Autologous Skeletal Myoblasts Research Articles

Efficacy of Autologous Skeletal Myoblast Cell Sheet Transplantation for Liver Regeneration in Liver Failure.

No effective therapies have yet been established for liver regeneration in liver failure. Autologous skeletal myoblast cell sheet transplantation has been proven to improve cardiac function in patients with heart failure, and one of the mechanisms has been reported to be a paracrine effect by various growth factors associated with liver regeneration. Therefore, the present study focused on the effect of myoblast cells on liver regeneration in vitro and in vivo. We assessed the effect of myoblast cells on the cells comprising the liver in vitro in association with liver regeneration. In addition, we examined in vivo effect of skeletal myoblast cell sheet transplantation in C57/BL/6 mouse models of liver failure, such as liver fibrosis induced by thioacetamide and hepatectomy. In vitro, the myoblast cells exhibited a capacity to promote the proliferation of hepatic epithelial cells and the angiogenesis of liver sinusoidal endothelial cells, and suppress the activation of hepatic stellate cells. In vivo, sheet transplantation significantly suppressed liver fibrosis in the induced liver fibrosis model and accelerated liver regeneration in the hepatectomy model. Autologous skeletal myoblast cell sheet transplantation significantly improved the liver failure in the in vitro and in vivo models. Sheet transplantation is expected to have the potential to be a clinically therapeutic option for liver regeneration in liver failure.

Autologous skeletal myoblast patch implantation prevents the deterioration of myocardial ischemia and right heart dysfunction in a pressure-overloaded right heart porcine model.

Right ventricular dysfunction is a predictor for worse outcomes in patients with congenital heart disease. Myocardial ischemia is primarily associated with right ventricular dysfunction in patients with congenital heart disease and may be a therapeutic target for right ventricular dysfunction. Previously, autologous skeletal myoblast patch therapy showed an angiogenic effect for left ventricular dysfunction through cytokine paracrine effects; however, its efficacy in right ventricular dysfunction has not been evaluated. Thus, this study aimed to evaluate the angiogenic effect of autologous skeletal myoblast patch therapy and amelioration of metabolic and functional dysfunction, in a pressure-overloaded right heart porcine model. Pulmonary artery stenosis was induced by a vascular occluder in minipigs; after two months, autologous skeletal myoblast patch implantation on the right ventricular free wall was performed (n = 6). The control minipigs underwent a sham operation (n = 6). The autologous skeletal myoblast patch therapy alleviated right ventricular dilatation and ameliorated right ventricular systolic and diastolic dysfunction. 11C-acetate kinetic analysis using positron emission tomography showed improvement in myocardial oxidative metabolism and myocardial flow reserve after cell patch implantation. On histopathology, a higher capillary density and vascular maturity with reduction of myocardial ischemia were observed after patch implantation. Furthermore, analysis of mRNA expression revealed that the angiogenic markers were upregulated, and ischemic markers were downregulated after patch implantation. Thus, autologous skeletal myoblast patch therapy ameliorated metabolic and functional dysfunction in a pressure-overloaded right heart porcine model, by alleviating myocardial ischemia through angiogenesis.

Abstract 13717: Autologous Skeletal Myoblast Patch Remodeled Swine Pressure-overloaded Right Heart by Amelioration in Myocardial Ischemia

