Cardiac stem cell therapy to modulate inflammation upon myocardial infarction

Background

After myocardial infarction (MI) a local inflammatory reaction clears the damaged myocardium from dead cells and matrix debris at the onset of scar formation. The intensity and duration of this inflammatory reaction are intimately linked to post-infarct remodeling and cardiac dysfunction. Strikingly, treatment with standard anti-inflammatory drugs worsens clinical outcome, suggesting a dual role of inflammation in the cardiac response to injury. Cardiac stem cell therapy with different stem or progenitor cells, e.g. mesenchymal stem cells (MSC), was recently found to have beneficial effects, mostly related to paracrine actions. One of the suggested paracrine effects of cell therapy is modulation of the immune system.

Scope of review

MSC are reported to interact with several cells of the immune system and could therefore be an excellent means to reduce detrimental inflammatory reactions and promote the switch to the healing phase upon cardiac injury. This review focuses on the potential use of MSC therapy for post-MI inflammation. To understand the effects MSC might have on the post-MI heart the cellular and molecular changes in the myocardium after MI need to be understood.

Major conclusions

By studying the general pathways involved in immunomodulation, and examining the interactions with cell types important for post-MI inflammation, it becomes clear that MSC treatment might provide a new therapeutic opportunity to improve cardiac outcome after acute injury.

General significance

Using stem cells to target the post-MI inflammation is a novel therapy which could have considerable clinical implications. This article is part of a Special Issue entitled Biochemistry of Stem Cells.     

The safety and efficacy of mesenchymal stem cell therapy in diabetic lower extremity vascular disease: a meta-analysis and systematic review

Background aimsSeveral studies have shown the efficacy of mesenchymal stem cell (MSC) therapy for lower extremity vascular disease (LEVD) in diabetic patients, but the results are not consistent. Therefore, the authors conducted a meta-analysis of randomized controlled trials (RCTs) to examine the safety and efficacy of MSC therapy in diabetic patients with LEVD.MethodsEight available databases were searched in both English and Chinese to identify RCTs comparing MSC therapy-based conventional treatment with conventional treatment alone in diabetic patients with LEVD. Three investigators independently screened the literature, extracted the data and assessed the risk bias. Meta-analysis was performed using RevMan 5.4.1 and Stata 14.0.ResultsA total of 10 studies involving 453 patients were included. Compared with conventional treatment only, patients receiving MSC therapy-based conventional treatment had a higher ulcer healing rate, greater number of reduced ulcers and shorter complete healing time. MSC therapy also increased ankle–brachial index and transcutaneous oxygen pressure. In addition, four of the included studies showed that MSC therapy significantly improved the number of new collateral vessels. Moreover, no more adverse events were recorded in the MSC group.ConclusionsThis meta-analysis suggests that MSC therapy promotes ulcer healing in diabetic LEVD patients with ulcers, improves blood supply and has a favorable safety profile. More large and well-designed RCTs with long-term follow-up are still needed to explore the safety and efficacy of MSC therapy in diabetic patients with LEVD.     

Substrate Stiffness and Oxygen as Regulators of Stem Cell Differentiation during Skeletal Tissue Regeneration: A Mechanobiological Model

Extrinsic mechanical signals have been implicated as key regulators of mesenchymal stem cell (MSC) differentiation. It has been possible to test different hypotheses for mechano-regulated MSC differentiation by attempting to simulate regenerative events such as bone fracture repair, where repeatable spatial and temporal patterns of tissue differentiation occur. More recently, in vitro studies have identified other environmental cues such as substrate stiffness and oxygen tension as key regulators of MSC differentiation; however it remains unclear if and how such cues determine stem cell fate in vivo. As part of this study, a computational model was developed to test the hypothesis that substrate stiffness and oxygen tension regulate stem cell differentiation during fracture healing. Rather than assuming mechanical signals act directly on stem cells to determine their differentiation pathway, it is postulated that they act indirectly to regulate angiogenesis and hence partially determine the local oxygen environment within a regenerating tissue. Chondrogenesis of MSCs was hypothesized to occur in low oxygen regions, while in well vascularised regions of the regenerating tissue a soft local substrate was hypothesised to facilitate adipogenesis while a stiff substrate facilitated osteogenesis. Predictions from the model were compared to both experimental data and to predictions of a well established computational mechanobiological model where tissue differentiation is assumed to be regulated directly by the local mechanical environment. The model predicted all the major events of fracture repair, including cartilaginous bridging, endosteal and periosteal bony bridging and bone remodelling. It therefore provides support for the hypothesis that substrate stiffness and oxygen play a key role in regulating MSC fate during regenerative events such as fracture healing.     

