Hepatocyte growth factor or vascular endothelial growth factor gene transfer maximizes mesenchymal stem cell-based myocardial salvage after acute myocardial infarction

The beneficial effects of mesenchymal stem cells and their exosomes on myocardial infarction and critical considerations for enhancing their efficacy

Mesenchymal stem cells (MSCs) are multipotent stromal cells with regenerative, anti-inflammatory, and immunomodulatory properties. MSCs and their exosomes significantly improved structural and functional alterations after myocardial infarction (MI) in preclinical studies and clinical trials. By reprograming intracellular signaling pathways, MSCs attenuate inflammatory response, oxidative stress, apoptosis, pyroptosis, and endoplasmic reticulum (ER) stress and improve angiogenesis, mitochondrial biogenesis, and myocardial remodeling after MI. MSC-derived exosomes contain a mixture of non-coding RNAs, growth factors, anti-inflammatory mediators, and anti-fibrotic factors. Although primary results from clinical trials were promising, greater efficacies can be achieved by controlling several modifiable factors. The optimum timing of transplantation, route of administration, origin of MSCs, number of doses, and number of cells per dose need to be further investigated by future studies. Newly, highly effective MSC delivery systems have been developed to improve the efficacy of MSCs and their exosomes. Moreover, MSCs can be more efficacious after being pretreated with non-coding RNAs, growth factors, anti-inflammatory or inflammatory mediators, and hypoxia. Similarly, viral vector-mediated overexpression of particular genes can augment the protective effects of MSCs on MI. Therefore, future clinical trials must consider these advances in preclinical studies to properly reflect the efficacy of MSCs or their exosomes for MI.

Metformin promotes angiogenesis by enhancing VEGFa secretion by adipose-derived stem cells via the autophagy pathway

Human adipose tissue-derived stem cell (ADSC) derivatives are cell-free, with low immunogenicity and no potential tumourigenicity, making them ideal for aiding wound healing. However, variable quality has impeded their clinical application. Metformin (MET) is a 5' adenosine monophosphate-activated protein kinase activator associated with autophagic activation. In this study, we assessed the potential applicability and underlying mechanisms of MET-treated ADSC derivatives in enhancing angiogenesis. We employed various scientific techniques to evaluate the influence of MET on ADSC, assess angiogenesis and autophagy in MET-treated ADSC in vitro, and examine whether MET-treated ADSC increase angiogenesis. We found that low MET concentrations exerted no appreciable effect on ADSC proliferation. However, MET was observed to enhance the angiogenic capacity and autophagy of ADSC. MET-induced autophagy was associated with increased vascular endothelial growth factor A production and release, which contributed to promoting the therapeutic efficacy of ADSC. In vivo experiments confirmed that in contrast to untreated ADSC, MET-treated ADSC promoted angiogenesis. Our findings thus indicate that the application of MET-treated ADSC would be an effective approach to accelerate wound healing by promoting angiogenesis at wound sites.

LPS preconditioning of MSC-CM improves protection against hypoxia/reoxygenation-induced damage in H9c2 cells partly via HMGB1/Bach1 signalling

Mesenchymal stem cell-derived conditioned medium (MSC-CM) improves cardiac function after myocardial infarction; however, this cardioprotective effect is moderate and transient. Lipopolysaccharide (LPS) pretreatment partially improves MSC-CM-mediated cardioprotective effects owing to the presence of paracrine factors. However, the mechanism underlying these improved effects remains unknown. To study the effect of LPS-pretreated MSC-CM on hypoxia/reoxygenation (H/R)-induced injury, MSCs were treated with or without LPS (400 ng/mL) for 48 h, and the supernatant was collected (MSC-CM). Subsequently, H9c2 cells were co-cultured with Nor-CM (CM derived from LPS-untreated MSCs) and LPS-CM (CM derived from LPS-pretreated MSCs) for 24 h and subjected to H/R. MSC-CM inhibited the progression of H/R-induced injury in H9c2 cells, and this protective effect was enhanced via LPS pretreatment as evidenced by the improved apoptosis assessment index (i.e. caspase-3 and B-cell lymphoma-2 [Bcl-2] expression) and decreased levels of lactic dehydrogenase (LDH) and cardiac troponin (cTn). In addition, the results of haematoxylin-eosin staining (H&E), transmission electron microscopy (TEM) and TdT-mediated dUTP nick-end labelling (TUNEL) validated that MSC-CM inhibited H/R-induced injury in H9c2 cardiomyocytes. LPS pretreatment downregulated the expression of high mobility group box-1 (HMGB1) and BTB and CNC homology-1 (Bach1) proteins in MSCs but upregulated the expression of vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF) and insulin-like growth factor (IGF). HMGB1 knockdown (MSC/siHMGB1-CM) significantly decreased the expression of Bach1 and increased the expression of VEGF, HGF and IGF. Bach1 knockdown (MSC/siBach1-CM) did not alter the production of HMGB1 but increased the expression of VEGF and IGF. LPS pretreatment did not alter the expression of the paracrine factors VEGF and HGF in the MSC/siHMGB1 group but increased their expression in the MSC/siBach1 group. The myocyte anti-apoptotic effects of MSCs/siBach1-CM were similar to those of untreated MSCs, which were not enhanced by LPS. LPS-pretreated MSC-CM protects H9c2 cells against H/R-induced injury partly through the HMGB1/Bach1 signalling pathway.

Effective treatment of intractable diseases using nanoparticles to interfere with vascular supply and angiogenic process

Angiogenesis is a vital biological process involving blood vessels forming from pre-existing vascular systems. This process contributes to various physiological activities, including embryonic development, hair growth, ovulation, menstruation, and the repair and regeneration of damaged tissue. On the other hand, it is essential in treating a wide range of pathological diseases, such as cardiovascular and ischemic diseases, rheumatoid arthritis, malignancies, ophthalmic and retinal diseases, and other chronic conditions. These diseases and disorders are frequently treated by regulating angiogenesis by utilizing a variety of pro-angiogenic or anti-angiogenic agents or molecules by stimulating or suppressing this complicated process, respectively. Nevertheless, many traditional angiogenic therapy techniques suffer from a lack of ability to achieve the intended therapeutic impact because of various constraints. These disadvantages include limited bioavailability, drug resistance, fast elimination, increased price, nonspecificity, and adverse effects. As a result, it is an excellent time for developing various pro- and anti-angiogenic substances that might circumvent the abovementioned restrictions, followed by their efficient use in treating disorders associated with angiogenesis. In recent years, significant progress has been made in different fields of medicine and biology, including therapeutic angiogenesis. Around the world, a multitude of research groups investigated several inorganic or organic nanoparticles (NPs) that had the potential to effectively modify the angiogenesis processes by either enhancing or suppressing the process. Many studies into the processes behind NP-mediated angiogenesis are well described. In this article, we also cover the application of NPs to encourage tissue vascularization as well as their angiogenic and anti-angiogenic effects in the treatment of several disorders, including bone regeneration, peripheral vascular disease, diabetic retinopathy, ischemic stroke, rheumatoid arthritis, post-ischemic cardiovascular injury, age-related macular degeneration, diabetic retinopathy, gene delivery-based angiogenic therapy, protein delivery-based angiogenic therapy, stem cell angiogenic therapy, and diabetic retinopathy, cancer that may benefit from the behavior of the nanostructures in the vascular system throughout the body. In addition, the accompanying difficulties and potential future applications of NPs in treating angiogenesis-related diseases and antiangiogenic therapies are discussed.

