Young Bone Marrow Sca-1 Cells Rejuvenate the Aged Heart by Promoting Epithelial-to-Mesenchymal Transition

Electroacupuncture improves cardiac function after myocardial infarction by regulating the mobilization and migration of endogenous stem cells

OBJECTIVE

The aim of this study was to explore the role and mechanisms of electroacupuncture (EA) in the regulation of chemokines in endogenous stem cell mobilization and myocardial regeneration after myocardial infarction (MI).

METHODS

An MI model was constructed in adult male Sprague-Dawley rats by ligating the left anterior descending coronary artery. After 4 weeks of treatment, echocardiography was used to detect changes in cardiac function, and Masson's trichrome staining was used to detect collagen deposition. In addition, immunofluorescence staining was applied to examine von Willebrand factor (vWF)-positive vessels, the expression of cardiac troponin T (cTnT) and proliferation marker Ki67, and the number of c-kit-positive, C-X-C chemokine receptor type 4 (CXCR4)-positive, and Sca-1-positive endogenous stem cells in the infarcted area. In addition, the expression of stromal cell-derived factor (SDF)-1 and stem cell factor (SCF) was detected.

RESULTS

EA increased the ejection fraction after MI, reduced collagen deposition and cellular apoptosis, and increased the number of blood vessels compared with an untreated model group. EA significantly promoted cellular proliferation, except for myocardial cells, and significantly increased the number of c-kit-, CXCR4- and Sca-1-positive stem cells. Moreover, the expression of SDF-1 and SCF in myocardial tissue in the EA group was significantly higher than that in the (untreated) MI group.

CONCLUSIONS

EA appears to promote angiogenesis and reduce collagen deposition, thus improving the cardiac function of rats with MI. The underlying mechanism of action may involve endogenous stem cell mobilization mediated by SDF-1/CXCR4 and SCF/c-kit.

Modified Taohong Siwu decoction improves cardiac function after myocardial ischaemia and reperfusion in rats by promoting endogenous stem cell mobilization and regulating metabolites

CONTEXT

Taohong Siwu decoction (THSWD) has been shown to promote heart repair in myocardial infarction.

OBJECTIVE

To determine the effects of modified THSWD (THSWD plus four ingredients) on myocardial ischaemia and reperfusion (I/R) injury.

MATERIALS AND METHODS

Sixty Sprague-Dawley rats were randomly divided into the I/R group and three different modified THSWD dose groups (gavage administration, 1.215, 2.43, and 4.86 g, respectively). 2,3,5-Triphenyltetrazolium chloride and Evans blue staining were used to detect the infarct area at 24 h after treatment. The serum biochemical indexes and cell apoptosis were examined to determine myocardial injury. The number of endogenous stem cells, expression of stromal dell derived factor-1 (SDF-1) and stem cell factor (SCF), and cardiac function were measured at 4 weeks. The serum was collected for metabolomic analysis.

RESULTS

The high-dose modified THSWD group presented a reduced infarction area (decreased by 21.3%), decreased levels of lactate dehydrogenase and creatinine kinase, attenuated cell apoptosis, and enhanced superoxide dismutase activity in early stage I/R compared with other groups. The serum SCF and SDF-1 levels were higher in the high-dose group than in the I/R group. At 4 weeks, the infarct size and collagen content were the lowest, and the ejection fraction and fractional shortening values were the highest in the high-dose group. Moreover, high-dose modified THSWD affected the metabolism of phosphonate and phosphonate, taurine, and hypotaurine.

CONCLUSIONS

Endogenous stem cell mobilization and metabolic regulation were related to the cardioprotection of modified THSWD. We provided a new strategy and direction for the treatment of cardiovascular diseases with traditional Chinese medicine.

