Delivery of Stem Cells and BMP-2 With Functionalized Self-Assembling Peptide Enhances Regeneration of Infarcted Myocardium.

Stem cell transplantation is a promising therapeutic strategy for myocardial infarction (MI). However, engraftment, survival and differentiation of the transplanted stem cells in ischemic and inflammatory microenvironment are poor. We designed a novel self-assembly peptide (SAP) by modifying the peptide RADA16 with cell-adhesive motif and BMP-2 (bone morphogenetic protein-2)-binding motif. Effects of the functionalized SAP on adhesion, survival and differentiation of c-kit+ MSCs (mesenchymal stem cells) were examined. Myocardial regeneration, neovascularization and cardiac function were assessed after transplantation of the SAP loading c-kit+ MSCs and BMP-2 in rat MI models. The SAP could spontaneously assemble into well-ordered nanofibrous scaffolds. The cells adhered to the SAP scaffolds and spread well. The SAP protected the cells in the condition of hypoxia and serum deprivation. Following degradation of the SAP, BMP-2 was released sustainedly and induced c-kit+ MSCs to differentiate into cardiomyocytes. At four weeks after transplantation of the SAP loading c-kit+ MSCs and BMP-2, myocardial regeneration and angiogenesis were enhanced, and cardiac function was improved significantly. The cardiomyocytes differentiated from the engrafted c-kit+ MSCs were increased markedly. The differentiated cells connected with recipient cardiomyocytes to form gap junctions. Collagen volume was decreased dramatically. These results suggest that the functionalized SAP promotes engraftment, survival and differentiation of stem cells effectively. Local sustained release of BMP-2 with SAP is a viable strategy to enhance differentiation of the engrafted stem cells and repair of the infarcted myocardium.

A Configurationally Confined Thermally Activated Delayed Fluorescent Two-Coordinate CuI Complex for Efficient Blue Electroluminescence.

Thermally activated delayed fluorescence (TADF) from linear two-coordinate coinage metal complexes is sensitive to the geometric arrangement of the ligands. Herein we realize the tuning of configuration from coplanar to orthogonal gradually by variation of substituents. In a complex with confined twist configuration, its blue emission peaking at 458 nm presents a high ΦPL of 0.74 and a short τTADF of 1.9 µs, which indicates a fast enough kr,TADF of 3.9×105  s-1 and a depressed knr of 1.4×105  s-1 . Such outstanding luminescent properties are attributed to the proper overlap of HOMO and LUMO on CuI d orbitals that guarantees not only small ΔEST but also sufficient transition oscillator strength for fast k r , S 1 ${{k}_{{\rm r},{{\rm S}}_{1}}}$ . Vacuum-deposited blue OLEDs with either doped or host-free emissive layer present external quantum efficiencies over 20 % and 10 %, respectively, demonstrating the practicality of the configurationally confined strategy for efficient linear CuI TADF emitters.

Retinoic acid released from self-assembling peptide activates cardiomyocyte proliferation and enhances repair of infarcted myocardium.

The limited cardiomyocyte proliferation is insufficient for repair of the myocardium. Therefore, activating cardiomyocyte proliferation might be a reasonable option for myocardial regeneration. Here, we investigated effect of retinoic acid (RA) on inducing adult cardiomyocyte proliferation and assessed efficacy of self-assembling peptide (SAP)-released RA in activating regeneration of the infarcted myocardium. Effect of RA on inducing cardiomyocyte proliferation was examined with the isolated cardiomyocytes. Expression of the cell cycle-associated genes and paracrine factors in the infarcted myocardium was examined at one week after treatment with SAP-carried RA. Cardiomyocyte proliferation, myocardial regeneration and improvement of cardiac function were assessed at four weeks after treatment. In the adult rat myocardium, expression of RA synthetase gene Raldh2 and RA concentration were decreased significantly. After treatment with RA, the proliferated cardiomyocytes were increased. The formulated SAP could sustainedly release RA. After treatment with SAP-carried RA, expression of the pro-proliferative genes in cell cycle and paracrine factors in the infarcted myocardium were up-regulated. Myocardial regeneration was enhanced, and cardiac function was improved significantly. These results demonstrate that RA can induce adult cardiomyocytes to proliferate effectively. The sustained release of RA with SAP is a promise strategy to enhance repair of the infarcted myocardium.

c-kit+VEGFR-2+ Mesenchymal Stem Cells Differentiate into Cardiovascular Cells and Repair Infarcted Myocardium after Transplantation.