Introduction: Myocardial ischemia (MI) is majorly seen in the right ventricular (RV) dysfunction in patients with congenital heart disease secondary to residual hemodynamic stressors in form of pressure-overloaded, suggesting therapeutic target for RV dysfunction may be how to control MI. Autologous skeletal myoblast patch showed the angiogenetic effect for left ventricular dysfunction by cytokine paracrine effects, which are expected to be sufficiently effective against pressure-overloaded RV dysfunction. Hypothesis: An autologous skeletal myoblast patch alleviates the MI in a pressure-overloaded right heart in swine model, leading to amelioration of metabolic and functional dysfunction. Methods: Five-month-old mini-pigs underwent pulmonary artery banding. Two months after banding, myoblast patch derived from autologous skeletal muscles were placed on the epicardium of RV free wall. Groups were as follows: control (C, n=6), sheet implantation (S, n=6). Two months after sheet implantation, cardiac function exam and C11-Acetate positron emission tomography (PET) were done, and hearts were dissected for histologic and real-time polymerase chain reaction (RT-PCR) analysis. Results: Two months after sheet implantation, RV dysfunction was significantly ameliorated in group S than group C (RVEF; S 44.9+/-2.2 vs C 31.9+/-2.1 % [p=0.0042]). PET revealed the deterioration of myocardial blood flow (Rest/Stress; S 3.22+/-0.39 vs C 2.13+/-0.92 min -1 [p=0.0421]) and myocardial oxidative metabolism (K mono -Rest/Stress: S 3.17+/-0.69 vs C 2.03+/-0.65 min -1 [p=0.0421]) were suppressed in group S than group C. In histologic analysis, group S presented more angiogenesis in CD31 expression (S 18.3+/-1.5 vs C 10.7+/-2.8 units/cells [p=0.0122]). In RT-PCR analysis, mRNA expression of vascular endothelial growth factor (S 1.28+/-0.35 vs C 0.75+/-0.17 folds [p=0.030]), hepatocyte growth factor (S 1.70+/-0.79 vs C 0.74+/-0.10 folds [p=0.030]), and chemokine stromal cell-derived factor-1 (S 1.49+/-0.97 vs C 0.35+/-0.20 folds [p=0.030]) were upregulated in group S than group C. Conclusions: Autologous skeletal myoblast patch ameliorated metabolic and functional dysfunction in a swine model of pressure-overloaded right heart by alleviation of MI.

Autologous skeletal myoblast sheet prevents cardiomyocyte ischemia and right heart dysfunction in pressure-overloaded right heart porcine model

Abstract Introduction Severe heart failure (HF) with congenital heart disease (CHD) have demonstrated life threatening disorder despite of remarkable progress in medical therapies. Autologous skeletal myoblast sheet transplantation therapy showed clinical efficacy for left ventricular dysfunction by cytokine paracrine effects, which are expected to be sufficiently effective against right ventricular (RV) dysfunction which is often seen in end-stage of CHD patients with severe HF. Hypothesis An autologous skeletal myoblast sheet transplantation alleviates RV dysfunction in a pressure-overloaded right heart in a porcine model. Methods Five-to-six-month-old Göttingen mini-pigs underwent pulmonary artery banding with vascular occluding system. To create the porcine model of chronic pressure-overloaded right heart, vascular occluding system was gradually inflated, over a month, to make pulmonary stenosis to banding velocity >3.0 m/s measured by echocardiography (UCG), and then fixed for another month. Two months after banding, autologous skeletal myoblast sheet was placed on the epicardium of the RV free wall and followed for 2 months. Groups were as follows: control (C, n=5), sheet implantation (S, n=5). Cardiac function was measured using UCG, cardiac computed tomography (CT), and cardiac catheterization (Cath). Two months after sheet implantation, hearts were dissected for histologic analysis. Results Before sheet implantation, RV dysfunction was equal in groups; however, 2 months after sheet implantation, RV dysfunction and myocardial ischemia was significantly ameliorated in group S than group C. On CT, RV ejection fraction exacerbation were well controlled in Group S compared to Group C (S 44.9±2.2 vs C 31.9±2.1% [p=0.0042]). UCG and Cath revealed well maintained systolic and diastolic function in Group S compared to Group C (Tei index: S 0.42±0.06 vs C 0.70±0.07 [p=0.0240], Fraction Area Change: S 45.8±7.8 vs C 19.5±1.3% [p=0.0240], Isovolumic Relaxation Time; S 44.3±9.2 vs C 97.3±9.5 ms [p=0.0304]). On C11-Acetate Positron Emission Tomography, myocardial ischemia was more prominent in Group C compared to Group S (K mono-Rest/Stress: S 3.17±0.69 vs C 2.03±0.65 min-1 [p=0.0421], Myocardial Blood Flow-Rest/Stress: S 3.22±0.39 vs C 2.13±0.92 min-1 [p=0.0421]). In histologic analysis, Group S presented less progressed hypertrophic change in periodic acid-Schiff stain (S 13.5±0.9 vs C 18.0±3.0 μg [p=0.0240]), anti-fibrotic changes in picrosirius red stain (S 3.0±0.3 vs C 4.2±0.2% [p=0.0421]), more angiogenesis in CD31 expression (S 18.3±1.5 vs C 10.7±2.8 / 104 μm2 [p=0.0240]), and less production of reactive oxygen species in fluorescent immunostaining (S 5.9±1.7 vs C 18.4±1.7% [p=0.0304]). Conclusion Autologous skeletal myoblast sheet transplantation alleviates cardiomyocyte Ischemia and RV dysfunction in a porcine model of pressure-overloaded right heart. Funding Acknowledgement Type of funding source: None