Rotator cuff tears: what have we learned from animal models?

Rotator cuff tendon tears are among the most common soft tissue injuries that occur at the shoulder. Despite advancements in surgical repair techniques, rotator cuff repairs experience a high rate of failure. The common occurrence of tears and the frequency of re-tears require a further understanding of the mechanisms associated with injuries, healing, and regeneration of the rotator cuff. This paper reviews in vivo studies using the various animal shoulder models of the rat, rabbit, sheep, canine, and primate. These animal models have been used to study intrinsic and extrinsic factors leading to shoulder degeneration, various suture techniques, effects of post-surgical treatment, numerous biologic and synthetic scaffolds, and an assortment of biologic augmentations used to accelerate healing. These effects can be examined in a controlled manner using animal models without other confounding factors that sometimes limit clinical studies. The clinically impactful results will be explained to highlight the specific knowledge gained from using animal models in rotator cuff research.     

Peripheral Blood Mononuclear Cells Enhance Cartilage Repair in in vivo Osteochondral Defect Model

This study characterized peripheral blood mononuclear cells (PBMC) in terms of their potential in cartilage repair and investigated their ability to improve the healing in a pre-clinical large animal model. Human PBMCs were isolated with gradient centrifugation and adherent PBMC’s were evaluated for their ability to differentiate into adipogenic, chondrogenic and osteogenic lineages and also for their expression of musculoskeletal genes. The phenotype of the PBMCs was evaluated using Stro-1, CD34, CD44, CD45, CD90, CD106, CD105, CD146 and CD166 cell surface markers. Osteochondral defects were created in the medial femoral condyle (MFC) of 24 Welsh mountain sheep and evaluated at a six month time point. Four cell treatment groups were evaluated in combination with collagen-GAG-scaffold: (1) MSC alone; (2) MSCs and PBMCs at a ratio of 20:1; (3) MSCs and PBMC at a ratio of 2:1 and (4) PBMCs alone. Samples from the surgical site were evaluated for mechanical properties, ICRS score and histological repair. Fresh PBMC samples were 90% positive for hematopoietic cell surface markers and negative for the MSC antibody panel (<1%, p = 0.006). However, the adherent PBMC population expressed mesenchymal stem cell markers in hypoxic culture and lacked CD34/45 positive cells (<0.2%). This finding demonstrated that the adherent cells had acquired an MSC-like phenotype and transformed in hypoxia from their original hematopoietic lineage. Four key genes in muskuloskeletal biology were significantly upregulated in adherent PBMCs by hypoxia: BMP2 4.2-fold (p = 0.0007), BMP6 10.7-fold (p = 0.0004), GDF5 2.0-fold (p = 0.002) and COL1 5.0-fold (p = 0.046). The monolayer multilineage analysis confirmed the trilineage mesenchymal potential of the adherent PBMCs. PBMC cell therapy was equally good as bone marrow MSC therapy for defects in the ovine large animal model. Our results show that PBMCs support cartilage healing and oxygen tension of the environment was found to have a key effect on the derivation of a novel adherent cell population with an MSC-like phenotype. This study presents a novel and easily attainable point-of-care cell therapy with PBMCs to treat osteochondral defects in the knee avoiding any cell manipulations outside the surgical room.     

Stem cell therapies in tendon-bone healing

Tendon-bone insertion injuries such as rotator cuff and anterior cruciate ligament injuries are currently highly common and severe. The key method of treating this kind of injury is the reconstruction operation. The success of this reconstructive process depends on the ability of the graft to incorporate into the bone. Recently, there has been substantial discussion about how to enhance the integration of tendon and bone through biological methods. Stem cells like bone marrow mesenchymal stem cells (MSCs), tendon stem/progenitor cells, synovium-derived MSCs, adipose-derived stem cells, or periosteum-derived periosteal stem cells can self-regenerate and potentially differentiate into different cell types, which have been widely used in tissue repair and regeneration. Thus, we concentrate in this review on the current circumstances of tendon-bone healing using stem cell therapy.     

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.     

