Search

Background: Stem cell-secreted extracellular vesicles (EVs) play essential roles in intercellular communication and restore cardiac function in animal models of ischemic heart disease. However, few studies have used EVs derived from clinical-grade stem cells and their derivatives with stable quality. Moreover, there is little information on the mechanism and time course of the multifactorial effect of EV therapy from the acute to the chronic phase, the affected cells, and whether the effects are direct or indirect., Methods: Induced pluripotent stem cell-derived cardiomyocytes (iPSCM) were produced using a clinical-grade differentiation induction system. EVs were isolated from the conditioned medium by ultracentrifugation and characterized in silico, in vitro, and in vivo. A rat model of myocardial infarction was established by left anterior descending artery ligation and treated with iPSCM-derived EVs., Results: iPSCM-derived EVs contained microRNAs and proteins associated with angiogenesis, antifibrosis, promotion of M2 macrophage polarization, cell proliferation, and antiapoptosis. iPSCM-derived EV treatment improved left ventricular function and reduced mortality in the rat model by improving vascularization and suppressing fibrosis and chronic inflammation in the heart. EVs were uptaken by cardiomyocytes, endothelial cells, fibroblasts, and macrophages in the cardiac tissues. The pleiotropic effects occurred due to the direct effects of microRNAs and proteins encapsulated in EVs and indirect paracrine effects on M2 macrophages., Conclusions: Clinical-grade iPSCM-derived EVs improve cardiac function by regulating various genes and pathways in various cell types and may have clinical potential for treating ischemic heart disease., Competing Interests: Disclosure statement The authors declare no competing interests. This research was supported by the Japan Society for the Promotion of Science KAKENHI Grant (21K19528) and the Japan Agency for Medical Research and Development (AMED) Program Grant (JP22ym0126809)., (Copyright © 2023 International Society for the Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.)

Background: Heart failure (HF) is a major cause of death worldwide. The most effective treatment for HF is heart transplantation, but its use is limited by the scarcity of donor hearts. Recently, stem cell-based therapy has emerged as a promising approach for treating myocardial infarction. Our research group has been investigating the use of human induced pluripotent stem cell-derived cardiomyocyte patches as a potential therapeutic candidate. We have successfully conducted eight cases of clinical trials and demonstrated the safety and effectiveness of this approach. However, further advancements are necessary to overcome immune rejection and enhance therapeutic efficacy. In this study, we propose a novel and efficient technique for constructing mesenchymal stem cell (MSC) tissue sheets, which can be transplanted effectively for treating myocardial infarction repair., Methods: We applied a one-step method to construct the human adipose-derived mesenchymal stem cell (hADSC) tissue sheet on a poly(lactic-co-glycolic acid) fiber scaffold. Histology, immunofluorescence, and paracrine profile assessment were used to determine the organization and function of the hADSC tissue sheet. Echocardiography and pathological analyses of heart sections were performed to evaluate cardiac function, fibrosis area, angiogenesis, and left ventricular remodeling., Results: In vitro, the hADSC tissue sheet showed great organization, abundant ECM expression, and increased paracrine secretion than single cells. In vivo, the hADSC tissue sheet group demonstrated improved cardiac functional recovery, less ventricular remodeling, decreased fibrosis, and enhanced angiogenesis than the MI group., Conclusions: We developed thick and functional hADSC tissue sheets via the one-step strategy. The hADSC tissue sheet showed excellent performance in treating myocardial infarction in the rat model., (© 2023. The Author(s).)

Transplantation of human allogeneic induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) is a new, promising treatment for severe heart failure. However, immunorejection is a significant concern in allogeneic hiPSC-CM transplantation, requiring the administration of several immunosuppressive agents. An appropriate protocol for the administration of immunosuppressants may substantially affect the efficacy of hiPSC-CM transplantation in case of heart failure owing to allogeneic transplantation. In this study, we investigated the effect of immunosuppressant administration duration on the efficacy and safety of allogenic hiPSC-CM patch transplantation. We used a rat model of myocardial infarction to evaluate cardiac function using echocardiography six months after the transplantation of hiPSC-CM patches with immunosuppressant administration for either two or four months and compared them to control rats (sham operation, no immunosuppressant administration). Histological analysis performed at 6 months after hiPSC-CM patch transplantation revealed significant improvement in cardiac function in immunosuppressant-treated rats compared with those in the control group. Moreover, fibrosis and cardiomyocyte size was significantly reduced and the number of structurally mature blood vessels was significantly increased in the immunosuppressant-treated rats compared to control rats. However, there were no significant differences between the two immunosuppressant-treated groups. Our results show that prolonged administration of immunosuppressive agents did not enhance the effectiveness of hiPSC-CM patch transplantation, and therefore, highlight the importance of an appropriate immunological regimen for the clinical application of such transplantation., (© 2023. The Author(s).)

Background: Transplanting human induced pluripotent stem cell-derived cardiomyocyte (hiPSC-CM) tissue sheets effectively treat ischemic cardiomyopathy. Cardiac functional recovery relies on graft survival in which angiogenesis played an important part. ONO-1301 is a synthetic prostacyclin analog with proangiogenic effects. We hypothesized that transplantation of hiPSC-CM tissue sheets with slow-release ONO-1301 scaffold could promote hostgraft angiogenesis, enhance tissue survival and therapeutic effect., Methods: We developed hiPSC-CM tissue sheets with ONO-1301 slow-release scaffold and evaluated their morphology, gene expression, and effects on angiogenesis. Three tissue sheet layers were transplanted into a rat myocardial infarction (MI) model. Left ventricular ejection fraction, gene expression in the MI border zone, and angiogenesis effects were investigated 4 weeks after transplantation., Results: In vitro assessment confirmed the slow-release of ONO-1301, and its pro-angiogenesis effects. In addition, in vivo data demonstrated that ONO-1301 administration positively correlated with graft survival. Cardiac tissue as thick as ∼900 μm was retained in the ONO (+) treated group. Additionally, left ventricular ejection fraction of the ONO (+) group was significantly enhanced, compared to ONO (-) group. The ONO (+) group also showed significantly improved interstitial fibrosis, higher capillary density, increased number of mature blood vessels, along with an enhanced supply of oxygen, and nutrients., Conclusions: Slow-release ONO-1301 scaffold provided an efficient delivery method for thick hiPSC-CM tissue. ONO-1301 promotes angiogenesis between the host and graft and improves nutritional and oxygen supply, thereby enhancing the survival of transplanted cells, effectively improving ejection fraction, and therapeutic effects., Competing Interests: Disclosure statement The authors declare no competing nonfinancial interests, but the following competing financial interests. Y.S.’s laboratory received funding from the Cuorips Company. We greatly appreciate the researchers who contributed to the experiments: N. S., N. Y., A. T., and M. W. for supplying the cells and fabricating the scaffold. M. I., Y. S., and M. K. for their support in animal experiments and sample processing. This study was supported by the Japan Agency for Medical Research and Development (AMED) and the Japan Society for the Promotion of Science (JSPS): Grant-in-Aid for Scientific Research (A) (20H00542 to Y. S. and L. L.) and Grants-in-Aid for Scientific Research (C) (19K12801 to J. L.). X. Q. was supported by the Ministry of Education, Culture, Sports, Science, and Technology (MEXT) scholarship., (Copyright © 2023 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.)

Although mesenchymal stem cell transplantation has been successful in the treatment of ischemic cardiomyopathy, the underlying mechanisms remain unclear. Herein, we investigated whether mitochondrial transfer could explain the success of cell therapy in ischemic cardiomyopathy. Mitochondrial transfer in co-cultures of human adipose-derived mesenchymal stem cells and rat cardiomyocytes maintained under hypoxic conditions was examined. Functional recovery was monitored in a rat model of myocardial infarction following human adipose-derived mesenchymal stem cell transplantation. We observed mitochondrial transfer in vitro , which required the formation of cell-to-cell contacts and synergistically enhanced energy metabolism. Rat cardiomyocytes exhibited mitochondrial transfer 3 days following human adipose-derived mesenchymal stem cell transplantation to the ischemic heart surface post-myocardial infarction. We detected donor mitochondrial DNA in the recipient myocardium concomitant with a significant improvement in cardiac function. Mitochondrial transfer is vital for successful cell transplantation therapies and improves treatment outcomes in ischemic cardiomyopathy.

For ischemic cardiomyopathy (ICM) with limited therapeutic options, the induction of arteriogenesis has the potential to improve cardiac function through major restoration of blood flow. We hypothesized that transplantation of a Notch signaling-modified mesenchymal stem cell (SB623 cell) patch would induce angiogenesis and arteriogenesis in ischemic lesions, leading to improvement of left ventricular (LV) function in a rat ICM model. Two weeks after the induction of ischemia, SB623 cell patch transplantation into ICM rats (SB group, n = 10) or a sham operation (no-treatment group, n = 10) was performed. The LV ejection fraction was significantly improved at 6 weeks after SB623 cell patch transplantation ( P < 0.001). Histological findings revealed that the number of von Willebrand factor (vWF)-positive capillary vessels ( P < 0.01) and alpha smooth muscle actin (αSMA)- and vWF-positive arterioles with a diameter greater than 20 µm ( P = 0.002) was significantly increased in the SB group, suggesting the induction of angiogenesis and arteriogenesis. Moreover, rat cardiomyocytes treated with SB623 cell patch transplantation showed upregulation of ephrin-B2 ( P = 0.03) and EphB4 ( P = 0.01) gene expression, indicating arteriogenesis induction. In conclusion, SB623 cell patch transplantation improved LV function by inducing angiogenesis and arteriogenesis in a rat ICM model.

