Dinitrophenol modulates gene expression levels of angiogenic, cell survival and cardiomyogenic factors in bone marrow derived mesenchymal stem cells

Chemical Hypoxic Preconditioning Improves Survival and Proliferation of Mesenchymal Stem Cells

Increasing evidence has demonstrated that mesenchymal stem cells (MSCs) have been linked to tissue regeneration both in vitro and in vivo. However, poor engraftment and low survival rate of transplanted MSCs are still a major concern. It has been found that the proliferation, survival, and migration of MSCs are all increased by hypoxic preconditioning. However, the molecular mechanism through which hypoxic preconditioning enhances these beneficial properties of MSCs remains to be fully investigated. Therefore, the present study is aimed to investigate the mechanism by which hypoxic preconditioning enhances the survival of MSCs. We used proteomic analysis to explore the molecules that may contribute to the survival and proliferation of hypoxic preconditioned (HP) MSCs. The analysis revealed a higher expression of prelamin A/C (Lmna), glutamate dehydrogenase 1(Glud1), Actin, cytoplasmic 1(Actb), Alpha-enolase (Eno1), Glucose-6-phosphate 1-dehydrogenase (G6pd), Protein disulfide-isomerase A3 (Pdia3), Malate dehydrogenase (Mdh1), Peroxiredoxin-6 (Prdx6), Superoxide dismutase (Sod1), and Annexin A2 (Anxa2) in HP-MSCs. These proteins are possibly involved in cellular survival and proliferation through various cellular pathways. This research could aid in understanding the processes involved in hypoxic preconditioning of MSCs and designing of cell-based therapeutic strategies for tissue regeneration.

Angiogenesis induction as a key step in cardiac tissue Regeneration: From angiogenic agents to biomaterials

Cardiovascular diseases are the leading cause of death worldwide. After myocardial infarction, the vascular supply of the heart is damaged or blocked, leading to the formation of scar tissue, followed by several cardiac dysfunctions or even death. In this regard, induction of angiogenesis is considered as a vital process for supplying nutrients and oxygen to the cells in cardiac tissue engineering. The current review aims to summarize different approaches of angiogenesis induction for effective cardiac tissue repair. Accordingly, a comprehensive classification of induction of pro-angiogenic signaling pathways through using engineered biomaterials, drugs, angiogenic factors, as well as combinatorial approaches is introduced as a potential platform for cardiac regeneration application. The angiogenic induction for cardiac repair can enhance patient treatment outcomes and generate economic prospects for the biomedical industry. The development and commercialization of angiogenesis methods often involves collaboration between academic institutions, research organizations, and biomedical companies.

Zinc and hypoxic preconditioning: a strategy to enhance the functionality and therapeutic potential of bone marrow-derived mesenchymal stem cells

The therapeutic use of bone marrow mesenchymal stem cells (BM-MSCs) requires a large number of cells (1-100 × 10⁶ cells/kg of body weight). Extensive in vitro growth is limited due to the aging of cultured BM-MSCs which leads to abnormal morphology and senescence. Hypoxia increases BM-MSC proliferation, but the question of whether hypoxia preconditioning is safe for clinical application of BM-MSCs remains to be answered. Zinc is essential for cell proliferation and differentiation, especially for the regulation of DNA synthesis and mitosis. It is a structural constituent of numerous proteins on a molecular level, including transcription factors and enzymes of cellular signaling machinery. All the tissues, fluids, and organs of the human body contain zinc. More than 95% of zinc is intracellular, of which 44% is involved in the transcription of DNA. We investigated the effects of ZnCl₂ on proliferation, morphology, migration, population doubling time (PDT), and gene expression of BM-MSCs under hypoxic (1% O₂) and normoxic (21% O₂) environments. BM-MSCs were preconditioned with optimized concentrations of ZnCl₂ under normoxic and hypoxic environments and further examined for morphology by the phase-contrast inverted microscope, cell proliferation by MTT assay, PDT, cell migration ability, and gene expression analysis. Zinc significantly enhanced the proliferation of BM-MSCs, and it decreases PDT under hypoxic and normoxic environments as compared to control cells. Migration of BM-MSCs toward the site of injury increased and expression of HIF1-α significantly decreased under hypoxic conditions as compared to non-treated hypoxic cells and control. At late passages (P₉), the morphology of normoxic BM-MSCs was transformed into large, wide, and flat cells, and they became polygonal and lost their communication with other cells. Conversely, zinc-preconditioned BM-MSCs retained their spindle-shaped, fibroblast-like morphology at P₉. The expression of proliferative genes was found significantly upregulated, while downregulation of genes OCT4 and CCNA2 was observed in zinc-treated BM-MSCs under both normoxic and hypoxic conditions. ZnCl₂ treatment can be used for extensive expansion of BM-MSCs in aged populations to obtain a large number of cells required for systemic administration to produce therapeutic efficacy.