Mesenchymal Stromal Cells Overexpressing Farnesoid X Receptor Exert Cardioprotective Effects Against Acute Ischemic Heart Injury by Binding Endogenous Bile Acids

Bile acid metabolites have been increasingly recognized as pleiotropic signaling molecules that regulate cardiovascular functions, but their role in mesenchymal stromal cells (MSC)-based therapy has never been investigated. It is found that overexpression of farnesoid X receptor (FXR), a main receptor for bile acids, improves the retention and cardioprotection of adipose tissue-derived MSC (ADSC) administered by intramyocardial injection in mice with myocardial infarction (MI), which shows enhanced antiapoptotic, proangiogenic, and antifibrotic effects. RNA sequencing, LC-MS/MS, and loss-of-function studies reveal that FXR overexpression promotes ADSC paracrine angiogenesis via Angptl4. FXR overexpression improves ADSC survival in vivo but fails in vitro. By performing bile acid-targeted metabolomics using ischemic heart tissue, 19 bile acids are identified. Among them, cholic acid and deoxycholic acid significantly increase Angptl4 secretion from ADSC overexpressing FXR and further improve their proangiogenic capability. Moreover, ADSC overexpressing FXR shows significantly lower apoptosis by upregulating Nqo-1 expression only in the presence of FXR ligands. Retinoid X receptor α is identified as a coactivator of FXR. It is first demonstrated that there is a bile acid pool in the myocardial microenvironment. Targeting the bile acid-FXR axis may be a novel strategy for improving the curative effect of MSC-based therapy for MI.

Paracrine Factors Released by Stem Cells of Mesenchymal Origin and their Effects in Cardiovascular Disease: A Systematic Review of Pre-clinical Studies

Mesenchymal stem cell (MSC) therapy has gained significant traction in the context of cardiovascular repair, and have been proposed to exert their regenerative effects via the secretion of paracrine factors. In this systematic review, we examined the literature and consolidated available evidence for the “paracrine hypothesis”. Two Ovid SP databases were searched using a strategy encompassing paracrine mediated MSC therapy in the context of ischemic heart disease. This yielded 86 articles which met the selection criteria for inclusion in this study. We found that the MSCs utilized in these articles were primarily derived from bone marrow, cardiac tissue, and adipose tissue. We identified 234 individual protective factors across these studies, including VEGF, HGF, and FGF2; which are proposed to exert their effects in a paracrine manner. The data collated in this systematic review identifies secreted paracrine factors that could decrease apoptosis, and increase angiogenesis, cell proliferation, and cell viability. These included studies have also demonstrated that the administration of MSCs and indirectly, their secreted factors can reduce infarct size, and improve left ventricular ejection fraction, contractility, compliance, and vessel density. Furthering our understanding of the way these factors mediate repair could lead to the identification of therapeutic targets for cardiac regeneration.

Tongxinluo-pretreated mesenchymal stem cells facilitate cardiac repair via exosomal transfer of miR-146a-5p targeting IRAK1/NF-κB p65 pathway

Background

Bone marrow cells (BMCs), especially mesenchymal stem cells (MSCs), have shown attractive application prospects in acute myocardial infarction (AMI). However, the weak efficacy becomes their main limitation in clinical translation. Based on the anti-inflammation and anti-apoptosis effects of a Chinese medicine-Tongxinluo (TXL), we aimed to explore the effects of TXL-pretreated MSCs (MSCs^TXL) in enhancing cardiac repair and further investigated the underlying mechanism.

Methods

MSCs^TXL or MSCs and the derived exosomes (MSCs^TXL-exo or MSCs-exo) were collected and injected into the infarct zone of rat hearts. In vivo, the anti-apoptotic and anti-inflammation effects, and cardiac functional and histological recovery were evaluated. In vitro, the apoptosis was evaluated by western blotting and flow cytometry. miRNA sequencing was utilized to identify the significant differentially expressed miRNAs between MSCs^TXL-exo and MSCs-exo, and the miRNA mimics and inhibitors were applied to explore the specific mechanism.

Results

Compared to MSCs, MSCs^TXL enhanced cardiac repair with reduced cardiomyocytes apoptosis and inflammation at the early stage of AMI and significantly improved left ventricular ejection fraction (LVEF) with reduced infarct size in an exosome-dependent way. Similarly, MSCs^TXL-exo exerted superior therapeutic effects in anti-apoptosis and anti-inflammation, as well as improving LVEF and reducing infarct size compared to MSCs-exo. Further exosomal miRNA analysis demonstrated that miR-146a-5p was the candidate effector of the superior effects of MSCs^TXL-exo. Besides, miR-146a-5p targeted and decreased IRAK1, which inhibited the nuclear translocation of NF-κB p65 thus protecting H9C2 cells from hypoxia injury.

Conclusions

This study suggested that MSCs^TXL markedly facilitated cardiac repair via a new mechanism of the exosomal transfer of miR-146a-5p targeting IRAK1/NF-κB p65 pathway, which has great potential for clinical translation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02969-y.

Receptor tyrosine kinase inhibitors negatively impact on pro-reparative characteristics of human cardiac progenitor cells

Receptor tyrosine kinase inhibitors improve cancer survival but their cardiotoxicity requires investigation. We investigated these inhibitors’ effects on human cardiac progenitor cells in vitro and rat heart in vivo. We applied imatinib, sunitinib or sorafenib to human cardiac progenitor cells, assessing cell viability, proliferation, stemness, differentiation, growth factor production and second messengers. Alongside, sunitinib effects were assessed in vivo. Inhibitors decreased (p < 0.05) cell viability, at levels equivalent to ‘peak’ (24 h; imatinib: 91.5 ± 0.9%; sunitinib: 83.9 ± 1.8%; sorafenib: 75.0 ± 1.6%) and ‘trough’ (7 days; imatinib: 62.3 ± 6.2%; sunitinib: 86.2 ± 3.5%) clinical plasma levels, compared to control (100% viability). Reduced (p < 0.05) cell cycle activity was seen with imatinib (29.3 ± 4.3% cells in S/G2/M-phases; 50.3 ± 5.1% in control). Expression of PECAM-1, Nkx2.5, Wnt2, linked with cell differentiation, were decreased (p < 0.05) 2, 2 and 6-fold, respectively. Expression of HGF, p38 and Akt1 in cells was reduced (p < 0.05) by sunitinib. Second messenger (p38 and Akt1) blockade affected progenitor cell phenotype, reducing c-kit and growth factor (HGF, EGF) expression. Sunitinib for 9 days (40 mg/kg, i.p.) in adult rats reduced (p < 0.05) cardiac ejection fraction (68 ± 2% vs. baseline (83 ± 1%) and control (84 ± 4%)) and reduced progenitor cell numbers. Receptor tyrosine kinase inhibitors reduce cardiac progenitor cell survival, proliferation, differentiation and reparative growth factor expression.

MicroRNA-146a-5p-modified human umbilical cord mesenchymal stem cells enhance protection against diabetic nephropathy in rats through facilitating M2 macrophage polarization

Background

Diabetic nephropathy (DN) is a severe complication of diabetes mellitus and a common cause of end-stage renal disease (ESRD). Mesenchymal stem cells (MSCs) possess potent anti-inflammatory and immunomodulatory properties, which render them an attractive therapeutic tool for tissue damage and inflammation.

Methods

This study was designed to determine the protective effects and underlying mechanisms of human umbilical cord-derived MSCs (UC-MSCs) on streptozotocin-induced DN. Renal function and histological staining were used to evaluate kidney damage. RNA high-throughput sequencing on rat kidney and UCMSC-derived exosomes was used to identify the critical miRNAs. Co-cultivation of macrophage cell lines and UC-MSCs-derived conditional medium were used to assess the involvement of macrophage polarization signaling.

Results

UC-MSC administration significantly improved renal function, reduced the local and systemic inflammatory cytokine levels, and attenuated inflammatory cell infiltration into the kidney tissue in DN rats. Moreover, UC-MSCs shifted macrophage polarization from a pro-inflammatory M1 to an anti-inflammatory M2 phenotype. Mechanistically, miR-146a-5p was significantly downregulated and negatively correlated with renal injury in DN rats as determined through high-throughput RNA sequencing. Importantly, UC-MSCs-derived miR-146a-5p promoted M2 macrophage polarization by inhibiting tumor necrosis factor receptor-associated factor-6 (TRAF6)/signal transducer and activator of transcription (STAT1) signaling pathway. Furthermore, miR-146a-5p modification in UC-MSCs enhanced the efficacy of anti-inflammation and renal function improvement.

Conclusions

Collectively, our findings demonstrate that UC-MSCs-derived miR-146a-5p have the potential to restore renal function in DN rats through facilitating M2 macrophage polarization by targeting TRAF6. This would pave the way for the use of miRNA-modified cell therapy for kidney diseases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02855-7.