Nanoparticle-Based Follistatin Messenger RNA Therapy for Reprogramming Metastatic Ovarian Cancer and Ameliorating Cancer-Associated Cachexia

This study presents the first messenger RNA (mRNA) therapy for metastatic ovarian cancer and cachexia-induced muscle wasting based on lipid nanoparticles that deliver follistatin (FST) mRNA predominantly to cancer clusters following intraperitoneal administration. The secreted FST protein, endogenously synthesized from delivered mRNA, efficiently reduces elevated activin A levels associated with aggressive ovarian cancer and associated cachexia. By altering the cancer cell phenotype, mRNA treatment prevents malignant ascites, delays cancer progression, induces the formation of solid tumors, and preserves muscle mass in cancer-bearing mice by inhibiting negative regulators of muscle mass. Finally, mRNA therapy provides synergistic effects in combination with cisplatin, increasing the survival of mice and counteracting muscle atrophy induced by chemotherapy and cancer-associated cachexia. The treated mice develop few nonadherent tumors that are easily resected from the peritoneum. Clinically, this nanomedicine-based mRNA therapy can facilitate complete cytoreduction, target resistance, improve resilience during aggressive chemotherapy, and improve survival in advanced ovarian cancer.

SDF-1/CXCR4-Mediated Stem Cell Mobilization Involved in Cardioprotective Effects of Electroacupuncture on Mouse with Myocardial Infarction

Stem cell-based therapeutic strategies have obtained a significant breakthrough in the treatment of cardiovascular diseases, particularly in myocardial infarction (MI). Nevertheless, limited retention and poor migration of stem cells are still problems for stem cell therapeutic development. Hence, there is an urgent need to develop new strategies that can mobilize stem cells to infarcted myocardial tissues effectively. Electroacupuncture (EA) intervention can improve cardiac function and alleviate myocardial injury after MI, but its molecular mechanism is still unclear. This study is aimed at observing the effects of EA treatment on the stem cell mobilization and revealing possible mechanisms in the MI model of mice. EA treatment at Neiguan (PC6) and Xinshu (BL15) acupoints was conducted on the second day after the ligation surgery. Then, the number of stem cells in peripheral blood after EA in MI mice and their cardiac function, infarct size, and collagen deposition was observed. We found that the number of CD34-, CD117-, Sca-1-, and CD90-positive cells increased at 6 h and declined at 24 h after EA intervention in the blood of MI mice. The expression of CXC chemokine receptor-4 (CXCR4) protein was upregulated at 6 h after EA treatment, while the ratio of LC3B II/I or p-ERK/ERK showed a reverse trend. In addition, there was obvious difference in EF and FS between wild-type mice and CXCR4+/− mice. The infarct size, collagen deposition, and apoptosis of the injured myocardium in CXCR4+/− mice increased but could be ameliorated by EA. In a word, our study demonstrates that EA alleviates myocardial injury via stem cell mobilization which may be regulated by the SDF-1/CXCR4 axis.

Stroke-Induced Neurological Dysfunction in Aged Mice Is Attenuated by Preconditioning with Young Sca-1+ Stem Cells

AIMS

To date, stroke remains one of the leading causes of death and disability worldwide. Nearly three-quarters of all strokes occur in the elderly (>65 years old), and a vast majority of these individuals develop debilitating cognitive impairments that can later progress into dementia. Currently, there are no therapies capable of reversing the cognitive complications which arise following a stroke. Instead, current treatment options focus on preventing secondary injuries, as opposed to improving functional recovery.

METHODS

We reconstituted aged (20-month old) mice with Sca-1+ bone marrow (BM) hematopoietic stem cells isolated from aged or young (2-month old) EGFP+ donor mice. Three months later the chimeric aged mice underwent cerebral ischemia/reperfusion by bilateral common carotid artery occlusion (BCCAO), after which cognitive function was evaluated. Immunohistochemical analysis was performed to evaluate host and recipient cells in the brain following BCCAO.

RESULTS

Young Sca-1+ cells migrate to the aged brain and give rise to beneficial microglial-like cells that ameliorate stroke-induced loss of cognitive function on tasks targeting the hippocampus and cerebellum. We also found that young Sca-1+ cell-derived microglial-like cells possess neuroprotective properties as they do not undergo microgliosis upon migrating to the ischemic hippocampus, whereas the cells originating from old Sca-1+ cells proliferate extensively and skew toward a pro-inflammatory phenotype following injury.

CONCLUSIONS

This study provides a proof-of-principle demonstrating that young BM Sca-1+ cells play a pivotal role in reversing stroke-induced cognitive impairments and protect the aged brain against secondary injury by attenuating the host cell response to injury.