Potential of stem cell seeded three-dimensional scaffold for regeneration of full-thickness skin wounds

Hypoxic wounds are tough to heal and are associated with chronicity, causing major healthcare burden. Available treatment options offer only limited success for accelerated and scarless healing. Traditional skin substitutes are widely used to improve wound healing, however, they lack proper vascularization. Mesenchymal stem cells (MSCs) offer improved wound healing; however, their poor retention, survival and adherence at the wound site negatively affect their therapeutic potential. The aim of this study is to enhance skin regeneration in a rat model of full-thickness dermal wound by transplanting genetically modified MSCs seeded on a three-dimensional collagen scaffold. Rat bone marrow MSCs were efficiently incorporated in the acellular collagen scaffold. Skin tissues with transplanted subcutaneous scaffolds were histologically analysed, while angiogenesis was assessed both at gene and protein levels. Our findings demonstrated that three-dimensional collagen scaffolds play a potential role in the survival and adherence of stem cells at the wound site, while modification of MSCs with jagged one gene provides a conducive environment for wound regeneration with improved proliferation, reduced inflammation and enhanced vasculogenesis. The results of this study represent an advanced targeted approach having the potential to be translated in clinical settings for targeted personalized therapy.

Insight in Hypoxia-Mimetic Agents as Potential Tools for Mesenchymal Stem Cell Priming in Regenerative Medicine

Hypoxia-mimetic agents are new potential tools in MSC priming instead of hypoxia incubators or chambers. Several pharmaceutical/chemical hypoxia-mimetic agents can be used to induce hypoxia in the tissues: deferoxamine (DFO), dimethyloxaloylglycine (DMOG), 2,4-dinitrophenol (DNP), cobalt chloride (CoCl2), and isoflurane (ISO). Hypoxia-mimetic agents can increase cell proliferation, preserve or enhance differentiation potential, increase migration potential, and induce neovascularization in a concentration- and stem cell source-dependent manner. Moreover, hypoxia-mimetic agents may increase HIF-1α, changing the metabolism and enhancing glycolysis like hypoxia. So, there is clear evidence that treatment with hypoxia-mimetic agents is beneficial in regenerative medicine, preserving stem cell capacities. These agents are not studied so wildly as hypoxia but, considering the low cost and ease of use, are believed to find application as pretreatment of many diseases such as ischemic heart disease and myocardial fibrosis and promote cardiac and cartilage regeneration. The knowledge of MSC priming is critical in evaluating safety procedures and use in clinics. In this review, similarities and differences between hypoxia and hypoxia-mimetic agents in terms of their therapeutic efficiency are considered in detail. The advantages, challenges, and future perspectives in MSC priming with hypoxia mimetic agents are also discussed.

The challenges and optimization of cell-based therapy for cardiovascular disease

With the hope of achieving real cardiovascular repair, cell-based therapy raised as a promising strategy for the treatment of cardiovascular disease (CVD) in the past two decades. Various types of cells have been studied for their reparative potential for CVD in the ensuing years. Despite the exciting results from animal experiments, the outcome of clinical trials is unsatisfactory and the development of cell-based therapy for CVD has hit a plateau nowadays. Thus, it is important to summarize the obstacles we are facing in this field in order to explore possible solutions for optimizing cell-based therapy and achieving real clinical application.