Sequential transplantation of exosomes and mesenchymal stem cells pretreated with a combination of hypoxia and Tongxinluo efficiently facilitates cardiac repair

Background

Bone marrow-derived mesenchymal stem cells (MSCs), which possess immunomodulatory characteristic, are promising candidates for the treatment of acute myocardial infarction (AMI). However, the low retention and survival rate of MSCs in the ischemic heart limit their therapeutic efficacy. Strategies either modifying MSCs or alleviating the inflammatory environment, which facilitates the recruitment and survival of the engrafted MSCs, may solve the problem. Thus, we aimed to explore the therapeutic efficacy of sequential transplantation of exosomes and combinatorial pretreated MSCs in the treatment of AMI.

Methods

Exosomes derived from MSCs were delivered to infarcted hearts through intramyocardial injection followed by the intravenous infusion of differentially pretreated MSCs on Day 3 post-AMI. Enzyme linked immunosorbent assay (ELISA) was performed to evaluate the inflammation level as well as the SDF-1 levels in the infarcted border zone of the heart. Echocardiography and histological analysis were performed to assess cardiac function, infarct size, collagen area and angiogenesis.

Results

Sequential transplantation of exosomes and the combinatorial pretreated MSCs significantly facilitated cardiac repair compared to AMI rats treated with exosomes alone. Notably, compared to the other three methods of cotransplantation, combinatorial pretreatment with hypoxia and Tongxinluo (TXL) markedly enhanced the CXCR4 level of MSCs and promoted recruitment, which resulted in better cardiac function, smaller infarct size and enhanced angiogenesis. We further demonstrated that exosomes effectively reduced apoptosis in MSCs in vitro.

Conclusion

Sequential delivery of exosomes and pretreated MSCs facilitated cardiac repair post-AMI, and combined pretreatment with hypoxia and TXL better enhanced the cardioprotective effects. This method provides new insight into the clinical translation of stem cell-based therapy for AMI.

Nanotechnology in cardiac stem cell therapy: cell modulation, imaging and gene delivery

The wide arena of applications opened by nanotechnology is multidimensional. It is already been proven that its prominence can continuously influence human life. The role of stem cells in curing degenerative diseases is another major area of research. Cardiovascular diseases are one of the major causes of death globally. Nanotechnology-assisted stem cell therapy could be used to tackle the challenges faced in the management of cardiovascular diseases. In spite of the positive indications and proven potential of stem cells to differentiate into cardiomyocytes for cardiac repair and regeneration during myocardial infarction, this therapeutic approach still remains in its infancy due to several factors such as non-specificity of injected cells, insignificant survival rate, and low cell retention. Attempts to improve stem cell therapy using nanoparticles have shown some interest among researchers. This review focuses on the major hurdles associated with cardiac stem cell therapy and the role of nanoparticles to overcome the major challenges in this field, including cell modulation, imaging, tracking and gene delivery.

This review summarizes the potential challenges present in cardiac stem cell therapy and the major role of nanotechnology to overcome these challenges including cell modulation, tracking and imaging of stem cells.

Chronic exposure to tramadol induces cardiac inflammation and endothelial dysfunction in mice

Tramadol is an opioid extensively used to treat moderate to severe pain; however, prolonged therapy is associated with several tissues damage. Chronic use of tramadol was linked to increased hospitalizations due to cardiovascular complications. Limited literature has described the effects of tramadol on the cardiovascular system, so we sought to investigate these actions and elucidate the underlying mechanisms. Mice received tramadol hydrochloride (40 mg/kg body weight) orally for 4 successive weeks. Oxidative stress, inflammation, and cardiac toxicity were assessed. In addition, eNOS expression was evaluated. Our results demonstrated marked histopathological alteration in heart and aortic tissues after exposure to tramadol. Tramadol upregulated the expression of oxidative stress and inflammatory markers in mice heart and aorta, whereas downregulated eNOS expression. Tramadol caused cardiac damage shown by the increase in LDH, Troponin I, and CK-MB activities in serum samples. Overall, these results highlight the risks of tramadol on the cardiovascular system.

Emerging Applications of Nanotechnology in Healthcare Systems: Grand Challenges and Perspectives

Healthcare, as a basic human right, has often become the focus of the development of innovative technologies. Technological progress has significantly contributed to the provision of high-quality, on-time, acceptable, and affordable healthcare. Advancements in nanoscience have led to the emergence of a new generation of nanostructures. Each of them has a unique set of properties that account for their astonishing applications. Since its inception, nanotechnology has continuously affected healthcare and has exerted a tremendous influence on its transformation, contributing to better outcomes. In the last two decades, the world has seen nanotechnology taking steps towards its omnipresence and the process has been accelerated by extensive research in various healthcare sectors. The inclusion of nanotechnology and its allied nanocarriers/nanosystems in medicine is known as nanomedicine, a field that has brought about numerous benefits in disease prevention, diagnosis, and treatment. Various nanosystems have been found to be better candidates for theranostic purposes, in contrast to conventional ones. This review paper will shed light on medically significant nanosystems, as well as their applications and limitations in areas such as gene therapy, targeted drug delivery, and in the treatment of cancer and various genetic diseases. Although nanotechnology holds immense potential, it is yet to be exploited. More efforts need to be directed to overcome these limitations and make full use of its potential in order to revolutionize the healthcare sector in near future.

Hypoimmune induced pluripotent stem cell-derived cell therapeutics treat cardiovascular and pulmonary diseases in immunocompetent allogeneic mice

The emerging field of regenerative cell therapy is still limited by the few cell types that can reliably be differentiated from pluripotent stem cells and by the immune hurdle of commercially scalable allogeneic cell therapeutics. Here, we show that gene-edited, immune-evasive cell grafts can survive and successfully treat diseases in immunocompetent, fully allogeneic recipients. Transplanted endothelial cells improved perfusion and increased the likelihood of limb preservation in mice with critical limb ischemia. Endothelial cell grafts transduced to express a transgene for alpha1-antitrypsin (A1AT) successfully restored physiologic A1AT serum levels in mice with genetic A1AT deficiency. This cell therapy prevented both structural and functional changes of emphysematous lung disease. A mixture of endothelial cells and cardiomyocytes was injected into infarcted mouse hearts, and both cell types orthotopically engrafted in the ischemic areas. Cell therapy led to an improvement in invasive hemodynamic heart failure parameters. Our study supports the development of hypoimmune, universal regenerative cell therapeutics for cost-effective treatments of major diseases.

hAECs and their exosomes improve cardiac function after acute myocardial infarction in rats

BACKGROUND

Human amniotic epithelial cells (hAECs) are seed cells used to treat acute myocardial infarction (AMI), but their mechanism remains unclear.

METHODS

We cultured hAECs and extracted exosomes from culture supernatants. Next, we established a stable AMI model in rats and treated them with hAECs, exosomes, or PBS. We assess cardiac function after treatment by echocardiography. Additionally, heart tissues were collected and analyzed by Masson's trichrome staining. We conducted the tube formation and apoptosis assays to explore the potential mechanisms.

RESULTS

Cardiac function was improved, and tissue fibrosis was decreased following implantation of hAECs and their exosomes. Echocardiography showed that the EF and FS were lower in the control group than in the hAEC and exosome groups, and that the LVEDD and LVESD were higher in the control group (P<0.05). Masson's trichrome staining showed that the fibrotic area was larger in the control group. Tube formation was more efficient in the hAEC and exosome groups (P<0.0001). Additionally, the apoptosis rates of myocardial cells in the hAEC and exosome groups were significantly decreased (P<0.0001).

CONCLUSIONS

hAECs and their exosomes improved the cardiac function of rats after AMI by promoting angiogenesis and reducing the apoptosis of cardiac myocytes.

