Intracoronary Transplantation of Mesenchymal Stem Cells with Overexpressed Integrin-Linked Kinase Improves Cardiac Function in Porcine Myocardial Infarction

Mesenchymal stem cells may alleviate angiotensin II-induced myocardial fibrosis and hypertrophy by upregulating SFRS3 expression

INTRODUCTION AND OBJECTIVES

The development of cardiac fibrosis (CF) and hypertrophy (CH) can lead to heart failure. Mesenchymal stem cells (MSCs) have shown promise in treating cardiac diseases. However, the relationship between MSCs and splicing factor arginine/serine rich-3 (SFRS3) remains unclear. In this study, our objectives are to investigate the effect of MSCs on SFRS3 expression, and their impact on CF and CH. Additionally, we aim to explore the function of the overexpression of SFRS3 in angiotensin II (Ang II)-treated cardiac fibroblasts (CFBs) and cardiac myocytes (CMCs).

METHODS

Rat cardiac fibroblasts (rCFBs) or rat cardiac myocytes (rCMCs) were co-cultured with rat MSCs (rMSCs). The function of SFRS3 in Ang II-induced rCFBs and rCMCs was studied by overexpressing SFRS3 in these cells, both with and without the presence of rMSCs. We assessed the expression of SFRS3 and evaluated the cell cycle, proliferation and apoptosis of rCFBs and rCMCs. We also measured the levels of interleukin (IL)-β, IL-6 and tumor necrosis factor (TNF)-α and assessed the degree of fibrosis in rCFBs and hypertrophy in rCMCs.

RESULTS

rMSCs induced SFRS3 expression and promoted cell cycle, proliferation, while reducing apoptosis of Ang II-treated rCFBs and rCMCs. Co-culture of rMSCs with these cells also repressed cytokine production and mitigated the fibrosis of rCFBs, as well as hypertrophy of rCMCs triggered by Ang II. Overexpression of SFRS3 in the rCFBs and rCMCs yielded identical effects to rMSC co-culture.

CONCLUSION

MSCs may alleviate Ang II-induced cardiac fibrosis and cardiomyocyte hypertrophy by increasing SFRS3 expression in vitro.

Genetically modified mesenchymal stromal cells: a cell-based therapy offering more efficient repair after myocardial infarction

Myocardial infarction (MI) is a serious complication of coronary artery disease. This condition is common worldwide and has a profound impact on patients' lives and quality of life. Despite significant advances in the treatment of heart disease in modern medicine, the efficient treatment of MI still faces a number of challenges. Problems such as scar formation and loss of myocardial function after a heart attack still limit patients' recovery. Therefore, the search for a new therapeutic tool that can promote repair and regeneration of myocardial tissue has become crucial. In this context, mesenchymal stromal cells (MSCs) have attracted much attention as a potential therapeutic tool. MSCs are a class of adult stem cells with multidirectional differentiation potential, derived from bone marrow, fat, placenta and other tissues, and possessing properties such as self-renewal and immunomodulation. The application of MSCs may provide a new direction for the treatment of MI. These stem cells have the potential to differentiate into cardiomyocytes and vascular endothelial cells in damaged tissue and to repair and protect myocardial tissue through anti-inflammatory, anti-fibrotic and pro-neovascularization mechanisms. However, the clinical results of MSCs transplantation for the treatment of MI are less satisfactory due to the limitations of the native function of MSCs. Genetic modification has overcome problems such as the low survival rate of transplanted MSCs in vivo and enhanced their functions of promoting neovascularization and differentiation into cardiomyocytes, paving the way for them to become an effective tool for repair therapy after MI. In previous studies, MSCs have shown some therapeutic potential in experimental animals and preliminary clinical trials. This review aims to provide readers with a comprehensive and in-depth understanding to promote the wider application of engineering MSCs in the field of MI therapy, offering new hope for recovery and improved survival of cardiac patients.

The Role of Stem Cells in the Treatment of Cardiovascular Diseases

Cardiovascular diseases (CVDs) are the leading cause of death and include several vascular and cardiac disorders, such as atherosclerosis, coronary artery disease, cardiomyopathies, and heart failure. Multiple treatment strategies exist for CVDs, but there is a need for regenerative treatment of damaged heart. Stem cells are a broad variety of cells with a great differentiation potential that have regenerative and immunomodulatory properties. Multiple studies have evaluated the efficacy of stem cells in CVDs, such as mesenchymal stem cells and induced pluripotent stem cell-derived cardiomyocytes. These studies have demonstrated that stem cells can improve the left ventricle ejection fraction, reduce fibrosis, and decrease infarct size. Other studies have investigated potential methods to improve the survival, engraftment, and functionality of stem cells in the treatment of CVDs. The aim of the present review is to summarize the current evidence on the role of stem cells in the treatment of CVDs, and how to improve their efficacy.

Enhanced interaction between genome-edited mesenchymal stem cells and platelets improves wound healing in mice

Impaired wound healing poses a significant burden on the healthcare system and patients. Stem cell therapy has demonstrated promising potential in the treatment of wounds. However, its clinical application is hindered by the low efficiency of cell homing. In this study, we successfully integrated P-selectin glycoprotein ligand-1 (PSGL-1) into the genome of human adipose-derived mesenchymal stem cells (ADSCs) using a Cas9-AAV6-based genome editing tool platform. Our findings revealed that PSGL-1 knock-in enhanced the binding of ADSCs to platelets and their adhesion to the injured site. Moreover, the intravenous infusion of PSGL-1 -engineered ADSCs (KI-ADSCs) significantly improved the homing efficiency and residence rate at the site of skin lesions in mice. Mechanistically, PSGL-1 knock-in promotes the release of some therapeutic cytokines by activating the canonical WNT/β-catenin signaling pathway and accelerates the healing of wounds by promoting angiogenesis, re-epithelialization, and granulation tissue formation at the wound site. This study provides a novel strategy to simultaneously address the problem of poor migration and adhesion of mesenchymal stem cells (MSCs).