A rotating wall vessel (RWV) bioreactor was constructed for growing massive functional cardiac constructs to recover the function of a distressed rat heart. Three-dimensional cardiac tissues were engineered by seeding human-induced pluripotent stem cell-derived cardiomyocytes on poly(lactic-co-glycolic acid) fiber sheets (3D-hiPSC-CTs) and cultured in the RWV bioreactor (RWV group) or under static conditions (control group). The tissues were transplanted into a myocardial infarction nude rat model, and cardiac performance was evaluated. In the RWV group, cell viability and contractile and electrical properties significantly improved, mature cardiomyocytes were observed, and mechanical stress-related mediators of mammalian target of rapamycin signaling were upregulated compared with those of the control. Four weeks post-transplantation, tissue survival and left ventricular ejection fraction significantly improved in the RWV group. Hence, dynamic culture in an RWV bioreactor could provide a superior culture environment for improved performance of 3D-hiPSC-CTs, providing a means for functional cardiomyogenesis in myocyte-loss heart failure., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Objectives: Although adipose-derived stem cells (ADSCs) have shown promise in cardiac regeneration, stable engraftment is still challenging. Acellular bioengineered cardiac patches have shown promise in positively altering ventricular remodeling in ischemic cardiomyopathy. We hypothesized that combining an ADSC sheet approach with a bioengineered patch would enhance ADSC engraftment and positively promote cardiac function compared with either therapy alone in a rat ischemic cardiomyopathy model., Methods: Cardiac patches were generated from poly(ester carbonate urethane) urea and porcine decellularized cardiac extracellular matrix. ADSCs constitutively expressing green fluorescent protein were established from F344 rats and transplanted as a cell sheet over the left ventricle 3 days after left anterior descending artery ligation with or without an overlying cardiac patch. Cardiac function was serially evaluated using echocardiography for 8 weeks, comparing groups with combined cells and patch (group C, n = 9), ADSCs alone (group A, n = 7), patch alone (group P, n = 6) or sham groups (n = 7)., Results: Much greater numbers of ADSCs survived in the C versus A groups (P < .01). At 8 weeks posttransplant, the percentage fibrotic area was lower (P < .01) in groups C and P compared with the other groups and vasculature in the peri-infarct zone was greater in group C versus other groups (P < .01), and hepatocyte growth factor expression was higher in group C than in other groups (P < .05). Left ventricular ejection fraction was higher in group C versus other groups., Conclusions: A biodegradable cardiac patch enhanced ADSC engraftment, which was associated with greater cardiac function and neovascularization in the peri-infarct zone following subacute myocardial infarction., (Published by Elsevier Inc.)

Although prostacyclin is an endogenous factor for the protection and regeneration of damaged tissue, the use of clinically available prostacyclin analogues for treating chronic pathological conditions is limited owing to their short half-lives. A new reagent, ONO-1301SR, which is a unique synthetic prostacyclin agonist polymerized with lactic and glycolic acid, has been demonstrated to constitutively release prostacyclin analogues to adjacent tissues, suggesting its therapeutic potential via slow-release delivery into a specific organ. In this study, we investigated the regenerative effect of direct epicardial delivery of the ONO-1301SR on a heart with a chronic myocardial infarct. An ameroid constrictor was placed on the left anterior descending coronary artery of Göttingen minipigs for 4 weeks to induce ischemic cardiomyopathy; this was followed by direct epicardial placement of ONO-1301SR-immersed gelatinous sheet, or only a gelatinous sheet on the anterolateral surface of the heart. Epicardial placement of ONO-1301SR resulted in significant recovery of global cardiac functions and regional wall motion of the lateral wall. Importantly, after epicardial placement of ONO-1301SR for 4 weeks, the myocardial blood flow significantly increased in the lateral region as assessed by 13 N-ammonia positron emission tomography; this finding was consistent with significantly increased capillary density in the peri-infarct area with up-regulated angiogenic cytokine expression. Conclusion: Use of the slow-release drug delivery system of prostacyclin agonist yielded regenerative angiogenesis, including increased regional blood perfusion and systolic function in a porcine model of chronic myocardial infarction., (© 2021. The Japanese Society for Artificial Organs.)

Although endogenous cardiac repair by recruitment of stem cells may serve as a therapeutic approach to healing a damaged heart, how to effectively enhance the migration of stem cells to the damaged heart is unclear. Here, we examined whether the combined administration of prostacyclin agonist (ONO1301), a multiple-cytokine inducer, and stem cell niche laminin-221 (LM221), enhances regeneration through endogenous cardiac repair. We administered ONO1301- and LM221-immersed sheets, LM221-immersed sheets, ONO1301-immersed sheets, and PBS-immersed sheets (control) to an acute infarction rat model. Four weeks later, cardiac function, histology, and cytokine expression were analysed. The combined administration of LM221 and ONO1301 upregulated angiogenic and chemotactic factors in the myocardium after 4 weeks and enhanced the accumulation of ILB4 positive cells, SMA positive cells, and platelet-derived growth factor receptor alpha (PDGFRα) and CD90 double-positive cells, leading to the generation of mature microvascular networks. Interstitial fibrosis reduced and functional recovery was prominent in LM221- and ONO1301-administrated hearts as compared with those in ONO1301-administrated or control hearts. LM221 and ONO1301 combination enhanced recruitment of PDGFRα and CD90 double-positive cells, maturation of vessels, and functional recovery in rat acute myocardial infarction hearts, highlighting a new promising acellular approach for the failed heart., (© 2021. The Author(s).)

In this chapter, we introduce the method for fabricating thick and anisotropic cardiac tissue for heart regeneration. Aligned and biodegradable nanofiber can be prepared by electrospinning Food and Drug Administration-approved poly (lactic-co-glycolic acid) on a rotating drum. After the nanofibers are transferred on to a polydimethylsiloxane frame, the cardiomyocytes could be plated on the nanofiber to form thick and anisotropic cardiac tissue rapidly. Cardiac tissue-like construct could be easily created by one-step method, and transplanted onto the hearts of myocardium infarction models and lead to their functional recovery., (© 2021. Springer Science+Business Media, LLC, part of Springer Nature.)

Background Extracellular matrix, especially laminin-221, may play crucial roles in viability and survival of human-induced pluripotent stem cell-derived cardiomyocytes (hiPS-CMs) after in vivo transplant. Then, we hypothesized laminin-221 may have an adjuvant effect on therapeutic efficacy by enhancing cell viability and survival after transplantation of 3-dimensional engineered cardiac tissue (ECT) to a rat model of myocardial infarction. Methods and Results In vitro study indicates the impacts of laminin-221 on hiPS-CMs were analyzed on the basis of mechanical function, mitochondrial function, and tolerance to hypoxia. We constructed 3-dimensional ECT containing hiPS-CMs and fibrin gel conjugated with laminin-221. Heart function and in vivo behavior were assessed after engraftment of 3-dimensional ECT (laminin-conjugated ECT, n=10; ECT, n=10; control, n=10) in a rat model of myocardial infarction. In vitro assessment indicated that laminin-221 improves systolic velocity, diastolic velocity, and maximum capacity of oxidative metabolism of hiPS-CMs. Cell viability and lactate dehydrogenase production revealed that laminin-221 improved tolerance to hypoxia. Furthermore, analysis of mRNA expression revealed that antiapoptotic genes were upregulated in the laminin group under hypoxic conditions. Left ventricular ejection fraction of the laminin-conjugated ECT group was significantly better than that of other groups 4 weeks after transplantation. Laminin-conjugated ECT transplantation was associated with significant improvements in expression levels of rat vascular endothelial growth factor. In early assessments, cell survival was also improved in laminin-conjugated ECTs compared with ECT transplantation without laminin-221. Conclusions In vitro laminin-221 enhanced mechanical and metabolic function of hiPS-CMs and improved the therapeutic impact of 3-dimensional ECT in a rat ischemic cardiomyopathy model. These findings suggest that adjuvant laminin-221 may provide a clinical benefit to hiPS-CM constructs.

Objectives: High-mobility group box 1 protein (HMGB1) fragment enhances bone marrow-derived mesenchymal stem cell (BM-MSC) recruitment to damaged tissue to promote tissue regeneration. This study aimed to evaluate whether systemic injection of HMGB1 fragment could promote tissue repair in a rat model of myocardial infarction (MI)., Methods: HMGB1 (n = 14) or phosphate buffered saline (n = 12, control) was administered to MI rats for 4 days. Cardiac performance and left ventricular remodeling were evaluated using ultrasonography and immunostaining. BM-MSC recruitment to damaged tissue in green fluorescent protein-bone marrow transplantation (GFP-BMT) models was evaluated using immunostaining., Results: At four weeks post-treatment, the left ventricular ejection fraction was significantly improved in the HMGB1 group compared to that in the control. Interstitial fibrosis and cardiomyocyte hypertrophy were also significantly attenuated in the HMGB1 group compared to the control. In the peri-infarction area, VEGF-A mRNA expression was significantly higher and TGFβ expression was significantly attenuated in the HMGB1 group than in the control. In GFP-BMT rats, GFP+/PDGFRα+ cells were significantly mobilized to the peri-infarction area in the HMGB1 group compared to that in the control, leading to the formation of new vasculature. In addition, intravital imaging revealed that more GFP+/PDGFRα+ cells were recruited to the peri-infarction area in the HMGB1 group than in the control 12 h after treatment., Conclusions: Systemic administration of HMGB1 induced angiogenesis and reduced fibrosis by recruiting PDGFRα+ mesenchymal cells from the bone marrow, suggesting that HMGB1 administration might be a new therapeutic approach for heart failure after MI., Competing Interests: The authors have no competing interests to declare.

