clinical treatment methods and cardiac donors for myocardial infarction, hydrogels with good compatibility have been gradually applied to the treatment of myocardial infarction. Specifically, based on the three processes of pathophysiology of myocardial infarction, we summarized various types of hydrogels designed for myocardial tissue engineering in recent years, including natural hydrogels, intelligent hydrogels, growth factors, stem cells, and microRNA-loaded hydrogels. In addition, we also describe the heart patch and preparation techniques that promote the repair of MI heart function. Although most of these hydrogels are still in the preclinical research stage and lack of clinical trials, they have great potential for further application in the future. It is expected that this review will improve our knowledge of and offer fresh approaches to treating myocardial infarction.

Conservative Hypomethylation of Mesenchymal Stem Cells and Their Secretome Restored the Follicular Development in Cisplatin-Induced Premature Ovarian Failure Mice

Premature ovarian failure (POF) is one of the main causes of infertility in women under the age of 40 years. Recently, epigenetic reprogramming, particularly DNA hypomethylation, has emerged as a promising strategy to enhance the therapeutic potential of mesenchymal stem cells (MSCs). Thus, it is crucial to elucidate how far global hypomethylation of MSCs genome can maintain their pluripotency and viability and improve their therapeutic effect in chemotherapy-induced POF mice. Herein, the genomic DNA of bone marrow-derived MSCs (BM-MSCs) was hypomethylated by the DNA methyltransferase inhibitor (5-Aza-dC), and the degree of global hypomethylation was assessed by methylation-sensitive HepII/MspI restriction analysis. Next, mildly hypomethylated cells and their secretome were independently transplanted (or infused) in POF mice, established via cisplatin-mediated gonadotoxicity. We found that conservative global hypomethylation of BM-MSCs genome with low doses of 5-Aza-dC (≤0.5 μM) has maintained cell viability and MSCs-specific clusters of differentiation (CD). Engraftment of mildly hypomethylated cells in POF mice, or infusion of their secretome, improved the concentrations of estradiol (E2), follicle-stimulating hormone (FSH), and anti-Mullerian hormone (AMH). Furthermore, mice restored their normal body weight, ovarian size, and ovarian follicle count. This was associated with improved follicular development, where the populations of healthy primordial, primary, secondary, and tertiary follicles were significantly ameliorated, relative to mice transplanted with normally methylated cells. This observational study suggests that transplantation of mildly hypomethylated BM-MSCs cells and their secretome can restore the structural and functional integrity of the damaged ovaries in POF mice. Also, it presents conservative hypomethylation of BM-MSCs and their secretome as a promising alternative to MSCs transplantation.

Advances in Genetic Reprogramming: Prospects from Developmental Biology to Regenerative Medicine

The foundations of cell reprogramming were laid by Yamanaka and co-workers, who showed that somatic cells can be reprogrammed into pluripotent cells (induced pluripotency). Since this discovery, the field of regenerative medicine has seen advancements. For example, because they can differentiate into multiple cell types, pluripotent stem cells are considered vital components in regenerative medicine aimed at the functional restoration of damaged tissue. Despite years of research, both replacement and restoration of failed organs/ tissues have remained elusive scientific feats. However, with the inception of cell engineering and nuclear reprogramming, useful solutions have been identified to counter the need for compatible and sustainable organs. By combining the science underlying genetic engineering and nuclear reprogramming with regenerative medicine, scientists have engineered cells to make gene and stem cell therapies applicable and effective. These approaches have enabled the targeting of various pathways to reprogramme cells, i.e., make them behave in beneficial ways in a patient-specific manner. Technological advancements have clearly supported the concept and realization of regenerative medicine. Genetic engineering is used for tissue engineering and nuclear reprogramming and has led to advances in regenerative medicine. Targeted therapies and replacement of traumatized , damaged, or aged organs can be realized through genetic engineering. Furthermore, the success of these therapies has been validated through thousands of clinical trials. Scientists are currently evaluating induced tissue-specific stem cells (iTSCs), which may lead to tumour-free applications of pluripotency induction. In this review, we present state-of-the-art genetic engineering that has been used in regenerative medicine. We also focus on ways that genetic engineering and nuclear reprogramming have transformed regenerative medicine and have become unique therapeutic niches.

Mesenchymal Stem Cells: A Promising Treatment for Thymic Involution

The thymus is the main immune organ in the body. However, the thymus gradually degenerates in early life, leading to a reduction in T-cell production and a decrease in immune function. Mesenchymal stem cells (MSCs) are a promising alternative for the treatment of thymus senescence due to their homing ability to the site of inflammation and their paracrine, anti-inflammatory, and antioxidant properties. However, the heterogeneity, difficulty of survival in vivo, short residence time, and low homing efficiency of the injected MSCs affect the clinical therapeutic effect. This article reviews strategies to improve the efficacy of mesenchymal stem cell therapy, including the selection of appropriate cell doses, transplantation frequency, and interval cycles. The survival rate of MSCs can be improved to some extent by improving the infusion mode of MSCs, such as simulating the in vivo environment, applying the biological technology of hydrogels and microgels, and iron oxide labeling technology, which can improve the curative effect and homing of MSCs, promote the regeneration of thymic epithelial cells, and restore the function of the thymus.

Enzyme-controlled, nutritive hydrogel for mesenchymal stromal cell survival and paracrine functions

Culture-adapted human mesenchymal stromal cells (hMSCs) are appealing candidates for regenerative medicine applications. However, these cells implanted in lesions as single cells or tissue constructs encounter an ischemic microenvironment responsible for their massive death post-transplantation, a major roadblock to successful clinical therapies. We hereby propose a paradigm shift for enhancing hMSC survival by designing, developing, and testing an enzyme-controlled, nutritive hydrogel with an inbuilt glucose delivery system for the first time. This hydrogel, composed of fibrin, starch (a polymer of glucose), and amyloglucosidase (AMG, an enzyme that hydrolyze glucose from starch), provides physiological glucose levels to fuel hMSCs via glycolysis. hMSCs loaded in these hydrogels and exposed to near anoxia (0.1% pO2) in vitro exhibited improved cell viability and angioinductive functions for up to 14 days. Most importantly, these nutritive hydrogels promoted hMSC viability and paracrine functions when implanted ectopically. Our findings suggest that local glucose delivery via the proposed nutritive hydrogel can be an efficient approach to improve hMSC-based therapeutic efficacy.

Mild heat treatment in vitro potentiates human adipose stem cells: delayed aging and improved quality for long term culture

BACKGROUND

Mesenchymal stem cells (MSCs) have gained significant attention for diverse biomedical applications, including cell-based therapy. Hence, in vitro expansion of MSCs is critical; however, in vitro MSC culture, especially long-term culture, inevitably leads to significant loss of stemness, growth, and differentiation potential.

METHOD

Effects of mild heat treatment (HT) conditions (temperature, duration, and repetition) on the characteristics of adipose tissue-derived MSCs in vitro were systematically investigated. Characteristics of the MSCs subjected to the predetermined HT conditions (41 or 44ºC, 1 h, and 2X HT) were first analyzed in a single passage using various assays. In addition, the feasibility of HT for long-term MSC culture was studied. The RNA sequencing analyses were performed to elucidate the mechanism of HT effects on MSCs.

RESULTS

A comprehensive exploration of various HT conditions revealed that specific mild HT at 41ºC or 44ºC for 1 h upregulated the expression of heat shock proteins and stemness markers and enhanced differentiation potentials. Furthermore, periodic mild HT extended the maintenance of growth rate and stemness of MSCs up to an additional 10 passages, which substantially retarded their spontaneous aging during subsequent in vitro culture. RNA sequencing analyses unveiled that HT downregulated genes associated with aging and apoptosis.

CONCLUSION

Our study successfully demonstrated that mild HT of MSCs has positive effects on their application in various biomedical fields, enhancing their capabilities and slowing down the aging process.