Effect of Co-culturing Fibroblasts in Human Skeletal Muscle Cell Sheet on Angiogenic Cytokine Balance and Angiogenesis.

Skeletal muscle comprises a heterogeneous population of myoblasts and fibroblasts. Autologous skeletal muscle myoblasts are transplanted to patients with ischemia to promote cardiac regeneration. In damaged hearts, various cytokines secreted from the skeletal muscle myoblasts promote angiogenesis and consequently the recovery of cardiac functions. However, the effect of skeletal muscle fibroblasts co-cultured with skeletal muscle myoblasts on angiogenic cytokine production and angiogenesis has not been fully understood. To investigate these effects, production of vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF) was measured using the culture medium of monolayers prepared from various cell densities (mono-culture) and proportions (co-culture) of human skeletal muscle myoblasts (HSMMs) and human skeletal muscle fibroblasts (HSMFs). HSMM and HSMF mono-cultures produced VEGF, whereas HSMF mono-culture produced HGF. The VEGF productivity observed in a monolayer comprising low proportion of HSMFs was two-fold greater than that of HSMM and HSMF mono-cultures. The production of VEGF in HSMMs but not in HSMFs was directly proportional to the cell density. VEGF productivity in non-confluent cells with low cell-to-cell contact was higher than that in confluent cells with high cell-to-cell contact. The dynamic migration of cells in a monolayer was examined to analyze the effect of HSMFs on myoblast-to-myoblast contact. The random and rapid migration of HSMFs affected the directional migration of surrounding HSMMs, which disrupted the myoblast alignment. The effect of heterogeneous populations of skeletal muscle cells on angiogenesis was evaluated using human umbilical vein endothelial cells (HUVECs) incubated with fabricated multilayer HSMM sheets comprising various proportions of HSMFs. Co-culturing HSMFs in HSMM sheet at suitable ratio (30 or 40%) enhances endothelial network formation. These findings indicate the role of HSMFs in maintaining cytokine balance and consequently promoting angiogenesis in the skeletal muscle cell sheets. This approach can be used to improve transplantation efficiency of engineered tissues.

Current status of cardiac regenerative medicine; An update on point of view to cell therapy application.

Cardiovascular diseases (CVDs) are the leading cause of death globally. Because of the economic and social burden of acute myocardial infarction and its chronic consequences in surviving patients, understanding the pathophysiology of myocardial infarction injury is a major priority for cardiovascular research. MI is defined as cardiomyocytes death caused by an ischemic that resulted from the apoptosis, necrosis, necroptosis, and autophagy. The phases of normal repair following MI including inflammatory, proliferation, and maturation. Normal repair is slow and inefficient generally so that other treatments are required. Because of difficulties, outcomes, and backwashes of traditional therapies including coronary artery bypass grafting, balloon angioplasty, heart transplantation, and artificial heart operations, the novel strategy in the treatment of MI, cell therapy, was newly emerged. In cell therapy, a new population of cells has created that substitute with damaged cells. Different types of stem cell and progenitor cells have been shown to improve cardiac function through various mechanisms, including the formation of new myocytes, endothelial cells, and vascular smooth muscle cells. Bone marrow- and/or adipose tissue-derived mesenchymal stem cells, embryonic stem cells, autologous skeletal myoblasts, induced pluripotent stem cells, endothelial progenitor cells, cardiac progenitor cells and cardiac pericytes considered as a source for cell therapy. In this study, we focused on the point of view of the cell sources.