Mechanisms and therapeutic strategies of extracellular vesicles in cardiovascular diseases

Cardiovascular disease (CVD) significantly impacts global society since it is the leading cause of death and disability worldwide, and extracellular vesicle (EV)-based therapies have been extensively investigated. EV delivery is involved in mediating the progression of CVDs and has great potential to be biomarker and therapeutic molecular carrier. Besides, EVs from stem cells and cardiac cells can effectively protect the heart from various pathologic conditions, and then serve as an alternative treatment for CVDs. Moreover, the research of using EVs as delivery carriers of therapeutic molecules, membrane engineering modification of EVs, or combining EVs with biomaterials further improves the application potential of EVs in clinical treatment. However, currently there are only a few articles summarizing the application of EVs in CVDs. This review provides an overview of the role of EVs in the pathogenesis and diagnosis of CVDs. It also focuses on how EVs promote the repair of myocardial injury and therapeutic methods of CVDs. In conclusion, it is of great significance to review the research on the application of EVs in the treatment of CVDs, which lays a foundation for further exploration of the role of EVs, and clarifies the prospect of EVs in the treatment of myocardial injury.

Suppression of SMOC2 alleviates myocardial fibrosis via the ILK/p38 pathway

Background

Fibrosis of the myocardium is one of the main pathological changes of adverse cardiac remodeling, which is associated with unsatisfactory outcomes in patients with heart disease. Further investigations into the precise molecular mechanisms of cardiac fibrosis are urgently required to seek alternative therapeutic strategies for individuals suffering from heart failure. SMOC2 has been shown to be essential to exert key pathophysiological roles in various physiological processes in vivo, possibly contributing to the pathogenesis of fibrosis. A study investigating the relationship between SMOC2 and myocardial fibrosis has yet to be conducted.

Methods

Mice received a continuous ISO injection subcutaneously to induce cardiac fibrosis, and down-regulation of SMOC2 was achieved by adeno-associated virus-9 (AAV9)-mediated shRNA knockdown. Neonatal fibroblasts were separated and cultured in vitro with TGFβ to trigger fibrosis and infected with either sh-SMOC2 or sh-RNA as a control. The role and mechanisms of SMOC2 in myocardial fibrosis were further examined and analyzed.

Results

SMOC2 knockdown partially reversed cardiac functional impairment and cardiac fibrosis in vivo after 21 consecutive days of ISO injection. We further demonstrated that targeting SMOC2 expression effectively slowed down the trans-differentiation and collagen deposition of cardiac fibroblasts stimulated by TGFβ. Mechanistically, targeting SMOC2 expression inhibited the induction of ILK and p38 in vivo and in vitro, and ILK overexpression increased p38 phosphorylation activity and compromised the protective effects of sh-SMOC2-mediated cardiac fibrosis.

Conclusion

Therapeutic SMOC2 silencing alleviated cardiac fibrosis through inhibition of the ILK/p38 signaling, providing a preventative and control strategy for cardiac remodeling management in clinical practice.

Mesenchymal stromal cells: what have we learned so far about their therapeutic potential and mechanisms of action?

Mesenchymal stromal cells (MSCs) have been found to be safe and effective in a wide range of animal models of human disease. MSCs have been tested in thousands of clinical trials, but results show that while these cells appear to be safe, they tend to lack efficacy. This has raised questions about whether animal models are useful for predicting efficacy in patients. However, a problem with animal studies is that there is a lack of standardisation in the models and MSC therapy regimes used; there appears to be publication bias towards studies reporting positive outcomes; and the reproducibility of results from animal experiments tends not to be confirmed prior to clinical translation. A further problem is that while some progress has been made towards investigating the mechanisms of action (MoA) of MSCs, we still fail to understand how they work. To make progress, it is important to ensure that prior to clinical translation, the beneficial effects of MSCs in animal studies are real and can be repeated by independent research groups. We also need to understand the MoA of MSCs to assess whether their effects are likely to be beneficial across different species. In this review, we give an overview of the current clinical picture of MSC therapies and discuss what we have learned from animal studies. We also give a comprehensive update of what we know about the MoA of MSCs, particularly in relation to their role in immunomodulation.

Mesenchymal Stem Cells Therapies on Fibrotic Heart Diseases

Stem cell therapy is a promising alternative approach to heart diseases. The most prevalent source of multipotent stem cells, usually called somatic or adult stem cells (mesenchymal stromal/stem cells, MSCs) used in clinical trials is bone marrow (BM-MSCs), adipose tissue (AT-MSCs), umbilical cord (UC-MSCs) and placenta. Therapeutic use of MSCs in cardiovascular diseases is based on the benefits in reducing cardiac fibrosis and inflammation that compose the cardiac remodeling responsible for the maintenance of normal function, something which may end up causing progressive and irreversible dysfunction. Many factors lead to cardiac fibrosis and failure, and an effective therapy is lacking to reverse or attenuate this condition. Different approaches have been shown to be promising in surpassing the poor survival of transplanted cells in cardiac tissue to provide cardioprotection and prevent cardiac remodeling. This review includes the description of pre-clinical and clinical investigation of the therapeutic potential of MSCs in improving ventricular dysfunction consequent to diverse cardiac diseases.