Functionally enhanced cell spheroids for stem cell therapy: Role of TIMP1 in the survival and therapeutic effectiveness of stem cell spheroids

Stem cell therapy has emerged as a promising regenerative medicine strategy but is limited by poor cell survival, leading to low therapeutic outcomes. We developed cell spheroid therapeutics to overcome this limitation. We utilized solid-phase FGF2 to form functionally enhanced cell spheroid-adipose derived (FECS-Ad), a type of cell spheroid that preconditions cells with intrinsic hypoxia to increase the survival of transplanted cells. We demonstrated an increase in hypoxia-inducible factor 1-alpha (HIF-1α) levels in FECS-Ad, which led to the upregulation of tissue inhibitor of metalloproteinase 1 (TIMP1). TIMP1 enhanced the survival of FECS-Ad, presumably through the CD63/FAK/Akt/Bcl2 anti-apoptotic signaling pathway. Cell viability of transplanted FECS-Ad was reduced by TIMP1 knockdown in an in vitro collagen gel block and a mouse model of critical limb ischemia (CLI). TIMP1 knockdown in FECS-Ad inhibited angiogenesis and muscle regeneration induced by FECS-Ad transplanted into ischemic mouse tissue. Genetic overexpression of TIMP1 in FECS-Ad further promoted the survival and therapeutic efficacy of transplanted FECS-Ad. Collectively, we suggest that TIMP1 acts as a key survival factor to improve the survival of transplanted stem cell spheroids, which provides scientific evidence for enhanced therapeutic efficacy of stem cell spheroids, and FECS-Ad as a potential therapeutic agent to treat CLI. STATEMENT OF SIGNIFICANCE: We used FGF2-tethered substrate platform to form adipose-derived stem cell spheroids, as we named as functionally enhanced cell spheroid-adipose derived (FECS-Ad). In this paper, we showed that intrinsic hypoxia of spheroids upregulated expression of HIF-1α, which in turn upregulated expression of TIMP1. Our paper highlights TIMP1 as a key survival factor to improve survival of transplanted stem cell spheroids. We believe that our study has a very strong scientific impact as extending transplantation efficiency is essential for successful stem cell therapy.

The protective effects of hyperoxic pre-treatment in human-derived adipose tissue mesenchymal stem cells against in vitro oxidative stress and a rat model of renal ischaemia-reperfusion

Objective: Improvement of cell survival is essential for achieving better clinical outcomes in stem cell therapy. We investigated the effects of hyperoxic pre-treatment (HP) on the viability of human adipose stromal stem cells (ASCs).Materials and Methods: MTT and Western blot tests were used to assess cell viability and the expression of apoptosis-related proteins, respectively. For the in-vivo trial, the rats were subjected to renal ischaemia-reperfusion (IR).Results: The results showed that HP could significantly increase the viability of ASCs and decrease apoptotic markers (Bax/BCL-2 ratio and Caspase-3) compared with control cells. There were some additional effects with regard to the improvement of renal structure and function in the animal model. However, the difference between the treated and non-treated transplanted ASCs failed to reach significance.Conclusion: These results suggested that HP could increase the survival of ASCs against oxidative stress-induced damages in the in-vitro condition, but this strategy was not highly effective in renal IR.

Adipokines at the crossroads of obesity and mesenchymal stem cell therapy

Mesenchymal stem cell (MSC) therapy is an emerging treatment strategy to counteract metabolic syndromes, including obesity and its comorbid disorders. However, its effectiveness is challenged by various factors in the obese environment that negatively impact MSC survival and function. The identification of these detrimental factors will provide opportunities to optimize MSC therapy for the treatment of obesity and its comorbidities. Dysregulated production of adipokines, a group of cytokines and hormones derived from adipose tissue, has been postulated to play a pivotal role in the development of obesity-associated complications. Intriguingly, adipokines have also been implicated in the modulation of viability, self-renewal, proliferation, and other properties of MSC. However, the involvement of adipokine imbalance in impaired MSC functionality has not been completely understood. On the other hand, treatment of obese individuals with MSC can restore the serum adipokine profile, suggesting the bidirectionality of the adipokine-MSC relationship. In this review, we aim to discuss the current knowledge on the central role of adipokines in the crosstalk between obesity and MSC dysfunction. We also summarize recent advances in the use of MSC for the treatment of obesity-associated diseases to support the hypothesis that adipokines modulate the benefits of MSC therapy in obese patients.

Transcription Factors - the Essence of Heart Regeneration: A Potential Novel Therapeutic Strategy

Myocardial cell injury and following sequelae are the primary reasons for death globally. Unfortunately, myocardiocytes in adults have limited regeneration capacity. Therefore, the generation of neo myocardiocytes from non-myocardial cells is a surrogate strategy. Transcription factors (TFs) can be recruited to achieve this tremendous goal. Transcriptomic analyses have suggested that GATA, Mef2c, and Tbx5 (GMT cocktail) are master TFs to transdifferentiate/reprogram cell linage of fibroblasts, somatic cells, mesodermal cells into myocardiocytes. However, adding MESP1, MYOCD, ESRRG, and ZFPM2 TFs induces the generation of more efficient and physiomorphological features for induced myocardiocytes. Moreover, the same cocktail of transcription factors can induce the proliferation and differentiation of induced/pluripotent stem cells into myocardial cells. Amelioration of impaired myocardial cells involves the activation of healing transcription factors, which are induced by inflammation mediators; IL6, tumor growth factor β, and IL22. Transcription factors regulate the cellular and subcellular physiology of myocardiocytes to include mitotic cell cycling regulation, karyokinesis and cytokinesis, hypertrophic growth, adult sarcomeric contractile protein gene expression, fatty acid metabolism, and mitochondrial biogenesis and maturation. Cell therapy by transcription factors can be applied to cardiogenesis and ameliorating impaired cardiocytes. Transcription factors are the cornerstone in cell differentiation.

Mesenchymal stromal cell spheroids in sulfated alginate enhance muscle regeneration

The therapeutic efficacy of mesenchymal stromal cells (MSCs) for tissue regeneration is critically linked to the potency of the complex mixture of growth factors, cytokines, exosomes, and other biological cues that they secrete. The duration of cell-based approaches is limited by rapid loss of cells upon implantation, motivating the need to prolong cell viability and extend the therapeutic influence of the secretome. We and others demonstrated that the secretome is upregulated when MSCs are formed into spheroids. Although the efficacy of the MSC secretome has been characterized in the literature, no studies have reported the therapeutic benefit of in situ sequestration of the secretome within a wound site using engineered biomaterials. We previously demonstrated the capacity of sulfated alginate hydrogels to sequester components of the MSC secretome for prolonged presentation in vitro, yet the efficacy of this platform has not been evaluated in vivo. In this study, we used sulfated alginate hydrogels loaded with MSC spheroids to aid in the regeneration of a rat muscle crush injury. We hypothesized that the use of sulfated alginate to bind therapeutically relevant growth factors from the MSC spheroid secretome would enhance muscle regeneration by recruiting host cells into the tissue site. The combination of sulfated alginate and MSC spheroids resulted in decreased collagen deposition, improved myogenic marker expression, and increased neuromuscular junctions 2 weeks after injury. These data indicate that MSC spheroids delivered in sulfated alginate represent a promising approach for decreased fibrosis and increased functional regeneration of muscle. STATEMENT OF SIGNIFICANCE: The therapeutic efficacy of mesenchymal stromal cells (MSCs) for tissue regeneration is attributed to the complex diversity of the secretome. Cell-based approaches are limited by rapid cell death, motivating the need to extend the availability of the secretome. We previously demonstrated that sulfated alginate hydrogels sequester components of the MSC secretome for prolonged presentation in vitro, yet no studies have reported the in situ sequestration of the secretome. Herein, we transplanted MSC spheroids in sulfated alginate hydrogels to promote muscle regeneration. MSC spheroids in sulfated alginate decreased collagen deposition, improved myogenic marker expression, and increased neuromuscular junctions. These data indicate that MSC spheroids delivered in sulfated alginate represent a promising approach for decreasing fibrosis and increasing functional muscle regeneration.