Resent study suggests that c-kit+ cells in bone marrow-derived MSCs may differentiate toward cardiamyocytes. However, the properties of c-kit+ MSCs remain unclear. This study isolated c-kit+VEGFR-2+ cells from rat bone marrow-derived MSCs, and assessed potential of c-kit+VEGFR-2+ MSCs to differentiate towards cardiovascular cells and their efficiency of repairing the infarcted myocardium after transplantation. Gene expression profile of the cells was analyzed with RNA-sequencing. Potential of differentiation of the cells was determined after induction. Rat models of myocardial infarction were established by ligation of the left anterior descending coronary artery. The cells were treated with hypoxia and serum deprivation for four hours before transplantation. Improvement of cardiac function and repair of the infarcted myocardium were assessed at four weeks after transplantation. Gene expression profile revealed that c-kit+VEGFR-2+ MSCs expressed most smooth muscle-specific and myocardium-specific genes, while expression of endothelium-specific genes was upregulated significantly. After induction with VEGF or TGF-ß for two weeks, the cells expressed CD31 and α-SMA respectively. At three weeks, BMP-2-induced cells expressed cTnT. After transplantation of the cells, cardiac function was improved, scar size of the infarcted myocardium was decreased, and angiogenesis and myocardial regeneration were enhanced significantly. Moreover, paracrine in the myocardium was increased after transplantation. These results suggest that c-kit+VEGFR-2+ MSCs have a potential of differentiation towards cardiovascular cells. Transplantation of c-kit+VEGFR-2+ MSCs is effective for repair of the infarcted myocardium. c-kit+VEGFR-2+ MSCs may be a reliable source for cell therapy of ischaemic diseases.

Reducing lipofuscin accumulation and cardiomyocytic senescence of aging heart by enhancing autophagy.

Cardiomyocytes are particularly prone to lipofuscin accumulation. In the aging heart, lipofuscin accumulation is augmented. This study examined distribution of lipofuscin and senescent cardiomyocytes and evaluated improvement of lipofuscin accumulation and cardiomyocytic senescence of the aging heart after treatment with rapamycin. The results of Schmorl staining, Sudan black staining and autofluorescence detection showed that there was more lipofuscin in the myocardium of the ventricles especially in the left ventricle. The conductive tissue contained less lipofuscin than the myocardium. In the aged hearts, lipofuscin accumulation and senescent cardiomyocytes were increased, and the level of autophagy was reduced. In double staining of Sudan black B and senescence-associated ß-galactosidase, 10%-20% lipofuscin-loaded cardiomyocytes became senescent. All senescent cardiomyocytes contained lipofuscin deposits. After enhancing autophagy with feed of rapamycin for six months, lipofuscin accumulation and senescence of cardiomyocytes were improved in old rats. Colocalization of autophagic structure and lipofuscin as well as electron micrographs showed that some lipofuscin-loaded lysosomes were sequestrated by autophagic structures. This study suggests that rapamycin-enhanced autopahgy is effective for reducing lipofuscinogenesis and promoting degradation of lipofuscin. Therefore, enhancing autophagy is a novel therapy for alleviating lipofuscin accumulation and myocardial senescence.

Thymosin ß4 released from functionalized self-assembling peptide activates epicardium and enhances repair of infarcted myocardium.