Non-coding RNAs in cardiac regeneration: Mechanism of action and therapeutic potential

In the past two decades, thousands of non-coding RNAs (ncRNAs) have been discovered, annotated, and characterized in nearly every tissue under both physiological and pathological conditions. Here, we will focus on the role of ncRNAs, including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs) in ischemic heart disease (IHD), which remains the leading cause of morbidity and mortality in humans-resulting in 8.9 million deaths annually. Cardiomyocyte (CM) proliferation, differentiation, and survival in addition to neovascularization of injured tissues and the prevention of fibrosis are commonly regarded as critically important for the recovery of the heart following myocardial infarction (MI). An abundance of evidence has been accumulated to show ncRNAs participate in cardiac recovery after MI. Because miRNAs are important regulators of cardiac regeneration, the therapeutic potential of at least five of these molecules has been assessed in large animal models of human IHD. In particular, miRNA-based interventions based on miR-132 and miR-92a inhibition in related diseases have displayed favorable outcomes that have provided the impetus for miRNA-based clinical trials for IHD. At the same time, the functional roles of lncRNAs and circRNAs in cardiac regeneration are also being explored. In the present review, we will summarize the latest ncRNA studies aimed at reversing damage to the ischemic heart and discuss the therapeutic potential of targeting miRNAs, lncRNAs, and circRNAs to stimulate cardiac regeneration.

Age-related defects in autophagy alter the secretion of paracrine factors from bone marrow mononuclear cells

Bone marrow mononuclear cell therapy improves cardiac repair after myocardial infarction (MI), in-part through signaling to resident cardiac cells, such as fibroblasts, which regulate scar formation. The efficacy of cell therapy declines with age, as aging of both donor and recipient cells decreases repair responses. Autophagy regulates the microenvironment by both extracellular vesicle (EV)-dependent and independent secretion pathways. We hypothesized that age-related autophagy changes in bone marrow cells (BMCs) alter paracrine signaling, contributing to lower cell therapy efficacy. Here, we demonstrate that young Sca-1+ BMCs exhibited a higher LC3II/LC3I ratio compared to old Sca-1+ BMCs, which was accentuated when BMCs were cultured under hypoxia. To examine the effect on paracrine signaling, old cardiac fibroblasts were cultured with conditioned medium (CM) from young and old Sca-1+ BMCs. Young, but not old CM, enhanced fibroblast proliferation, migration, and differentiation, plus reduced senescence. These beneficial effects were lost when autophagy or EV secretion in BMCs was blocked pharmacologically, or by siRNA knockdown of Atg7. Therefore, both EV-dependent and -independent paracrine signaling from young BMCs is responsible for paracrine stimulation of old cardiac fibroblasts. In vivo, bone marrow chimerism of old mice with young BMCs increased the number of LC3b+ cells in the heart compared to old mice reconstituted with old BMCs. These data suggest that the deterioration of autophagy with aging negatively impacts the paracrine effects of BMCs, and provide mechanistic insight into the age-related decline in cell therapy efficacy that could be targeted to improve the function of old donor cells.

Bioengineering strategies to control epithelial-to-mesenchymal transition for studies of cardiac development and disease

Epithelial-to-mesenchymal transition (EMT) is a process that occurs in a wide range of tissues and environments, in response to numerous factors and conditions, and plays a critical role in development, disease, and regeneration. The process involves epithelia transitioning into a mobile state and becoming mesenchymal cells. The investigation of EMT processes has been important for understanding developmental biology and disease progression, enabling the advancement of treatment approaches for a variety of disorders such as cancer and myocardial infarction. More recently, tissue engineering efforts have also recognized the importance of controlling the EMT process. In this review, we provide an overview of the EMT process and the signaling pathways and factors that control it, followed by a discussion of bioengineering strategies to control EMT. Important biological, biomaterial, biochemical, and physical factors and properties that have been utilized to control EMT are described, as well as the studies that have investigated the modulation of EMT in tissue engineering and regenerative approaches in vivo, with a specific focus on the heart. Novel tools that can be used to characterize and assess EMT are discussed and finally, we close with a perspective on new bioengineering methods that have the potential to transform our ability to control EMT, ultimately leading to new therapies.