Acute Changes in Myocardial Expression of Heat Shock Proteins and Apoptotic Response Following Blood, delNido, or Custodiol Cardioplegia in Infants Undergoing Open-Heart Surgery

Stress caused by cardioplegic ischemic arrest was shown to alter the expression levels of heat shock proteins (Hsp), but little is known about their effects, particularly on pediatric hearts. This study aimed to investigate whether myocardial cellular stress and apoptotic response changes due to different cardioplegia (CP) solutions during cardiopulmonary bypass (CPB) in infants and to determine their influence on surgical/clinical outcomes. Therefore, twenty-seven infants for surgical closure of ventricular septal defect were randomly assigned to a CP solution: normothermic blood (BCP), delNido (dNCP), and Custodiol (CCP). Hsp levels and apoptosis were determined by immunoblotting in cardiac tissue from the right atrium before and after CP, and their correlations with cardiac parameters were evaluated. No significant change was observed in Hsp27 levels. Hsp60, Hsp70, and Hsp90 levels decreased significantly in the BCP-group but increased markedly in the CCP-group. Decreased Hsp60 and increased Hsp70 expression were detected in dNCP-group. Importantly, apoptosis was not observed in dNCP- and CCP-groups, whereas marked increases in cleaved caspase-3 and -8 were determined after BCP. Serum cardiac troponin-I (cTn-I), myocardial injury marker, was markedly lower in the BCP- and dNCP-groups than CCP. Additionally, Hsp60, Hsp70, and Hsp90 levels were positively correlated with aortic cross-clamp time, total perfusion time, and cTn-I release. Our findings show that dNCP provides the most effective myocardial preservation in pediatric open-heart surgery and indicate that an increase in Hsp70 expression may be associated with a cardioprotective effect, while an increase in Hsp60 and Hsp90 levels may be an indicator of myocardial damage during CPB.

Hypoxia, Serum Starvation, and TNF-α Can Modify the Immunomodulation Potency of Human Adipose-Derived Stem Cells

INTRODUCTION

Adipose-derived stem cells (ADSCs) are mesenchymal stem cells (MSCs) that are found in adipose tissues, which are easily obtained from liposuction procedures using an enzyme mixture. The adhering cells are then selectively cultivated. ADSCs have great potential in regenerative medicine because they are plentiful, easily accessible, and less invasive. They also have an impressive proliferation ability and can be differentiated into mesenchymal lineages and trans-differentiating into many other cell types. In particular, they have extraordinary abilities in immunomodulation. This study aimed to investigate the effects of culture conditions (hypoxia, starvation, and TNF-α treatment) on the immunomodulation of human ADSCs.

METHODS

Human ADSCs were expanded in vitro in the standard condition before they were cultured in different stress conditions. ADSCs from passages fifth were confirmed as MSCs by some standard assays suggested by the International Society for Cell and Gene Therapy. These MSCs were used to culture in four different stress conditions: hypoxia, serum starvation, and TNF-α treatment in 48 h. After treatments, MSCs were used to evaluate their immunomodulation capacity using MSCs mixed lymphocyte reaction assay, and the concentrations of IDO, PGE2, IL-6, and IL-10 were secreted in the culture medium.

RESULTS

In different stress conditions, ADSCs exhibited different responses related to their immunomodulation. In serum starvation, ADSCs exerted a strong secretion of IDO and PGE2, whereas they showed strong IL-6 secretion in the TNF-α-supplemented medium. When exposed to lymphocytes, ADSCs caused an increase in the ratio of regulatory T cells (Tregs), and co-culture lymphocytes with ADSCs induced in hypoxic malnutrition conditions increased the IL-10 level the most. In addition, when exposed to dendritic cells (DCs), ADSCs inhibited the mature marker expressions of the DCs.

CONCLUSION

The current research showed that ADSCs change their immunomodulation properties to survive in in vitro culture environments. Treatment of ADSCs in the starvation medium for 48 h can increase the immunomodulation of ADSCs.

Craniofacial Bone Tissue Engineering: Current Approaches and Potential Therapy

Craniofacial bone defects can result from various disorders, including congenital malformations, tumor resection, infection, severe trauma, and accidents. Successfully regenerating cranial defects is an integral step to restore craniofacial function. However, challenges managing and controlling new bone tissue formation remain. Current advances in tissue engineering and regenerative medicine use innovative techniques to address these challenges. The use of biomaterials, stromal cells, and growth factors have demonstrated promising outcomes in vitro and in vivo. Natural and synthetic bone grafts combined with Mesenchymal Stromal Cells (MSCs) and growth factors have shown encouraging results in regenerating critical-size cranial defects. One of prevalent growth factors is Bone Morphogenetic Protein-2 (BMP-2). BMP-2 is defined as a gold standard growth factor that enhances new bone formation in vitro and in vivo. Recently, emerging evidence suggested that Megakaryocytes (MKs), induced by Thrombopoietin (TPO), show an increase in osteoblast proliferation in vitro and bone mass in vivo. Furthermore, a co-culture study shows mature MKs enhance MSC survival rate while maintaining their phenotype. Therefore, MKs can provide an insight as a potential therapy offering a safe and effective approach to regenerating critical-size cranial defects.

Myocardial and mitochondrial effects of the anhydrase carbonic inhibitor ethoxzolamide in ischemia-reperfusion

We have previously demonstrated that inhibition of extracellularly oriented carbonic anhydrase (CA) isoforms protects the myocardium against ischemia-reperfusion injury. In this study, our aim was to assess the possible further contribution of CA intracellular isoforms examining the actions of the highly diffusible cell membrane permeant inhibitor of CA, ethoxzolamide (ETZ). Isolated rat hearts, after 20 min of stabilization, were assigned to the following groups: (1) Nonischemic control: 90 min of perfusion; (2) Ischemic control: 30 min of global ischemia and 60 min of reperfusion (R); and (3) ETZ: ETZ at a concentration of 100 μM was administered for 10 min before the onset of ischemia and then during the first 10 min of reperfusion. In additional groups, ETZ was administered in the presence of SB202190 (SB, a p38MAPK inhibitor) or chelerythrine (Chel, a protein kinase C [PKC] inhibitor). Infarct size, myocardial function, and the expression of phosphorylated forms of p38MAPK, PKCε, HSP27, and Drp1, and calcineurin Aβ content were assessed. In isolated mitochondria, the Ca2+ response, Ca2+ retention capacity, and membrane potential were measured. ETZ decreased infarct size by 60%, improved postischemic recovery of myocardial contractile and diastolic relaxation increased P-p38MAPK, P-PKCε, P-HSP27, and P-Drp1 expression, decreased calcineurin content, and normalized calcium and membrane potential parameters measured in isolated mitochondria. These effects were significantly attenuated when ETZ was administered in the presence of SB or Chel. These data show that ETZ protects the myocardium and mitochondria against ischemia-reperfusion injury through p38MAPK- and PKCε-dependent pathways and reinforces the role of CA as a possible target in the management of acute cardiac ischemic diseases.

peri-Adventitial delivery of smooth muscle cells in porous collagen scaffolds for treatment of experimental abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is associated with the loss of vascular smooth muscle cells (SMCs) within the vessel wall. Direct delivery of therapeutic cells is challenging due to impaired mechanical integrity of the vessel wall. We hypothesized that porous collagen scaffolds can be an effective vehicle for the delivery of human-derived SMCs to the site of AAA. The purpose was to evaluate if the delivery of cell-seeded scaffolds can abrogate progressive expansion in a mouse model of AAA. Collagen scaffolds seeded with either primary human aortic SMCs or induced pluripotent stem cell derived-smooth muscle progenitor cells (iPSC-SMPs) had >80% in vitro cell viability and >75% cell penetrance through the scaffold's depth, while preserving smooth muscle phenotype. The cell-seeded scaffolds were successfully transplanted onto the murine aneurysm peri-adventitia on day 7 following AAA induction using pancreatic porcine elastase infusion. Ultrasound imaging revealed that SMC-seeded scaffolds significantly reduced the aortic diameter by 28 days, compared to scaffolds seeded with iPSC-SMPs or without cells (acellular scaffold), respectively. Bioluminescence imaging demonstrated that both cell-seeded scaffold groups had cellular localization to the aneurysm but a decline in survival with time. Histological analysis revealed that both cell-seeded scaffold groups had more SMC retention and less macrophage invasion into the medial layer of AAA lesions, when compared to the acellular scaffold treatment group. Our data suggest that scaffold-based SMC delivery is feasible and may constitute a platform for cell-based AAA therapy.