The epicardium plays an important role in cardiomyogenesis during development, while it becomes quiescent in adult heart during homeostasis. This study investigates the efficiency of thymosin ß4 (Tß4) release with RPRHQGVM conjugated to the C-terminus of RADA16-I (RADA-RPR), the functionalized self-assembling peptide (SAP), to activate the epicardium and repairing the infarcted myocardium. Methods: The functionalized SAP was constituted with self-assembling motif, Tß4-binding site, and cell adhesive ligand. Myocardial infarction (MI) models of the transgenic mice were established by ligation of the left anterior descending coronary artery. At one week after intramyocardial injection of Tß4-conjugated SAP, the activation of the epicardium was assessed. At four weeks after implantation, the migration and differentiation of epicardium-derived cells (EPDCs) as well as angiogenesis, lymphangiogenesis and myocardial regeneration were examined. Results: We found that the designer RADA-RPR bound Tß4 and adhered to EPDCs and that Tß4 released from the functionalized SAP could effectively activate the epicardium and induce EPDCs to differentiate towards cardiovascular cells as well as lymphatic endothelial cells. Moreover, SAP-released Tß4 (SAP-Tß4) promoted proliferation of cardiomyocytes. Furthermore, angiogenesis, lymphangiogenesis and myocardial regeneration were enhanced in the MI models at 4 weeks after delivery of SAP-Tß4 along with attenuation of adverse myocardial remodeling and significantly improved cardiac function. Conclusions: These results demonstrate that sustained release of Tß4 from the functionalized SAP can activate the epicardium and effectively enhance the repair of infarcted myocardium. We believe the delivery of SAP-Tß4 may be a promising strategy for MI therapy.

Impact of Economic Policy Uncertainty on Carbon Emissions: Evidence from 137 Multinational Countries.

With growing economic policy uncertainty (EPU) and the importance of protecting the natural environment worldwide, the relationship between EPU and carbon emissions should be investigated further. However, conclusions in the existing literature on the relationship between EPU and carbon emission are inconclusive. This paper aims to examine the influence of EPU on carbon emissions according to the Stochastic Impacts by Regression on Population, Affluence and Technology (STIRPAT) model. To investigate such essential issues, we conduct GMM estimations by utilizing cross-country data covering 137 countries during the period 1970-2018, obtained from World Bank and OECD statistics. Our empirical estimations support that EPU would bring about more carbon emissions, while we conduct empirical analysis by changing the system of measurement, employing alternative estimation and constructing new samples. Our study provides substantial policy implications for government participation in international treaties on environmental protection to mitigate environmental degradation.

Rapamycin-Preactivated Autophagy Enhances Survival and Differentiation of Mesenchymal Stem Cells After Transplantation into Infarcted Myocardium.

Stem cell transplantation has been limited by poor survival of the engrafted cells in hostile microenvironment of the infarcted myocardium. This study investigated cytoprotective effect of rapamycin-preactivated autophagy on survival of the transplanted mesemchymal stem cells (MSCs). MSCs isolated from rat bone marrow were treated with 50 nmol/L rapamycin for 2 h, and then the cytoprotective effect of rapamycin was examined. After intramyocardial transplantation in rat ischemia/reperfusion models, the survival and differentiation of the rapamycin-pretreated calls were accessed. After treatment with rapamycin, autophagic activities and lysososme production of the cells were increased significantly. In the condition of short-term or long-term hypoxia and serum deprivation, the apoptotic cells in rapamycin-pretreated cells were less, and secretion of HGF, IGF-1, SCF, SDF-1 and VEGF was increased. After transplantation of rapamycin-pretreated cells, repair of the infarcted myocardium and restoration of cardial function were enhanced dramatically. Expression of HGF, IGF-1, SCF, SDF-1, VEGF, HIF-1α and IL-10 in the myocardium was upregulated, while expression of IL-1ß and TNF-α was downregulated. Tracing of GFP and Sry gene showed that the survival of rapamycin-pretreated cells was increased. Cardiomyogenesis and angiogenesis in the infarcted myocardium were strengthened. Some rapamycin-pretreated cells differentiated into cardiomyocytes or endothelial cells. These results demonstrate that moderate preactivation of autophagy with rapamycin enhances the survival and differentiation of the transplanted MSCs. Rapamycin-primed MSCs can promote repair of the infarcted myocardium and improvement of cardiac function effectively.