Background: Transplantation of skeletal myoblast sheets is a promising strategy for the treatment of heart failure, and its therapeutic effects have already been proven in both animal disease models and clinical trials. Myoblast sheets reportedly demonstrate their therapeutic effects by producing many paracrine factors. Although the quality of processed cells for transplantation can be evaluated by the positive ratio of CD56, a myoblast marker, it is unclear which cell populations from isolated cells produce paracrine factors that have an impact on therapeutic effects, and whether these therapeutic effects are closely correlated with CD56-positive cells isolated from the skeletal muscle is also unclear. Therefore, we hypothesized that CD56-negative cells as well as CD56-positive cells isolated from the skeletal muscle produce paracrine factors and have therapeutic effects in skeletal muscle-derived cell sheet therapy for heart failure., Methods: Cell surface and intracellular markers of CD56-negative non-myogenic cells (NMCs) and CD56-positive myoblasts were evaluated. We also analyzed cytokine expression, tube formation ability, and stem cell mobilization in both cell populations. Finally, we assessed the therapeutic effects of the cell populations in a rat myocardial infarction model., Results: Analysis of cell surface and intracellular markers revealed that CD56-negative NMCs expressed fibroblast markers and a higher level of mesenchymal cell markers, such as CD49b and CD140a, than myoblasts. Both NMCs and myoblasts expressed various cytokines in vitro with different expression patterns. In addition, NMCs induced tube formation (control vs. myoblasts vs. NMCs: 100 ± 11.2 vs. 142 ± 8.3 vs. 198 ± 7.4%) and stem cell mobilization (control vs. myoblasts vs. NMCs: 100 ± 6.8 vs. 210 ± 22.9 vs. 351 ± 36.0%) to a higher degree in vitro than did myoblasts. The effect of NMCs and myoblasts on the improvement of cardiac function and suppression of myocardial fibrosis in rat myocardial infarction model was comparable., Conclusion: These results indicate that NMCs exhibit therapeutic effects in skeletal muscle-derived cell sheet therapy for heart failure. Thus, accurate parameters correlating with therapeutic effects need to be further explored.

Background: The extracellular matrix, in particular basement membrane components such as laminins (LMs), is essential for stem cell differentiation and self-renewal. LM511 and LM221 are the main extracellular matrix components of the epicardium, where stem cells were abundant. Here, we examined whether LMs affected the regeneration process by modulating stem cell activities., Methods: In vitro, adhesive, and proliferative activities of mesenchymal stem cells (MSCs) were evaluated on LM511 and LM221. To examine the effects of LMs in vivo, we established an acute myocardial infarction model by ligation of the proximal part of the left anterior descending artery at the height of the left atrial appendage and then placed atelocollagen sheets with or without LM511 and LM221 over the anterolateral surface of the left ventricular wall. Four or 8 weeks later, cardiac function, histology, and cytokine expressions were analyzed., Results: MSCs showed greater proliferation and adhesive properties on LM511 than on LM221. In vivo, at 4 weeks, isolectin B4-positive cells were significantly higher in the LM511-transplanted group than in the control group. Moreover, some isolectin B4-positive cells expressed both platelet-derived growth factor receptor α and CD90, suggesting that LM511 enhanced MSC recruitment and attachment at the implanted site. After 8 weeks, these cells were more abundant than at 4 weeks. Transplantation with LM511-conjugated sheets increased the expression of cardioprotective and angiogenic factors., Conclusions: Transplantation with LM511-conjugated sheets enhanced MSC localization to the implantation site and modulated stem cells activities, leading to angiogenesis in acute myocardial infarction rat models.

Background: The efficacy of cell transplantation in heart failure is reportedly modest, but adjuvant drugs combined with cell therapy may improve this efficacy. Peroxisome proliferator-activated receptor (PPAR)γ, one of the hypoglycemic medicine for diabetes mellitus, reportedly enhances cytokine production in adipose tissue-derived regenerative cells (ADRCs). We hypothesized that combined administration of PPARγ agonists and ADRCs may enhance the paracrine effects of adiponectin (APN), leading to functional recovery in a chronic myocardial infarction (MI) model., Methods: ADRCs were isolated from adipose tissues of adult rats by gradient centrifugation and embedded in bio-compatible fibrin-glue to produce ADRCs grafts. In the in vitro study, the ADRCs grafts released APN, which was significantly enhanced by the PPARγ agonist (PGZ, pioglitazone). Transplantation of ADRCs grafts (group A), ADRCs mixed with PGZ (group AP), APN knockdown-ADRCs (group Si) or PGZ (group P) onto the epicardium or a sham operation (group C) was performed (n = 10-20 per group)., Results: The AP group showed significant improvement in ejection fraction compared to that in the other groups. In the AP group, a significantly larger number of M2-polarized macrophages was detected and existed for a significantly longer duration in the infarct area. Furthermore, comparing Si group and P group, western blotting of T-cadherin revealed that exogenous APN and local expression of T-cadherin were essential to this histological change and recovery of cardiac function., Conclusions: Combined administration of PPARγ agonist and ADRSCs activated M2-polarized macrophages with enhancement of APN paracrine effects and lead to better cardiac function in a rat infarction model.

Aims: Accumulating evidence demonstrates that cardiomyocyte death contributes to the onset and progression of heart failure (HF) after myocardial injury. Recent studies revealed that immune/inflammatory reactions play important roles in cardiovascular diseases. However, it remains unclear whether immunosurveillance system, which eliminates cytopathic cells, including infected or malignant cancer cells, is involved in cardiomyocyte death, though cardiomyocytes are exposed to pathological stresses during post-infarct remodelling. The aim of this study is to clarify the pathophysiological significance of Natural Killer Group 2 member D (NKG2D)/NKG2D ligand (NKG2DL)-mediated cell death in HF after myocardial infarction (MI)., Methods and Results: MI was generated by ligating left anterior descending artery in mice. The expression of NKG2D, NKG2DLs, especially Retinoic acid early induced transcript-1ɛ (Rae-1ɛ), perforin and granzyme B was concomitantly up-regulated after MI. Immunohistological analysis revealed that Rae-1 was expressed on the membranes of injured cardiomyocytes in the infarct and border area. The MI-induced increase of Rae-1 expression was suppressed in p53-/- mice and Rae-1 was induced by the overexpression of p53. We identified p53-binding sites in Rae-1ɛ gene promoter, by chromatin immunoprecipitation assay, indicating that Rae-1 expression was mediated partially through p53. Flow cytometric analysis indicated that NKG2D-expressing immune cells in the post-infarct myocardium were mainly γδT cells. The co-culture with γδT cells increased the frequency of apoptotic cells in the cultured cardiomyocytes. The blockade of NKG2D/NKG2DL interaction by intraperitoneal injection of anti-Rae-1ɛ antibody after MI reduced the frequency of apoptotic cardiomyocytes, accompanied by suppression of cardiac fibrosis, attenuating cardiac dysfunction. Finally, tamoxifen-inducible cardiomyocyte-specific Rae-1ɛ overexpressing mice exhibited the susceptibility to post-infarct remodelling with increased cardiomyocyte apoptosis and severer cardiac dysfunction., Conclusion: The interaction between immune cells and cardiomyocytes via NKG2D/NKG2DL induces cardiomyocyte death, exacerbating cardiac remodelling after MI. The blockade of NKG2D/NKG2DL interaction could be a promising therapeutic strategy against HF., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2018. For permissions, please email: journals.permissions@oup.com.)

Background: Somatic stem cell (SC) therapy can improve cardiac performance following ischemic injury. In this study, we investigated whether induced pluripotent SC-derived cardiomyocytes (iPS-CMs) are more effective than somatic SCs, such as skeletal myoblasts (SM) and mesenchymal (M)SCs, in promoting functional recovery upon transplantation in a porcine model of myocardial infarction., Methods: Myocardial injury was induced by ameroid ring placement in immunosuppressed female mini pigs; after 1 month, epicardial cell transplantation was performed with iPS-CMs (n = 7), SMs (n = 7), and MSCs (n = 7). Control pigs underwent sham operation (n = 8)., Results: Cell therapy improved functional recovery 2 months after myocardial infarction, as evidenced by increased ejection fraction (iPS-CM, +7.3% ± 2.2% and SM, +5.8% ± 5.4% vs control, -4.4% ± 3.8%; P < 0.05). The analysis of regional contractile function in the infarcted zone revealed an increase in transverse peak strain (iPS-CM, +4.6% ± 2.2% vs control, -3.8% ± 4.7%; P < 0.05). The C-11 acetate kinetic analysis by positron emission tomography showed that the work-metabolic cardiac energy efficacy increased by the transplantation of iPS-CMs, but was reduced by the other cell types. This was accompanied by decreased myocardial wall stress in the infarcted zone (iPS-CM, -27.6 ± 32.3 Pa and SM, -12.8 ± 27 Pa vs control, +40.5 ± 33.9 Pa; P < 0.05)., Conclusions: The iPS-CM is superior to other somatic cell sources in terms of improving regional contractile function and cardiac bioenergetic efficiency, suggesting greater clinical benefits in severely damaged myocardium.