Mononuclear phagocyte system blockade using extracellular vesicles modified with CD47 on membrane surface for myocardial infarction reperfusion injury treatment

Mesenchymal stem cell (MSC)-derived extracellular vesicles (EVs) with anti-apoptotic and anti-inflammatory properties have been intensively studied. However, rapid clearance by the mononuclear phagocyte system remains a huge barrier for the delivery of extracellular vesicle contents into target organs and restricts its wider application, particularly in the heart. CD47 is a transmembrane protein that enables cancer cells to evade clearance by macrophages through CD47^- signal regulatory proteinα binding, which initiates a "don't eat me" signal. This study aimed to explore the biodistribution and delivery efficiency of EVs carrying the membrane protein CD47 and specific anti-apoptotic miRNAs. EVs were isolated from MSCs overexpressing CD47 (CD47-EVs) and identified. Fluorescence-labeled EVs were injected through the tail vein and tracked using fluorescence imaging. In silico analysis was performed to determine miRNA profiles in MSCs and in a heart-derived H9c2 cardiomyoblast cell line under hypoxia vs. normoxia conditions. Electro CD47-EV was constructed by encapsulating purified CD47-EV with miR-21a via electroporation. The effect of miR21-EVs on the pro-apoptotic gene encoding phosphatase and tensin homolog (PTEN) was evaluated by dual-luciferase assay, qPCR, and western blotting. Exogenous miR21 distribution, PTEN protein level, blood vessel density, anti-apoptotic effect by TdT-mediated dUTP nick-end labeling staining, and macrophage and leukocyte infiltration in the myocardium were assessed by immunofluorescence staining. Cardiac functional recovery during the early stage and recovery period was evaluated using echocardiography. The results showed that CD47-EVs were still detectable in the plasma 120 min after the tail vein injection, compared to the detection time of less than 30 min observed with the unmodified EVs. More strikingly, CD47-EVs preferentially accumulated in the heart in the ischemia-reperfusion (I/R) + CD47-EV group [heart total fluorescence radiance ( × 10⁵ Photons/sec/cm²/sr) 51.62 ± 11.30 v.s. 10.08 ± 3.15 in the I/R + unmodified EVs group] 8 h post-injection. Exogenous miR-21 is efficiently internalized into cardiomyocytes, inhibits apoptosis, alleviates inflammation, and improves cardiac function. In conclusion, electro CD47-EVs efficiently improve biodistribution in the heart, shedding new light on the application of a two-step EV delivery method (CD47 genetic modification followed by therapeutic content electrotransfection) as a potential therapeutic tool for myocardial I/R injury that may benefit patients in the future.

Current Status and Limitations of Myocardial Infarction Large Animal Models in Cardiovascular Translational Research

Establishing an appropriate disease model that mimics the complexities of human cardiovascular disease is critical for evaluating the clinical efficacy and translation success. The multifaceted and complex nature of human ischemic heart disease is difficult to recapitulate in animal models. This difficulty is often compounded by the methodological biases introduced in animal studies. Considerable variations across animal species, modifications made in surgical procedures, and inadequate randomization, sample size calculation, blinding, and heterogeneity of animal models used often produce preclinical cardiovascular research that looks promising but is irreproducible and not translatable. Moreover, many published papers are not transparent enough for other investigators to verify the feasibility of the studies and the therapeutics' efficacy. Unfortunately, successful translation of these innovative therapies in such a closed and biased research is difficult. This review discusses some challenges in current preclinical myocardial infarction research, focusing on the following three major inhibitors for its successful translation: Inappropriate disease model, frequent modifications to surgical procedures, and insufficient reporting transparency.

Immediate Intracoronary Delivery of Human Umbilical Cord Mesenchymal Stem Cells Reduces Myocardial Injury by Regulating the Inflammatory Process Through Cell-Cell Contact with T Lymphocytes

Inflammatory response regulation is a mechanism through which human umbilical cord mesenchymal stem cells (HUCMSCs) improve myocardial ischemia reperfusion injury (IRI); however, the timing of HUCMSC delivery to achieve maximum effectiveness is controversial. To investigate the effects of HUCMSC delivery on the acute inflammatory stage of IRI, we transplanted HUCMSCs or HUCMSCs with cyclosporin A (CsA) through the coronary artery simultaneously during ischemia reperfusion in pigs. Ferumoxytol-labeled HUCMSCs (HUCMSC), HUCMSCs with cyclosporin A (HUCMSC+CsA), and PBS (control) groups were investigated to evaluate the homing of transplanted cells and changes in infarct features, cardiac activity, and inflammatory response at three time points post-transplantation. Animals were sacrificed 2 weeks later for histological analysis of the hearts. We detected Prussian blue-dyed granules distributed around T lymphocyte clusters in the infarct area in the HUCMSC group. Infarct size and collagen deposition in the infarct area were lower in the HUCMSC group than in the control and HUCMSC+CsA groups. Cardiac function was mildly impaired in both the control and HUCMSC groups, whereas added CsA had a more severe impact. The levels of proinflammatory markers were lower in the HUCMSC group than in the control group at 24-h follow-up, and the difference was more significant after adding CsA. There were more CD3⁺ T lymphocytes and Foxp3⁺ Tregs in the HUCMSC group infarct area than in the other two groups. Proliferation rate of T lymphocytes was higher in the HUCMSC group than in the other two groups. Indirect co-culture experiments in vitro showed that MSCs promoted the generation of CD4⁺CD25⁺ Foxp3⁺Tregs through a paracrine mechanism. These results indicate that immediate intracoronary delivery of HUCMSCs after ischemia reperfusion can reduce acute myocardial IRI and promote myocardial repair, mainly through T lymphocyte interactions to regulate the intense inflammatory response during the acute inflammatory stage.

Mesenchymal stem cell mediates cardiac repair through autocrine, paracrine and endocrine axes

In the past decade, despite key advances in therapeutic strategies following myocardial infarction, none can directly address the loss of cardiomyocytes following ischemic injury. Cardiac cell-based therapy is at the cornerstone of regenerative medicine that has shown potential for tissue repair. Mesenchymal stem cells (MSC) represent a strong candidate to heal the infarcted myocardium. While differentiation potential has been described as a possible avenue for MSC-based repair, their secreted mediators are responsible for the majority of the ascribed prohealing effects. MSC can either promote their own survival and proliferation through autocrine effect or secrete trophic factors that will act on adjacent cells through a paracrine effect. Prior studies have also documented beneficial effects even when MSCs were remotely delivered, much akin to an endocrine mechanism. This review aims to distinguish the paracrine activity of MSCs from an endocrine-like effect, where remotely transplanted cells can promote healing of the injured myocardium.