Enhancement of cardiac lymphangiogenesis by transplantation of CD34+VEGFR-3+ endothelial progenitor cells and sustained release of VEGF-C.

Impairment of cardiac lymphatic vessels leads to cardiac lymphedema. Recent studies have suggested that stimulation of lymphangiogenesis may reduce cardiac lymphedema. However, effects of lymphatic endothelial progenitor cells (LEPCs) on cardiac lymphangiogenesis are poorly understood. Therefore, this study investigated effectiveness of LEPC transplantation and VEGF-C release with self-assembling peptide (SAP) on cardiac lymphangiogenesis after myocardial infarction (MI). CD34+VEGFR-3+ EPCs isolated from rat bone marrow differentiated into lymphatic endothelial cells after VEGF-C induction. VEGF-C also stimulated the cells to incorporate into the lymphatic capillary-like structures. The functionalized SAP could adhere with the cells and released VEGF-C sustainedly. In the condition of hypoxia and serum deprivation or abdominal pouch assay, the SAP hydrogel protected the cells from apoptosis and necrosis. At 4 weeks after intramyocardial transplantation of the cells and VEGF-C loaded with SAP hydrogel in rat MI models, cardiac lymphangiogenesis was increased, cardiac edema and reverse remodeling were reduced, and cardiac function was improved significantly. Delivery with SAP hydrogel favored survival of the engrafted cells. VEGF-C released from the hydrogel promoted differentiation and incorporation of the cells as well as growth of pre-existed lymphatic vessels. Cardiac lymphangiogenesis was beneficial for elimination of the inflammatory cells in the infarcted myocardium. Moreover, angiogenesis and myocardial regeneration were enhanced after reduction of lymphedema. These results demonstrate that the combined delivery of LEPCs and VEGF-C with the functionalized SAP promotes cardiac lymphangiogenesis and repair of the infarcted myocardium effectively. This study represents a novel therapy for relieving myocardial edema in cardiovascular diseases.

Preinduction with bone morphogenetic protein-2 enhances cardiomyogenic differentiation of c-kit+ mesenchymal stem cells and repair of infarcted myocardium.

BACKGROUND: Preclinical and clinical trails show that c-kit+ cardiac stem cells can differentiate towards cardiovascular cells and improve cardiac function after myocardial infarction (MI). However, survival and differentiation of the engrafted stem cells within ischemic and inflammatory microenvironment are poor. METHODS: c-Kit+ cells were isolated from mesenchymal stem cells (MSCs) of rat bone marrow. Reliability of preinduction with bone morphogenetic protein-2 (BMP-2) in promotion of survival and differentiation of c-kit+ MSCs was assessed in vitro and after transplantation. RESULTS: c-Kit+ MSCs have a potential to differentiate towards cardiomyocytes. BMP-2 promotes proliferation, migration and paracrine of the cells, and protects the cells to survive in the hypoxic condition. After induction with 10 ng/mL BMP-2 for 24 h, the cells can differentiate into cardiomyocytes at four weeks. The electrophysiological characteristics of the differentiated cells are same as adult ventricular cardiomyocytes. In rat MI models, cardiac function was improved, the size of scar tissue was reduced, and regeneration of the myocardium and microvessels was enhanced significantly at four weeks after transplantation of BMP-2-preinduced cells. The survived cells and cardiomyocytes differentiated from the engrafted cells were increased greatly. CONCLUSION: The results suggest that transient treatment with BMP-2 can induce c-kit+ MSCs to differentiate into functional cardiomyocytes. Preinduction with BMP-2 enhances survival and differentiation of the cells. BMP-2-primed cells promote repair of the infarcted myocardium and improvement of cardiac function. Transplantation of BMP-2-preinduced c-kit+ MSCs is a feasible strategy for MI therapy.