Direct Reprogramming Induces Vascular Regeneration Post Muscle Ischemic Injury

Reprogramming non-cardiomyocytes (non-CMs) into cardiomyocyte (CM)-like cells is a promising strategy for cardiac regeneration in conditions such as ischemic heart disease. Here, we used a modified mRNA (modRNA) gene delivery platform to deliver a cocktail, termed 7G-modRNA, of four cardiac-reprogramming genes—Gata4 (G), Mef2c (M), Tbx5 (T), and Hand2 (H)—together with three reprogramming-helper genes—dominant-negative (DN)-TGFβ, DN-Wnt8a, and acid ceramidase (AC)—to induce CM-like cells. We showed that 7G-modRNA reprogrammed 57% of CM-like cells in vitro. Through a lineage-tracing model, we determined that delivering the 7G-modRNA cocktail at the time of myocardial infarction reprogrammed ∼25% of CM-like cells in the scar area and significantly improved cardiac function, scar size, long-term survival, and capillary density. Mechanistically, we determined that while 7G-modRNA cannot create de novo beating CMs in vitro or in vivo, it can significantly upregulate pro-angiogenic mesenchymal stromal cells markers and transcription factors. We also demonstrated that our 7G-modRNA cocktail leads to neovascularization in ischemic-limb injury, indicating CM-like cells importance in other organs besides the heart. modRNA is currently being used around the globe for vaccination against COVID-19, and this study proves this is a safe, highly efficient gene delivery approach with therapeutic potential to treat ischemic diseases.

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

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

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

AIMS

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

METHODS

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

RESULTS

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

CONCLUSION

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

Concise Review: Optimized Strategies for Stem Cell-Based Therapy in Myocardial Repair: Clinical Translatability and Potential Limitation

Ischemic heart diseases (IHDs) remain major public health problems with high rates of morbidity and mortality worldwide. Despite significant advances, current therapeutic approaches are unable to rescue the extensive and irreversible loss of cardiomyocytes caused by severe ischemia. Over the past 16 years, stem cell-based therapy has been recognized as an innovative strategy for cardiac repair/regeneration and functional recovery after IHDs. Although substantial preclinical animal studies using a variety of stem/progenitor cells have shown promising results, there is a tremendous degree of skepticism in the clinical community as many stem cell trials do not confer any beneficial effects. How to accelerate stem cell-based therapy toward successful clinical application attracts considerate attention. However, many important issues need to be fully addressed. In this Review, we have described and compared the effects of different types of stem cells with their dose, delivery routes, and timing that have been routinely tested in recent preclinical and clinical findings. We have also discussed the potential mechanisms of action of stem cells, and explored the role and underlying regulatory components of stem cell-derived secretomes/exosomes in myocardial repair. Furthermore, we have critically reviewed the different strategies for optimizing both donor stem cells and the target cardiac microenvironments to enhance the engraftment and efficacy of stem cells, highlighting their clinical translatability and potential limitation. Stem Cells 2018;36:482-500.

Proteomics-based network analysis characterizes biological processes and pathways activated by preconditioned mesenchymal stem cells in cardiac repair mechanisms

BACKGROUND

We have demonstrated that intramyocardial delivery of human mesenchymal stem cells preconditioned with a hyaluronan mixed ester of butyric and retinoic acid (MSCp⁺) is more effective in preventing the decay of regional myocardial contractility in a swine model of myocardial infarction (MI). However, the understanding of the role of MSCp⁺ in proteomic remodeling of cardiac infarcted tissue is not complete. We therefore sought to perform a comprehensive analysis of the proteome of infarct remote (RZ) and border zone (BZ) of pigs treated with MSCp⁺ or unconditioned stem cells.

METHODS

Heart tissues were analyzed by MudPIT and differentially expressed proteins were selected by a label-free approach based on spectral counting. Protein profiles were evaluated by using PPI networks and their topological analysis.