Mesenchymal stem cells rejuvenate cardiac muscle through regulating macrophage polarization

We have shown that the effects of transplantation of CD146+ mesenchymal stem cells (MSCs) on myocardial regeneration after myocardial infarction (MI) exceeds the effects of transplantation of MSCs, likely resulting from reduction of aging-associated cellular reactive oxygen species in injured cardiac muscle cells (CMCs). Since the role of macrophages in the MSC-mediated recovery of heart function after MI remains unclear, this question was thus addressed in the current study. We found that transplantation of MSCs did not alter the total number of the macrophages in the injured heart, but induced their polarization towards a M2-phenotype. Moreover, administration of tumor necrosis factor alpha (TNFα) into MSC-transplanted mice, which prevented M2-polarization of macrophages, abolished the effects of MSCs on recovery of heart function and on the reduction of infarcted cardiac tissue. Thus, our data suggest that MSCs may rejuvenate CMCs after ischemic injury at least partially through induction of M2-polarization of macrophages.

Comparison of umbilical cord tissue-derived mesenchymal stromal cells isolated from cryopreserved material and extracted by explantation and digestion methods utilizing a split manufacturing model

BACKGROUND AIMS

Umbilical cord (UC) tissue is recognized as an advantageous source of mesenchymal stromal cells (MSCs), whose therapeutic properties are being actively evaluated in pre-clinical and clinical trials. In recognition of its potential value, storage of UC tissue or cells from UC tissue in newborn stem cell banks is now commonplace; however, strategies for isolating UC-derived MSCs (UCMSCs) from UC tissue have not been standardized. The majority of newborn stem cell banks take one of two approaches to cord tissue processing and cryopreservation: enzymatic digestion of the fresh tissue with cryopreservation of the subsequent cell suspension or cryopreservation of the tissue as a composite whole with later, post-thaw isolation of cells by explantation. Evaluation of UCMSCs derived by these two principal preparation and cryopreservation strategies is important to understanding whether the methods currently employed by newborn stem cell banks retain the desirable clinical attributes of UC cells.

METHODS

UCMSCs were isolated from 10 UC tissue samples by both explantation and enzymatic digestion methods to allow for comparison of cells from the same donor. Cell isolates from both methods were compared pre- and post-cryopreservation as well as after serial passaging. Cell viability, morphology, growth kinetics, immunophenotype, cytokine secretion and differentiation capacity were evaluated.

RESULTS

UCMSCs could be derived from fresh UC tissue by both explantation and digestion methods and from thawed UC tissue by explantation. Initial cell populations isolated by digestion were heterogeneous and took longer to enrich for UCMSCs in culture than populations obtained by explantation. However, once isolated and enriched, UCMSCs obtained by either method showed no significant difference in viability, morphology, rate of proliferation, surface marker expression, levels of cytokine secretion or differentiation capacity.

CONCLUSIONS

Derivation of UCMSCs by explantation after thawing UC cryopreserved as a composite tissue may be favorable in terms of initial purity and number of cells achievable by a specific passage. However, we observed no evidence of functional difference between UCMSCs derived by explanation or digestion, suggesting that cells isolated from cryopreserved material obtained by either method maintain their therapeutic properties.

Intravenously delivered mesenchymal stem cells prevent microvascular obstruction formation after myocardial ischemia/reperfusion injury

Microvascular obstruction (MVO) after primary percutaneous coronary intervention (pPCI) is identified as an independent risk factor for poor prognosis in patients with acute myocardial infarction (AMI). The inflammatory response induced by ischemia and reperfusion (I/R) injury is considered one of the main mechanisms of MVO. Mesenchymal stem cells (MSCs) are a unique stromal cell type that confers an immunomodulatory effect in cardiac disease. The present study aimed to investigate whether immediate intravenous delivery of MSCs could be used as a potential therapeutic method to attenuate MVO formation. A cardiac catheterization-induced porcine model of myocardial I/R injury was established, and allograft MSCs were immediately delivered intravenously. Cardiac magnetic resonance (CMR) imaging was performed on days 2 and 7 after the operation to determine the infarct area, MVO, and cardiac function. The pigs with allograft MSCs showed decreased MVO and infarct size, as well as an improved left ventricular ejection fraction (LVEF). Histological analysis revealed decreased myocyte area, fibrosis, and inflammatory cell infiltration in the peri-infarct zone of pigs with allograft MSCs. Moreover, the concentrations of interleukin-1β (IL-1β), interleukin-6 (IL-6) and C-reactive protein (CRP) in the serum were reduced in the allograft MSC group compared to the control group. Flow cytometry indicated decreased natural killer (NK) cells in the peripheral blood and ischemic heart tissue in the pigs with allograft MSCs. In summary, allograft MSCs delivered intravenously and immediately after myocardial I/R injury can attenuate MVO formation in a porcine model through a decline in the number of NK cells in the myocardium.

Mesenchymal stem cells rejuvenate cardiac muscle after ischemic injury

Previous studies have shown that transplantation of mesenchymal stem cells (MSCs) enhances myocardial regeneration after myocardial infarction (MI), primarily resulting from the production and release of trophic growth factors and cytokines by MSCs. However, effects of MSCs or a subtype of MSCs on the ageing of injured cardiac muscle cells (CMCs) are limitedly known. Here, we addressed this question. CD146+ MSCs were isolated from total MSCs (tMSCs), and their effects on injured CMCs were assessed. In vivo, transplantation of isogenic CD146+ MSCs into MI-mice increased the proliferation of CMCs and reduced apoptosis of CMCs in a significantly higher degree than transplantation of tMSCs, resulting in significant improvement of the heart function. In vitro, CMCs were co-cultured under hypoxia condition with CD146+MSCs or tMSCs. We found that CD146+MSCs increased the proliferation of CMCs and reduced apoptosis of CMCs in a significantly higher degree, compared to tMSCs, likely resulting from reduction of aging-associated cellular reactive oxygen species in CMCs. Together, these data suggest that MSCs rejuvenate CMCs after ischemic injury and a subtype of MSCs, CD146+ MSCs, appears to have higher potential in coordinating this process.