Background: Allogeneic adipose-derived mesenchymal stem cells (ADSC) are promising cell sources for cell therapy to treat ischemic cardiomyopathy (ICM). We hypothesized that ADSC transplantation via the new cell spray method may be a feasible, safe, and effective treatment for ICM., Methods: Human ADSCs were acquired from white adipose tissue. Porcine ICM models were established by constriction of the left anterior descending coronary artery. Adipose-derived mesenchymal stem cells were spread over the surface of the heart via cell spray in fibrinogen and thrombin solutions. The cardiac function was compared with that of the control group., Results: Adipose-derived mesenchymal stem cells were successfully transplanted forming a graft-like gel film covering the infarct myocardium. Premature ventricular contractions were rarely detected in the first 3 days after transplantation. Echocardiography and magnetic resonance imaging revealed improved cardiac performance of the ADSC group at 4 and 8 weeks after transplantation. Systolic and diastolic parameters were significantly greater in the ADSC group at 8 weeks after transplantation. Histological examination showed significantly attenuated left ventricular remodeling and a greater vascular density in the infarct border area in the ADSC group. Moreover, the coronary flow reserve was maintained, and expression levels of angiogenesis-related factors in the infarct border and remote areas were significantly increased., Conclusions: Spray method implantation of allogenic ADSCs can improve recovery of cardiac function in a porcine infarction model. This new allogenic cell delivery system may help to resolve current limitations of invasiveness and cost in stem cell therapy.

Background: Tissue-engineered cardiac constructs have potential in the functional recovery of heart failure; however, the preservation of these constructs is crucial for the development and widespread application of this treatment. We hypothesized that tissue-engineered skeletal myoblast (SMB) constructs may be preserved by vitrification to conserve biological function and structure., Results: Scaffold-free cardiac cell-sheet constructs were prepared from SMBs and immersed in a vitrification solution containing ethylene glycol, sucrose, and carboxyl poly-L-lysine. The cell sheet was wrapped in a thin film and frozen rapidly above liquid nitrogen to achieve vitrification (vitrification group, n = 8); fresh, untreated SMB sheets (fresh group, n = 8) were used as the control. The cryopreserved SMB sheets were thawed at 2 days, 1 week, 1 month, and 3 months after cryopreservation for assessment. Thawed, cryopreserved SMB sheets were transplanted into rat hearts in a myocardial infarction nude rat model, and their effects on cardiac function were evaluated. Cell viability in the cardiac constructs of the vitrification group was comparable to that of the fresh group, independent of the period of cryopreservation (p > 0.05). The structures of the cell-sheet constructs, including cell-cell junctions such as desmosomes, extracellular matrix, and cell membranes, were maintained in the vitrification group for 3 months. The expression of cytokine genes and extracellular matrix proteins (fibronectin, collagen I, N-cadherin, and integrin α5) showed similar levels in the vitrification and fresh groups. Moreover, in an in vivo experiment, the ejection fraction was significantly improved in animals treated with the fresh or cryopreserved constructs as compared to that in the sham-treated group (p < 0.05)., Conclusions: Overall, these results show that the vitrification method proposed here preserves the functionality and structure of scaffold-free cardiac cell-sheet constructs using human SMBs after thawing, suggesting the potential clinical application of this method in cell-sheet therapy.

Objectives: We previously reported that cell sheet transplantation combined with an omentopexy (OP) procedure is more effective for repairing heart damage when compared with cell sheet transplantation alone. However, a simultaneous (conventional) laparotomy as part of the OP may adversely affect the general condition of critically ill heart failure patients who would otherwise benefit from cell sheet transplantation, which is a paradox to be reconciled before this treatment can be applied in a clinical setting. We devised a novel endoscopic approach termed 'transphrenic peritoneoscopy' (TPP) for minimal access to abdominal organs from the thoracic cavity. Herein, we evaluated the feasibility and safety of TPP with an OP in a porcine myocardial infarction model., Methods: Myocardial infarction was induced in 4 mini pigs by placing an ameroid constrictor around the left anterior descending artery. One month later, a left thoracotomy was performed in 2 randomly selected mini pigs, and a laparoscopic port was placed on the left diaphragm to gain access into the abdominal cavity. Using a low-pressure pneumoperitoneum, a flexible gastrointestinal endoscope was advanced, then the omentum was partially grasped with endoscopic forceps and brought back into the thoracic cavity via the diaphragm. Skeletal myoblast cell sheets were then implanted over the impaired myocardium, followed by placing the omentum over the sheets., Results: TPP-assisted OP was accomplished in 2 post-myocardial infarction mini pigs with severe heart failure with an intra-abdominal pressure ≤8 mmHg within 30 min (22 and 27 min, respectively). Necropsy findings revealed a viable omentum flap and pedicle in both animals, with no evidence of procedure-related complications. Angiographic and histological analyses confirmed vessel communication between the omentum and the left ventricle., Conclusions: Our TPP approach was shown to be feasible and safe with a low-pressure pneumoperitoneum, while the omentum flap was durable. This successful combination of techniques may provide less-invasive endoscopic intervention and regenerative therapy.

High-purity cardiomyocytes (CMs) derived from human induced pluripotent stem cells (hiPSCs) are promising for drug development and myocardial regeneration. However, most hiPSC-derived CMs morphologically and functionally resemble immature rather than adult CMs, which could hamper their application. Here, we obtained high-quality cardiac tissue-like constructs (CTLCs) by cultivating hiPSC-CMs on low-thickness aligned nanofibers made of biodegradable poly(D,L-lactic-co-glycolic acid) polymer. We show that multilayered and elongated CMs could be organized at high density along aligned nanofibers in a simple one-step seeding process, resulting in upregulated cardiac biomarkers and enhanced cardiac functions. When used for drug assessment, CTLCs were much more robust than the 2D conventional control. We also demonstrated the potential of CTLCs for modeling engraftments in vitro and treating myocardial infarction in vivo. Thus, we established a handy framework for cardiac tissue engineering, which holds high potential for pharmaceutical and clinical applications., (Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.)

One of the major challenges in cell-based cardiac regenerative medicine is the in vitro construction of three-dimensional (3D) tissues consisting of induced pluripotent stem cell-derived cardiomyocyte (iPSC-CM) and a blood vascular network supplying nutrients and oxygen throughout the tissue after implantation. We have successfully built a vascularized iPSC-CM 3D-tissue using our validated cell manipulation technique. In order to evaluate an availability of the 3D-tissue as a biomaterial, functional morphology of the tissues was examined by light and transmission electron microscopy through their implantation into the rat infarcted heart. Before implantation, the tissues showed distinctive myofibrils within iPSC-CMs and capillary-like endothelial tubes, but their profiles were still like immature. In contrast, engraftment of the tissues to the rat heart led the iPSC-CMs and endothelial tubes into organization of cell organelles and junctional apparatuses and prompt development of capillary network harboring host blood supply, respectively. A number of capillaries in the implanted tissues were derived from host vascular bed, whereas the others were likely to be composed by fusion of host and implanted endothelial cells. Thus, our vascularized iPSC-CM 3D-tissues may be a useful regenerative paradigm which will require additional expanded and long-term studies.

Objective: The angiogenic potential of endothelial progenitor cells (EPCs) may be limited by the absence of their natural biologic foundation, namely smooth muscle pericytes. We hypothesized that joint delivery of EPCs and smooth muscle cells (SMCs) in a novel, totally bone marrow-derived cell sheet will mimic the native architecture of a mature blood vessel and act as an angiogenic construct to limit post infarction ventricular remodeling., Methods: Primary EPCs and mesenchymal stem cells were isolated from bone marrow of Wistar rats. Mesenchymal stem cells were transdifferentiated into SMCs by culture on fibronectin-coated culture dishes. Confluent SMCs topped with confluent EPCs were detached from an Upcell dish to create a SMC-EPC bi-level cell sheet. A rodent model of ischemic cardiomyopathy was then created by ligating the left anterior descending artery. Rats were randomized into 3 groups: cell sheet transplantation (n = 9), no treatment (n = 12), or sham surgery control (n = 7)., Results: Four weeks postinfarction, mature vessel density tended to increase in cell sheet-treated animals compared with controls. Cell sheet therapy significantly attenuated the extent of cardiac fibrosis compared with that of the untreated group (untreated vs cell sheet, 198 degrees [interquartile range (IQR), 151-246 degrees] vs 103 degrees [IQR, 92-113 degrees], P = .04). Furthermore, EPC-SMC cell sheet transplantation attenuated myocardial dysfunction, as evidenced by an increase in left ventricular ejection fraction (untreated vs cell sheet vs sham, 33.5% [IQR, 27.8%-35.7%] vs 45.9% [IQR, 43.6%-48.4%] vs 59.3% [IQR, 58.8%-63.5%], P = .001) and decreases in left ventricular dimensions., Conclusions: The bone marrow-derived, spatially arranged SMC-EPC bi-level cell sheet is a novel, multilineage cellular therapy obtained from a translationally practical source. Interactions between SMCs and EPCs augment mature neovascularization, limit adverse remodeling, and improve ventricular function after myocardial infarction., (Copyright © 2017 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.)

