Preconditioning Stem Cells for Cardiovascular Disease

Nd:YAG-photobiomodulation enhanced ADSCs multilineage differentiation and immunomodulation potentials

To investigate the effects of Nd: YAG (1064 nm) photobiomodulation on multilineage differentiation and immunomodulation potentials of adipose tissue-derived stem cells (ADSCs) in vitro and in vivo. For in vitro experiments, cells were divided into the control group (non-irradiated control ADSCs) and photobiomodulation groups. 0.5 J/cm2, 1 J/cm2, 2 J/cm2, and 4 J/cm2 were used for proliferation assays; for ADSCs adipogenic differentiation assays, 0.5 J/cm2, 1 J/cm2 were applied; 1 J/cm2 was used for migration and immunomodulation assays. The differentiation abilities were assessed by qPCR, Oil Red O staining, and Alizarin Red staining. The immunomodulation potential was assessed by qPCR and human cytokine array. DSS-induced colitis model. was used to test the effect of photobiomodulation on ADSCs immunomodulation potentials in vivo. Nd:YAG-based photobiomodulation dose-dependently promoted ADSCs proliferation and migration; 1 J/cm2 showed the best promotion effect on proliferation. Moreover, Nd:YAG photobiomodulation promoted ADSCs osteogenic differentiation and brown adipose adipogenic differentiation. The potential immunomodulation assays showed Nd:YAG photobiomodulation improved Anti-inflammation capacity of ADSCs and photobiomodulation irradiated ADSCs effectively alleviated DSS-induced colitis severity in vivo. Our study suggests Nd:YAG photobiomodulation might enhance the ADSCs multilineage differentiation and immunomodulation potentials. These results might help to enhance ADSCs therapeutic effects for clinical application. However, further studies are needed to explore the mechanisms of Nd:YAG photobiomodulation promoting multilineage differentiation and immunomodulation potentials of ADSCs.

miR-130a activates the VEGFR2/STAT3/HIF1α axis to potentiate the vasoregenerative capacity of endothelial colony-forming cells in hypoxia

Hypoxia modulates reparative angiogenesis, which is a tightly regulated pathophysiological process. MicroRNAs (miRNAs) are important regulators of gene expression in hypoxia and angiogenesis. However, we do not yet have a clear understanding of how hypoxia-induced miRNAs fine-tune vasoreparative processes. Here, we identify miR-130a as a mediator of the hypoxic response in human primary endothelial colony-forming cells (ECFCs), a well-characterized subtype of endothelial progenitors. Under hypoxic conditions of 1% O2, miR-130a gain-of-function enhances ECFC pro-angiogenic capacity in vitro and potentiates their vasoreparative properties in vivo. Mechanistically, miR-130a orchestrates upregulation of VEGFR2, activation of STAT3, and accumulation of HIF1α via translational inhibition of Ddx6. These findings unveil a new role for miR-130a in hypoxia, whereby it activates the VEGFR2/STAT3/HIF1α axis to enhance the vasoregenerative capacity of ECFCs.

Astragaloside IV Promotes Antiphotoaging by Enhancing the Proliferation and Paracrine Activity of Adipose-Derived Stem Cells

Photoaging is a degenerative biological process. As a kind of pluripotent stem cells, adipose-derived stem cells (ADSCs) are widely used in the treatment of photoaging. Therefore, we aimed to find an effective way to improve the antiaging ability of ADSCs. In this study, we isolated ADSCs and assessed multilineage differentiation ability and markers. Cultured ADSCs were preconditioned with astragaloside IV (ASI) at 10^-7, 10^-6, and 10^-5 M. Cell proliferation was assessed by CCK-8 assay and cytokine secretion by enzyme-linked immunosorbent assay (ELISA). A fibroblast photoaging model was established and cocultured with normal ADSCs or ASI-treated ADSCs. Matrix metalloproteinase-1 (MMP1) and type I procollagen (PC-I) secreted by human dermal fibroblasts were measured by ELISA. The effects of ASI-treated ADSCs on skin texture, including dermal thickness, collagen content, and microvessel density, in a photoaging animal model were analyzed using H&E staining, Masson staining, and CD31 immunohistochemistry, respectively. We found that 10^-6 M ASI could significantly promote cell proliferation and stimulate robust secretion of growth factors in ADSCs. Furthermore, our data showed that ASI-treated ADSCs could markedly reverse the ultraviolet B-induced decrease of PC-I secretion and increase of MMP-1 release in fibroblasts. Moreover, in photoaged skin of nude mice, ASI-treated ADSCs significantly increased dermal thickness, collagen content, and microvessel density.