Improved therapeutics of modified mesenchymal stem cells: an update

Background

Mesenchymal stromal cells (MSCs) have attracted intense interest due to their powerful intrinsic properties of self-regeneration, immunomodulation and multi-potency, as well as being readily available and easy to isolate and culture. Notwithstanding, MSC based therapy suffers reduced efficacy due to several challenges which include unfavorable microenvironmental factors in vitro and in vivo.

Body

In the quest to circumvent these challenges, several modification techniques have been applied to the naïve MSC to improve its inherent therapeutic properties. These modification approaches can be broadly divided into two groups to include genetic modification and preconditioning modification (using drugs, growth factors and other molecules). This field has witnessed great progress and continues to gather interest and novelty. We review these innovative approaches in not only maintaining, but also enhancing the inherent biological activities and therapeutics of MSCs with respect to migration, homing to target site, adhesion, survival and reduced premature senescence. We discuss the application of the improved modified MSC in some selected human diseases. Possible ways of yet better enhancing the therapeutic outcome and overcoming challenges of MSC modification in the future are also elaborated.

Conclusion

The importance of prosurvival and promigratory abilities of MSCs in their therapeutic applications can never be overemphasized. These abilities are maintained and even further enhanced via MSC modifications against the inhospitable microenvironment during culture and transplantation. This is a turning point in MSC-based therapy with promising preclinical studies and higher future prospect.

Amniotic fluid stem cells ameliorate cisplatin-induced acute renal failure through induction of autophagy and inhibition of apoptosis

BACKGROUND

We have recently demonstrated that amniotic fluid stem cells (AFSC) express renal progenitor markers and can be differentiated in vitro into renal lineage cell types, viz, juxtaglomerular and renal proximal tubular epithelial-like cells. Here, we have evaluated the therapeutic efficacy of AFSC in a cisplatin-induced rat model of acute renal failure (ARF) and investigated the underlying mechanisms responsible for their renoprotective effects.

METHODS

ARF was induced in Wistar rats by intra-peritoneal injection of cisplatin (7 mg/kg). Five days after cisplatin injection, rats were randomized into two groups and injected with either AFSC or normal saline intravenously. On days 8 and 12 after cisplatin injection, the blood biochemical parameters, histopathological changes, apoptosis and expression of pro-apoptotic, anti-apoptotic, and autophagy-related proteins in renal tissues were studied in both groups of rats. To further confirm whether the protective effects of AFSC on cisplatin-induced apoptosis were dependent on autophagy, chloroquine, an autophagy inhibitor, was administered by the intra-peritoneal route.

RESULTS

Administration of AFSC in ARF rats resulted in improvement of renal function and attenuation of renal damage as reflected by significant decrease in blood urea nitrogen, serum creatinine levels, tubular cell apoptosis as assessed by Bax/Bcl2 ratio, and expression of the pro-apoptotic proteins, viz, PUMA, Bax, cleaved caspase-3, and cleaved caspase-9, as compared to the saline-treated group. Furthermore, in the AFSC-treated group as compared to the saline-treated group, there was a significant increase in the activation of autophagy as evident by increased expression of LC3-II, ATG5, ATG7, Beclin1, and phospho-AMPK levels with a concomitant decrease in phospho-p70S6K and p62 expression levels. Chloroquine administration led to significant reduction in the anti-apoptotic effects of the AFSC therapy and further deterioration in the renal structure and function caused by cisplatin.

CONCLUSION

AFSC led to amelioration of cisplatin-induced ARF which was mediated by inhibition of apoptosis and activation of autophagy. The protective effects of AFSC were blunted by chloroquine, an inhibitor of autophagy, highlighting that activation of autophagy is an important mechanism of action for the protective role of AFSC in cisplatin-induced renal injury.

Anti-fibrotic mechanisms of exogenously-expanded mesenchymal stromal cells for fibrotic diseases

Most chronic diseases involving inflammation have a fibrotic component that involves remodeling and excess accumulation of extracellular matrix components. Left unchecked, fibrosis leads to organ failure and death. Mesenchymal stromal cells (MSCs) are emerging as a potent cell-based therapy for a wide spectrum of fibrotic conditions due to their immunomodulatory, anti-inflammatory and anti-fibrotic properties. This review provides an overview of known mechanisms by which MSCs mediate their anti-fibrotic actions and in relation to animal models of pulmonary, liver, renal and cardiac fibrosis. Recent MSC clinical trials results in liver, lung, skin, kidney and hearts are discussed and next steps for future MSC-based therapies including pre-activated or genetically-modified cells, or extracellular vesicles are also considered.

Unmodified autologous stem cells at point of care for chronic myocardial infarction

BACKGROUND

Numerous studies investigated cell-based therapies for myocardial infarction (MI). The conflicting results of these studies have established the need for developing innovative approaches for applying cell-based therapy for MI. Experimental studies on animal models demonstrated the potential of fresh, uncultured, unmodified, autologous adipose-derived regenerative cells (UA-ADRCs) for treating acute MI. In contrast, studies on the treatment of chronic MI (CMI; > 4 wk post-MI) with UA-ADRCs have not been published so far. Among several methods for delivering cells to the myocardium, retrograde delivery into a temporarily blocked coronary vein has recently been demonstrated as an effective option.

AIM

To test the hypothesis that in experimentally-induced chronic myocardial infarction (CMI; > 4 wk post-MI) in pigs, retrograde delivery of fresh, uncultured, unmodified, autologous adipose-derived regenerative cells (UA-ADRCs) into a temporarily blocked coronary vein improves cardiac function and structure.

METHODS

The left anterior descending (LAD) coronary artery of pigs was blocked for 180 min at time point T0. Then, either 18 × 10⁶ UA-ADRCs prepared at “point of care” or saline as control were retrogradely delivered via an over-the-wire balloon catheter placed in the temporarily blocked LAD vein 4 wk after T0 (T1). Effects of cells or saline were assessed by cardiac magnetic resonance (CMR) imaging, late gadolinium enhancement CMR imaging, and post mortem histologic analysis 10 wk after T0 (T2).