It has been shown that the size of myocardial infarction in rats created by coronary ligation technique is not uniform, varying from 4% to 65%. We hypothesized that infarct size variability induced by coronary artery ligation might be caused by coronary artery branching pattern. Coronary artery angiography was performed in 50 normal Lewis rats and in chronic myocardial infarction models in which coronary artery was ligated immediately below the left atrial appendage or 2mm distal to the left atrial appendage (n = 25 for each), followed by histological analysis. Unlike the human, the rats had a single major septal artery arising from the proximal part of the left coronary artery (n = 30) or right coronary artery (n = 20). There were three branching patterns of left circumflex artery (LCX): 33 (66%) had LCX branching peripherally from a long left main coronary artery (LMCA), while the remainder 17 (34%) had the LCX branching from the proximal part of the septal artery or a short LMCA. The rats with distal coronary ligation presented myocardial infarction localized to an anterior territory irrespective of LCX branching pattern. In the rats with proximal coronary ligation, 64% (n = 16) had broad myocardial infarction involving the anterior and lateral territories, while the remainder (36%, n = 9) had myocardial infarction localized to an anterior territory with the intact LCX arising proximally from a short LMCA. The interventricular septum was spared from infarction in all rats because of its anatomical location. Infarct size variations were caused not only by ligation site but also by varying LCX branching patterns. There are potential risks to create different sizes of myocardial infarction, particularly when targeting a broad range of myocardial infarction. The territory of the septal artery always appears to be spared from myocardial infarction induced by the coronary ligation technique.

Background: The sympathetic nervous system is critical in maintaining the normal physiological function of the heart. Its dysfunction in pathological states may exacerbate the substrate for arrhythmias. Obviously, knowledge of its three-dimensional (3D) structure is important, however, it has been revealed by conventional methods only to a limited extent. In this study, a new method of tissue clearance in combination with immunostaining unravels the 3D structure of the sympathetic cardiac network as well as its changes after myocardial infarction., Methods and Results: Hearts isolated from adult male mice were optically cleared using the CUBIC-perfusion protocol. After making the hearts transparent, sympathetic nerves and coronary vessels were immunofluorescently labeled, and then images were acquired. The spatial distribution of sympathetic nerves was visualized not only along the epicardial surface, but also transmurally. They were distributed over the epicardial surface and penetrated into the myocardium to twist around coronary vessels, but also independent from the coronary vasculature. At 2 weeks after myocardial infarction, we were able to quantify both denervation distal from the site of infarction and nerve sprouting (hyperinnervation) at the ischemic border zone of the hearts in a 3D manner. The nerve density at the ischemic border zone was more than doubled in hearts with myocardial infarction compared to intact mice hearts (3D analyses; n = 5, p<0.05)., Conclusions: There is both sympathetic hyperinnervation and denervation after myocardial infarction. Both can be visualized and quantified by a new imaging technique in transparent hearts and thereby become a useful tool in elucidating the role of the sympathetic nervous system in arrhythmias associated with myocardial infarction.

In vitro expanded beating cardiac myocytes derived from induced pluripotent stem cells (iPSC-CMs) are a promising source of therapy for cardiac regeneration. Meanwhile, the cell sheet method has been shown to potentially maximize survival, functionality, and integration of the transplanted cells into the heart. It is thus hypothesized that transplanted iPSC-CMs in a cell sheet manner may contribute to functional recovery via direct mechanical effects on the myocardial infarction (MI) heart. F344/NJcl-rnu/rnu rats were left coronary artery ligated (n = 30), followed by transplantation of Dsred-labeled iPSC-CM cell sheets of murine origin over the infarct heart surface. Effects of the treatment were assessed, including in vivo molecular/cellular evaluations using a synchrotron radiation scattering technique. Ejection fraction and activation recovery interval were significantly greater from day 3 onward after iPSC-CM transplantation compared to those after sham operation. A number of transplanted iPSC-CMs were present on the heart surface expressing cardiac myosin or connexin 43 over 2 weeks, assessed by immunoconfocal microscopy, while mitochondria in the transplanted iPSC-CMs gradually showed mature structure as assessed by electron microscopy. Of note, X-ray diffraction identified 1,0 and 1,1 equatorial reflections attributable to myosin and actin-myosin lattice planes typical of organized cardiac muscle fibers within the transplanted cell sheets at 4 weeks, suggesting cyclic systolic myosin mass transfer to actin filaments in the transplanted iPSC-CMs. Transplantation of iPSC-CM cell sheets into the heart yielded functional and electrical recovery with cyclic contraction of transplanted cells in the rat MI heart, indicating that this strategy may be a promising cardiac muscle replacement therapy.

Adipose stem cells (ASCs) are a source of regenerative cells available for autologous transplantation to hearts. We compared protective actions of ASC sheets on rat myocardial infarction (MI) in comparison with those of skeletal myoblast cell sheets. Their effects on infarcted hearts were evaluated by biological, histochemical as well as physiological analyses. ASC sheets secreted higher concentrations of angiogenic factors (HGF, VEGF, and bFGF; P < 0.05) under normoxic and hypoxic conditions than those of myoblast cell sheets, associated with reduction of cell apoptosis (P < 0.05). Like myoblast cell sheets, ASC sheets improved cardiac function (P < 0.05) and decreased the plasma level of ANP (P < 0.05) in MI hearts. ASC sheets restored cardiac remodeling characterized by fibrosis, cardiac hypertrophy and impaired angiogenesis (P < 0.05), which was associated with increases in angiogenic factors (P < 0.05). In isolated perfused rat hearts, ASC sheets improved both systolic and diastolic functions, which was comparable to cardiac functions of myoblast cell sheets, while both cell sheets failed to restore cardiac contractile response to either isoproterenol, pimobendan or dibutyryl cAMP. These results indicated that ASC sheets improved cardiac function and remodeling of MI hearts mediated by their paracrine action and this improvement was comparable to those by myoblast cell sheets.

Background: Because human cardiac stem cells (CSC) have regeneration potential in damaged cardiac tissue, there is increasing interest in using them in cell-based therapies for cardiac failure. However, culture conditions, by which CSCs are expanded while maintaining their therapeutic potential, have not been optimized. We hypothesized that the plating cell-density would affect proliferation activity, differentiation and therapeutic potential of CSCs through the Notch signaling pathway., Methods and Results: Human CSCs were plated at 4 different densities. The population doubling time, C-KIT positivity, and dexamethasone-induced multidifferentiation potential were examined in vitro. The therapeutic potential of CSCs was assessed by transplanting them into a rat acute myocardial infarction (AMI) model. The low plating density (340cells/cm(2)) maintained the multidifferentiation potential with greater proliferation activity and C-KIT positivity in vitro. On the other hand, the high plating density (5,500cells/cm(2)) induced autonomous differentiation into endothelial cells by activating Notch signaling in vitro. CSCs cultured at low or high density with Notch signal inhibitor showed significantly greater therapeutic potential in vivo compared with those cultured at high density., Conclusions: CSCs cultured with reduced Notch signaling showed better cardiomyogenic differentiation and therapeutic potentials in a rat AMI model. Thus, reducing Notch signaling is important when culturing CSCs for clinical applications.

Purpose: Myocardial infarction (MI) remains a major cause of mortality because of the limited regenerative capacity of the myocardium. Transplantation of somatic tissue-derived cells into the heart has been shown to enhance the endogenous healing process, but the magnitude of its therapeutic effects is dependent upon the cell-source or cell-delivery method. We investigated the therapeutic effects of C-Kit positive cardiac cell (CSC) cell-sheet transplantation therapy in a rat model of MI., Methods and Results: CSCs of human origin were sorted and cultured to generate scaffold-free CSC cell-sheets. One-layered or 3-layered cell-sheets were transplanted into nude rats 1 h after left coronary artery ligation. We observed a significant increase in the left ventricular ejection fraction and a significant decrease in left ventricular systolic dimension at 2 and 4 weeks in the 3-layer group, but not in the 1-layer or sham groups. Consistently, there was less accumulation of interstitial fibrosis in the 3-layer group than in the 1-layer or sham groups. Moreover, capillary density was significantly greater in the 3-layer group than in the 1-layer or sham groups., Conclusions: The 3-layered cell-sheet improved cardiac function associated with angiogenic and anti-fibrotic effects. Thus, CSC is a promising cell-source to use with the cell-sheet method for the treatment of cardiac failure, as long as a sufficient number of cells are delivered.