Insight on stem cell preconditioning and instructive biomaterials to enhance cell adhesion, retention, and engraftment for tissue repair

Stem cells are a promising solution for the treatment of a variety of diseases. However, the limited survival and engraftment of transplanted cells due to a hostile ischemic environment is a bottleneck for effective utilization and commercialization. Within this environment, the majority of transplanted cells undergo apoptosis prior to participating in lineage differentiation and cellular integration. Therefore, in order to maximize the clinical utility of stem/progenitor cells, strategies must be employed to increase their adhesion, retention, and engraftment in vivo. Here, we reviewed key strategies that are being adopted to enhance the survival, retention, and engraftment of transplanted stem cells through the manipulation of both the stem cells and the surrounding environment. We describe how preconditioning of cells or cell manipulations strategies can enhance stem cell survival and engraftment after transplantation. We also discuss how biomaterials can enhance the function of stem cells for effective tissue regeneration. Biomaterials can incorporate or mimic extracellular function (ECM) function and enhance survival or differentiation of transplanted cells in vivo. Biomaterials can also promote angiogenesis, enhance engraftment and differentiation, and accelerate electromechanical integration of transplanted stem cells. Insight gained from this review may direct the development of future investigations and clinical trials.

Thioredoxin-1 (Trx1) engineered mesenchymal stem cell therapy increased pro-angiogenic factors, reduced fibrosis and improved heart function in the infarcted rat myocardium

INTRODUCTION

Engraftment of mesenchymal stem cells (MSCs) has emerged as a powerful candidate for mediating myocardial repair. In this study, we genetically modified MSCs with an adenovector encoding thioredoxin-1 (Ad.Trx1). Trx1 has been described as a growth regulator, a transcription factor regulator, a cofactor, and a powerful antioxidant. We explored whether engineered MSCs, when transplanted, are capable of improving cardiac function and angiogenesis in a rat model of myocardial infarction (MI).

METHODS

Rat MSCs were cultured and divided into MSC, MSC+Ad.LacZ, and MSC+Ad.Trx1 groups. The cells were assayed for proliferation, and differentiation potential. In addition, rats were divided into control-sham (CS), control-MI (CMI), MSC+Ad.LacZ-MI (MLZMI), and MSC+Ad.Trx1-MI (MTrxMI) groups. MI was induced by left anterior descending coronary artery (LAD) ligation, and MSCs preconditioned with either Ad.LacZ or Ad.Trx1 were immediately administered to four sites in the peri-infarct zone.

RESULTS

The MSC+Ad.Trx1 cells increased the proliferation capacity and maintained pluripotency, allowing them to divide into cardiomyocytes, smooth muscle, and endothelial cells. Western blot analysis, 4 days after treatment showed increased vascular endothelial growth factor (VEGF), heme oxygenase-1 (HO-1), and C-X-C chemokine receptor type 4 (CXCR4). Also capillary density along with myocardial function as examined by echocardiography was found to be increased. Fibrosis was reduced in the MTrxMI group compared to MLZMI and CMI. Visualization of Connexin-43 by immunohistochemistry confirmed increased intercellular connections in the MTrxMI rats compared to MLZMI.

CONCLUSION

Engineering MSCs to express Trx1 may prove to be a strategic therapeutic modality in the treatment of cardiac failure.

Pretreatment of mesenchymal stem cells with angiotensin II enhances paracrine effects, angiogenesis, gap junction formation and therapeutic efficacy for myocardial infarction

BACKGROUND

Pretreatment of mesenchymal stem cells (MSCs) with growth factors is reported to be an effective route for improving cell-based therapy of myocardial infarction (MI). Angiotensin II (Ang II) triggers vascular endothelial growth factor (VEGF) synthesis in MSCs. This study aimed to investigate the effects and mechanisms of Ang II pretreatment in enhancing the therapeutic efficacy of MSCs in MI.