Consistent Long-Term Therapeutic Efficacy of Human Umbilical Cord Matrix-Derived Mesenchymal Stromal Cells After Myocardial Infarction Despite Individual Differences and Transient Engraftment

Human mesenchymal stem cells gather special interest as a universal and feasible add-on therapy for myocardial infarction (MI). In particular, human umbilical cord matrix-derived mesenchymal stromal cells (UCM-MSC) are advantageous since can be easily obtained and display high expansion potential. Using isolation protocols compliant with cell therapy, we previously showed UCM-MSC preserved cardiac function and attenuated remodeling 2 weeks after MI. In this study, UCM-MSC from two umbilical cords, UC-A and UC-B, were transplanted in a murine MI model to investigate consistency and durability of the therapeutic benefits. Both cellular products improved cardiac function and limited adverse cardiac remodeling 12 weeks post-ischemic injury, supporting sustained and long-term beneficial therapeutic effect. Donor associated variability was found in the modulation of cardiac remodeling and activation of the Akt-mTOR-GSK3β survival pathway. In vitro, the two cell products displayed similar ability to induce the formation of vessel-like structures and comparable transcriptome in normoxia and hypoxia, apart from UCM-MSCs proliferation and expression differences in a small subset of genes associated with MHC Class I. These findings support that UCM-MSC are strong candidates to assist the treatment of MI whilst calling for the discussion on methodologies to characterize and select best performing UCM-MSC before clinical application.

Hypoxic Preconditioning Enhances Cellular Viability and Pro-angiogenic Paracrine Activity: The Roles of VEGF-A and SDF-1a in Rat Adipose Stem Cells

To achieve the full therapeutic potential of implanted adipose stem cells (ASCs) in vivo, it is crucial to improve the viability and pro-angiogenic properties of the stem cells. Here, we first simulated the conditions of ischemia and hypoxia using the in vitro oxygen-glucose deprivation (OGD) model and confirmed that hypoxic preconditioning of ASCs could provide improved protection against OGD and enhance ASC viability. Second, we assessed the effect of hypoxic preconditioning on pro-angiogenic potential of ASCs, with a particular focus on the role of vascular endothelial growth factor-A (VEGF-A) and stromal derived factor-1a (SDF-1a) paracrine activity in mediating angiogenesis. We found that the conditioned medium of ASCs (ASC^CM) with hypoxic preconditioning enhanced angiogenesis by a series of angiogenesis assay models in vivo and in vitro through the upregulation of and a synergistic effect between VEGF-A and SDF-1a. Finally, to investigate the possible downstream mechanisms of VEGF/VEGFR2 and SDF-1a/CXCR4 axes-driven angiogenesis, we evaluated relevant protein kinases involved the signal transduction pathway of angiogenesis and showed that VEGF/VEGFR2 and SDF-1a/CXCR4 axes may synergistically promote angiogenesis by activating Akt. Collectively, our findings demonstrate that hypoxic preconditioning may constitute a promising strategy to enhance cellular viability and angiogenesis of transplanted ASCs, therein improving the success rate of stem cell-based therapies in tissue engineering.

Transplantation of mesenchymal stem cells preserves podocyte homeostasis through modulation of parietal epithelial cell activation in adriamycin-induced mouse kidney injury model

To determine the role of the transplantation of bone marrow-derived mesenchymal stem cells (MSCs) in podocyte renewal, we studied BALB/C mice with or without adriamycin-induced acute kidney injury. MSCs were transplanted ectopically under the capsule of the left kidney or into the peritoneal cavity after the onset of kidney injury to test testing their local or systemic paracrine effects, respectively. Adriamycin produced increases in urine protein: creatinine ratios, blood urea nitrogen, and blood pressure, which improved after both renal subcapsular and intraperitoneal MSCs transplants. The histological changes of adriamycin kidney changes regressed in both kidneys and in only the ipsilateral kidney after intraperitoneal or renal subcapsular transplants indicating that the benefits of transplanted MSCs were related to the extent of paracrine factor distribution. Analysis of kidney tissues for p57-positive parietal epithelial cells (PECs) showed that MSC transplants restored adriamycin-induced decreases in the abundance of these cells to normal levels, although after renal subcapsular transplants these changes did not extend to contralateral kidneys. Moreover, adriamycin caused inflammatory activation of PECs with coexpression of CD44 and phospho-ERK, which was normalized in both or only ipsilateral kidneys depending on whether MSCs were transplanted in the peritoneal cavity or subcapsular space, respectively.

MicroRNA-206 antagomiR‒enriched extracellular vesicles attenuate lung ischemia‒reperfusion injury through CXCL1 regulation in alveolar epithelial cells

BACKGROUND

Our hypothesis is that the immunomodulatory capacities of mesenchymal stem cell‒derived extracellular vesicles (EVs) can be enhanced by specific microRNAs (miRNAs) to effectively attenuate post-transplant lung ischemia‒reperfusion (IR) injury.

METHODS

The expression of miR-206 was analyzed in bronchoalveolar lavage (BAL) fluid of patients on Days 0 and 1 after lung transplantation. Lung IR injury was evaluated in C57BL/6 mice using a left lung hilar-ligation model with or without treatment with EVs or antagomiR-206‒enriched EVs. Murine lung tissue was used for miRNA microarray hybridization analysis, and cytokine expression, lung injury, and edema were evaluated. A donation after circulatory death and murine orthotopic lung transplantation model was used to evaluate the protection by enriched EVs against lung IR injury. In vitro studies analyzed type II epithelial cell activation after coculturing with EVs.

RESULTS

A significant upregulation of miR-206 was observed in the BAL fluid of patients on Day 1 after lung transplantation compared with Day 0 and in murine lungs after IR injury compared with sham. Treatment with antagomiR-206‒enriched EVs attenuated lung dysfunction, injury, and edema compared with treatment with EVs alone after murine lung IR injury. Enriched EVs reduced lung injury and neutrophil infiltration as well as improved allograft oxygenation after murine orthotopic lung transplantation. Enriched EVs significantly decreased proinflammatory cytokines, especially epithelial cell‒dependent CXCL1 expression, in the in vivo and in vitro IR injury models.

CONCLUSIONS

EVs can be used as biomimetic nanovehicles for protective immunomodulation by enriching them with antagomiR-206 to mitigate epithelial cell activation and neutrophil infiltration in the lungs after IR injury.

The Roles of Nanoparticles in Stem Cell-Based Therapy for Cardiovascular Disease

Cardiovascular disease (CVD) is currently one of the primary causes of mortality and morbidity worldwide. Nanoparticles (NPs) are playing increasingly important roles in regulating stem cell behavior because of their special features, including shape, size, aspect ratio, surface charge, and surface area. In terms of cardiac disease, NPs can facilitate gene delivery in stem cells, track the stem cells in vivo for long-term monitoring, and enhance retention after their transplantation. The advantages of applying NPs in peripheral vascular disease treatments include facilitating stem cell therapy, mimicking the extracellular matrix environment, and utilizing a safe non-viral gene delivery tool. However, the main limitation of NPs is toxicity, which is related to their size, shape, aspect ratio, and surface charge. Currently, there have been many animal models proving NPs’ potential in treating CVD, but no extensive applications of stem-cell therapy using NPs are available in clinical practice. In conclusion, NPs might have significant potential uses in clinical trials of CVD in the future, thereby meeting the changing needs of individual patients worldwide.

Hydrogel-Based Localized Nonviral Gene Delivery in Regenerative Medicine Approaches-An Overview

Hydrogel-based nonviral gene delivery constitutes a powerful strategy in various regenerative medicine scenarios, as those concerning the treatment of musculoskeletal, cardiovascular, or neural tissues disorders as well as wound healing. By a minimally invasive administration, these systems can provide a spatially and temporarily defined supply of specific gene sequences into the target tissue cells that are overexpressing or silencing the original gene, which can promote natural repairing mechanisms to achieve the desired effect. In the present work, we provide an overview of the most avant-garde approaches using various hydrogels systems for controlled delivery of therapeutic nucleic acid molecules in different regenerative medicine approaches.

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.