Background: A prostacyclin analogue, ONO-1301, is reported to upregulate beneficial proteins, including stromal cell derived factor-1 (SDF-1). We hypothesized that the sustained-release delivery of ONO-1301 would enhance SDF-1 expression in the acute myocardial infarction (MI) heart and induce bone marrow cells (BMCs) to home to the myocardium, leading to improved cardiac function in mice., Methods and Results: ONO-1301 significantly upregulated SDF-1 secretion by fibroblasts. BMC migration was greater to ONO-1301-stimulated than unstimulated conditioned medium. This increase was diminished by treating the BMCs with a CXCR4-neutralizing antibody or CXCR4 antagonist (AMD3100). Atelocollagen sheets containing a sustained-release form of ONO-1301 (n = 33) or ONO-1301-free vehicle (n = 48) were implanted on the left ventricular (LV) anterior wall immediately after permanent left-anterior descending artery occlusion in C57BL6/N mice (male, 8-weeks-old). The SDF-1 expression in the infarct border zone was significantly elevated for 1 month in the ONO-1301-treated group. BMC accumulation in the infarcted hearts, detected by in vivo imaging after intravenous injection of labeled BMCs, was enhanced in the ONO-1301-treated hearts. This increase was inhibited by AMD3100. The accumulated BMCs differentiated into capillary structures. The survival rates and cardiac function were significantly improved in the ONO-1301-treated group (fractional area change 23±1%; n = 22) compared to the vehicle group (19±1%; n = 20; P = 0.004). LV anterior wall thinning, expansion of infarction, and fibrosis were lower in the ONO-1301-treated group., Conclusions: Sustained-release delivery of ONO-1301 promoted BMC recruitment to the acute MI heart via SDF-1/CXCR4 signaling and restored cardiac performance, suggesting a novel mechanism for ONO-1301-mediated acute-MI heart repair.

Background: The implantation of skeletal myoblast (SMB) cell-sheets over the damaged area of a myocardial infarction (MI) has been shown to improve global left ventricular (LV) function through a paracrine effect. However, the regeneration process has not been fully evaluated. We hypothesized that the use of tissue Doppler strain M-mode imaging to assess myocardial layer-specific strain might enable detailed visual evaluation of the regenerative ability of SMBs., Methods and Results: SMBs were cultured on temperature-responsive culture dishes to generate cell-sheets. At 4 weeks after inducing anterior MI, the animals were divided into 2 groups: SMB cell-sheet implantation and sham operation (n=6 in each). A total of 30 cell-sheets (1.5×10(7) cells/sheet) were placed on the epicardium, covering the infarct and border regions. Subendocardial and subepicardial strain values were measured in the infarct, border, and remote regions by tissue Doppler strain analysis. SMB cell-sheet implantation produced the following major effects: progression of LV remodeling was prevented and global LV ejection fraction increased; the subendocardial strain was significantly greater than the subepicardial strain in the treated border region; vascular density in the subendocardium was significantly higher than in the subepicardium in the treated region; the expression of vascular endothelial growth factor was significantly increased., Conclusions: Tissue Doppler strain analysis allows precise evaluation of the effect of cell-sheet implantation on layer-specific myocardial function.

Background: Human induced pluripotent stem cell-derived cardiomyocytes (hiPS-CMs) are a promising source of cells for regenerating myocardium. However, several issues, especially the large-scale preparation of hiPS-CMs and elimination of undifferentiated iPS cells, must be resolved before hiPS cells can be used clinically. The cell-sheet technique is one of the useful methods for transplanting large numbers of cells. We hypothesized that hiPS-CM-sheet transplantation would be feasible, safe, and therapeutically effective for the treatment of ischemic cardiomyopathy., Methods and Results: Human iPS cells were established by infecting human dermal fibroblasts with a retrovirus carrying Oct3/4, Sox2, Klf4, and c-Myc. Cardiomyogenic differentiation was induced by WNT signaling molecules, yielding hiPS-CMs that were almost 90% positive for α-actinin, Nkx2.5, and cardiac troponin T. hiPS-CM sheets were created using thermoresponsive dishes and transplanted over the myocardial infarcts in a porcine model of ischemic cardiomyopathy induced by ameroid constriction of the left anterior descending coronary artery (n=6 for the iPS group receiving sheet transplantation and the sham-operated group; both groups received tacrolimus daily). Transplantation significantly improved cardiac performance and attenuated left ventricular remodeling. hiPS-CMs were detectable 8 weeks after transplantation, but very few survived long term. No teratoma formation was observed in animals that received hiPS-CM sheets., Conclusions: The culture system used yields a large number of highly pure hiPS-CMs, and hiPS-CM sheets could improve cardiac function after ischemic cardiomyopathy. This newly developed culture system and the hiPS-CM sheets may provide a basis for the clinical use of hiPS cells in cardiac regeneration therapy.

Transplantation of human cardiomyoblast-like cells (hCLCs) from human adipose tissue-derived multi-lineage progenitor cells improved left ventricular function and survival of rats with myocardial infarction. Here we examined the effect of intracoronary artery transplantation of human CLCs in a swine model of chronic heart failure. Twenty-four pigs underwent balloon-occlusion of the first diagonal branch followed by reperfusion, with a second balloon-occlusion of the left ascending coronary artery 1 week later followed by reperfusion. Four weeks after the second occlusion/reperfusion, 17 of the 18 surviving animals with severe chronic MI (ejection fraction <35% by echocardiography) were immunosuppressed then randomly assigned to receive either intracoronary artery transplantation of hCLCs hADMPCs or placebo lactic Ringer's solution with heparin. Intracoronary artery transplantation was followed by the distribution of DiI-stained hCLCs into the scarred myocardial milieu. Echocardiography at post-transplant days 4 and 8 weeks showed rescue and maintenance of cardiac function in the hCLCs transplanted group, but not in the control animals, indicating myocardial functional recovery by hCLCs intracoronary transplantation. At 8 week post-transplantation, 7 of 8 hCLCs transplanted animals were still alive compared with only 1 of the 5 control (p=0.0147). Histological studies at week 12 post-transplantation demonstrated engraftment of the pre DiI-stained hCLCs into the scarred myocardium and their expression of human specific alpha-cardiac actin. Human alpha cardiac actin-positive cells also expressed cardiac nuclear factors; nkx2.5 and GATA-4. Our results suggest that intracoronary artery transplantation of hCLCs is a potentially effective therapeutic strategy for future cardiac tissue regeneration., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Myoblast sheet transplantation for cardiac failure is a promising therapy to enhance cardiac function via paracrine mechanism. However, their efficacies of treatment showed a gradual decline. The gene modification of the implanted myoblast is important in improving the long-term results of the treatment. Elastin fiber enhances the extensibility of the infarcted wall and can prevent left ventricular dilation. We therefore hypothesized that the elastin gene modification of the implanted myoblast could strengthen and maintain the long-term improvement effects of cardiac function. In this study, we evaluated long-term follow-up benefits of functional myoblast sheets that secrete elastin in an infarcted model. The animal models were divided into three groups: a group transplanted with nontransfected, wild-type, skeletal myoblast-type sheets (WT-rSkM); group transplanted with myoblast sheets that secreted elastin fragments (ELN-rSkM); and a control group (ligation only). Cardiac function was examined by echocardiography, and cardiac remodeling after infarction was evaluated by histological examination. The cardiac function was significantly improved and the left ventricle end-diastolic dimensions were significantly reduced in the ELN-rSkM group. Histological analysis showed that left ventricular remodeling was attenuated in the ELN-rSkM group and that elastic fiber was formed in the epicardial area of ELN-rSkM group. The functionalization of myoblast sheet by elastin gene transfer showed the long-term improvement of cardiac function. Expressed recombinant elastin fiber prevented the dilation of the left ventricular chamber after myocardial infarction. The functional myoblast sheet transplantation maintained the treatment effect by the paracrine effect of myoblast and the formed recombinant elastin.

Background: Impairment of diastolic function and late remodeling are concerns after left ventricular restoration (LVR) for ischemic cardiomyopathy. This study aims to evaluate the effects of combined surgery of myoblast sheets (MS) implantation and LVR., Methods: Rat myocardial infarction model was established 2 weeks after left anterior descending artery ligation. They were divided into three groups: sham operation (n=15; group sham), LVR by plicating the infracted area (n=15; group LVR), and MS implantation with LVR (n=15; group LVR+MS)., Results: Serial echocardiographic study revealed significant LV redilatation and decrease of ejection fraction 4 weeks after LVR in group LVR. MS implantation combined with LVR prevented those later deteriorations of LV function in group LVR+MS. Four weeks after the operation, a hemodynamic assessment using a pressure-volume loop showed significantly preserved diastolic function in group LVR+MS; end-diastolic pressure (LVR vs. LVR+MS: 9.0±6.6 mm Hg vs. 2.0±1.0 mm Hg, P<0.05), end-diastolic pressure-volume relationship (LVR vs. LVR+MS 42±23 vs. 13±6, P<0.05). Histological examination revealed cellular hypertrophy and LV fibrosis were significantly less and vascular density was significantly higher in group LVR+MS than in the other two groups. Reverse transcription polymerase chain reaction demonstrated significantly suppressed expression of transforming growth factor-beta, Smad2, and reversion-inducing cysteine-rich protein with Kazal motifs in group LVR+MS., Conclusions: MS implantation decreased cardiac fibrosis by suppressing the profibrotic gene expression and attenuated the impairment of diastolic function and the late remodeling after LVR. It is suggesting that MS implantation may improve long-term outcome of LVR for ischemic heart disease.