RESULTS

The proteomic remodeling was largely prevented in MSCp⁺ group. Extracellular proteins involved in fibrosis were down-regulated, while energetic pathways were globally up-regulated. Cardioprotectant pathways involved in the production of keto acid metabolites were also activated. Additionally, we found that new hub proteins support the cardioprotective phenotype characterizing the left ventricular BZ treated with MSCp⁺. In fact, the up-regulation of angiogenic proteins NCL and RAC1 can be explained by the increase of capillary density induced by MSCp⁺.

CONCLUSIONS

Our results show that angiogenic pathways appear to be uniquely positioned to integrate signaling with energetic pathways involving cardiac repair.

GENERAL SIGNIFICANCE

Our findings prompt the use of proteomics-based network analysis to optimize new approaches preventing the post-ischemic proteomic remodeling that may underlie the limited self-repair ability of adult heart.

Preconditioning of mesenchymal stem cells with 2,4-dinitrophenol improves cardiac function in infarcted rats

AIMS

The aim of this study is to determine if preconditioning of bone marrow derived mesenchymal stem cells (MSCs) with 2,4-dinitrophenol (DNP) improves survival of transplanted stem cells in a rat model of myocardial infarction (MI), and to asses if this strategy has measurable impact on cardiac function.

MAIN METHODS

MSCs were preconditioned with DNP. In vitro cell adhesion assay and qRT-PCR were performed to analyze the expression of genes involved in cardiomyogenesis, cell adhesion and angiogenesis. MI was produced by occlusion of left anterior descending coronary artery. One million cells were transplanted by intramyocardial injection into the infarcted myocardium. Echocardiography was performed after two and four weeks of cellular transplantation. Hearts were harvested after four weeks and processed for histological analysis.

KEY FINDINGS

DNP treated MSCs adhered to the surface more (p<0.001) as compared to the normal MSCs. Gene expression levels were significantly upregulated in case of DNP treatment. The number of viable MSCs was more (p<0.001) in animals that received DNP treated MSCs, leading to significant improvement in cardiac function. Histological analysis revealed significant reduction in scar formation (p<0.001), maintenance of left ventricular wall thickness (p<0.001), and increased angiogenesis (p<0.01).

SIGNIFICANCE

The study evidenced for the first time that MSCs preconditioned with DNP improved cardiac function after transplantation. This can be attributed to improved survival, homing, adhesion, and cardiomyogenic and angiogenic differentiation of DNP treated MSCs in vivo.

Hypoxic Preconditioning Improves the Therapeutic Potential of Aging Bone Marrow Mesenchymal Stem Cells in Streptozotocin-Induced Type-1 Diabetic Mice

Insulin replacement is the current therapeutic option for type-1 diabetes. However, exogenous insulin cannot precisely represent the normal pattern of insulin secretion. Another therapeutic strategy is transplantation of pancreatic islets, but this is limited by immune rejection, intrinsic complications, and lack of donor availability. Stem cell therapy that results in the regeneration of insulin-producing cells represents an attractive choice. However, with advancing age, stem cells also undergo senescence, which leads to changes in the function of various cellular processes that result in a decrease in the regeneration potential of these aging stem cells. In this study, the effect of young and aging mesenchymal stem cells (MSCs) on the regeneration of pancreatic beta cells in streptozotocin (STZ)-induced type-1 diabetic mice was observed after hypoxic preconditioning. Hypoxia was chemically induced by 2, 4-dinitrophenol (DNP). Plasma insulin and glucose levels were measured at various time intervals, and pancreatic sections were analyzed histochemically. The effect of DNP was also analyzed on apoptosis of MSCs by flow cytometry and on gene expression of certain growth factors by quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR). We observed that hypoxic preconditioning caused changes in the gene expression levels of growth factors in both young and aging MSCs. Young MSCs showed significant regeneration potential compared with the aging cells in vivo. However, hypoxic preconditioning was able to improve the regeneration potential of aging MSCs. It is concluded from the present study that the regeneration potential of aging MSCs into pancreatic β-cells can be enhanced by hypoxic preconditioning, which causes changes in the gene expression of certain growth factors.