Mechanical Cues Regulating Proangiogenic Potential of Human Mesenchymal Stem Cells through YAP-Mediated Mechanosensing

Stem cells secrete trophic factors that induce angiogenesis. These soluble factors are promising candidates for stem cell-based therapies, especially for cardiovascular diseases. Mechanical stimuli and biophysical factors presented in the stem cell microenvironment play important roles in guiding their behaviors. However, the complex interplay and precise role of these cues in directing pro-angiogenic signaling remain unclear. Here, a platform is designed using gelatin methacryloyl hydrogels with tunable rigidity and a dynamic mechanical compression bioreactor to evaluate the influence of matrix rigidity and mechanical stimuli on the secretion of pro-angiogenic factors from human mesenchymal stem cells (hMSCs). Cells cultured in matrices mimicking mechanical elasticity of bone tissues in vivo show elevated secretion of vascular endothelial growth factor (VEGF), one of representative signaling proteins promoting angiogenesis, as well as increased vascularization of human umbilical vein endothelial cells (HUVECs) with a supplement of conditioned media from hMSCs cultured across different conditions. When hMSCs are cultured in matrices stimulated with a range of cyclic compressions, increased VEGF secretion is observed with increasing mechanical strains, which is also in line with the enhanced tubulogenesis of HUVECs. Moreover, it is demonstrated that matrix stiffness and cyclic compression modulate secretion of pro-angiogenic molecules from hMSCs through yes-associated protein activity.

Long-noncoding RNA MALAT1 sponges microRNA-92a-3p to inhibit doxorubicin-induced cardiac senescence by targeting ATG4a

The clinical application of doxorubicin (Dox) is limited due to its undesirable cardiotoxicity side effects. Cellular senescence plays an important role in Dox-induced cardiotoxicity. Exosomes derived from stem cells showed a therapeutic effect in Dox-induced cardiomyopathy (DIC). Hypoxia-preconditioned exosomes (exosome^Hypoxia) display pro-metabolism and pro-survival abilities. Several long-noncoding RNAs/microRNAs act as competing endogenous RNAs (ceRNAs) modulating DIC. No study investigated whether exosome^Hypoxia could attenuate DIC through modulating ceRNAs.Treatment of the human adipose-derived mesenchymal stem cells with hypoxia induced lncRNA-MALAT1 accumulation in the secreted exosomes. In addition, the lncRNA-MALAT1 was identified as an exosomal transfer RNA to repress miR-92a-3p expression. Silencing the lncRNA-MALAT1 in MSCs or miR-92a-3p overexpression in cardiomyocytes significantly impaired the rejuvenation induced by exosome^Hypoxia. TargetScan and luciferase assay showed that miR-92a-3p targeted the ATG4a 3' untranslated region. Silencing ATG4a blocked the anti-senescent effect of exosome^Hypoxia.This study identified the lncRNA-MALAT1 that functioned as ceRNA binding to miR-92a-3p, leading to ATG4a activation, thus improving mitochondrial metabolism. LncRNA-MALAT1/miR-92a-3p/ATG4a partially mediates the cardioprotective roles of exosome^Hypoxia in Dox-induced cardiac damage. Exosome^Hypoxia may serve as a potential therapeutic target against DIC.

Down-Regulated Exosomal MicroRNA-221 - 3p Derived From Senescent Mesenchymal Stem Cells Impairs Heart Repair

The composition and biological activity of donor cells is largely determined by the exosomes they secrete. In this study, we isolated exosomes from young (Young-Exo) and aged (Age-Exo) mesenchymal stem cells (MSCs) and compared their regeneration activity. Young Exo MSCs were more efficient than Aged-Exo at promoting the formation of endothelial tube, reducing fibrosis, and inhibiting apoptosis of cardiomyocytes in vitro; and improving cardiac structure and function in vivo in the hearts of rats following myocardial infarction (MI). MicroRNA sequencing and polymerase chain reaction (PCR) analysis revealed that miR-221-3p was significantly down-regulated in Aged-Exo. The aged MSCs were rejuvenated and their reparative cardiac ability restored when miR-221-3p was overexpressed in Aged-Exo. The protective effect was lost when miR-221-3p expression was knocked down in Young-Exo. These effects of miR-221-3p were achieved through enhancing Akt kinase activity by inhibiting phosphatase and tensin homolog (PTEN). In conclusion, exosomal miR-221-3p secreted from Aged MSCs attenuated the function of angiogenesis and promoted survival of cardiomyocytes. Up-regulation of miR-221-3p in aged MSCs improved their ability of angiogenesis, migration and proliferation, and suppressed apoptosis via the PTEN/Akt pathway.

Nanomedicine for Gene Delivery for the Treatment of Cardiovascular Diseases

Background:

Myocardial infarction (MI) is the most severe ischemic heart disease and di-rectly leads to heart failure till death. Target molecules have been identified in the event of MI including increasing angiogenesis, promoting cardiomyocyte survival, improving heart function and restraining inflammation and myocyte activation and subsequent fibrosis. All of which are substantial in cardiomy-ocyte protection and preservation of cardiac function.

Methodology:

To modulate target molecule expression, virus and non-virus-mediated gene transfer have been investigated. Despite successful in animal models of MI, virus-mediated gene transfer is hampered by poor targeting efficiency, low packaging capacity for large DNA sequences, immunogenicity induced by virus and random integration into the human genome.

Discussion:

Nanoparticles could be synthesized and equipped on purpose for large-scale production. They are relatively small in size and do not incorporate into the genome. They could carry DNA and drug within the same transfer. All of these properties make them an alternative strategy for gene transfer. In the review, we first introduce the pathological progression of MI. After concise discussion on the current status of virus-mediated gene therapy in treating MI, we overview the history and development of nanoparticle-based gene delivery system. We point out the limitations and future perspective in the field of nanoparticle vehicle.

Conclusion:

Ultimately, we hope that this review could help to better understand how far we are with nanoparticle-facilitated gene transfer strategy and what obstacles we need to solve for utilization of na-nomedicine in the treatment of MI.

Cardioprotective effects of rat adipose‑derived stem cells differ under normoxic/physioxic conditions and are associated with paracrine factor secretion

Adipose tissue‑derived stem cells (ASCs) are beneficial for myocardial regeneration. The physiological oxygen content of human organs is estimated to range between 1 and 11%. However, in the majority of previous in vitro studies with cultured ASCs, the O2 concentration was artificially set to 21%. The present study aimed to compare the protective effects of rat ASCs on neonatal rat ventricular myocytes (NRVMs) under normoxic (21% O2) and physioxic (5% O2) conditions. Rat NRVMs cultured under normoxia or physioxia were treated with H2O2 or left untreated, and further co‑cultured with ASCs in 21% or 5% O2. The apoptosis of NRVMs was evaluated by Annexin V staining and quantitating the protein levels of Bcl‑2 and Bax by western blotting. The oxidative stress of NRVMs was determined by a glutathione/oxidized glutathione assay kit. The concentrations of secreted vascular endothelium growth factor (VEGF), insulin like growth factor‑1 (IGF‑1) and basic fibroblast growth factor (bFGF) in the culture medium were quantified by enzyme‑linked immunosorbent assay. Under both normoxia and physioxia, co‑culture with ASCs protected H2O2‑exposed NRVMs from apoptosis and significantly alleviated the oxidative stress in NRVMs. The protective effects of ASCs were associated with increased secretion of VEGF, IGF‑1 and bFGF. ASCs cultured in 5% O2 exhibited certain cardioprotective effects against H2O2 stress. The results of the present study suggested that O2 concentrations influenced the cardioprotective effects of ASCs. VEGF, IGF‑1 and bFGF may serve a role in the myocardial regeneration mediated by transplanted ASCs.

Stem Cell-Derived Exosomes in Autism Spectrum Disorder

Neurodevelopmental lifelong pathologies defined by problems with social interaction, communication capacity and presence of repetitive/stereotyped clusters of behavior and interests are grouped under the definition of autism spectrum disorder (ASD). ASD prevalence is still increasing, indicating the need to identify specific biomarkers and novel pharmacotherapies. Neuroinflammation and neuro-immune cross-talk dysregulation are specific hallmarks of ASD, offering the possibility of treating these disorders by stem cell therapy. Indeed, cellular strategies have been postulated, proposed and applied to ASD. However, less is known about the molecular action mechanisms of stem cells. As a possibility, the positive and restorative effects mediated by stem cells could be due to their paracrine activity, by which stem cells produce and release several ameliorative and anti-inflammatory molecules. Among the secreted complex tools, exosomes are sub-organelles, enriched by RNA and proteins, that provide cell-to-cell communication. Exosomes could be the mediators of many stem cell-associated therapeutic activities. This review article describes the potential role of exosomes in alleviating ASD symptoms.