RESULTS

Unlike the delivery of saline, delivery of UA-ADRCs demonstrated statistically significant improvements in cardiac function and structure at T2 compared to T1 (all values given as mean ± SE): Increased mean LVEF (UA-ADRCs group: 34.3% ± 2.9% at T1 vs 40.4 ± 2.6% at T2, P = 0.037; saline group: 37.8% ± 2.6% at T1 vs 36.2% ± 2.4% at T2, P > 0.999), increased mean cardiac output (UA-ADRCs group: 2.7 ± 0.2 L/min at T1 vs 3.8 ± 0.2 L/min at T2, P = 0.002; saline group: 3.4 ± 0.3 L/min at T1 vs 3.6 ± 0.3 L/min at T2, P = 0.798), increased mean mass of the left ventricle (UA-ADRCs group: 55.3 ± 5.0 g at T1 vs 71.3 ± 4.5 g at T2, P < 0.001; saline group: 63.2 ± 3.4 g at T1 vs 68.4 ± 4.0 g at T2, P = 0.321) and reduced mean relative amount of scar volume of the left ventricular wall (UA-ADRCs group: 20.9% ± 2.3% at T1 vs 16.6% ± 1.2% at T2, P = 0.042; saline group: 17.6% ± 1.4% at T1 vs 22.7% ± 1.8% at T2, P = 0.022).

CONCLUSION

Retrograde cell delivery of UA-ADRCs in a porcine model for the study of CMI significantly improved myocardial function, increased myocardial mass and reduced the formation of scar tissue.

Mutations in ILK, encoding integrin-linked kinase, are associated with arrhythmogenic cardiomyopathy

Arrhythmogenic cardiomyopathy is a genetic heart muscle disorder characterized by fibro-fatty replacement of cardiomyocytes leading to life-threatening ventricular arrhythmias, heart failure, and sudden cardiac death. Mutations in genes encoding cardiac junctional proteins are known to cause about half of cases, while remaining genetic causes are unknown. Using exome sequencing, we identified 2 missense variants (p.H33N and p.H77Y) that were predicted to be damaging in the integrin-linked kinase (ILK) gene in 2 unrelated families. The p.H33N variant was found to be de novo. ILK links integrins and the actin cytoskeleton, and is essential for the maintenance of normal cardiac function. Both of the new variants are located in the ILK ankyrin repeat domain, which binds to the first LIM domain of the adaptor proteins PINCH1 and PINCH2. In silico binding studies proposed that the human variants disrupt the ILK-PINCH complex. Recombinant mutant ILK expressed in H9c2 rat myoblast cells shows aberrant prominent cytoplasmic localization compared to the wild-type. Expression of human wild-type and mutant ILK under the control of the cardiac-specific cmlc2 promotor in zebrafish shows that p.H77Y and p.P70L, a variant previously reported in a dilated cardiomyopathy family, cause cardiac dysfunction and death by about 2-3 weeks of age. Our findings provide genetic and functional evidence that ILK is a cardiomyopathy disease gene and highlight its relevance for diagnosis and genetic counseling of inherited cardiomyopathies.

Silica-coated magnetic nanoparticles labeled endothelial progenitor cells alleviate ischemic myocardial injury and improve long-term cardiac function with magnetic field guidance in rats with myocardial infarction

Low retention of endothelial progenitor cells (EPCs) in the infarct area has been suggested to be responsible for the poor clinical efficacy of EPC therapy for myocardial infarction (MI). This study aimed to evaluate whether magnetized EPCs guided through an external magnetic field could augment the aggregation of EPCs in an ischemia area, thereby enhancing therapeutic efficacy. EPCs from male rats were isolated and labeled with silica‐coated magnetic iron oxide nanoparticles to form magnetized EPCs. Then, the proliferation, migration, vascularization, and cytophenotypic markers of magnetized EPCs were analyzed. Afterward, the magnetized EPCs (1 × 10⁶) were transplanted into a female rat model of MI via the tail vein at 7 days after MI with or without the guidance of an external magnet above the infarct area. Cardiac function, myocardial fibrosis, and the apoptosis of cardiomyocytes were observed at 4 weeks after treatment. In addition, EPC retention and the angiogenesis of ischemic myocardium were evaluated. Labeling with magnetic nanoparticles exhibited minimal influence to the biological functions of EPCs. The transplantation of magnetized EPCs guided by an external magnet significantly improved the cardiac function, decreased infarction size, and reduced myocardial apoptosis in MI rats. Moreover, enhanced aggregations of magnetized EPCs in the infarcted border zone were observed in rats with external magnet‐guided transplantation, accompanied by the significantly increased density of microvessels and upregulated the expression of proangiogenic factors, when compared with non‐external‐magnet‐guided rats. The magnetic field‐guided transplantation of magnetized EPCs was associated with the enhanced aggregation of EPCs in the infarcted border zone, thereby improving the therapeutic efficacy of MI.

ILK promotes survival and self-renewal of hypoxic MSCs via the activation of lncTCF7-Wnt pathway induced by IL-6/STAT3 signaling

Mesenchymal stem cells (MSCs) have been applied in treating various diseases including myocardial infarction (MI) and achieved a bit of success; however, the decreased survival rate of MSCs after transplantation greatly limited the efficacy for cell therapy. How to improve the MSC survival rate in stem cell transplantation has undoubtedly become urgent and genetic engineering may be an ideal and feasible way. In this study, we explored the effects on MSCs survival and self-renewal by overexpression of integrin-linked kinase (ILK) in MSCs under hypoxic stimulation and aimed to reveal the molecular mechanisms from the point of paracrine function of MSCs. We first found that overexpression of ILK induced the expression and secretion of IL-6 increased significantly in MSCs under hypoxic stimulation, and the survival and self-renewal of MSCs exposed to hypoxia were enhanced after ILK overexpression. Then the activation of JAK2/STAT3 signaling was detected because of the increased IL-6, and an lncRNA, named lncTCF7, was upregulated remarkably, promoting the activation of Wnt pathway that was required for keeping cell viability and stemness of MSCs. Moreover, we further verified that inhibition of STAT3 signaling by WP1066 and silencing lncTCF7 expression eliminated the protective effects of ILK overexpression on cell survival and self-renewal of MSCs under hypoxic sitmulation. In conclusion, our results uncovered a novel function of ILK to promote MSC survival and self-renewal, suggesting more application potentials of MSC cell therapy on MI.