Background: Patient movement has been considered an important source of errors in cardiac PET. This study was aimed at evaluating the effects of such movement on myocardial blood flow (MBF) and perfusable tissue fraction (PTF) measurements in intravenous ¹⁵O-water PET., Methods: Nineteen ¹⁵O-water scans were performed on ten healthy volunteers and three patients with severe cardiac dysfunction under resting conditions. Motions of subjects during scans were estimated by monitoring locations of markers on their chests using an optical motion-tracking device. Each sinogram of the dynamic emission frames was corrected for subject motion. Variation of regional MBF and PTF with and without the motion corrections was evaluated., Results: In nine scans, motions during ¹⁵O-water scan (inter-frame (IF) motion) and misalignments relative to the transmission scan (inter-scan (IS) motion) larger than the spatial resolution of the PET scanner (4.0 mm) were both detected by the optical motion-tracking device. After correction for IF motions, MBF values changed from 0.845 ± 0.366 to 0.780 ± 0.360 mL/minute/g (P < .05). In four scans with only IS motion detected, PTF values changed significantly from 0.465 ± 0.118 to 0.504 ± 0.087 g/mL (P< .05), but no significant change was found in MBF values., Conclusions: This study demonstrates that IF motion during ¹⁵O-water scan at rest can be source of error in MBF measurement. Furthermore, estimated MBF is less sensitive than PTF values to misalignment between transmission and ¹⁵O-water emission scans.

Cell-based therapies are promising strategies for myocardial repair following myocardial infarction. Induced pluripotent stem (iPS) cells have the potential to generate many cardiomyocytes, and they hold significant promise for the application of regenerative medicine to heart failure. Here, we developed cardiac tissue sheets, termed bioengineered myocardium (BM), from mouse iPS cells and measured cardiac performance following BM implantation in a rat chronic myocardial infarction model. Immunostaining analyses revealed that the α-actinin(+) cell population was isolated with more than 99% purity under specific culture conditions. To evaluate the contribution of BM to the improvements in cardiac performance, we induced myocardial infarction in 30 F344/NJcl-rnu/rnu rats by left anterior descending coronary ligation. The rats were randomly divided into two groups, 2 weeks after ligation: a BM implantation group (n = 15) and a sham group (n = 15). Echocardiography and catheter examination showed that the BM implantation significantly improved cardiac function and attenuated cardiac remodeling compared with the sham group. Histological analyses demonstrated that the implanted BM survived at the epicardial implantation site 4 weeks after implantation. The implanted BM survived and attenuated left ventricular remodeling in the rat chronic myocardial infarction model. Thus, BM derived from iPS cells might be a promising new treatment for heart failure.

Objective: A key challenge to applying cell transplantation to treat severely damaged myocardium is in delivering large numbers of cells with minimum cell loss. We developed a new implantation method using skeletal myoblast (SMB) sheets, wrapped with an omentum flap as a blood supply to deliver huge numbers of SMBs to the damaged heart. We examined whether this method could be used to deliver a large amount of cells to deteriorated porcine myocardium., Methods: Cell sheets were obtained by culturing mini-pig autologous SMB cells on temperature-responsive culture dishes. Myocardial infarction was induced by placing an ameroid constrictor around the left anterior descending artery. The mini-pigs were divided into 4 treatment groups (n = 6 in each): cell sheets with omentum, cell sheets only, omentum only, and sham operation. Each animal implant consisted of 30 cell sheets (1.5 × 10(7) cells per sheet). Six 5-layer constructs were each placed on a different area, immediately adjacent to but not overlapping one another, to cover the infarct and border regions., Results: The new regenerative cell delivery system using SMB sheets covered and wrapped with omentum resulted in (1) a significantly reduced infarct size causing, at least in part, a thin scar with thick well-vascularized cardiac tissue; (2) increased angiogenesis, as determined by a significantly higher vascular density; and (3) improved cardiac function, as determined by echocardiography, compared with the conventional method (SMB sheet implantation)., Conclusions: This cell delivery system shows potential for repairing the severely failed heart., (Copyright © 2011. Published by Mosby, Inc.)

Background: A drug delivery system that constitutively and effectively retains cardioprotective reagents in the targeted myocardium has long been sought to treat acute myocardial infarction. We hypothesized that a scaffold-free induced adipocyte cell-sheet (iACS), transplanted on the surface of the heart, might intramyocardially secrete multiple cardioprotective factors including adiponectin (APN), consequently attenuating functional deterioration after acute myocardial infarction., Methods and Results: Induced ACS were generated from adipose tissue-derived cells of wild-type (WT) mice (C57BL/6J), which secreted abundant APN, hepatocyte growth factor, and vascular endothelial growth factor in vitro. Transplanted iACS secreted APN into the myocardium of APN-knockout (KO) mice at 4 weeks. APN was also detected in the plasma of iACS-transplanted APN-KO mice at 3 months (245 ± 113 pg/mL). After left anterior descending artery ligation, iACS, generated from either WT (n=40) or APN-KO (n=40) mice, were grafted onto the surface of the anterior left ventricular wall of WT mice, or only left anterior descending artery ligation was performed (n=43). Two days later, inflammation and infarct size were significantly diminished only in the WT-iACS treated mice. One month later, cardiomyocyte diameter and percent fibrosis were smaller, whereas ejection fraction and survival were greater in the WT-iACS treated mice compared with the KO-iACS-treated or nontreated mice., Conclusions: Cardioprotective factors including APN, hepatocyte growth factor, and vascular endothelial growth factor were secreted from iACS. Transplantation of iACS onto the acute myocardial infarction heart attenuated infarct size, inflammation, and left ventricular remodeling, mediated by intramyocardially secreted APN in a constitutive manner. This method might be a novel drug delivery system to treat heart disease.

Unlabelled: A pig model of reduced left ventricular (LV) function and remodeling or chronic heart failure with long survival after myocardial infarction (MI) has not been established. The aim of this study was to evaluate the pathophysiologic status of a pig model of old MI using a series of PET studies., Methods: Twenty-seven male farm pigs were divided into 2 groups: 7 animals in the control group and 20 animals that underwent a proximal coronary artery (CA) occlusion using an ameroid constrictor after distal CA ligation. A series of PET examinations was performed to assess LV volumes, LV functions, myocardial perfusion response to adenosine, and viability as water-perfusable tissue index., Results: The distal CA ligation inhibited arrhythmia during and after the operation, and a transmural anteroseptal MI, with an infarction area of 27% ± 5% of the whole left ventricle, was generated with a survival rate of 75% at 4 mo. Wall motion evaluated by (18)F-FDG PET was diffusely reduced, including the noninfarcted wall. Global LV ejection fraction as assessed by gated C(15)O PET was reduced (39% ± 16%) in the group undergoing occlusion, compared with the control group (66% ± 16%, P < 0.05). LV end-systolic (31.4 ± 9.2 cm(3)) and end-diastolic (52.7 ± 10.2 cm(3)) volumes were increased, compared with controls (15.2 ± 9.4 cm(3), P < 0.01, and 41.7 ± 11.5 cm(3), P < 0.05, respectively). Histology showed hypertrophy and development of microscopic fibrosis in noninfarcted myocardium. PET demonstrated the reduced myocardial perfusion response to adenosine and also reduced water-perfusable tissue index in remote segments., Conclusion: The pig model of old MI generated by the chronic proximal CA obstruction after distal ligation was characterized by LV dysfunction and remodeling, with a high survival rate.

Background: The limitations of syngenic cell therapy include patient safety and quality control of the source cells. Therefore, it is important to develop and assess procedures using allogenic cells. We investigated the impact of allogenic skeletal myoblast (SMB) transplantation on acute myocardial infarction with respect to immune response, donor cell survival, and therapeutic efficacy., Methods: Female Lewis rats underwent proximal left anterior descending coronary artery ligation. Fifteen minutes later, they underwent major histocompatibility (MHC)-matched Lewis SMB transplantation (group S) and MHC-mismatched ACI SMB transplantation (group A), or treated with buffer injection as a control (group C)., Results: Flow cytometry showed that the SMBs expressed MHC antigens and B7 signal molecules in vitro. In group A, transcription levels of interleukin-2 receptor and interferon-γ were significantly increased 7 days after transplantation, and the area surrounding the donor SMBs was intensely infiltrated with CD4- and CD8-positive cells. Estimation of the number of donor cells in the recipient left ventricular chamber revealed that except for day 0, group A had fewer donor SMBs, which disappeared faster, compared with group S. Echocardiography demonstrated that the ejection fraction (EF) of group A was lower than that of group S., Conclusion: MHC-mismatched allogenic SMB transplantation in infarcted myocardium induces the immune response and acceleration of donor cell clearance, decreasing the therapeutic effect. Donor cell survival and inflammation may play important roles in the therapeutic mechanism of SMB transplantation therapy for acute myocardial infarction.

Background: We hypothesized that autologous skeletal cell (SC) sheets regenerate the infract myocardium in porcine heart as a preclinical trial., Methods and Results: The impaired heart was created by implantation of ameroid constrictor on left anterior descending for 4 weeks. SCs isolated from leg muscle were cultured and detached from the temperature-responsive domain-coated dishes as single monolayer cell sheet at 20 degrees C. The following therapies were conducted: SC sheets (SC group, n=5); sham (C group n=5). Echocardiography demonstrated that cardiac performance was significantly improved in the SC group 3 and 6 months after operation (fractional area shortening, 3 months; SC vs. C=49.5+/-2.8 vs. 24.6+/-2.0%, P<0.05) and left ventricle dilatation was well attenuated in the SC group. Color kinesis index showed that distressed regional diastolic and systolic function in infarcted anterior wall was significantly recovered (SC vs. C=57.4+/-8.6 vs. 30.2+/-4.7%, P<0.05, diastolic: 58.5+/-4.5 vs. 35.4+/-6.6%, P<0.05, systolic). Factor VIII immunostains demonstrated that vascular density was significantly higher in the SC group than the C group. And % fibrosis and cell diameter were significantly lower in the SC group. And hematoxylin-eosin staining depicted that skeletal origin cells and well-developed-layered smooth muscle cells were detected in the implanted area. Positron emission tomography showed better myocardial perfusion and more viable myocardial tissue in the distressed myocardium receiving SC sheets compared with the myocardium receiving no sheets., Conclusions: SC sheet implantation improved cardiac function by attenuating the cardiac remodeling in the porcine ischemic myocardium, suggesting a promising strategy for myocardial regeneration therapy in the impaired myocardium.