Serelaxin inhibits differentiation and fibrotic behaviors of cardiac fibroblasts by suppressing ALK-5/Smad2/3 signaling pathway.

Serelaxin, a recombinant form of human relaxin-2, is currently regarded as a novel drug for treatment of acute heart failure. However, whether therapeutic effects of serelaxin are achieved by inhibiting cardiac fibrosis remains unclear. In this study, we investigate effects of serelaxin on inhibiting cardiac fibrosis. Cardiac fibroblasts (CFs) were isolated from the hearts of adult rats. Effects of serelaxin on differentiation of CFs towards myofibroblasts (MFs) and their fibrotic behaviors after induction with TGF-ß1 were examined. Synthesis and degradation of collagens, secretion of IL-10, and expression of ALK-5 and p-Smad2/3 of TGF-ß1-induced cells were assessed after treatment with serelaxin. Serelaxin inhibited differentiation of TGF-ß1-induced CFs towards MFs, and reduced proliferation and migration of the induced cells. Moreover, serelaxin down-regulated expression of collagen I/III and TIMP-2, and up-regulated expression of MMP-2 and MMP-9 in the cells. After treatment with serelaxin, activity of MMP-2 and MMP-9 and secretion of IL-10 increased, expression of ALK-5 and the level of Smad2/3 phosphorylation was reduced significantly. These results suggest that serelaxin can inhibit differentiation of TGF-ß1-induced CFs towards MFs, reduce production of collagens by suppressing ALK-5/Smad2/3 signaling pathway, and enhance extracellular matrix degradation by increasing MMP-2/TIMP-2 ratio and IL-10 secretion. Serelaxin may be a potential therapeutic drug for inhibiting cardiac fibrosis.

Autophagy promotes degradation of polyethyleneimine-alginate nanoparticles in endothelial progenitor cells.

Polyethyleneimine (PEI)-alginate (Alg) nanoparticle (NP) is a safe and effective vector for delivery of siRNA or DNA. Recent studies suggest that autophagy is related to cytotoxicity of PEI NPs. However, contribution of autophagy to degradation of PEI-Alg NPs remains unknown. CD34+VEGFR-3+ endothelial progenitor cells isolated from rat bone marrow were treated with 25 kDa branched PEI modified by Alg. After treatment with the NPs, morphological changes and distribution of the NPs in the cells were examined with scanning and transmission electron microscopies. Cytotoxicity of the NPs was analyzed by reactive oxygen species (ROS) production, lactate dehydrogenase leakage and induction of apoptosis. The level of autophagy was assessed with expression of Beclin-1 and LC3 and formation of autophagic structures and amphisomes. Colocalization of LC3-positive puncta and the NPs was determined by LC3-GFP tracing. Cytotoxicity of PEI NPs was reduced greatly after modification with Alg. PEI-Alg NPs were distributed in mitochondria, rough endoplasmic reticula and nuclei as well as cytoplasm. After phagocytosis of the NPs, expression of Beclin-1 mRNA and LC3 protein was upregulated, and the number of LC3-positive puncta, autophagic structures and amphisomes increased significantly. The number of lysosomes also increased obviously. There were LC3-positive puncta in nuclei, and some puncta were colocalized with the NPs. These results demonstrate that the activated autophagy promotes degradation of PEI-Alg NPs via multiple pathways.

Thymosin ß4 promotes the survival and angiogenesis of transplanted endothelial progenitor cells in the infarcted myocardium.