Immunoengineering the next generation of arthritis therapies

Immunoengineering continues to revolutionize healthcare, generating new approaches for treating previously intractable diseases, particularly in regard to cancer immunotherapy. In joint diseases, such as osteoarthritis (OA) and rheumatoid arthritis (RA), biomaterials and anti-cytokine treatments have previously been at that forefront of therapeutic innovation. However, while many of the existing anti-cytokine treatments are successful for a subset of patients, these treatments can also pose severe risks, adverse events and off-target effects due to continuous delivery at high dosages or a lack of disease-specific targets. The inadequacy of these current treatments has motivated the development of new immunoengineering strategies that offer safer and more efficacious alternative therapies through the precise and controlled targeting of specific upstream immune responses, including direct and mechanistically-driven immunoengineering approaches. Advances in the understanding of the immunomodulatory pathways involved in musculoskeletal disease, in combination with the growing emphasis on personalized medicine, stress the need for carefully considering the delivery strategies and therapeutic targets when designing therapeutics to better treat RA and OA. Here, we focus on recent advances in biomaterial and cell-based immunomodulation, in combination with genetic engineering, for therapeutic applications in joint diseases. The application of immunoengineering principles to the study of joint disease will not only help to elucidate the mechanisms of disease pathogenesis but will also generate novel disease-specific therapeutics by harnessing cellular and biomaterial responses. STATEMENT OF SIGNIFICANCE: It is now apparent that joint diseases such as osteoarthritis and rheumatoid arthritis involve the immune system at both local (i.e., within the joint) and systemic levels. In this regard, targeting the immune system using both biomaterial-based or cellular approaches may generate new joint-specific treatment strategies that are well-controlled, safe, and efficacious. In this review, we focus on recent advances in immunoengineering that leverage biomaterials and/or genetically engineered cells for therapeutic applications in joint diseases. The application of such approaches, especially synergistic strategies that target multiple immunoregulatory pathways, has the potential to revolutionize our understanding, treatment, and prevention of joint diseases.

Preconditioned Mesenchymal Stromal Cells to Improve Allotransplantation Outcome

Mesenchymal stromal cells (MSCs) are tissue-derived progenitor cells with immunomodulatory as well as multilineage differentiation capacities, and have been widely applied as cellular therapeutics in different disease systems in both preclinical models and clinical studies. Although many studies have applied MSCs in different types of allotransplantation, the efficacy varies. It has been demonstrated that preconditioning MSCs prior to in vivo administration may enhance their efficacy. In the field of organ/tissue allotransplantation, many recent studies have shown that preconditioning of MSCs with (1) pretreatment with bioactive factors or reagents such as cytokines, or (2) specific gene transfection, could prolong allotransplant survival and improve allotransplant function. Herein, we review these preconditioning strategies and discuss potential directions for further improvement.

Immune-modulatory alginate protects mesenchymal stem cells for sustained delivery of reparative factors to ischemic myocardium

Paracrine factors secreted by mesenchymal stem cells (MSCs) have been previously shown to improve cardiac function following acute myocardial infarction (MI). However, cell therapy activates the innate immune response, leading to the rapid elimination of transplanted cells and only short-term therapeutic delivery. Herein, we describe a new strategy to deliver sustained paracrine-mediated MSC therapy to ischemic myocardium. Using an immune evasive, small molecule modified alginate, we encapsulated rat MSC cells in a core-shell hydrogel capsule and implanted them in the pericardial sac of post-MI rats. Encapsulated cells allowed diffusion of reparative paracrine factors at levels similar to non-encapsulated cells in vitro. Encapsulation enabled sustained cell survival with localization over the heart for 2 weeks. The effect of the experimental group on ventricular function and fibrosis was compared with blank (cell free) capsules and unencapsulated MSCs injected into infarcted myocardium. MSC capsules improved post-MI ventricular function ∼2.5× greater than MSC injection. After 4 weeks, post-MI fibrosis was reduced ∼2/3 with MSC capsules, but unchanged with MSC injection. MSC encapsulation with alginate core-shell capsules sustains cell survival and potentiates efficacy of therapy.

Optimization of oxidative stress for mesenchymal stromal/stem cell engraftment, function and longevity

Mesenchymal stromal/stem cells (MSCs) are multipotent cells that possess great potential as a cellular therapeutic based on their ability to differentiate to different lineages and to modulate immune responses. However, their potential is limited by their low tissue abundance, and thus the need for robust ex vivo expansion prior to their application. This creates its own issues, namely replicative senescence, which could lead to reduced MSC functionality and negatively impact their engraftment. Ex vivo expansion and MSC aging are associated with greater oxidative stress. Therefore, there is great need to identify strategies to reduce oxidative stress in MSCs. This review summarizes the achievements made to date in addressing oxidative stress in MSCs and speculates about interesting avenues of future investigation to solve this critical problem.

Mesenchymal Stem Cell Transplantation for Ischemic Diseases: Mechanisms and Challenges

Ischemic diseases are conditions associated with the restriction or blockage of blood supply to specific tissues. These conditions can cause moderate to severe complications in patients, and can lead to permanent disabilities. Since they are blood vessel-related diseases, ischemic diseases are usually treated with endothelial cells or endothelial progenitor cells that can regenerate new blood vessels. However, in recent years, mesenchymal stem cells (MSCs) have shown potent bioeffects on angiogenesis, thus playing a role in blood regeneration. Indeed, MSCs can trigger angiogenesis at ischemic sites by several mechanisms related to their trans-differentiation potential. These mechanisms include inhibition of apoptosis, stimulation of angiogenesis via angiogenic growth factors, and regulation of immune responses, as well as regulation of scarring to suppress blood vessel regeneration when needed. However, preclinical and clinical trials of MSC transplantation in ischemic diseases have shown some limitations in terms of treatment efficacy. Such studies have emphasized the current challenges of MSC-based therapies. Treatment efficacy could be enhanced if the limitations were better understood and potentially resolved. This review will summarize some of the strategies by which MSCs have been utilized for ischemic disease treatment, and will highlight some challenges of those applications as well as suggesting some strategies to improve treatment efficacy.

Extracellular Vesicles Secreted by Mesenchymal Stromal Cells Exert Opposite Effects to Their Cells of Origin in Murine Sodium Dextran Sulfate-Induced Colitis

Several reports have described a beneficial effect of Mesenchymal Stromal Cells (MSCs) and of their secreted extracellular vesicles (EVs) in mice with experimental colitis. However, the effects of the two treatments have not been thoroughly compared in this model. Here, we compared the effects of MSCs and of MSC-EV administration in mice with colitis induced by dextran sulfate sodium (DSS). Since cytokine conditioning was reported to enhance the immune modulatory activity of MSCs, the cells were kept either under standard culture conditions (naïve, nMSCs) or primed with a cocktail of pro-inflammatory cytokines, including IL1β, IL6 and TNFα (induced, iMSCs). In our experimental conditions, nMSCs and iMSCs administration resulted in both clinical and histological worsening and was associated with pro-inflammatory polarization of intestinal macrophages. However, mice treated with iEVs showed clinico-pathological improvement, decreased intestinal fibrosis and angiogenesis and a striking increase in intestinal expression of Mucin 5ac, suggesting improved epithelial function. Moreover, treatment with iEVs resulted in the polarization of intestinal macrophages towards and anti-inflammatory phenotype and in an increased Treg/Teff ratio at the level of the intestinal lymph node. Collectively, these data confirm that MSCs can behave either as anti- or as pro-inflammatory agents depending on the host environment. In contrast, EVs showed a beneficial effect, suggesting a more predictable behavior, a safer therapeutic profile and a higher therapeutic efficacy with respect to their cells of origin.