间充质干细胞的来源及其对肝脏损伤及修复的研究进展

全球终末期肝病、肝衰竭的发病率和死亡率逐年升高,且目前肝移植是唯一疗效确切的治疗选择,但是,肝移植的使用受到肝源供体严重不足,长期存活率低,医疗费用昂贵等缺点使得原位肝移植的应用受限,绝大多数患者无法受益。为了克服肝脏器官短缺,干细胞替代治疗策略逐渐成为另一个肝病治疗的重要选择,干细胞治疗,特别是间充质干细胞（MSC）提供了一个新的肝病治疗选择。MSC是一群贴壁生长的成纤维细胞样细胞,由于MSC能够分化为多种类型的细胞,能够产生多种的细胞因子和生长因子,具有造血支持和免疫调节和抗炎功能,MSC被认为在再生医学领域具有重大的科学和实用价值。另外,由于MSC应用于治疗实验性肝损伤能明显提高动物存活率,明显改善肝功能。此外,一些临床前研究和临床研究也表明MSC对肝损伤性疾病具有显著地疗效。因此MSC在损伤性和退行性肝脏疾病的治疗具有广阔的应用前景。本文综述了MSC在肝损伤疾病治疗应用的进展,并对MSC在肝病治疗中的应用前景进行了展望。     

Heterogeneity of mesenchymal stromal cell preparations

As an archetype of human adult stem cells that can readily be harvested, enriched and expanded in vitro, mesenchymal stromal cells (MSC) have been reported to be of significance for regenerative medicine. The literature is replete with reports on their developmental potentials in pre-clinical model systems. Different preparative protocols have been shown to yield MSC-like cell cultures or even cell lines, from starting materials as diverse as bone marrow, fat tissue, fetal cord blood and peripheral blood. However, MSC are still ill-defined by physical, phenotypic and functional properties. The quality of preparations from different laboratories varies tremendously and the cell products are notoriously heterogeneous. The source and freshness of the starting material, culture media used, presence of animal sera, cytokines, cell density, number of passages upon culture, etc., all have a significant impact on the (1) cell type components and heterogeneity of the initial population, (2) differential expansion of specific subsets, with different potentials of the end products, and (3) long-term functional fate of MSC as well as other types of progenitor cells that are co-cultivated with them. Consequently, there is an urgent need for the development of reliable reagents, common guidelines and standards for MSC preparations and of precise molecular and cellular markers to define subpopulations with diverse pathways of differentiation and divergent potentials.     

The generation of three-dimensional tissue structures with mesenchymal stem cells

Mesenchymal stem cells (MSCs) are multipotent stem cells, found in the bone-marrow and other adult tissues, which give rise to various cell lineages. Although MSCs are biologically important, and may have widespread therapeutic potential, they are not well-characterised, particularly in terms of their cell surface receptors and in vivo phenotype. We aimed to develop a three-dimensional (3-D) MSC in vitro model, in order to understand the factors involved in the regulation of lineage specification routes. A suitable model, which replicates the MSC microenvironment as accurately as possible, will allow more detailed investigations into the phenotype of the cells. Our MSC spheroids appear to have an enhanced mesenchymal differentiation compared to two-dimensional MSC monolayers. With this in vitro system, it is possible to perform real-time analysis of cellular differentiation status. MSC spheroids may also be amenable for use in high-throughput assays. A more-recent research project aims to generate knockout micro-tissues, based on human 3-D MSCs, as an alternative to animal studies.     

Fibrin glue as the cell-delivery vehicle for mesenchymal stromal cells in regenerative medicine

The use of tissue-engineering techniques such as stem-cell therapy to renew injured tissues is a promising strategy in regenerative medicine. As a cell-delivery vehicle, fibrin glues (FG) facilitate cell attachment, growth and differentiation and, ultimately, tissue formation and organization by its three-dimensional structure. Numerous studies have provided evidence that stromal cells derived from bone marrow (bone marrow stromal cells; BMSC) and adipose tissue (adipose-derived stromal cells; ADSC) contain a population of adult multipotent mesenchymal stromal cells (MSC) and endothelial progenitor cells that can differentiate into several lineages. By combining MSC with FG, the implantation could take advantage of the mutual benefits. Researchers and physicians have pinned their hopes on stem cells for developing novel approaches in regenerative medicine. This review focuses on the therapeutic potential of MSC with FG in bone defect reconstruction, cartilage and tendon injury repair, ligament, heart and nerve regeneration, and, furthermore, wound healing.     