The survival of transplanted stem cells in ischemic tissue is poor. In the present study, the effects of thymosin ß4 (Tß4) on the survival and angiogenesis of endothelial progenitor cells (EPCs) and improvement in cardiac functions after transplantation of Tß4-treated EPCs in the infarcted myocardium were investigated. EPCs were isolated from bone marrow of adult male rats and incubated in Endothelial Basal Medium-2. Then the cells were treated with Tß4 at different concentrations (0.05, 0.1 and 0.2 µM), and cells incubated with DMEM were set as controls. MTT assay, Transwell assay and tube formation in Matrigel were used to detect cell viability, migration and angiogenesis, respectively. For examining the protective effect of Tß4 on EPCs, the cells were also incubated in the condition of hypoxia and serum deprivation. p-Akt expression was also examined using western blot analysis. Rat models of myocardial infarction (MI) were established by ligation of the anterior descending branch of the left coronary artery. At four weeks after intramyocardial injection of Tß4-treated EPCs, the changes in cardiac functions, size of the scar tissue and density of microvessels were examined by echocardiography, Masson's trichrome staining, immunohistochemistry and fluorescence in situ hybridization (FISH) for the Y-chromosome. Tß4 enhanced EPC viability, protected the cells from apoptosis in hypoxia and serum deprivation, and promoted the proliferation and migration of the cells and formation of capillary-like structures in the cells. Moreover, Tß4 increased p-Akt expression in the cells. The cytoprotective and proangiogenic effects of Tß4 were in a dose-dependent manner. Tß4-treated EPCs improved cardiac function, enhanced the repair of the infarcted myocardium, and promoted angiogenesis after transplantation in the infarcted myocardium. In conclusion, pretreatment of EPCs with Tß4 is a novel strategy for the repair of ischemic tissue after transplantation in MI.

Hypoxic preconditioning-induced autophagy enhances survival of engrafted endothelial progenitor cells in ischaemic limb.

Recent clinical studies have suggested that endothelial progenitor cells (EPCs) transplantation provides a modest benefit for treatment of the ischaemic diseases such as limb ischaemia. However, cell-based therapies have been limited by poor survival of the engrafted cells. This investigation was designed to establish optimal hypoxia preconditioning and evaluate effects of hypoxic preconditioning-induced autophagy on survival of the engrafted EPCs. Autophagy of CD34+ VEGFR-2+ EPCs isolated from rat bone marrow increased after treatment with 1% O2 . The number of the apoptotic cells in the hypoxic cells increased significantly after autophagy was inhibited with 3-methyladenine. According to balance of autophagy and apoptosis, treatment with 1% O2 for 2 hrs was determined as optimal preconditioning for EPC transplantation. To examine survival of the hypoxic cells, the cells were implanted into the ischaemic pouch of the abdominal wall in rats. The number of the survived cells was greater in the hypoxic group. After the cells loaded with fibrin were transplanted with intramuscular injection, blood perfusion, arteriogenesis and angiogenesis in the ischaemic hindlimb were analysed with laser Doppler-based perfusion measurement, angiogram and the density of the microvessels in histological sections, respectively. Repair of the ischaemic tissue was improved significantly in the hypoxic preconditioning group. Loading the cells with fibrin has cytoprotective effect on survival of the engrafted cells. These results suggest that activation of autophagy with hypoxic preconditioning is an optimizing strategy for EPC therapy of limb ischaemia.

Mesenchymal stem cell-loaded cardiac patch promotes epicardial activation and repair of the infarcted myocardium.

Cardiac patch is considered a promising strategy for enhancing stem cell therapy of myocardial infarction (MI). However, the underlying mechanisms for cardiac patch repairing infarcted myocardium remain unclear. In this study, we investigated the mechanisms of PCL/gelatin patch loaded with MSCs on activating endogenous cardiac repair. PCL/gelatin patch was fabricated by electrospun. The patch enhanced the survival of the seeded MSCs and their HIF-1α, Tß4, VEGF and SDF-1 expression and decreased CXCL14 expression in hypoxic and serum-deprived conditions. In murine MI models, the survival and distribution of the engrafted MSCs and the activation of the epicardium were examined, respectively. At 4 weeks after transplantation of the cell patch, the cardiac functions were significantly improved. The engrafted MSCs migrated across the epicardium and into the myocardium. Tendency of HIF-1α, Tß4, VEGF, SDF-1 and CXCL14 expression in the infarcted myocardium was similar with expression in vitro. The epicardium was activated and epicardial-derived cells (EPDCs) migrated into deep tissue. The EPDCs differentiated into endothelial cells and smooth muscle cells, and some of EPDCs showed to have differentiated into cardiomyocytes. Density of blood and lymphatic capillaries increased significantly. More c-kit+ cells were recruited into the infarcted myocardium after transplantation of the cell patch. The results suggest that epicardial transplantation of the cell patch promotes repair of the infarcted myocardium and improves cardiac functions by enhancing the survival of the transplanted cells, accelerating locality paracrine, and then activating the epicardium and recruiting endogenous c-kit+ cells. Epicardial transplantation of the cell patch may be applied as a novel effective MI therapy.