Photobiomodulation plus Adipose-derived Stem Cells Improve Healing of Ischemic Infected Wounds in Type 2 Diabetic Rats

In this study, we sought to investigate the impact of photobiomodulation and adipose-derived stem cells (ADS), alone and in combination, on the maturation step of wound healing in an ischemic infected delayed healing wound model in rats with type 2 diabetes mellitus (DM2). We randomly divided 24 adult male rats into 4 groups (n = 6 per group). DM2 plus an ischemic delayed healing wound were induced in all rats. The wounds were infected with methicillin-resistant Staphylococcus aureus. Group 1 was the control (placebo) group. Group 2 received only photobiomodulation (890 nm, 80 Hz, 0.324 J/cm², and 0.001 W/cm²). Group 3 received only the allograft ADS. Group 4 received allograft ADS followed by photobiomodulation. On days 0, 4, 8, 12, and 16, we performed microbiological examination (colony forming units, [CFU]), wound area measurement, wound closure rate, wound strength, and histological and stereological examinations. The results indicated that at day 16, there was significantly decreased CFU (Analysis of variance, p = 0.001) in the photobiomodulation + ADS (0.0 ± 0.0), ADS (1350 ± 212), and photobiomodulation (0.0 ± 0.0) groups compared with the control group (27250 ± 1284). There was significantly decreased wound area (Analysis of variance, p = 0.000) in the photobiomodulation + ADS (7.4 ± 1.4 mm²), ADS (11 ± 2.2 mm²), and photobiomodulation (11.4 ± 1.4 mm²) groups compared with the control group (25.2 ± 1.7). There was a significantly increased tensiometeric property (stress maximal load, Analysis of variance, p = 0.000) in the photobiomodulation + ADS (0.99 ± 0.06 N/cm²), ADS (0.51 ± 0.12 N/cm²), and photobiomodulation (0.35 ± 0.15 N/cm²) groups compared with the control group (0.18 ± 0.04). There was a significantly modulated inflammatory response in (Analysis of variance, p = 0.049) in the photobiomodulation + ADS (337 ± 96), ADS (1175 ± 640), and photobiomodulation (69 ± 54) treatments compared to control group (7321 ± 4099). Photobiomodulation + ADS gave significantly better improvements in CFU, wound area, and wound strength compared to photobiomodulation or ADS alone. Photobiomodulation, ADS, and their combination significantly hastened healing in ischemic methicillin-resistant Staphylococcus aureus infected delayed healing wounds in rats with DM2. Combined application of photobiomodulation plus ADS demonstrated an additive effect.

Transplantation efficacy of autologous bone marrow mesenchymal stem cells combined with atorvastatin for acute myocardial infarction (TEAM-AMI): rationale and design of a randomized, double-blind, placebo-controlled, multi-center, Phase II TEAM-AMI trial

Aim: To determine the efficacy and safety of intracoronary infusion of autologous bone marrow mesenchymal stem cells (MSCINJ) in combination with intensive atorvastatin (ATV) treatment for patients with anterior ST-segment elevation myocardial infarction-elevation myocardial infarction. Patients & methods: The trial enrolls a total of 100 patients with anterior ST-elevation myocardial infarction. The subjects are randomly assigned (1:1:1:1) to receive routine ATV (20 mg/d) with placebo or MSCsINJ and intensive ATV (80 mg/d) with placebo or MSCsINJ. The primary end point is the absolute change of left ventricular ejection fraction within 12 months. The secondary end points include parameters in cardiac function, remodeling and regeneration, quality of life, biomarkers and clinical outcomes. Results & conclusion: The trial will implicate the essential of cardiac micro-environment improvement (‘fertilizing’) for cell-based therapy.

Clinical Trial Registration: NCT03047772.

Bone marrow mesenchymal stem cell-derived exosomes protect against myocardial infarction by promoting autophagy

Exosomes have been demonstrated to be effective in the treatment of a variety of cardiac disorders. However, the effects of mesenchymal stem cell (MSC) exosomes on myocardial infarction is yet to be determined. The current study aimed to investigate the potential therapeutic effects of MSC exosomes on myocardial injuries that are caused by myocardial infarction. MSCs were isolated from rat bone marrow and were used for exosome enrichment using culture medium. Confirmation that MSCs and exosomes had been successfully extracted was performed using flow cytometry, electron microscopy and western blot analysis. A rat myocardial ischemia reperfusion (I/R) model was established by ligation of the left anterior descending coronary artery. Rat myocardial injuries were determined using 2,3,5-triphenyltetrazolium chloride, Masson and TUNEL staining. H9c2 cell proliferation, apoptosis and migration were analyzed using 5-ethynyl-2′-deoxyuridine, Hoechst staining, flow cytometry and Transwell assays. Marker gene expression was evaluated using reverse transcription-quantitative PCR, western blot analysis and immunofluorescence. Rat MSC exosomes were revealed to suppress myocardial injury and the myocardiocyte functions that were induced by I/R. The results also demonstrated decreased apoptotic protease activating factor-1 and increased autophagy-related protein 13 expression. The H9c2 cell proliferation and migration inhibition, as well as cell apoptosis during hypoxia-reoxygenation (H/R), were suppressed by rat MSC exosomes, with an alteration of the expression of apoptotic and autophagic genes also being demonstrated. The application of autophagy inhibitor 3-methyladenine significantly mitigated the effect of exosomes on H9c2 cell proliferation and apoptosis, which were induced by H/R. Rat MSC exosomes inhibited myocardial infarction pathogenesis, possibly by regulating autophagy.

Conditioned Serum Enhances the Chondrogenic and Immunomodulatory Behavior of Mesenchymal Stem Cells

Osteoarthritis is one of the most common chronic health conditions associated with pain and disability. Advanced therapies based on mesenchymal stem cells have become valuable options for the treatment of these pathologies. Conditioned serum (CS, “Orthokine”) has been used intra-articularly for osteoarthritic patients. In this work, we hypothesized that the rich content on anti-inflammatory proteins and growth factors of CS may exert a beneficial effect on the biological activity of human adipose-derived mesenchymal stem cells (hAdMSCs). In vitro studies were designed using hAdMSCs cocultured with CS at different concentrations (2.5, 5, and 10%). Chondrogenic differentiation assays and immunomodulatory experiments using in vitro-stimulated lymphocytes were performed. Our results demonstrated that CS significantly enhanced the differentiation of hAdMSCs toward chondrocytes. Moreover, hAdMSCs pre-sensitized with CS reduced the lymphocyte proliferation as well as their differentiation toward activated lymphocytes. These results suggest that in vivo coadministration of CS and hAdMSCs may have a beneficial effect on the therapeutic potential of hAdMSCs. Moreover, these results indicate that intra-articular administration of CS might influence the biological behavior of resident stem cells increasing their chondrogenic differentiation and inherent immunomodulatory activity. To our knowledge, this is the first in vitro study reporting this combination.

Local pharmacological induction of angiogenesis: Drugs for cells and cells as drugs

The past decades have seen significant advances in pro-angiogenic strategies based on delivery of molecules and cells for conditions such as coronary artery disease, critical limb ischemia and stroke. Currently, three major strategies are evolving. Firstly, various pharmacological agents (growth factors, interleukins, small molecules, DNA/RNA) are locally applied at the ischemic region. Secondly, preparations of living cells with considerable bandwidth of tissue origin, differentiation state and preconditioning are delivered locally, rarely systemically. Thirdly, based on the notion, that cellular effects can be attributed mostly to factors secreted in situ, the cellular secretome (conditioned media, exosomes) has come into the spotlight. We review these three strategies to achieve (neo)angiogenesis in ischemic tissue with focus on the angiogenic mechanisms they tackle, such as transcription cascades, specific signalling steps and cellular gases. We also include cancer-therapy relevant lymphangiogenesis, and shall seek to explain why there are often conflicting data between in vitro and in vivo. The lion's share of data encompassing all three approaches comes from experimental animal work and we shall highlight common technical obstacles in the delivery of therapeutic molecules, cells, and secretome. This plethora of preclinical data contrasts with a dearth of clinical studies. A lack of adequate delivery vehicles and standardised assessment of clinical outcomes might play a role here, as well as regulatory, IP, and manufacturing constraints of candidate compounds; in addition, completed clinical trials have yet to reveal a successful and efficacious strategy. As the biology of angiogenesis is understood well enough for clinical purposes, it will be a matter of time to achieve success for well-stratified patients, and most probably with a combination of compounds.