METHODS

MSCs and endothelial cells (ECs) were isolated from Sprague-Dawley rats. After pretreated with or without 100 nM of Ang II for 24 h, the MSCs were directly injected into the border zones of the ischemic heart. Cardiac function, fibrosis, infarct size, VEGF expression, angiogenesis, and cell differentiation in the infarcted myocardium were determined after 30 days. The cell apoptosis of MSCs post hypoxia was assessed using flow cytometry. The angiogenic activity of MSCs was analyzed using tube formation assay. The gap junction protein connexin-43 (Cx43) expression was detected.

RESULTS

Compared with the MSC group, pretreatment of MSCs with Ang II resulted in better cardiac function, less cardiac fibrosis, smaller infarct size, and higher expression of VEGF and Von Willebrand Factor in ischemic myocardium, but no promotion of cardiomyocyte-like differentiation of MSCs. Ang II pretreatment enhanced the survival of MSCs and the H9c2 cells surrounding MSCs, and augmented the tube formation of ECs and MSCs. Ang II pretreatment up-regulated the Cx43 expression.

CONCLUSIONS

The pretreatment of MSCs with Ang II improved the outcome of MSC-based therapy for MI via the mechanisms of enhancing the paracrine production of VEGF, angiogenesis, and gap junction formation.

Diazoxide pretreatment enhances L6 skeletal myoblast survival and inhibits apoptosis induced by hydrogen peroxide

Skeletal myoblast (SKM) transplantation is a promising approach to regenerate tissue and improve the function of the injured heart. However, the number of survival cells transplanted to host myocardium is quite poor due to high rate of apoptosis; diazoxide (DZ) is a highly selective mito-KATP channel opener that may reduce cell apoptosis by relieving reactive oxygen species (ROS) damage. The aim of this study is to explore the protective effects of DZ on L6 SKM damage induced by hydrogen peroxide (H(2)O(2) ) in vitro. Different dose and time of H(2)O(2) and DZ treatment were performed and only 24 hr of 1.00 mmol/L H(2) O(2) treatment and 200 μmol/L DZ pretreatment for 30 min were used for further experiment. L6 SKMs were cultured and divided into control group (no treatment), H(2)O(2) group (24 hr of 1.00 mmol/L H(2) O(2) treatment) and DZ + H(2)O(2) group (pretreated with 200 μmol/L DZ for 30 min before 24 hr of 1.00 mmol/L H(2) O(2) treatment). Compared with control group, H(2)O(2) treatment caused cell damage, increased lactate dehydrogenase release, cell apoptosis, and bax gene expression, while reduced cell proliferation and decreased bcl-2 expression. DZ pretreatment may protect cells from damage induced by H(2)O(2) and reduce cell apoptosis by increasing bcl-2 and decreasing bax expression. DZ pretreatment may also promote cell proliferation measured by both PCNA expression and flow cytometry method. These results suggest that DZ may protect L6 SKMs from damage induced by H(2)O(2) by maintaining integrity of cell membrane, reducing apoptosis and increasing proliferation in vitro.

Hypoxic preconditioning induces the expression of prosurvival and proangiogenic markers in mesenchymal stem cells

Stem cells transplanted to the ischemic myocardium usually encounter massive cell death within a few days of therapy. Hypoxic preconditioning (HPC) is currently employed as a strategy to prepare stem cells for increased survival and engraftment in the heart. However, HPC of stem cells has provided varying results, supposedly due to the differences in the oxygen concentration, duration of exposure, and passage conditions. In the present study, we determined the effect of HPC on rat mesenchymal stem cells (MSCs) exposed to 0.5% oxygen concentration for 24, 48, or 72 h. We evaluated the expression of prosurvival, proangiogenic, and functional markers such as hypoxia-inducible factor-1α, VEGF, phosphorylated Akt, survivin, p21, cytochrome c, caspase-3, caspase-7, CXCR4, and c-Met. MSCs exposed to 24-h hypoxia showed reduced apoptosis on being subjected to severe hypoxic conditions. They also had significantly higher levels of prosurvival, proangiogenic, and prodifferentiation proteins when compared with longer exposure (72 h). Cells taken directly from the cryopreserved state did not respond effectively to the 24-h HPC as those that were cultured under normoxia before HPC. Cells cultured under normoxia before HPC showed decreased apoptosis, enhanced expression of connexin-43, cardiac myosin heavy chain, and CD31. The preconditioned cells were able to differentiate into the cardiovascular lineage. The results suggest that MSCs cultured under normoxia before 24-h HPC are in a state of optimal expression of prosurvival, proangiogenic, and functional proteins that may increase the survival and engraftment in the infarct heart. These results could provide further insights into optimal preparation of MSCs which would greatly influence the effectiveness of cell therapy in vivo.