Cytoprotective effect of autophagy on phagocytosis of apoptotic cells by macrophages.

Clearance of the apoptotic cells by phagocytes plays pivotal roles in maintenance of tissue homeostasis, promotion of immunological tolerance and anti-inflammatory response. Recent studies show that autophagy is involved in phagocytosis of the apoptotic cells. However, contribution of autophagy to phagocytosis of the apoptotic cells by macrophages is not clearly defined. Here, we assessed cytoprotective effect of autophagy on clearance of the apoptotic cells. Apoptosis of murine splenic lymphocytes and human T-cell leukemia cells was induced with cyclophosphamide. After engulfment of the apoptotic cells, expression of Belin-1 and LC3 in macrophages was upregulated, the number of MDC-positive vesicles, LC3-positive autophagosomes and autophagic ultrastructures increased significantly. Autophagosome was fused with phagosome containing fragments of the nuclei or other debris of the apoptotic cells to form amphisome. Some cells in macrophages phagocytosing the apoptotic cells became apoptotic. After autophagy of macrophages was inhibited with 3-MA, viability and survival of macrophages reduced, phagocytosis of the apoptotic cells by macrophages deceased significantly. These results demonstrate that autophagy plays an important role in promoting clearance of the apoptotic cells by protecting macrophages from apoptosis during phagocytosis as well as degrading the contents of phagosomes via amphisome formation.

Stem cell-loaded nanofibrous patch promotes the regeneration of infarcted myocardium with functional improvement in rat model.

Myocardial infarction (MI) leads to the loss of cardiomyocytes, followed by left ventricular (LV) remodeling and cardiac dysfunction. The authors hypothesize that an elastic, biodegradable nanofibrous cardiac patch loaded with mesenchymal stem cells (MSC) could restrain LV remodeling and improve cardiac function after MI. Poly(ε-caprolactone)/gelatin (PG) nanofibers were fabricated by electrospinning, and the nanofibers displayed a porous and uniform nanofibrous structure with a diameter of 244±51nm. An MI model was established by ligation of the left anterior descending coronary artery of female Sprague-Dawley rats. The PG nanofibrous patch seeded with MSC, isolated from rat bone marrow, was implanted on the epicardium of the infarcted region of the LV wall of the heart. After transplantation, the PG-cell patch restricted the expansion of the LV wall effectively and reduced the scar size, and the density of the microvessels increased. Cells within the patch were able to migrate towards the scar tissue, and promoted new blood vessel formation at the infarct site. Angiogenesis and the cardiac functions improved significantly after 4weeks of implantation. The MSC-seeded PG nanofibrous patches are demonstrated to provide sufficient mechanical support, to induce angiogenesis and to accelerate cardiac repair in a rat model of MI. The study highlights the positive impact of implantation of an MSC-seeded PG nanofibrous patch as a novel constituent for MI repair.

Inhibition of lymphangiogenesis of endothelial progenitor cells with VEGFR-3 siRNA delivered with PEI-alginate nanoparticles.