Engineered cell-degradable poly(2-alkyl-2-oxazoline) hydrogel for epicardial placement of mesenchymal stem cells for myocardial repair

Epicardial placement of mesenchymal stromal cells (MSCs) is a promising strategy for cardiac repair post-myocardial infarction, but requires the design of biomaterials to maximise the retention of donor cells on the heart surface and control their phenotype. To this end, we propose the use of a poly(2-alkyl-2-oxazoline) (POx) derivative, based on 2-ethyl-2-oxazoline and 2-butenyl-2-oxazoline. This POx polymer can be cured rapidly (less than 2 min) via photo-irradiation due to the use of di-cysteine cell degradable peptides. We report that the cell-degradable properties of the resulting POx hydrogels enables the regulation of cell protrusion in corresponding 3D matrices and that this, in turn, regulates the secretory phenotype of MSCs. In particular, the expression of pro-angiogenic genes was upregulated in partially cell-degradable POx hydrogels. Improved angiogenesis was confirmed in an in vitro microfluidic assay. Finally, we confirmed that, owing to the excellent tissue adhesive properties of thiol-ene crosslinked hydrogels, the epicardial placement of MSC-loaded POx hydrogels promoted the recovery of cardiac function and structure with reduced interstitial fibrosis and improved neovascular formation in a rat myocardial infarction model. This report demonstrates that engineered synthetic hydrogels displaying controlled mechanical, cell degradable and bioactive properties are particularly attractive candidates for the epicardial placement of stem cells to promote cardiac repair post myocardial infarction.

Regulation of cardiomyocyte fate plasticity: a key strategy for cardiac regeneration

With the high morbidity and mortality rates, cardiovascular diseases have become one of the most concerning diseases worldwide. The heart of adult mammals can hardly regenerate naturally after injury because adult cardiomyocytes have already exited the cell cycle, which subseqently triggers cardiac remodeling and heart failure. Although a series of pharmacological treatments and surgical methods have been utilized to improve heart functions, they cannot replenish the massive loss of beating cardiomyocytes after injury. Here, we summarize the latest research progress in cardiac regeneration and heart repair through altering cardiomyocyte fate plasticity, which is emerging as an effective strategy to compensate for the loss of functional cardiomyocytes and improve the impaired heart functions. First, residual cardiomyocytes in damaged hearts re-enter the cell cycle to acquire the proliferative capacity by the modifications of cell cycle-related genes or regulation of growth-related signals. Additionally, non-cardiomyocytes such as cardiac fibroblasts, were shown to be reprogrammed into cardiomyocytes and thus favor the repair of damaged hearts. Moreover, pluripotent stem cells have been shown to transform into cardiomyocytes to promote heart healing after myocardial infarction (MI). Furthermore, in vitro and in vivo studies demonstrated that environmental oxygen, energy metabolism, extracellular factors, nerves, non-coding RNAs, etc. play the key regulatory functions in cardiac regeneration. These findings provide the theoretical basis of targeting cellular fate plasticity to induce cardiomyocyte proliferation or formation, and also provide the clues for stimulating heart repair after injury.

In vivo monitoring platform of transplanted human stem cells using magnetic resonance imaging

As stem cells show great promise in regenerative therapy, stem cell-mediated therapeutic efficacy must be demonstrated through the migration and transplantation of stem cells into target disease areas at the pre-clinical level. In this study, we developed manganese-based magnetic nanoparticles with hollow structures (MnOHo) and modified them with the anti-human integrin β1 antibody (MnOHo-Ab) to enable the minimal-invasive monitoring of transplanted human stem cells at the pre-clinical level. Compared to common magnetic resonance imaging (MRI)-based stem cell monitoring systems that use pre-labeled stem cells with magnetic particles before stem cell injection, the MnOHo-Ab is a new technology that does not require stem cell modification to monitor the therapeutic capability of stem cells. Additionally, MnOHo-Ab provides improved T1 MRI owing to the hollow structure of the MnOHo. Particularly, the anti-integrin β1 antibody (Ab) introduced in the MnOHo targets integrin β1 expressed in the entire stem cell lineage, enabling targeted monitoring regardless of the differentiation stage of the stem cells. Furthermore, we verified that intravenously injected MnOHo-Ab specifically targeted human induced pluripotent stem cells (hiPSCs) that were transferred to mice testes and differentiated into various lineages. The new stem cell monitoring method using MnOHo-Ab demonstrates whether the injected human stem cells have migrated and transplanted themselves in the target area during long-term stem cell regenerative therapy.

Toward Biological Pacing by Cellular Delivery of Hcn2/SkM1

Electronic pacemakers still face major shortcomings that are largely intrinsic to their hardware-based design. Radical improvements can potentially be generated by gene or cell therapy-based biological pacemakers. Our previous work identified adenoviral gene transfer of Hcn2 and SkM1, encoding a "funny current" and skeletal fast sodium current, respectively, as a potent combination to induce short-term biological pacing in dogs with atrioventricular block. To achieve long-term biological pacemaker activity, alternative delivery platforms need to be explored and optimized. The aim of the present study was therefore to investigate the functional delivery of Hcn2/SkM1 via human cardiomyocyte progenitor cells (CPCs). Nucleofection of Hcn2 and SkM1 in CPCs was optimized and gene transfer was determined for Hcn2 and SkM1 in vitro. The modified CPCs were analyzed using patch-clamp for validation and characterization of functional transgene expression. In addition, biophysical properties of Hcn2 and SkM1 were further investigated in lentivirally transduced CPCs by patch-clamp analysis. To compare both modification methods in vivo, CPCs were nucleofected or lentivirally transduced with GFP and injected in the left ventricle of male NOD-SCID mice. After 1 week, hearts were collected and analyzed for GFP expression and cell engraftment. Subsequent functional studies were carried out by computational modeling. Both nucleofection and lentiviral transduction of CPCs resulted in functional gene transfer of Hcn2 and SkM1 channels. However, lentiviral transduction was more efficient than nucleofection-mediated gene transfer and the virally transduced cells survived better in vivo. These data support future use of lentiviral transduction over nucleofection, concerning CPC-based cardiac gene delivery. Detailed patch-clamp studies revealed Hcn2 and Skm1 current kinetics within the range of previously reported values of other cell systems. Finally, computational modeling indicated that CPC-mediated delivery of Hcn2/SkM1 can generate stable pacemaker function in human ventricular myocytes. These modeling studies further illustrated that SkM1 plays an essential role in the final stage of diastolic depolarization, thereby enhancing biological pacemaker functioning delivered by Hcn2. Altogether these studies support further development of CPC-mediated delivery of Hcn2/SkM1 and functional testing in bradycardia models.

Allogeneic mesenchymal stem cell sheet therapy: A new frontier in drug delivery systems

The evolution of drug discovery exploded in the early 20th century with the advent of critical scientific advancements in organic chemistry, chemical analysis, and purification. Early drug generations focused largely on symptom control and pain management, effective targets for small-molecule drugs. Recently, the attention in drug discovery has shifted to pursuit of radical cures. Cell therapy presents the ideal attributes of a promising new drug, targeting specific tissues based on chemotactic cues and modulating secretion of instructive regenerative molecules in response to dynamic signaling from disease environments. To actuate the therapeutic potential of cell therapy toward worldwide clinical use, cell delivery methods that can effectively localize and engraft mesenchymal stem cells (MSCs) with high disease-site fidelity and enable dynamic MSC bioactive function are paramount. In this review, we discuss the evolution of cell therapies with a focus on stem cell advantages, as well as the limitations to these therapies. This review aims to introduce cell sheet technology as a breakthrough cell therapy with demonstrated therapeutic success across indications for heart, liver, and kidney tissue regeneration. Opportunities and anticipated clinical impacts of cell sheet technology using MSCs are discussed.