Long-acting phosphodiesterase-5 inhibitor, tadalafil, induces sustained cardioprotection against lethal ischemic injury

The ability of pharmacological preconditioning mimetics to confer long-lasting and sustained cardioprotection may be a logical criterion to develop a drug that can be used clinically for cardioprotection. We propose here that the use of long-acting phosphodiesterase-5 inhibitor, tadalafil, may confer sustained cardioprotection against ischemia. Tadalafil (5 mg/kg) was administered orally to male C57B/6J mice (n = 6 in each treatment subgroup at each time point studied). Hearts were isolated and subjected to 40 min of ischemia and 30 min of reperfusion on Langendorff's apparatus at 1, 12, 24, 36, 48, 60, 72, and 108 h after tadalafil administration. In 1- to 48-h subgroups, tadalafil was given once at 0 h only. In 60- and 72-h subgroups, tadalafil was given twice at 0 and 36 h. Similarly, in the 108-h subgroup, tadalafil was administered at 0, 36, and 72 h. In the same subgroups, wortmannin (15 microg/kg ip), an inhibitor of phosphatidylinositol 3-kinase or 5-hydroxydecanoic acid (5 mg/kg ip), an inhibitor of mitochondrial ATP-sensitive K(+) channels, was given together with tadalafil, and the hearts were subjected to ischemia-reperfusion at 36 h to determine whether the effect of tadalafil on ischemia-reperfusion injury was abolished. As a result, tadalafil treatment reduced left ventricular end-diastolic pressure and increased left ventricular developed pressure as well as reduced lactate dehydrogenase release. This protection remained till 36-40 h, and thereafter it vanished. The readministration of tadalafil at 36 and 72 h restored the protection till 108 h. Tadalafil treatment accelerated Akt phosphorylation in cardiac tissue and decreased myocyte apoptosis. The administration of wortmannin abolished the beneficial effects of tadalafil on hemodynamic parameters and myocyte apoptosis, together with significantly reduced Akt phosphorylation. 5-Hydroxydecanoic acid also abolished the antiapoptotic effect of tadalafil. It is concluded that tadalafil treatment induces the long-term protection of ischemic myocardium via phosphatidylinositol 3-kinase/Akt signaling pathway.

Cardiomyocyte death and renewal in the normal and diseased heart

During post-natal maturation of the mammalian heart, proliferation of cardiomyocytes essentially ceases as cardiomyocytes withdraw from the cell cycle and develop blocks at the G0/G1 and G2/M transition phases of the cell cycle. As a result, the response of the myocardium to acute stress is limited to various forms of cardiomyocyte injury, which can be modified by preconditioning and reperfusion, whereas the response to chronic stress is dominated by cardiomyocyte hypertrophy and myocardial remodeling. Acute myocardial ischemia leads to injury and death of cardiomyocytes and nonmyocytic stromal cells by oncosis and apoptosis, and possibly by a hybrid form of cell death involving both pathways in the same ischemic cardiomyocytes. There is increasing evidence for a slow, ongoing turnover of cardiomyocytes in the normal heart involving death of cardiomyocytes and generation of new cardiomyocytes. This process appears to be accelerated and quantitatively increased as part of myocardial remodeling. Cardiomyocyte loss involves apoptosis, autophagy, and oncosis, which can occur simultaneously and involve different individual cardiomyocytes in the same heart undergoing remodeling. Mitotic figures in myocytic cells probably represent maturing progeny of stem cells in most cases. Mitosis of mature cardiomyocytes that have reentered the cell cycle appears to be a rare event. Thus, cardiomyocyte renewal likely is mediated primarily by endogenous cardiac stem cells and possibly by blood-born stem cells, but this biological phenomenon is limited in capacity. As a consequence, persistent stress leads to ongoing remodeling in which cardiomyocyte death exceeds cardiomyocyte renewal, resulting in progressive heart failure. Intense investigation currently is focused on cell-based therapies aimed at retarding cardiomyocyte death and promoting myocardial repair and possibly regeneration. Alteration of pathological remodeling holds promise for prevention and treatment of heart failure, which is currently a major cause of morbidity and mortality and a major public health problem. However, a deeper understanding of the fundamental biological processes is needed in order to make lasting advances in clinical therapeutics in the field.