Lymphangiogenesis is implicated in lymphatic metastasis of tumor cells. Recently, growing evidences show that endothelial progenitor cells (EPCs) are involved in lymphangiogenesis. This study has investigated effects of VEGF-C/VEGFR-3 (vascular endothelial growth factor receptor-3) signaling pathway on EPC differentiation and effectiveness of inhibiting lymphatic formation of EPCs with VEGFR-3 siRNA delivered in PEI (polyethylenimine)-alginate nanoparticles. CD34(+)VEGFR-3(+) EPCs were sorted from mononuclear cells of human cord blood. Under induction with VEGF-C, the cells differentiated toward lymphatic endothelial cells. The nanoparticles were formulated with 25 kDa branched PEI and alginate. The size and surface charge of PEI-alginate nanoparticles loading VEGFR-3 siRNA (N/P = 16) are 139.1 nm and 7.56 mV respectively. VEGFR-3 siRNA specifically inhibited expression of VEGFR-3 mRNA in the cells. After treatment with PEI-alginate/siRNA nanocomplexes, EPCs could not differentiate into lymphatic endothelial cells, and proliferation, migration and lymphatic formation of EPC-derived cells were suppressed significantly. These results demonstrate that VEGFR-3 signaling plays an important role in differentiation of CD34(+)VEGFR-3(+) EPCs. VEGFR-3 siRNA delivered with PEI-alginate nanoparticles can effectively inhibit differentiation and lymphangiogenesis of EPCs. Inhibiting VEGFR-3 signaling with siRNA/nanocomplexes would be a potential therapy for suppression of tumor lymphangiogenesis and lymphatic metastasis.

CD34+ VEGFR-3+ progenitor cells have a potential to differentiate towards lymphatic endothelial cells.

Endothelial progenitor cells (EPCs) play an important role in postnatal neovascularization. However, it is poorly understood whether EPCs contribute to lymphangiogenesis. Here, we assessed differentiation of a novel population of EPCs towards lymphatic endothelial cells and their lymphatic formation. CD34(+) VEGFR-3(+) EPCs were isolated from mononuclear cells of human cord blood by fluorescence-activated cell sorting. These cells expressed CD133 and displayed the phenotype of the endothelial cells. Cell colonies appeared at 7-10 days after incubation. The cells of the colonies grew rapidly and could be repeatedly subcultured. After induction with VEGF-C for 2 weeks, CD34(+) VEGFR-3(+) EPCs could differentiate into lymphatic endothelial cells expressing specific markers 5'-nucleotidase, LYVE-1 and Prox-1. The cells also expressed hyaluronan receptor CD44. The differentiated cells had properties of proliferation, migration and formation of lymphatic capillary-like structures in three-dimensional collagen gel and Matrigel. VEGF-C enhanced VEGFR-3 mRNA expression. After interfering with VEGFR-3 siRNA, the effects of VEGF-C were diminished. These results demonstrate that there is a population of CD34(+) VEGFR-3(+) EPCs with lymphatic potential in human cord blood. VEGF-C/VEGFR-3 signalling pathway mediates differentiation of CD34(+) VEGFR-3(+) EPCs towards lymphatic endothelial cells and lymphangiogenesis. Cord blood-derived CD34(+) VEGFR-3(+) EPCs may be a reliable source in transplantation therapy for lymphatic regenerative diseases.

Methods for assessing effects of Wnt/ß-catenin signaling in senescence of mesenchymal stem cells.

Mesenchymal stem cells (MSCs) represent a main population of stem cells and can differentiate into multiple cell lineages. Recently, MSC transplantation has been applied to repair the malfunctioned tissues. However, increasing evidences show that some MSCs expanded in vitro and in the aged individuals become senescent. Capacity of senescent MSCs in repairing the tissues may decrease significantly. Interestingly, preventing MSC senescence is a powerful potential strategy to delay aging of individuals and promote application of cell therapy for treating aging-related diseases. Therefore, it is necessary to explore mechanisms of MSC senescence in detail. Methods to assess MSC senescence in vitro include induction of senescence, detection of senescent changes and investigation of the molecules involved in senescence. Here we describe the methods to detect MSC senescence induced with old serum and investigate effects of Wnt/ß-catenin signaling on MSC senescence.