Down-Regulation of Lnc-CYP7A1-1 Rejuvenates Aged Human Mesenchymal Stem Cells to Improve Their Efficacy for Heart Repair Through SYNE1

Background

Several long non-coding RNAs (lncRNAs) have been associated with cell senescence, termed senescence-associated lncRNAs (SAL-RNAs). However, the mechanisms involved for SAL-RNAs in aging are not fully elucidated. In the present study, we investigated the effects of SAL-RNAs on aged human bone marrow-derived mesenchymal stem cells (hBM-MSCs), and the possible means to counteract such effects to improve the regenerative capacity of aged hBM-MSCs.

Methods

By comparing the lncRNAs expression of hBM-MSCs derived from young and old individuals, lnc-CYP7A1-1 was identified as being significantly increased with age. Using predictive software, the expression of Spectrin Repeat Containing Nuclear Envelope Protein 1 (SYNE1), was found to be decreased with age. Next, through lentiviral constructs, we downregulated the expression of lnc-CYP7A1-1 or SYNE1 in hBM-MSCs separately. Additionally, hBM-MSCs proliferation, survival, migration, and senescence were investigated in vitro. In vivo, lnc-CYP7A1-1 downregulated aged hBM-MSCs were implanted into infarcted mouse hearts after myocardial infarction (MI), and cardiac function was measured. Through lentivirus-mediated downregulation of lnc-CYP7A1-1 in aged hBM-MSCs, we revealed that cell senescence was decreased, whereas cell proliferation, migration, and survival were increased. On the other hand, downregulation of SYNE1, the target gene of lnc-CYP7A1-1, in young hBM-MSCs increased cell senescence, yet decreased cell proliferation, migration, and survival. Downregulation of lnc-CYP7A1-1 in aged hBM-MSCs induced cell rejuvenation, yet this effect was attenuated by repression of SYNE1. In vivo, transplantation of lnc-CYP7A1-1 downregulated old hBM-MSCs improved cardiac function after MI.

Conclusion

Down-regulation of lnc-CYP7A1-1 rejuvenated aged hBM-MSCs and improved cardiac function when implanted into the infarcted mouse hearts, possibly through its target gene SYNE1.

Rab27a deletion impairs the therapeutic potential of endothelial progenitor cells for myocardial infarction

Endothelial progenitor cell (EPC) transplantation has shown advantages in the treatment of myocardial infarction (MI) in animal models and clinical trials through mechanisms of direct intercellular contacts, autocrine, and paracrine. However, the effects of EPC transplantation for MI treatment remain controversial and the underlying mechanisms have not been fully elucidated. Here, we explored the role of Rab27a in the therapeutic potential of EPC transplantation in MI. We found that Rab27a knockout impaired the viability, and reduced the proliferation and tube formation function of ECPs. The recovery of cardiac function and improvement of ventricular remodeling from EPCs transplantation were significantly damaged by Rab27a deletion in vivo. Rab27a deletion inhibited the protein expression of phosphoinositide 3-kinase (PI3K) and cyclin D1 and the phosphorylation levels of Akt and FoxO3a. Therefore, Rab27a knockout suppressed the PI3K-Akt-FoxO3a/cyclin D1 signaling pathway. Furthermore, Rab27a ablation dramatically reduced exosome release in EPCs. These results demonstrated that Rab27a plays an essential role in EPC functions. The elucidation of this mechanism provides novel insights into EPC transplantation as a promising treatment for post-MI injuries.

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.

The Role of Transcription Factor 21 in Epicardial Cell Differentiation and the Development of Coronary Heart Disease

Transcription factor 21 (TCF21) is specific for mesoderm and is expressed in the embryos' mesenchymal derived tissues, such as the epicardium. It plays a vital role in regulating cell differentiation and cell fate specificity through epithelial-mesenchymal transformation during cardiac development. For instance, TCF21 could promote cardiac fibroblast development and inhibit vascular smooth muscle cells (VSMCs) differentiation of epicardial cells. Recent large-scale genome-wide association studies have identified a mass of loci associated with coronary heart disease (CHD). There is mounting evidence that TCF21 polymorphism might confer genetic susceptibility to CHD. However, the molecular mechanisms of TCF21 in heart development and CHD remain fundamentally problematic. In this review, we are committed to providing a detailed introduction of the biological roles of TCF21 in epicardial fate determination and the development of CHD.