Renogenic characterization and in vitro differentiation of rat amniotic fluid stem cells into renal proximal tubular- and juxtaglomerular-like cells

The aim of the present study was to investigate the renogenic characteristics of amniotic fluid stem cells (AFSCs) and to evaluate their in vitro differentiation potential into renal proximal tubular-like cells and juxtaglomerular-like cells. We culture expanded AFSCs derived from rat amniotic fluid. The AFSCs grew as adherent spindle-shaped cells and expressed mesenchymal markers CD73, CD90, and CD105 as well as renal progenitor markers WT1, PAX2, SIX2, SALL1, and CITED1. AFSCs exhibited an in vitro differentiation potential into renal proximal tubular epithelial-like cells, as shown by the upregulation of expression of proximal tubular cell-specific genes like AQP1, CD13, PEPT1, GLUT5, OAT1, and OCT1. AFSCs could also be differentiated into juxtaglomerular-like cells as demonstrated by the expression of renin and α-SMA. The AFSCs also expressed pluripotency markers OCT4, NANOG, and SOX2 and could be induced into embryoid bodies with differentiation into all the three germ layers, highlighting the pluripotent nature of these cells. Our results show that amniotic fluid contains a population of primitive stem cells that express renal-progenitor markers and also possess the propensity to differentiate into two renal lineage cell types and, thus, may have a therapeutic potential in renal regenerative medicine.

Effect of transplantation of cardiac stem cells overexpressing integrin-linked kinase on cardiac function of rats with acute myocardial infarction

In the present study, we aimed to investigate the effect of transplantation of cardiac stem cells (CSCs) overexpressing integrin-linked kinase (ILK) on cardiac function of rats with acute myocardial infarction (MI). A total of 60 rats were randomly divided into normal saline (NS) group (n=20), green fluorescent protein (GFP)-CSC group (n=20) and ILK-CSC group (n=20). In the ILK-CSC group, CSCs in rats were transfected with GFP adenovirus vector overexpressing ILK. The rat model of MI was established. The cardiac function 4 weeks after transplantation was detected via echocardiography, and the exhaustive swimming experiment was performed to observe the exercise load capacity. Moreover, Ki-67 and P-H3 proteins in myocardial tissues of rats were detected via immunohistochemistry, and the expression of GFP was observed under a fluorescence microscope. Cells in the GFP-CSC group were transfected with the empty GFP adenovirus, while those in NS group were not transfected, and other treatments in these two groups were the same as those in the ILK-CSC group. Four weeks after transplantation, left ventricular end-systolic diameter (LVESD) and left ventricular end-diastolic diameter (LVEDD) of rats in the ILK-CSC group were smaller than those in the GFP-CSC group, but left ventricular ejection fraction (LVEF) (69.88±5.61 mm) was higher than that in the GFP-CSC group (P<0.05). The exercise time in the ILK-CSC group (12.69±0.58 min) was longer than that in the GFP-CSC and NS groups (P<0.05). The expression levels of Ki-67 and P-H3 proteins in myocardial cells of rats in the ILK-CSC group were higher than those in the GFP-CSC and NS groups (P<0.05). The number of transplanted cells retained around the infarct region in the ILK-CSC group 3 days after transplantation was obviously larger than that in the GFP-CSC group (P<0.001). Intramyocardial injection of CSCs overexpressing ILK immediately after the establishment of rat model of MI can promote myocardial cell proliferation, improve cardiac function and increase exercise capacity of rats.

Cardiac shock wave therapy promotes arteriogenesis of coronary micrangium, and ILK is involved in the biomechanical effects by proteomic analysis

Cardiac Shock Wave Therapy (CSWT) improves myocardial perfusion and ameliorates cardiac remodeling after acute myocardial infarction (AMI), but the precise mechanisms remain obscure. Herein, we have applied CSWT to a rat model of AMI to demonstrate the arteriogenesis of coronary micrangium and protein expression changes in ischemic myocardium after CSWT. Four weeks after CSWT, the fraction shortening of rats was improved greatly and the cardiomyocyte apoptosis index was significantly lower than the AMI group (P < 0.05). Besides, the fibrotic area was markedly decreased in the CSWT group. In the infarction border zone, the thickness of smooth muscle layer was expanded apparently after CSWT. Label-free quantitative proteomic analysis and bioinformatics analysis revealed that the differentially expressed proteins were largely enriched in the focal adhesion signaling pathway. And integrin linked kinase (ILK) may be a key factor contributed to arteriogenesis of coronary micrangium during CSWT. In conclusion, non-invasive cardiac shock wave could promote arteriogenesis of coronary micrangium and alleviate myocardial apoptosis and fibrosis after AMI. Furthermore, focal adhesion signaling pathway may have a central role in the related signal network and ILK was closely related to the arteriogenesis of coronary micrangium during CSWT.

Molecular imaging in stem cell-based therapies of cardiac diseases

In the past 15years, despite that regenerative medicine has shown great potential for cardiovascular diseases, the outcome and safety of stem cell transplantation has shown controversial results in the published literature. Medical imaging might be useful for monitoring and quantifying transplanted cells within the heart and to serially characterize the effects of stem cell therapy of the myocardium. From the multiple available noninvasive imaging techniques, magnetic resonance imaging and nuclear imaging by positron (PET) or single photon emission computer tomography (SPECT) are the most used clinical approaches to follow the fate of transplanted stem cells in vivo. In this article, we provide a review on the role of different noninvasive imaging modalities and discuss their advantages and disadvantages. We focus on the different in-vivo labeling and reporter gene imaging strategies for stem cell tracking as well as the concept and reliability to use imaging parameters as noninvasive surrogate endpoints for the evaluation of the post-therapeutic outcome.