Multilineage potential of stable human mesenchymal stem cell line derived from fetal marrow

Human bone marrow contains two major cell types, hematopoietic stem cells (HSCs) and mesenchymal stem cells (MSCs). MSCs possess self-renewal capacity and pluripotency defined by their ability to differentiate into osteoblasts, chondrocytes, adipocytes and muscle cells. MSCs are also known to differentiate into neurons and glial cells in vitro, and in vivo following transplantation into the brain of animal models of neurological disorders including ischemia and intracerebral hemorrhage (ICH) stroke. In order to obtain sufficient number and homogeneous population of human MSCs, we have clonally isolated permanent and stable human MSC lines by transfecting primary cell cultures of fetal human bone marrow MSCs with a retroviral vector encoding v-myc gene. One of the cell lines, HM3.B10 (B10), was found to differentiate into neural cell types including neural stem cells, neurons, astrocytes and oligodendrocytes in vitro as shown by expression of genetic markers for neural stem cells (nestin and Musashi1), neurons (neurofilament protein, synapsin and MAP2), astrocytes (glial fibrillary acidic protein, GFAP) and oligodendrocytes (myelin basic protein, MBP) as determined by RT-PCR assay. In addition, B10 cells were found to differentiate into neural cell types as shown by immunocytochical demonstration of nestin (for neural stem cells), neurofilament protein and beta-tubulin III (neurons) GFAP (astrocytes), and galactocerebroside (oligodendrocytes). Following brain transplantation in mouse ICH stroke model, B10 human MSCs integrate into host brain, survive, differentiate into neurons and astrocytes and induce behavioral improvement in the ICH animals. B10 human MSC cell line is not only a useful tool for the studies of organogenesis and specifically for the neurogenesis, but also provides a valuable source of cells for cell therapy studies in animal models of stroke and other neurological disorders.     

Melatonin preconditioning is an effective strategy for mesenchymal stem cell‐based therapy for kidney disease

Based on multiple studies in animal models, mesenchymal stem cell (MSC)‐based therapy appears to be an innovative intervention approach with tremendous potential for the management of kidney disease. However, the clinical therapeutic effects of MSCs in either acute kidney injury (AKI) or chronic kidney disease (CKD) are still under debate. Hurdles originate from the harsh microenvironment in vivo that decreases the cell survival rate, paracrine activity and migratory capacity of MSCs after transplantation, which are believed to be the main reasons for their limited effects in clinical applications. Melatonin is traditionally regarded as a circadian rhythm‐regulated neurohormone but in recent years has been found to exhibit antioxidant and anti‐inflammatory properties. Because inflammation, oxidative stress, thermal injury, and hypoxia are abnormally activated in kidney disease, application of melatonin preconditioning to optimize the MSC response to the hostile in vivo microenvironment before transplantation is of great importance. In this review, we discuss current knowledge concerning the beneficial effects of melatonin preconditioning in MSC‐based therapy for kidney disease. By summarizing the available information and discussing the underlying mechanisms, we aim to improve the therapeutic effects of MSC‐based therapy for kidney disease and accelerate translation to clinical application.     

MSC attenuate diabetes-induced functional impairment in adipocytes via secretion of insulin-like growth factor-1

The function of subcutaneous adipocytes in promoting wound healing is significantly suppressed in diabetic wounds. Recent studies have demonstrated the ability of mesenchymal stem cell (MSC) to ameliorate impaired diabetic wound healing. We hypothesized that MSC function may involve subcutaneous adipocytes. The abnormal function of subcutaneous adipocytes from STZ induced diabetic mice including glucose uptake and free fatty acid (FFA) secretion level were assessed. Then these cells were co-cultured with MSC via a transwell system to observe the changes of metabolic index and glucose transporter four (GLUT4) as well as phosphoinositide 3-kinase/protein kinase (PI3K/AKT) signaling pathway expression. The results of metabolic index suggest that MSC obviously attenuated the diabetes-induced functional impairment. Both mRNA and protein expression analyses showed that PI3K/AKT insulin signaling pathway and GLUT4 expression were up-regulated. These changes were substantially associated with a increased level of insulin-like growth factor-1 (IGF-1) secretion from MSC. These findings suggest that MSC could attenuate abnormal function of diabetic adipocytes by IGF-1secretion, which was more or less associated with the beneficial effects of MSC on improving diabetic wound healing.     