Cell-Based Therapy in Cardiac Regeneration: An Overview.

Although pioneering preclinical research on the use of cell therapy for cardiac regeneration was conducted in the last quarter of the 20th century,1,2 a preponderance of advances have occurred in the 21st century, making this a relatively young field. In the first important clinical trial of cardiac cell therapy, begun in 2001, Menasche et al3 implanted autologous skeletal myoblasts into postinfarct scar at the time of coronary artery bypass surgery. Although the transplanted cells remained viable and exhibited contraction, they formed the nidus for serious ventricular tachyarrhythmias, which led to premature discontinuation of the trial. Despite this outcome, the trial energized the field, accelerating both preclinical and clinical research, albeit not with skeletal myoblasts. The extensive progress in cardiac regeneration is reviewed in this Compendium, and as occurs frequently in science, important observations have led to more questions and challenges (Table). View this table: Table. Important Challenges to Cell Therapy for Cardiac Regeneration Many cell types have been evaluated as candidates for cardiac regeneration. Among the earliest clinical trials, Zeiher’s group infused autologous bone marrow-derived progenitor cells into the coronary arteries of patients with acute,4 as well as healed myocardial infarction (MI)5 and reported improvements in left ventricular (LV) function. However, these results have not been fully confirmed by later studies, as pointed out in the review in the Compendium by Banarjee, Bolli, and Hare.6 Pittenger et al7 were among the first to direct attention to bone marrow-derived (stromal) mesenchymal stem cells (MSCs), emphasizing that these cells proliferated extensively in culture and suggesting that they could be attractive candidates for transplantation. In 2004, Chen et al8 reported that intracoronary infusion of autologous bone marrow-derived MSCs improved cardiac function. Zimmet and Hare pointed out that MSCs lack histocompatibility type II markers and elude rejection by …

Peer review report 1 on “Tooth extraction in a patient after autologous skeletal myoblast sheet transplantation for severe dilated cardiomyopathy”

Peer review report 1 on “Tooth extraction in a patient after autologous skeletal myoblast sheet transplantation for severe dilated cardiomyopathy”

Peer review report 2 on “Tooth extraction in a patient after autologous skeletal myoblast sheet transplantation for severe dilated cardiomyopathy”

Peer review report 2 on “Tooth extraction in a patient after autologous skeletal myoblast sheet transplantation for severe dilated cardiomyopathy”

An in silico prediction tool for the expansion culture ofhuman skeletal muscle myoblasts.

Regenerative therapy using autologous skeletal myoblasts requires a large number of cells to be prepared for high-level secretion of cytokines and chemokines to induce good regeneration of damaged regions. However, myoblast expansion culture is hindered by a reduction in growth rate owing to cellular quiescence and differentiation, therefore optimization is required. We have developed a kinetic computational model describing skeletal myoblast proliferation and differentiation, which can be used as a prediction tool for the expansion process. In the model, myoblasts migrate, divide, quiesce and differentiate as observed during in vitro culture. We assumed cell differentiation initiates following cell–cell attachment for a defined time period. The model parameter values were estimated by fitting to several predetermined experimental datasets. Using an additional experimental dataset, we confirmed validity of the developed model. We then executed simulations using the developed model under several culture conditions and quantitatively predicted that non-uniform cell seeding had adverse effects on the expansion culture, mainly by reducing the existing ratio of proliferative cells. The proposed model is expected to be useful for predicting myoblast behaviours and in designing efficient expansion culture conditions for these cells.