Adipose tissue-derived mesenchymal stem cells (ADMSCs) are multipotent cells. Here we examined whether human ADMSCs (hADMSCs) could differentiate into cardiomyoblast-like cells (CLCs) by induction with dimethylsulfoxide and whether the cells would be utilized to treat cardiac dysfunction. Dimethylsulfoxide induced the expression of various cardiac markers in hADMSCs, such as alpha-cardiac actin, cardiac myosin light chain, and myosin heavy chain; none of which were detected in noncommitted hADMSCs. The induced cells were thus designated as hADMSC-derived CLCs (hCLCs). To confirm their beneficial effect on cardiac function, hCLC patches were transplanted onto the Nude rat myocardial infarction model, and compared with noncommitted hADMSC patch transplants and sham operations. Echocardiography demonstrated significant short-term improvement of cardiac function in both the patch-transplanted groups. However, long-term follow-up showed rescue and maintenance of cardiac function in the hCLC patch-transplanted group only, but not in the noncommitted hADMSC patch-transplanted animals. The hCLCs, but not the hADMSCs, engrafted into the scarred myocardium and differentiated into human cardiac troponin I-positive cells, and thus regarded as cardiomyocytes. Transplantation of the hCLC patches also resulted in recovery of cardiac function and improvement of long-term survival rate. Thus, transplantation of hCLC patches is a potentially effective therapeutic strategy for future cardiac tissue regeneration.

Objective: We previously showed that autologous myoblast sheets constructed with tissue-engineering techniques improved the function of the impaired heart. In this study, we evaluated the effects of layered myoblast sheets to clarify whether increasing the number of sheets provides improvement of cardiac function., Methods: Myoblast sheets were constructed in dishes that release confluent cells from the dish surface via temperature reduction. Sixty infarcted Lewis rats underwent implantation of myoblast sheets on the infarcted area. There were 4 groups (n = 15 in each group): S1: one layer, S3: three layers, S5: five layers, and a sham group. We examined cardiac function by echocardiography and catheterization, mRNA expression by real time reverse-transcriptase polymerase chain reaction, and histology., Results: The ejection fraction and end-systolic pressure-volume relationship in the S5 and S3 groups were significantly improved. End-diastolic area was significantly reduced in the S5 group. The mRNAs for hepatocyte growth factor, vascular endothelial growth factor, and stromal cell-derived factor-1 were all up-regulated in dose-dependent fashion. On histologic examination, fibrosis was most decreased in S5, and vascular density was increased. Cellular hypertrophy was attenuated in both the S5 and S3 groups. Elastic fibers were massively up-regulated in the infarction and implanted sheets in the S5 and S3 groups, with expression of the elastin gene., Conclusions: Implantation of three- and five-layered myoblast sheets yields favorable results, with better improvement of cardiac function, induction of angiogenesis, more elastic fibers, and less fibrosis. Thus, layered myoblast sheets, in optimal numbers, may attenuate adverse cardiac remodeling of the infarcted heart.

To explore a new source of cell therapy for myocardial infarction (MI), we assessed the usefulness of mesenchymal stem cells derived from synovial membrane samples (SM MSCs). We developed a model of MI by ligation of the proximal left anterior descending coronary artery (LAD) in Lewis rats. Two weeks after ligation, 5 x 10(6) SM MSCs were injected into the MI scar area (T group, n = 9), while buffer was injected into the control group (C group, n = 9). Cardiac performances measured by echocardiography at 4 weeks after transplantation were significantly increased in the T group as compared with the C group. Masson's trichrome staining showed that SM MSC transplantation decreased collagen volume in the myocardium. Engrafted SM MSCs were found in the border zone of the infarct area. Immunohistological analysis showed that these cells were positive for the sarcomeric markers alpha-actinin and titin, and negative for desmin, troponin T, and connexin 43. SM MSC transplantation improved cardiac performance in a rat model of MI in the subacute phase, possibly through transdifferentiation of the engrafted cells into a myogenic lineage, which led to inhibition of myocardial fibrosis. Our results suggest that SM MSCs are a potential new regeneration therapy candidate for heart failure.

The goal of the study was to examine if allogenic mesenchymal stem cell (MSC) transplantation is a useful therapy for acute myocardial infarction (AMI). Buffer (control; group C, n=41), MSCs of male ACI rats (allogenic; group A, n=38, 5 x 10(6)), or MSCs of male LEW rats (syngenic; group S, n=40, 5 x 10(6)) were injected into the scar 15 min after myocardial infarction in female LEW rats. After 28 days, fractional left ventricular shortening significantly increased in groups A (21.3+/-1.7%, P=0.0467) and S (23.2+/-1.9%, P=0.0140), compared to group C (17.1+/-0.9%). Fibrosis in groups A and S was significantly lower. Quantitative PCR of the male-specific sry gene showed disappearance of donor cells within 28 days (5195+/-1975 cells). Secretion of vascular endothelial growth factor (VEGF) by MSCs was enhanced under hypoxic conditions in vitro. In groups A and S, the plasma VEGF concentration, VEGF level, and capillary density in recipient hearts increased after 28 days. Flow cytometry revealed the absence of B7 signal molecules on MSCs. A mixed lymphocyte reaction showed that ACI MSCs failed to stimulate proliferation of LEW lymphocytes. After 1 day after cell transplantation, transient increases in interleukin-1 beta and monocyte chemoattractant protein-1 in recipient hearts were enhanced in group A, with macrophage infiltration at the injection site. T cells remained at the level of normal tissue in all groups. We conclude that allogenic MSC transplantation therapy is useful for AMI. The donor MSCs disappear rapidly, but become a trigger of VEGF paracrine effect, without induction of immune rejection.

Background: Although angiogenic gene therapy has been reported to be effective in restoring ischemic heart function, there are several obstacles to its clinical application, such as unreliable efficiency of transfection and uncontrollable expression. We developed human HGF (hHGF)-producing cells that regulated hHGF production using the thymidine kinase gene of Herpes Simplex Virus (TK) and the Ganciclovir (GCV) system. We tested whether these cells induced and regulated angiogenic effects in infarcted myocardium., Methods: NIH3T3 cells were stably transfected with an hHGF cDNA expression plasmid (NIH/HGF). Next, the NIH/HGF cells were stably transfected with TK (NIH/HGF/TK). The left anterior descending artery was ligated in the heart of severe combined immunodeficiency rats, and four materials were transplanted: 1) NIH/HGF (n=10), 2) NIH/HGF/TK, with orally administered GCV (n=10), 3) NIH3T3 (n=10), and 4) culture medium (n=10)., Results: In vitro, the proliferation of NIH/HGF/TK cells was suppressed by GCV. In vivo, significant increases in cardiac performance and angiogenesis were observed in the NIH/HGF and NIH/HGF/TK groups 4 weeks after transplantation. Although tumorous lesions were detected in the NIH/HGF group, their growth was completely controlled in the NIH/HGF/TK group., Conclusions: Angiogenic gene cell therapy using the TK-GCV suicide gene system induces and regulates angiogenesis under the control of cell growth, suggesting it as a promising system for therapeutic angiogenesis.

Background: We hypothesized that tissue-engineered contractile cardiomyocyte sheets without a scaffold would show histological and electrical integration with impaired myocardium, leading to the regeneration of infarcted myocardium., Methods: Neonatal rat cardiomyocytes were cultured on Poly(N-isopropylacrylamide)-grafted polystyrene dishes and detached as a square cell sheet at 20 degrees C. Two sheets were stacked to make thicker contractile cardiac sheets. In cross-section, the stacked sheets looked like homogeneous heart-like tissue. Two weeks after rats were subjected to left anterior descending (LAD) ligation, two treatments were conducted: 1) cardiomyocyte sheet implantation (T group, n=10), and 2) fibroblast sheet implantation (F group, n=10). The control group underwent no additional treatment (C group, n=10)., Results: Echocardiography demonstrated that cardiac performance was significantly ameliorated in the T group 2, 4, and 8 weeks after implantation. The cardiomyocyte sheets became attached to the infarcted myocardium, showed angiogenesis, expressed connexin-43, and appeared as homogeneous tissue in the myocardium Electrophysiological experiments showed a QRS complex with one peak in the treated scar area in the T group, but two peaks, indicative of branch block, in that of the other groups. Furthermore, the threshold for pacing of the recipient heart was lower in the T group than in the other groups., Conclusions: Cardiomyocyte sheets integrated with the impaired myocardium and improved cardiac performance in a model of ischemic myocardium. Techniques using such tissue-engineered cell sheets are introducing the promising concept of tissue cardiomyoplasty to the field of regenerative medicine.