Conditioned medium harvested from Hif1α engineered mesenchymal stem cells ameliorates LAD-occlusion -induced injury in rat acute myocardial ischemia model

Acute myocardial infarction (AMI) is the most common type of ischemic heart diseases with a high mortality rate. Although recent advances in medical cares and therapies have increased the patient's outcomes, but, still there is no real and effective therapeutic modality for AMI. Hence, development of novel therapeutic strategies is under focus of investigations. MSCs-based therapy has been proposed for AMI, though its efficacy is controversial yet. It is believed that MSCs exert their healing effects via secretion of growth factors/cytokines. However, these cells produce a very minute amount of the factors under normal cultivation. Here, in an attempt to improve the potential therapeutic effect of MSCs-derived conditioned medium (CM) on AMI, we transfected the cells with a recombinant plasmid encoding Hif1α-3A (a mutant form of Hif1α stable under normoxic condition), so Hif1α expression and secretion into CM (MSCs-Hif1α-CM) could be up-regulated under normoxic condition. The therapeutic potential of the MSCs-Hif1α-3A-CM was investigated in a rat model of AMI and compared to the CM harvested from non-manipulated MSCs. Our results showed that the MSCs-Hif1α-3A-CM mitigated MI-induced tissues injury, decreased fibrosis, reduced apoptosis, and limited infarct area size. These findings propose a potential therapeutic strategy for treatment of AMI. However, further preclinical and clinical investigations in this regard are still needed.

The role of cells and their products in respiratory drug delivery: the past, present, and future

INTRODUCTION

Cell-based delivery systems offer considerable promise as novel and innovative therapeutics to target the respiratory system. These systems consist of cells and/or their extracellular vesicles that deliver their contents, such as anti-microbial peptides, micro RNAs, and even mitochondria to the lung, exerting direct therapeutic effects.

AREAS COVERED

The purpose of this article is to critically review the status of cell-based therapies in the delivery of therapeutics to the lung, evaluate current progress, and elucidate key challenges to the further development of these novel approaches. An overview as to how these cells and/or their products may be modified to enhance efficacy is given. More complex delivery cell-based systems, including cells or vesicles that are genetically modified to (over)express specific therapeutic products, such as proteins and therapeutic nucleic acids are also discussed. Focus is given to the use of the aerosol route to deliver these products directly into the lung.

EXPERT OPINION

The use of biological carriers to deliver chemical or biological agents demonstrates great potential in modern medicine. The next generation of drug delivery systems may comprise 'cell-inspired' drug carriers that are entirely synthetic, developed using insights from cell-based therapeutics to overcome limitations of current generation synthetic carriers.

Heat Shock Proteins and their Protective Roles in Stem Cell Biology

Stem cells (SCs) are discovered long back but the idea that SCs possess therapeutic potential came up just a few decades back. In a past decade stem cell therapy is highly emerged and displayed tremendous potential for the treatment of a wide range of diseases and disorders such as blindness and vision impairment, type I diabetes, infertility, HIV, etc. SCs are very susceptible to destruction after transplantation into the host because of the inability to sustain elevated stress conditions inside the damaged tissue/organ. Heat shock proteins (HSPs) are molecular chaperones/stress proteins expressed in response to stress (elevated temperature, harmful chemicals, ischemia, viruses, etc) inside a living cell. HSPs protect the cell from damage by assisting in the proper folding of cellular proteins. This review briefly summarises different types of HSPs, their classification, cellular functions as well as the role of HSPs in regulating SC self-renewal and survival in the transplanted host. Applications of HSP modulated SCs in regenerative medicine and for the treatment of ischemic heart disease, myocardial infarction (MI), osteoarthritis, ischemic stroke, spinocerebellar ataxia type 3 (SCA3), leukemia, hepatic ischemia-reperfusion injury, Graft-versus-host disease (GVHD) and Parkinson's disease (PD) are discussed. In order to provide potential insights in understanding molecular mechanisms related to SCs in vertebrates, correlations between HSPs and SCs in cnidarians and planarians are also reviewed. There is a need to advance research in order to validate the use of HSPs for SC therapy and establish effective treatment strategies.

Exosomes from SIRT1-Overexpressing ADSCs Restore Cardiac Function by Improving Angiogenic Function of EPCs

Acute myocardial infarction (AMI) is one of the leading causes of mortality in cardiovascular diseases. The aim of this study was to investigate whether exosomes from Sirtuin 1 (SIRT1)-overexpressing adipose-derived stem cells (ADSCs) had a protective effect on AMI. The expression of C-X-C chemokine receptor type 7 (CXCR7) was significantly downregulated in peripheral blood endothelial progenitor cells (EPCs) from AMI patients (AMI-EPCs) compared with that in healthy donors, which coincided with impaired tube formation. The exosomes from SIRT1 overexpression in ADSCs (ADSCs-SIRT1-Exos) increased the expression of C-X-C motif chemokine 12 (CXCL12) and nuclear factor E2 related factor 2 (Nrf2) in AMI-EPCs, which promoted migration and tube formation of AMI-EPCs, and overexpression of CXCR7 helped AMI-EPCs to restore the function of cell migration and tube formation. Moreover, CXCR7 was downregulated in the myocardium of AMI mice, and knockout of CXCR7 exacerbated AMI-induced impairment of cardiovascular function. Injection of ADSCs-SIRT1-Exos increased the survival and promoted the recovery of myocardial function with reduced infarct size and post-AMI left ventricular remodeling, induced vasculogenesis, and decreased AMI-induced myocardial inflammation. These findings showed that ADSCs-SIRT1-Exos may recruit EPCs to the repair area and that this recruitment may be mediated by Nrf2/CXCL12/CXCR7 signaling.

Exogenous Signaling Molecules Released from Aptamer-Functionalized Hydrogels Promote the Survival of Mesenchymal Stem Cell Spheroids

Mesenchymal stem cells (MSCs) have a very low survival rate after in vivo delivery, which limits their great promise for treating human diseases. Various strategies have been studied to overcome this challenge. However, an overlooked but important potential is to apply exogenous signaling molecules as biochemical cues to promote MSC survival, presumably because it is well-known that MSCs themselves can release a variety of potent signaling molecules. Thus, the purpose of this work was to examine and understand whether the release of exogenous signaling molecules from hydrogels can promote the survival of MSC spheroids. Our data show that more vascular endothelial growth factor (VEGF) but not platelet-derived growth factor BB (PDGF-BB) were released from MSC spheroids in comparison with 2D cultured MSCs. Aptamer-functionalized fibrin hydrogel (aFn) could release exogenous VEGF and PDGF-BB in a sustained manner. PDGF-BB-loaded aFn promoted MSC survival by ∼70% more than VEGF-loaded aFn under the hypoxic condition in vitro. Importantly, PDGF-BB-loaded aFn could double the survival rate of MSC spheroids in comparison with VEGF-loaded aFn during the one-week test in vivo. Therefore, this work demonstrated that defined exogenous signaling molecules (e.g., PDGF-BB) can function as biochemical cues for promoting the survival of MSC spheroids in vivo.

Overexpression of heat shock protein 70 enhanced mesenchymal stem cell treatment efficacy in phosgene-induced acute lung injury

In our previous study, we have confirmed that in phosgene-induced acute lung injury (ALI) rats, mesenchymal stem cells (MSCs) can treat the disease. Moreover, heat shock protein 70 (Hsp70) can be used as a protective protein, and Hsp70 upregulated drastically when exposed to stressful conditions. We aimed to assess that MSCs overexpressed Hsp70 could enhance the capacity of MSCs and have a good therapeutic effect on phosgene-induced ALI. We transduced MSCs with Hsp70 and then we tested the function of the transduced MSCs. Sprague Dawley rats inhaled phosgene in a closed container for 5 minutes. The transduced MSCs and MSCs were administered via the trachea immediately. Rats in each group were killed at 6, 24, and 48 hours after exposure. Compared to MSCs, MSCs overexpressed Hsp70 enhanced MSCs viability, antiapoptotic ability, and migration ability, and these effects disappeared when using the phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) pathway inhibitor. Furthermore, the results of pathological alterations improved. The lung wet-to-dry ratio declined. The lung injury index total protein content and total cells in bronchoalveolar lavage fluid (BALF) also declined. The level of tumor necrosis factor α declined and the level of interleukin-10 improved in BALF and serum. MSCs overexpressed Hsp70 can enhance the capacity and efficacy of MSCs in the treatment of phosgene-induced ALI and may be mediated through the PI3k/AKT signaling pathway. This article introduces a new approach to stem cell therapy for improving the efficacy of phosgene-induced ALI.