EPO protects mesenchymal stem cells from hyperglycaemic injury via activation of the Akt/FoxO3a pathway

INTRODUCTION

Mesenchymal stem cell (MSC)-based therapies have demonstrated positive outcomes for treating cardiovascular disease. However, the proliferative ability of MSCs decreases during chronic exposure to hyperglycaemia; their ability to contribute to endogenous injury repair is thus reduced. Erythropoietin (EPO) was recently reported to protect against hyperglycaemia-related injury in various cells and may be a good candidate for enhancing MSC functions under hyperglycaemic conditions.

METHODS

Bone marrow-derived MSCs were isolated from male donor rats weighing 60-80 g. The roles of EPO in regulating cell viability, senescence, angiogenesis and inflammation were investigated using the Cell Counting Kit-8 (CCK-8) assay and 5-ethynyl-2'-deoxyuridine (EdU) assays; senescence-associated β-galactosidase (SA-β-gal) staining; VEGF, HGF, IGF, bFGF ELISAs and TNF-α ELISA, respectively. ROS production was measured by flow cytometry. The expression levels of Akt, forkhead box class O3a (FoxO3a) and VEGF proteins in MSCs were analysed by western blotting. Matrigel was used for tube formation assays.

RESULTS

The results of the current study showed that EPO has beneficial effects on MSCs exposed to hyperglycaemia by promoting proliferation, inhibiting senescence and the release of pro-inflammatory factors, increasing the secretion of proangiogenic cytokines, and enhancing the ability of MSCs to stimulate tube formation among human umbilical vein endothelial cells (HUVECs). In addition, the beneficial effects of EPO may result from the activation of the Akt/FoxO3a signalling pathway.

CONCLUSIONS

Our study demonstrates for the first time that EPO protects MSCs from hyperglycaemia-induced damage by targeting the Akt/FoxO3a signalling pathway.

Enrichment of vascular endothelial growth factor secreting mesenchymal stromal cells enhances therapeutic angiogenesis in a mouse model of hind limb ischemia

Critical limb ischemia, a severe manifestation of peripheral artery disease, is emerging as a major concern in aging societies worldwide. Notably, cell-based gene therapy to induce angiogenesis in ischemic tissue has been investigated as treatment. Despite many studies demonstrating the efficacy of this approach, better therapies are required to prevent serious sequelae such as claudication, amputation and other cardiovascular events. We have now established a simplified method to enhance the effects of therapeutic transgenes by selecting for and transplanting only transduced cells. Herein, mesenchymal stromal cells were transfected to co-express vascular endothelial growth factor as angiogenic factor and enhanced green fluorescent protein as marker. Transfected cells were then collected using flow cytometry based on green fluorescence and transplanted into ischemic hind limbs in mice. Compared with unsorted or untransfected cells, purified cells significantly improved blood perfusion within 21days, suggesting that transplanting only cells that overexpress vascular endothelial growth factor enhances therapeutic angiogenesis. Importantly, this approach may prove to be useful in cell-based gene therapy against a wide spectrum of diseases, simply by replacing the gene to be delivered or the cell to be transplanted.

The Effects of Periostin in a Rat Model of Isoproterenol: Mediated Cardiotoxicity

Periostin is an extracellular matrix protein from fasciclin family, and it plays an important role in the cell adhesion, migration, and growth of the organism. Periostin prevents apoptosis while stimulating cardiomyocytes. The present study was designed to investigate cardioprotective effects of the recombinant murine periostin peptide administration in a rat model of isoproterenol (ISO)-induced myocardial injury. The experiment was performed on 84 adult male Sprague Dawley rats in 4 groups (n = 21): control group (1), periostin-treated group (2), ISO-treated group (3), and ISO + periostin-treated group (4). The groups were further divided into three subgroups based on the duration of the experiment in which rats were killed on days 1, 7, and 28 (n = 7). Growth factors (VEGF, ANGPT, FGF-2, TGFβ), mitosis and apoptosis (Bcl-2, Bax, PCNA, Ki-67, phospho-histone H3), cell cycle activators and inhibitors (cyclin D1, D2, A2, Cdc2), the origin of regenerating cells (cKit and CD45) mRNA were detected using quantitative real-time polymerase chain reaction (PCR) and PCR array. Immunohistochemistry staining was used to directly detect protein level and distribution in the heart tissues. Administration of periostin following ISO-induced cardiotoxicity revealed that periostin alleviated deleterious effects of ISO through several pathways: (1) periostin induced mitotic activity of endothelial/fibroblastic cells, (2) periostin drives cardiomyocytes into S and M phases, thus promoting proliferation of cardiomyocytes, (3) periostin contributed to collagen degradation, tissue remodeling, and reduced cardiac fibrosis during the healing process following myocardial damage while preserving tissue matrix, (4) periostin stimulated angiogenesis by upregulating THBS1, TGFB2, and HGF genes, (5) periostin regulated cell growth and proliferation while maintaining cell shape and cellular muscle contractions (ACTB) and functioned as chemoattractant factor (CCL2) at the beginning of myocardial damage.

Hepatocyte growth factor plays a particular role in progression of overall cardiac damage in experimental pulmonary hypertension

Background: HGF/MET pathway may have a role in pulmonary hypertension (PH). However, the link between the pathway and development of target organ damage in PH remains elusive. We aimed to demonstrate the relation between plasma HGF and HGF/MET tissue expressions in affected organs during PH progression. Methods: 12 weeks old male Wistar rats were injected with monocrotaline (MCT, 60 mg/kg, s.c.) to induce PH and sacrificed after 1, 2 and 4 weeks. Controls received saline. mRNA levels of HGF regulatory complex (Hgf, Met, Hgfa, Hai-1, Hai-2) were determined in right and left ventricles (RV, LV), lungs, pulmonary artery and liver by RT-qPCR. HGF protein levels in plasma were analysed by ELISA. Results: PH development was associated with a progressive elevation of HGF plasma levels that correlated with relative RV mass. Furthermore, Hgf mRNA expressions at week 4 were upregulated solely in the cardiac ventricles while being downregulated in a. pulmonalis, lungs and liver. Met and Hai-1/Hai-2 followed a similar pattern and were upregulated in cardiac ventricles, where Hgfa remained unchanged, but downregulated in lungs. Conclusion: We suggest that cardiac overexpression of Hgf might contribute to increased plasma HGF in MCT-induced PH. HGF could be exploited as a cardiospecific biomarker and HGF/MET pathway as a target in drug discovery for PH.

Reversible Left Ventricular Systolic Dysfunction Secondary to Pazopanib

Pazopanib is a tyrosine kinase inhibitor used for the treatment of advanced renal cell carcinoma and advanced soft tissue sarcoma. We describe a case report of a patient with spindle cell sarcoma who developed severe left ventricular systolic dysfunction after starting pazopanib therapy with subsequent recovery of left ventricular ejection fraction upon stopping therapy.

Angiogenic growth factors in myocardial infarction: a critical appraisal

In the recent past, substantial advances have been made in the treatment of myocardial infarction (MI). Despite the impact of these positive developments, MI remains to be a leading cause of morbidity as well as mortality. An interesting hypothesis is that the development of new blood vessels (angiogenesis) or the remodeling of preexisting collaterals may form natural bypasses that could compensate for the occlusion of an epicardial coronary artery. A number of angiogenic factors are proven to be elicited during MI. Exogenous supplementation of these growth factors either in the form of recombinant protein or gene would enhance the collateral vessel formation and thereby improve the outcome after MI. The aim of this review is to describe the nature and potentials of different angiogenic factors, their expression, their efficacy in animal studies, and clinical trials pertaining to MI.