Improvement of therapeutic effects of mesenchymal stem cells in myocardial infarction through genetic suppression of microRNA-142

Transplanted mesenchymal stem cells (MSCs) have been shown to contribute to myocardial repair after myocardial infarction (MI), primarily through production and secretion some growth factors and cytokines related to cell survival and regeneration. Further improvement of the therapeutic potential of MSCs appears to be an attractive strategy for MI treatment. CXC chemokine receptor (CXCR) 7 is the receptor for stromal cell-derived factor-1 (SDF-1), an important chemokine that is essential for tissue repair and angiogenesis. SDF-1/CXCR7 axis plays a critical role in the mobilization, recruitment and function of MSCs during tissue regeneration. Here, we depleted miR-142 that targets CXCR7 in MSCs cells through expression of antisense of miR-142, resulting in enhanced expression of CXCR7 in these miR-142-depleted MSCs (md-MSCs). In vitro, presence of md-MSCs reduced hypoxia-induced cardiac muscle cell apoptosis in a more pronounced manner than MSCs. In vivo, compared to transplantation of MSCs, transplantation of md-MSCs further enhanced cardiac re-vascularization and further improved cardiac functions after MI in mice. Together, our data suggest that depletion of miR-142 in MSCs may improve their therapeutic effects on MI.

Tuning of major signaling networks (TGF-β, Wnt, Notch and Hedgehog) by miRNAs in human stem cells commitment to different lineages: Possible clinical application

Two distinguishing characteristics of stem cells, their continuous division in the undifferentiated state and growth into any cell types, are orchestrated by a number of cell signaling pathways. These pathways act as a niche factor in controlling variety of stem cells. The core stem cell signaling pathways include Wingless-type (Wnt), Hedgehog (HH), and Notch. Additionally, they critically regulate the self-renewal and survival of cancer stem cells. Conversely, stem cells' main properties, lineage commitment and stemness, are tightly controlled by epigenetic mechanisms such as DNA methylation, histone modifications and non-coding RNA-mediated regulatory events. MicroRNAs (miRNAs) are cellular switches that modulate stem cells outcomes in response to diverse extracellular signals. Numerous scientific evidences implicating miRNAs in major signal transduction pathways highlight new crosstalks of cellular processes. Aberrant signaling pathways and miRNAs levels result in developmental defects and diverse human pathologies. This review discusses the crosstalk between the components of main signaling networks and the miRNA machinery, which plays a role in the context of stem cells development and provides a set of examples to illustrate the extensive relevance of potential novel therapeutic targets.

Intracoronary Administration of Allogeneic Adipose Tissue-Derived Mesenchymal Stem Cells Improves Myocardial Perfusion But Not Left Ventricle Function, in a Translational Model of Acute Myocardial Infarction

BACKGROUND

Autologous adipose tissue-derived mesenchymal stem cells (ATMSCs) therapy is a promising strategy to improve post-myocardial infarction outcomes. In a porcine model of acute myocardial infarction, we studied the long-term effects and the mechanisms involved in allogeneic ATMSCs administration on myocardial performance.

METHODS AND RESULTS

Thirty-eight pigs underwent 50 minutes of coronary occlusion; the study was completed in 33 pigs. After reperfusion, allogeneic ATMSCs or culture medium (vehicle) were intracoronarily administered. Follow-ups were performed at short (2 days after acute myocardial infarction vehicle-treated, n=10; ATMSCs-treated, n=9) or long term (60 days after acute myocardial infarction vehicle-treated, n=7; ATMSCs-treated, n=7). At short term, infarcted myocardium analysis showed reduced apoptosis in the ATMSCs-treated animals (48.6±6% versus 55.9±5.7% in vehicle; P=0.017); enhancement of the reparative process with up-regulated vascular endothelial growth factor, granulocyte macrophage colony-stimulating factor, and stromal-derived factor-1α gene expression; and increased M2 macrophages (67.2±10% versus 54.7±10.2% in vehicle; P=0.016). In long-term groups, increase in myocardial perfusion at the anterior infarct border was observed both on day-7 and day-60 cardiac magnetic resonance studies in ATMSCs-treated animals, compared to vehicle (87.9±28.7 versus 57.4±17.7 mL/min per gram at 7 days; P=0.034 and 99±22.6 versus 43.3±14.7 22.6 mL/min per gram at 60 days; P=0.0001, respectively). At day 60, higher vascular density was detected at the border zone in the ATMSCs-treated animals (118±18 versus 92.4±24.3 vessels/mm2 in vehicle; P=0.045). Cardiac magnetic resonance-measured left ventricular ejection fraction of left ventricular volumes was not different between groups at any time point.

CONCLUSIONS

In this porcine acute myocardial infarction model, allogeneic ATMSCs-based therapy was associated with increased cardioprotective and reparative mechanisms and with better cardiac magnetic resonance-measured perfusion. No effect on left ventricular volumes or ejection fraction was observed.

Cardiac repair in a mouse model of acute myocardial infarction with trophoblast stem cells

Various stem cells have been explored for the purpose of cardiac repair. However, any individual stem cell population has not been considered as the ideal source. Recently, trophoblast stem cells (TSCs), a newly described stem cell type, have demonstrated extensive plasticity. The present study evaluated the therapeutic effect of TSCs transplantation for heart regeneration in a mouse model of myocardial infarction (MI) and made a direct comparison with the most commonly used mesenchymal stem cells (MSCs). Transplantation of TSCs and MSCs led to a remarkably improved cardiac function in contrast with the PBS control, but only the TSCs exhibited the potential of differentiation into cardiomyocytes in vivo. In addition, a significantly high proliferation level of both transplanted stem cells and resident cardiomyocytes was observed in the TSCs group. These findings primary revealed the therapeutic potential of TSCs in transplantation therapy for MI.