Abstract 11478: Excellent Clinical Courses of Autologous Skeletal Myoblast Sheet Transplantation Compared to a Propensity Score-Matched Cardiac Resynchronization Therapy (Best of Basic Science Abstract)

Introduction: We recently reported a multi-center, single-arm, phase II study that evaluated the efficacy and safety of autologous skeletal myoblast sheet (TCD-51073) transplantation. The advantage of this procedure over a control group has not yet been analyzed. Hypothesis: TCD-51073 has better clinical outcome compared with background-matched control group. Methods: Seven patients with advanced heart failure due to ischemic etiology (TCD-51073 group, New York Heart Association [NYHA] class III; left ventricular ejection fraction (LVEF) <35%) refractory to optimal medical and coronary revascularization therapy, received TCD-51073 at 3 study centers between 2012 and 2013 with a 2-year follow-up period. As previously reported, 112 patients received cardiac resynchronization therapy (CRT) with follow-up at the University of Tokyo Hospital between 2007 and 2014. Results: Of them, 21 patients were selected for the control group by propensity score matching. No significant difference in baseline variables between the groups was observed. LVEF and NYHA class improved significantly in the TCD-51073 group during the 6-month study period (p<0.05). During the 2-year follow-up, 7 patients (33%) in the CRT group and no patient in the TCD-51073 group died due to cardiac disease or received VAD implantation (p=0.128 by the log-rank test). Conclusions: Transplantation of TCD-51073 is clinically advantageous in facilitating LV reverse remodeling, improving HF symptoms, and preventing cardiac death in patients with ischemic etiology when compared to background-matched patients receiving CRT.

Improved Clinical Course of Autologous Skeletal Myoblast Sheet Transplantation When Compared to a Propensity Score-Matched Cardiac Resynchronization Therapy Population

We recently reported a multi-center, single-arm, phase II study that evaluated the efficacy and safety of autologous skeletal myoblast sheet (TCD-51073) transplantation. The advantage of this procedure over a control group has not yet been analyzed. Seven patients with advanced heart failure due to ischemic etiology (TCD-51073 group, New York Heart Association [NYHA] class III; left ventricular ejection fraction (LVEF) <35%) refractory to optimal medical and coronary revascularization therapy, received TCD-51073 at 3 study centers between 2012 and 2013 with a 2-year follow-up period. As previously reported, 112 patients received cardiac resynchronization therapy (CRT) with follow-up at the University of Tokyo Hospital between 2007 and 2014. Of them, 21 patients were selected for the control group by propensity score matching. No significant difference in baseline variables between the groups was observed. LVEF and NYHA class improved significantly in the TCD-51073 group during the 6-month study period (p<0.05). During the 2-year follow-up, 7 patients (33%) in the CRT group and no patient in the TCD-51073 group died due to cardiac disease or received VAD implantation (p=0.128 by the log-rank test). Transplantation of TCD-51073 is clinically advantageous in facilitating LV reverse remodeling, improving HF symptoms, and preventing cardiac death in patients with ischemic etiology when compared to background-matched patients receiving CRT.

Improved clinical course of autologous skeletal myoblast sheet (TCD-51073) transplantation when compared to a propensity score-matched cardiac resynchronization therapy population.

We recently reported a multi-center, single-arm, phase II study that evaluated the efficacy and safety of autologous skeletal myoblast sheet (TCD-51073) transplantation. The advantage of this procedure over a control group has not yet been analyzed. Seven patients with advanced heart failure due to ischemic etiology (TCD-51073 group, New York Heart Association (NYHA) class III; left ventricular ejection fraction (LVEF) <35 %) refractory to optimal medical and coronary revascularization therapy, received TCD-51073 at 3 study centers between 2012 and 2013 with a 2-year follow-up period. As previously reported, 112 patients received cardiac resynchronization therapy (CRT) with follow-up at the University of Tokyo Hospital between 2007 and 2014. Of them, 21 patients were selected for the control group by propensity score matching. No significant difference in baseline variables between the groups was observed. LVEF and NYHA class improved significantly in the TCD-51073 group during the 6-month study period (p < 0.05). During the 2-year follow-up, 7 patients (33 %) in the CRT group and no patient in the TCD-51073 group died due to cardiac disease or received VAD implantation (p = 0.128 by the log-rank test). In conclusion, transplantation of TCD-51073 is clinically advantageous in facilitating LV reverse remodeling, improving HF symptoms, and preventing cardiac death in patients with ischemic etiology when compared to background-matched patients receiving CRT.