Dimeric Thymosin β4 Loaded Nanofibrous Interface Enhanced Regeneration of Muscular Artery in Aging Body through Modulating Perivascular Adipose Stem Cell-Macrophage Interaction

Regenerating nonthrombotic and compliant artery, especially in the aging body, remains a major surgical challenge, mainly owing to the inadequate knowledge of the major cell sources contributing to arterial regeneration and insufficient bioactivity of delivered peptides in grafts. Ultrathin nanofibrous sheaths stented with biodegrading elastomer present opening channels and reduced material residue, enabling fast cell recruitment and host remodeling, while incorporating peptides offering developmental cues are challenging. In this study, a recombinant human thymosin β4 dimer (DTβ4) that contains two complete Tβ4 molecules is produced. The adult perivascular adipose is found as the dominant source of vascular progenitors which, when stimulated by the DTβ4-loaded nanofibrous sheath, enables 100% patency rates, near-complete structural as well as adequate functional regeneration of artery, and effectively ameliorates aging-induced defective regeneration. As compared with Tβ4, DTβ4 exhibits durable regenerative activity including recruiting more progenitors for endothelial cells and smooth muscle cells, when incorporated into the ultrathin polycaprolactone sheath. Moreover, the DTβ4-loaded interface promotes smooth muscle cells differentiation, mainly through promoting M2 macrophage polarization and chemokines. Incorporating artificial DTβ4 into ultrathin sheaths of fast degrading vascular grafts creates an effective interface for sufficient muscular remodeling thus offering a robust tool for vessel replacement.

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.

Effects of age on retinal macrophage responses to acute elevation of intraocular pressure

There is accumulating evidence that aging shifts the central nervous system milieu towards a proinflammatory state, with increased reactivity of microglia in the aging eye and brain having been implicated in the development of age-related neurodegenerative conditions. Indeed, alterations to microglial morphology and function have been recognized as a part of normal aging. Here, we sought to assess the effects of age on the retinal microglial and macrophage response to acute intraocular pressure (IOP) elevation. Further, we performed experiments whereby bone marrow from young or middle-aged mice was used to reconstitute the bone marrow of whole-body irradiated 12 month old mice. Bone marrow chimeric mice then underwent cannulation and IOP elevation 8 weeks after whole-body irradiation and bone marrow transplantation in order to determine whether the age of bone marrow alters the macrophage response to retinal injury. Our data show retinal macrophage reactivity and microglial morphological changes were enhanced in older mice when compared to younger mice in response to injury. When IOP elevation was performed after whole-body irradiation and bone marrow rescue, we noted subretinal macrophage accumulation and glial reactivity was reduced compared to non-irradiated mice that had also undergone IOP elevation. This effect was evident in both groups of chimeric mice that had received either young or middle-aged bone marrow, suggesting irradiation itself may alter the macrophage and glial response to injury rather than the age of bone marrow.

M1-like macrophage-derived exosomes suppress angiogenesis and exacerbate cardiac dysfunction in a myocardial infarction microenvironment

The roles and the underlying mechanisms of M1-type macrophages in angiogenesis and postmyocardial infarction (MI) cardiac repair have remained unclear. In this study, we investigated the role of M1-like macrophage-derived exosomes in a MI microenvironment. We found that the proinflammatory M1-like-type macrophages released an extensive array of proinflammatory exosomes (M1-Exos) after MI. M1-Exos exerted an anti-angiogenic effect and accelerated MI injury. They also exhibited highly expressed proinflammatory miRNAs, such as miR-155. miR-155 was transferred to endothelial cells (ECs), leading to the inhibition of angiogenesis and cardiac dysfunction by downregulating its novel target genes, including Rac family small GTPase 1 (RAC1), p21 (RAC1)-activated kinase 2 (PAK2), Sirtuin 1 (Sirt1), and protein kinase AMP-activated catalytic subunit alpha 2 (AMPKα2). M1-Exos depressed Sirt1/AMPKα2-endothelial nitric oxide synthase and RAC1-PAK2 signaling pathways by simultaneously targeting the five molecule nodes (genes), reduced the angiogenic ability of ECs, aggravated myocardial injury, and restrained cardiac healing. The elucidation of this mechanism provides novel insights into the functional significance of M1 macrophages and their derived exosomes on angiogenesis and cardiac repair. This mechanism can be used as a novel potential therapeutic approach for the prevention and treatment of MI.