Novel Applications of Mesenchymal Stem Cell-derived Exosomes for Myocardial Infarction Therapeutics

Cardiovascular diseases (CVDs) are the leading cause of mortality and morbidity globally, representing approximately a third of all deaths every year. The greater part of these cases is represented by myocardial infarction (MI), or heart attack as it is better known, which occurs when declining blood flow to the heart causes injury to cardiac tissue. Mesenchymal stem cells (MSCs) are multipotent stem cells that represent a promising vector for cell therapies that aim to treat MI due to their potent regenerative effects. However, it remains unclear the extent to which MSC-based therapies are able to induce regeneration in the heart and even less clear the degree to which clinical outcomes could be improved. Exosomes, which are small extracellular vesicles (EVs) known to have implications in intracellular communication, derived from MSCs (MSC-Exos), have recently emerged as a novel cell-free vector that is capable of conferring cardio-protection and regeneration in target cardiac cells. In this review, we assess the current state of research of MSC-Exos in the context of MI. In particular, we place emphasis on the mechanisms of action by which MSC-Exos accomplish their therapeutic effects, along with commentary on the current difficulties faced with exosome research and the ongoing clinical applications of stem-cell derived exosomes in different medical contexts.

GARP is a key molecule for mesenchymal stromal cell responses to TGF-β and fundamental to control mitochondrial ROS levels

Multipotent mesenchymal stromal cells (MSCs) have emerged as a promising cell therapy in regenerative medicine and for autoimmune/inflammatory diseases. However, a main hurdle for MSCs-based therapies is the loss of their proliferative potential in vitro. Here we report that glycoprotein A repetitions predominant (GARP) is required for the proliferation and survival of adipose-derived MSCs (ASCs) via its regulation of transforming growth factor-β (TGF-β) activation. Silencing of GARP in human ASCs increased their activation of TGF-β which augmented the levels of mitochondrial reactive oxygen species (mtROS), resulting in DNA damage, a block in proliferation and apoptosis. Inhibition of TGF-β signaling reduced the levels of mtROS and DNA damage and restored the ability of GARP-/low ASCs to proliferate. In contrast, overexpression of GARP in ASCs increased their proliferative capacity and rendered them more resistant to etoposide-induced DNA damage and apoptosis, in a TGF-β-dependent manner. In summary, our data show that the presence or absence of GARP on ASCs gives rise to distinct TGF-β responses with diametrically opposing effects on ASC proliferation and survival.

Heat shock pretreatment improves mesenchymal stem cell viability by heat shock proteins and autophagy to prevent cisplatin-induced granulosa cell apoptosis

Background

Bone marrow mesenchymal stem cells (BMSCs) can partially repair chemotherapy-induced ovarian damage. However, low survival rate after transplantation hampers the therapeutic efficiency of BMSCs. Heat shock pretreatment (HSP) effectively improves the cell survival. This study attempted to investigate the mechanisms of HSP on BMSCs survival and the effects of heat shock-pretreated BMSCs (HS-MSCs) on cisplatin-induced granulosa cell (GC) apoptosis.

Methods

BMSCs were isolated, cultured, and identified. After receiving HSP for different duration times in a 42 °C water bath, the apoptotic rates of BMSCs were detected by Annexin V-FITC/PI to determine the optimal condition of HSP. Cisplatin was added to the medium of HS-MSCs to simulate chemotherapy environment. The proliferative curve, apoptotic rate, and viability of HS-MSCs were determined by CCK-8, Annexin V-FITC/PI, and Hoechst33342/PI respectively to explore the alteration of biological characteristics. The levels of heat shock protein 70 and 90 (HSP70 and HSP90) and the expressions of autophagy-related markers (Beclin1 and LC3B) were detected by Western blot. In addition, the autophagosomes were observed by transmission electronic microscopy to discuss the possible mechanisms. The GCs were isolated, cultured, and identified. The HS-MSCs were co-cultured with GCs before and after the addition of cisplatin. Then, the apoptotic rate and viability of GCs were detected to investigate the therapeutic and preventive effects of HS-MSCs on GC apoptosis.

Results

After receiving HSP at 42 °C for 1 h, BMSCs represented the lowest apoptotic rate. After the addition of cisplatin, the apoptotic rate of HS-MSCs (11.94% ± 0.63%) was lower than that of BMSCs (14.30% ± 0.80%) and the percentage of HS-MSCs expressing bright blue/dull red fluorescence was lower than that of BMSCs. The expression of HSP70 and HSP90 increased, while the number of autophagosomes, the expression of Beclin1, and the LC3BII/LC3BI ratio decreased in HS-MSCs. The apoptotic rates of GCs co-cultured with HS-MSCs before and after the addition of cisplatin were 39.88% ± 1.65% and 36.72% ± 0.96%, both lower than those of cisplatin-induced GCs (53.81% ± 1.89%).

Conclusion

HSP can alleviate the apoptosis and improve the survival of BMSCs under chemotherapy environment. The mechanism may be associated with the elevated expression of HSP70 and HSP90 and the attenuation of autophagy. Moreover, HS-MSCs have both therapeutic and preventive effects on cisplatin-induced GC apoptosis.

Understanding and leveraging cell metabolism to enhance mesenchymal stem cell transplantation survival in tissue engineering and regenerative medicine applications

In tissue engineering and regenerative medicine, stem cell-specifically, mesenchymal stromal/stem cells (MSCs)-therapies have fallen short of their initial promise and hype. The observed marginal, to no benefit, success in several applications has been attributed primarily to poor cell survival and engraftment at transplantation sites. MSCs have a metabolism that is flexible enough to enable them to fulfill their various cellular functions and remarkably sensitive to different cellular and environmental cues. At the transplantation sites, MSCs experience hostile environments devoid or, at the very least, severely depleted of oxygen and nutrients. The impact of this particular setting on MSC metabolism ultimately affects their survival and function. In order to develop the next generation of cell-delivery materials and methods, scientists must have a better understanding of the metabolic switches MSCs experience upon transplantation. By designing treatment strategies with cell metabolism in mind, scientists may improve survival and the overall therapeutic potential of MSCs. Here, we provide a comprehensive review of plausible metabolic switches in response to implantation and of the various strategies currently used to leverage MSC metabolism to improve stem cell-based therapeutics.

Mesenchymal Stem Cells in Homeostasis and Systemic Diseases: Hypothesis, Evidences, and Therapeutic Opportunities

Mesenchymal stem cells (MSCs) are present in all organs and tissues, playing a well-known function in tissue regeneration. However, there is also evidence indicating a broader role of MSCs in tissue homeostasis. In vivo studies have shown MSC paracrine mechanisms displaying proliferative, immunoregulatory, anti-oxidative, or angiogenic activity. In addition, recent studies also demonstrate that depletion and/or dysfunction of MSCs are associated with several systemic diseases, such as lupus, diabetes, psoriasis, and rheumatoid arthritis, as well as with aging and frailty syndrome. In this review, we hypothesize about the role of MSCs as keepers of tissue homeostasis as well as modulators in a variety of inflammatory and degenerative systemic diseases. This scenario opens the possibility for the use of secretome-derived products from MSCs as new therapeutic agents in order to restore tissue homeostasis, instead of the classical paradigm "one disease, one drug".

Systemically transplanted mesenchymal stem cells induce vascular-like structure formation in a rat model of vaginal injury

The beneficial effect of mesenchymal stem cells (MSCs) on wound healing is mostly attributed to a trophic effect that promotes angiogenesis. Whether MSCs can contribute to the formation of new blood vessels by direct differentiation is still controversial. Pelvic floor dysfunction (PFD) is a group of disorders that negatively affect the quality of women's lives. Traditional vaginal surgical repair provides disappointing anatomical outcome. Stem cell transplantation may be used to supplement surgery and improve its outcome. Here we aimed to examine the engraftment, survival, differentiation and angiogenic effect of transplanted MSCs in a vaginal injury rat model. MSCs were obtained from the bone marrow of Sprague Drawley (SD) rats, expanded and characterized in vitro. The MSCs expressed CD90 and CD29, did not express CD45, CD34, CD11b and CD31 and could differentiate into osteogenic, chondrogenic and adipogenic lineages. Cells were labeled with either PKH-26 or GFP and transplanted systemically or locally to female SD rats, just after a standardized vaginal incision was made. Engraftment after local transplantation was less efficient at all-time points compared to systemic administration. In the systemically transplanted animal group, MSCs migrated to the injury site and were present in the healed vagina for at least 30 days. Both systemic and local MSCs transplantation promoted host angiogenesis. Systemically transplanted MSCs created new vascular-like structures by direct differentiation into endothelium. These findings pave the way to further studies of the potential role of MSCs transplantation in improving surgical outcome in women with PFD.