Mesenchymal stem cells: biological characteristics and potential clinical applications

Mesenchymal stem cells (MSC) are clonogenic, non-hematpoietic stem cells present in the bone marrow and are able to differentiate into multiple mesoderm-type cell lineages, for example, osteoblasts, chondrocytes, endothelial-cells and also non-mesoderm-type lineages, for example, neuronal-like cells. Several methods are currently available for isolation of the MSC based on their physical and physico-chemical characteristics, for example, adherence to plastics or other extracellular matrix components. Because of the ease of their isolation and their extensive differentiation potential, MSC are among the first stem cell types to be introduced in the clinic. Several studies have demonstrated the possible use of MSC in systemic transplantation for systemic diseases, local implantation for local tissue defects, as a vehicle for genes in gene therapy protocols or to generate transplantable tissues and organs in tissue engineering protocols. Before their widespread use in therapy, methods allowing the generation of large number of cells without affecting their differentiation potential as well as technologies that overcome immunological rejection (in case allogenic transplantation) must be developed.     

Mesenchymal stem cell‐derived exosomes ameliorate erection by reducing oxidative stress damage of corpus cavernosum in a rat model of artery injury

Erectile dysfunction (ED) is a common ageing male's disease, and vascular ED accounts for the largest proportion of all types of ED. One of the mechanisms of vascular ED in the clinic is arterial insufficiency, which mainly caused by atherosclerosis, trauma and surgical. Moreover, oxidative stress damage after tissue ischemia usually aggravated the progress of ED. As a new way of acellular therapy, mesenchymal stem cell‐derived exosomes (MSC‐Exos) have great potential in ED treatment. In the current study, we have explored the mechanism of MSC‐Exos therapy in a rat model of internal iliac artery injury‐induced ED. Compared with intracavernous (IC) injection of phosphate‐buffered saline after artery injury, of note, we observed that both mesenchymal stem cells (MSCs) and MSC‐Exos through IC injection could improve the erectile function to varying degrees. More specifically, IC injection MSC‐Exos could promote cavernous sinus endothelial formation, reduce the organization oxidative stress damage, and improve the nitric oxide synthase and smooth muscle content in the corpus cavernosum. With similar potency compared with the stem cell therapy and other unique advantages, IC injection of MSC‐ Exos could be an effective treatment to ameliorate erectile function in a rat model of arterial injury.     

WJSC 6th Anniversary Special Issues（2）:Mesenchymal stem cells Neurotrauma and mesenchymal stem cells treatment:From experimental studies to clinical trials

Mesenchymal stem cell(MSC)therapy has attracted the attention of scientists and clinicians around the world.Basic and pre-clinical experimental studies have highlighted the positive effects of MSC treatment after spinal cord and peripheral nerve injury.These effects are believed to be due to their ability to differentiate into other cell lineages,modulate inflammatory and immunomodulatory responses,reduce cell apoptosis,secrete several neurotrophic factors and respond to tissue injury,among others.There are many pre-clinical studies on MSC treatment for spinal cord injury(SCI)and peripheral nerve injuries.However,the same is not true for clinical trials,particularly those concerned with nerve trauma,indicating the necessity of more well-constructed studies showing the benefits that cell therapy can provide for individuals suffering the consequences of nerve lesions.As for clinical trials for SCI treatment the results obtained so far are not as beneficial as those described in experimental studies.For these reasons basic and pre-clinical studies dealing with MSC therapy should emphasize the standardization of protocols that could be translated to the clinical set with consistent and positive outcomes.This review is based on pre-clinical studies and clinical trials available in the literature from 2010 until now.At the time of writing this article there were 43 and 36 pre-clinical and 19 and 1 clinical trials on injured spinal cord and peripheral nerves,respectively.     

Mesenchymal stromal cells from umbilical cord blood

Mesenchymal Stromal Cells (MSC) are key candidates for cellular therapies. Although most therapeutic applications have focused on adult bone marrow derived MSC, increasing evidence suggests that MSC are present within a wide range of tissues. Umbilical cord blood (CB) has been proven to be a valuable source of hematopoietic stem cells, but its therapeutic potential extends beyond the hematopoietic component suggesting regenerative potential in solid organs as well. There is evidence that other stem or progenitor populations, such as MSC, exist in CB which might be responsible for these effects. Many different stem and progenitor cell populations have been postulated with potential ranging from embryonic like to lineage-committed progenitor cells. Based on the confusing data, this review focuses on a human CB derived, plastic adherent fibroblastoid population expressing similar characteristics to bone marrow derived MSC. It concentrates especially on concepts of isolation and expansion, comparing the phenotype with bone marrow derived MSC, describing the differentiation capacity and finally in the last the therapeutic potential with regard to regenerative medicine, stromal support, immune modulation and gene therapy.