Human mesenchymal stromal cell-derived extracellular vesicles attenuate aortic aneurysm formation and macrophage activation via microRNA-147

The formation of an abdominal aortic aneurysm (AAA) is characterized by inflammation, macrophage infiltration, and vascular remodeling. In this study, we tested the hypothesis that mesenchymal stromal cell (MSC)-derived extracellular vesicles (EVs) immunomodulate aortic inflammation, to mitigate AAA formation via modulation of microRNA-147. An elastase-treatment model of AAA was used in male C57BL/6 wild-type (WT) mice. Administration of EVs in elastase-treated WT mice caused a significant attenuation of aortic diameter and mitigated proinflammatory cytokines, inflammatory cell infiltration, an increase in smooth muscle cell α-actin expression, and a decrease in elastic fiber disruption, compared with untreated mice. A 10-fold up-regulation of microRNA (miR)-147, a key mediator of macrophage inflammatory responses, was observed in murine aortic tissue in elastase-treated mice compared with controls on d 14. EVs derived from MSCs transfected with miR-147 mimic, but not with miR-147 inhibitor, attenuated aortic diameter, inflammation, and leukocyte infiltration in elastase-treated mice. In vitro studies of human aortic tissue explants and murine-derived CD11b+ macrophages induced proinflammatory cytokines after elastase treatment, and the expression was attenuated by cocultures with EVs transfected with miR-147 mimic, but not with miR-147 inhibitor. Thus, our findings define a critical role of MSC-derived EVs in attenuation of aortic inflammation and macrophage activation via miR-147 during AAA formation.-Spinosa, M., Lu, G., Su, G., Bontha, S. V., Gehrau, R., Salmon, M. D., Smith, J. R., Weiss, M. L., Mas, V. R., Upchurch, G. R., Sharma, A. K. Human mesenchymal stromal cell-derived extracellular vesicles attenuate aortic aneurysm formation and macrophage activation via microRNA-147.

New strategies for improving stem cell therapy in ischemic heart disease

Stem cell therapy is a promising approach to the treatment of ischemic heart disease via replenishing cell loss after myocardial infarction. Both preclinical studies and clinical trials have indicated that cardiac function improved consistently, but very modestly after cell-based therapy. This mainly attributed to low cell survival rate, engraftment and functional integration, which became the major challenges to regenerative medicine. In recent years, several new cell types have been developed to regenerate cardiomyocytes and novel delivery approaches helped to increase local cell retention. New strategies, such as cell pretreatment, gene-based therapy, tissue engineering, extracellular vesicles application and immunologic regulation, have surged and brought about improved cell survival and functional integration leading to better therapeutic effects after cell transplantation. In this review, we summarize these new strategies targeting at challenges of cardiac regenerative medicine and discuss recent evidences that may hint their effectiveness in the future clinical settings.

Combining cell and gene therapy to advance cardiac regeneration

INTRODUCTION

The characterization of multipotent endogenous cardiac stem cells (eCSCs) and the breakthroughs of somatic cell reprogramming to boost cardiomyocyte replacement have fostered the prospect of achieving functional heart repair/regeneration.

AREAS COVERED

Allogeneic CSC therapy through its paracrine stimulation of the endogenous resident reparative/regenerative process produces functional meaningful myocardial regeneration in pre-clinical porcine myocardial infarction models and is currently tested in the first-in-man human trial. The in vivo test of somatic reprogramming and cardioregenerative non-coding RNAs revived the interest in gene therapy for myocardial regeneration. The latter, together with the advent of genome editing, has prompted most recent efforts to produce genetically-modified allogeneic CSCs that secrete cardioregenerative factors to optimize effective myocardial repair.

EXPERT OPINION

The current war against heart failure epidemics in western countries seeks to find effective treatments to set back the failing hearts prolonging human lifespan. Off-the-shelf allogeneic-genetically-modified CSCs producing regenerative agents are a novel and evolving therapy set to be affordable, safe, effective and available at all times for myocardial regeneration to either prevent or treat heart failure.

Strategies to enhance paracrine potency of transplanted mesenchymal stem cells in intractable neonatal disorders

Mesenchymal stem cell (MSC) transplantation represents the next breakthrough in the treatment of currently intractable and devastating neonatal disorders with complex multifactorial etiologies, including bronchopulmonary dysplasia, hypoxic ischemic encephalopathy, and intraventricular hemorrhage. Absent engraftment and direct differentiation of transplanted MSCs, and the "hit-and-run" therapeutic effects of these MSCs suggest that their pleiotropic protection might be attributable to paracrine activity via the secretion of various biologic factors rather than to regenerative activity. The transplanted MSCs, therefore, exert their therapeutic effects not by acting as "stem cells," but rather by acting as "paracrine factors factory." The MSCs sense the microenvironment of the injury site and secrete various paracrine factors that serve several reparative functions, including antiapoptotic, anti-inflammatory, antioxidative, antifibrotic, and/or antibacterial effects in response to environmental cues to enhance regeneration of the damaged tissue. Therefore, the therapeutic efficacy of MSCs might be dependent on their paracrine potency. In this review, we focus on recent investigations that elucidate the specifically regulated paracrine mechanisms of MSCs by injury type and discuss potential strategies to enhance paracrine potency, and thus therapeutic efficacy, of transplanted MSCs, including determining the appropriate source and preconditioning strategy for MSCs and the route and timing of their administration.

Mesenchymal stem cell therapy: A promising cell-based therapy for treatment of myocardial infarction

For decades, mesenchymal stem (MSCs) cells have been used for cardiovascular diseases as regenerative therapy. This review is an attempt to summarize the types of MSCs involved in myocardial infarction (MI) therapy, as well as its possible mechanisms effects, especially the paracrine one in MI focusing on the studies (human and animal) conducted within the last 10 years. Recently, reports showed that MSC therapy could have infarct-limiting effects after MI in both experimental and clinical trials. In this context, various types of MSCs can help cardiac regeneration by either revitalizing the cardiac stem cells or revascularizing the arteries and veins of the heart. Furthermore, MSCs could produce paracrine growth factors that increase the survival of nearby cardiomyocytes, as well as increase angiogenesis through recruitment of stem cell from bone marrow or inducing vessel growth from existing capillaries. Recent research suggests that the paracrine effects of MSCs could be mediated by extracellular vesicles including exosomes. Exosomal microRNAs (miRNAs) released by MSCs are promising therapeutic hotspot target for MI. This could be attributed to the role of miRNA in cardiac biology, including cardiac regeneration, stem cell differentiation, apoptosis, neovascularization, cardiac contractility and cardiac remodeling. Furthermore, gene-modified MSCs could be a recent promising therapy for MI to enhance the paracrine effects of MSCs, including better homing and effective cell targeted tissue regeneration. Although MSC therapy has achieved considerable attention and progress, there are critical challenges that remains to be overcome to achieve the most effective successful cell-based therapy in MI.

Molecular mechanisms of cardioprotective effects mediated by transplanted cardiac ckit+ cells through the activation of an inflammatory hypoxia-dependent reparative response

The regenerative effects of cardiac ckit⁺ stem cells (ckit⁺CSCs) in acute myocardial infarction (MI) have been studied extensively, but how these cells exert a protective effect on cardiomyocytes is not well known. Growing evidences suggest that in adult stem cells injury triggers inflammatory signaling pathways which control tissue repair and regeneration. Aim of the present study was to determine the mechanisms underlying the cardioprotective effects of ckit⁺CSCs following transplantation in a murine model of MI. Following isolation and in vitro expansion, cardiac ckit⁺CSCs were subjected to normoxic and hypoxic conditions and assessed at different time points. These cells adapted to hypoxia as showed by the activation of HIF-1α and the expression of a number of genes, such as VEGF, GLUT1, EPO, HKII and, importantly, of alarmin receptors, such as RAGE, P2X7R, TLR2 and TLR4. Activation of these receptors determined an NFkB-dependent inflammatory and reparative gene response (IRR). Importantly, hypoxic ckit⁺CSCs increased the secretion of the survival growth factors IGF-1 and HGF. To verify whether activation of the IRR in a hypoxic microenvironment could exert a beneficial effect in vivo, autologous ckit⁺CSCs were transplanted into mouse heart following MI. Interestingly, transplantation of ckit⁺CSCs lowered apoptotic rates and induced autophagy in the peri-infarct area; further, it reduced hypertrophy and fibrosis and, most importantly, improved cardiac function. ckit⁺CSCs are able to adapt to a hypoxic environment and activate an inflammatory and reparative response that could account, at least in part, for a protective effect on stressed cardiomyocytes following transplantation in the infarcted heart.