Molecular and Functional Verification of Wharton's Jelly Mesenchymal Stem Cells (WJ-MSCs) Pluripotency

The properties of mesenchymal stem cells (MSCs), especially their self-renewal and ability to differentiate into different cell lines, are widely discussed. Considering the fact that MSCs isolated from perinatal tissues reveal higher differentiation capacity than most adult MSCs, we examined mesenchymal stem cells isolated from Wharton's jelly of umbilical cord (WJ-MSCs) in terms of pluripotency markers expression. Our studies showed that WJ-MSCs express some pluripotency markers-such as NANOG, OCT-4, and SSEA-4-but in comparison to iPS cells expression level is significantly lower. The level of expression can be raised under hypoxic conditions. Despite their high proliferation potential and ability to differentiate into different cells type, WJ-MSCs do not form tumors in vivo, the major caveat of iPS cells. Owing to their biological properties, high plasticity, proliferation capacity, and ease of isolation and culture, WJ-MSCs are turning out to be a promising tool of modern regenerative medicine.

Secretome of adipose-derived mesenchymal stem cells promotes skeletal muscle regeneration through synergistic action of extracellular vesicle cargo and soluble proteins

BACKGROUND

The mechanisms underpinning the regenerative capabilities of mesenchymal stem cells (MSC) were originally thought to reside in their ability to recognise damaged tissue and to differentiate into specific cell types that would replace defective cells. However, recent work has shown that molecules produced by MSCs (secretome), particularly those packaged in extracellular vesicles (EVs), rather than the cells themselves are responsible for tissue repair.

METHODS

Here we have produced a secretome from adipose-derived mesenchymal stem cells (ADSC) that is free of exogenous molecules by incubation within a saline solution. Various in vitro models were used to evaluate the effects of the secretome on cellular processes that promote tissue regeneration. A cardiotoxin-induced skeletal muscle injury model was used to test the regenerative effects of the whole secretome or isolated extracellular vesicle fraction in vivo. This was followed by bioinformatic analysis of the components of the protein and miRNA content of the secretome and finally compared to a secretome generated from a secondary stem cell source.

RESULTS

Here we have demonstrated that the secretome from adipose-derived mesenchymal stem cells shows robust effects on cellular processes that promote tissue regeneration. Furthermore, we show that the whole ADSC secretome is capable of enhancing the rate of skeletal muscle regeneration following acute damage. We assessed the efficacy of the total secretome compared with the extracellular vesicle fraction on a number of assays that inform on tissue regeneration and demonstrate that both fractions affect different aspects of the process in vitro and in vivo. Our in vitro, in vivo, and bioinformatic results show that factors that promote regeneration are distributed both within extracellular vesicles and the soluble fraction of the secretome.

CONCLUSIONS

Taken together, our study implies that extracellular vesicles and soluble molecules within ADSC secretome act in a synergistic manner to promote muscle generation.

Heat Shock Proteins: Protection and Potential Biomarkers for Ischemic Injury of Cardiomyocytes After Surgery

The heat shock proteins are endogenous proteins with the ability to act as molecular chaperones. Methods that provide cell protection by way of some damage can positively influence the results of surgery. The present review summarizes current knowledge concerning the cardioprotective role of the heat shock proteins as occurs in heart damage, including relevant information about the stresses that regulate the expression of these proteins and their potential role as biomarkers of heart disease.

Clinical Application of Stem/Stromal Cells in COPD

Chronic obstructive pulmonary disease (COPD) is a progressive life-threatening disease that is significantly increasing in prevalence and is predicted to become the third leading cause of death worldwide by 2030. At present, there are no true curative treatments that can stop the progression of the disease, and new therapeutic strategies are desperately needed. Advances in cell-based therapies provide a platform for the development of new therapeutic approaches in severe lung diseases such as COPD. At present, a lot of focus is on mesenchymal stem (stromal) cell (MSC)-based therapies, mainly due to their immunomodulatory properties. Despite increasing number of preclinical studies demonstrating that systemic MSC administration can prevent or treat experimental COPD and emphysema, clinical studies have not been able to reproduce the preclinical results and to date no efficacy or significantly improved lung function or quality of life has been observed in COPD patients. Importantly, the completed appropriately conducted clinical trials uniformly demonstrate that MSC treatment in COPD patients is well tolerated and no toxicities have been observed. All clinical trials performed so far, have been phase I/II studies, underpowered for the detection of potential efficacy. There are several challenges ahead for this field such as standardized isolation and culture procedures to obtain a cell product with high quality and reproducibility, administration strategies, improvement of methods to measure outcomes, and development of potency assays. Moreover, COPD is a complex pathology with a diverse spectrum of clinical phenotypes, and therefore it is essential to develop methods to select the subpopulation of patients that is most likely to potentially respond to MSC administration. In this chapter, we will discuss the current state of the art of MSC-based cell therapy for COPD and the hurdles that need to be overcome.

Role of interleukin-7 in fusion of rat bone marrow mesenchymal stem cells with cardiomyocytes in vitro and improvement of cardiac function in vivo

AIMS

Mesenchymal stem cells (MSCs) hold significant promise as potential therapeutic candidates following cardiac injury. However, to ensure survival of transplanted cells in ischemic environment, it is beneficial to precondition them with growth factors that play important role in cell survival and proliferation. Aim of this study is to use interleukin-7 (IL-7), a cell survival growth factor, to enhance the potential of rat bone marrow MSCs in terms of cell fusion in vitro and cardiac function in vivo.

METHODS

Mesenchymal stem cells were transfected with IL-7 gene through retroviral vector. Normal and transfected MSCs were co-cultured with neonatal cardiomyocytes (CMs) and cell fusion was analyzed by flow cytometry and fluorescence microscopy. These MSCs were also transplanted in rat model of myocardial infarction (MI) and changes at tissue level and cardiac function were assessed by histological analysis and echocardiography, respectively.

RESULTS

Co-culture of IL-7 transfected MSCs and CMs showed significantly higher (P < 0.01) number of fused cells as compared to normal MSCs. Histological analysis of hearts transplanted with IL-7 transfected MSCs showed significant reduction (P < 0.001) in infarct size and better preservation (P < 0.001) of left ventricular wall thickness as compared to normal MSCs. Presence of cardiac-specific proteins, α-actinin, and troponin-T showed that the transplanted MSCs were differentiated into cardiomyocytes. Echocardiographic recordings of the experimental group transplanted with transfected MSCs showed significant increase in the ejection fraction and fractional shortening (P < 0.01), and decrease in diastolic and systolic left ventricular internal diameters (P < 0.001) and end systolic and diastolic volumes (P < 0.01 and P < 0.001, respectively).

CONCLUSION

Interleukin-7 is able to enhance the fusogenic properties of MSCs and improve cardiac function. This improvement may be attributed to the supportive action of IL-7 on cell proliferation and cell survival contributing to the regeneration of damaged myocardium.

Functionally Improved Mesenchymal Stem Cells to Better Treat Myocardial Infarction

Myocardial infarction (MI) is one of the leading causes of death worldwide. Mesenchymal stem cell (MSC) transplantation is considered a promising approach and has made significant progress in preclinical studies and clinical trials for treating MI. However, hurdles including poor survival, retention, homing, and differentiation capacity largely limit the therapeutic effect of transplanted MSCs. Many strategies such as preconditioning, genetic modification, cotransplantation with bioactive factors, and tissue engineering were developed to improve the survival and function of MSCs. On the other hand, optimizing the hostile transplantation microenvironment of the host myocardium is also of importance. Here, we review the modifications of MSCs as well as the host myocardium to improve the efficacy of MSC-based therapy against MI.