Circumferential esophageal replacement using a tube-shaped tissue-engineered substitute: An experimental study in minipigs

Esophageal replacement by the colon or the stomach for malignant and nonmalignant esophageal diseases exposes to significant morbidity and mortality. In this setting, tissue engineering seems to be a seductive alternative. In a porcine model, we performed a 5-cm-long circumferential replacement of the cervical esophagus by a tubulized acellular matrix (small intestinal submucosa) cellularized with autologous skeletal myoblasts and covered by a human amniotic membrane seeded with autologous oral epithelial cells. The substitute was grown for 2weeks in the great omentum before esophageal replacement. Eighteen minipigs (divided into 3 groups: group A [substitute with esophageal endoprothesis; n=6], group B [substitute alone; n=6], and group C [endoprothesis alone; n=6]) were included. The esophageal endoprothesis was removed at 6months. Animals were killed sequentially over a 12 month-period. Clinical, endoscopic, radiologic and histologic outcomes were analyzed. All animals except 1 of in groups B and C died during the first 2months owing to refractory esophageal stenosis or endoprothesis extrusion. Nutritional autonomy without endoprothesis was observed in all animals of group A with a follow-up of >6months (n=3). A phenotype similar to that of native esophagus, consisting of a mature epithelium, submucosal glands, and a circular muscular layer, was observed after 9months. In this model, the circumferential replacement of the cervical esophagus by a tube-shaped tissue-engineered substitute under the temporary cover of an esophageal endoprothesis allowed nutritional autonomy and tissue remodeling toward an esophageal phenotype.

Extending Flaps Lifts an Infarcted Heart Toward Repair

Normal hearts comprise 2 × 109 myocytes, but this number may be doubled in excessively hypertrophied hearts. After a heart attack caused by blockage of one of the arteries that supply the heart, approximately 20% or more of cardiomyocytes are acutely and irreversibly lost in the ischemic area. However, the damage is not limited to the acute interruption of blood flow. Reperfusion of the ischemic territory can cause additional damage due to a burst of toxic reactive oxygen species. Moreover, additional cardiomyocytes are lost in the peri-infarct area during the subacute phase, leading to extension of the infarcted area. The ensuing remodeling response, which consists of cardiomyocyte hypertrophy and collagen accumulation, is insufficient to compensate for the massive cell loss, thus leading to scar expansion, ventricular chamber dilation, and failure.

Exogenous connexin43-expressing autologous skeletal myoblasts ameliorate mechanical function and electrical activity of the rabbit heart after experimental infarction.

Acute myocardial infarction is one of the major causes of mortality worldwide. For regeneration of the rabbit heart after experimentally induced infarction we used autologous skeletal myoblasts (SMs) due to their high proliferative potential, resistance to ischaemia and absence of immunological and ethical concerns. The cells were characterized with muscle-specific and myogenic markers. Cell transplantation was performed by injection of cell suspension (0.5 ml) containing approximately 6 million myoblasts into the infarction zone. The animals were divided into four groups: (i) no injection; (ii) sham injected; (iii) injected with wild-type SMs; and (iv) injected with SMs expressing connexin43 fused with green fluorescent protein (Cx43EGFP). Left ventricular ejection fraction (LVEF) was evaluated by 2D echocardiography in vivo before infarction, when myocardium has stabilized after infarction, and 3 months after infarction. Electrical activity in the healthy and infarction zones of the heart was examined ex vivo in Langendorff-perfused hearts by optical mapping using di-4-ANEPPS, a potential sensitive fluorescent dye. We demonstrate that SMs in the coculture can couple electrically not only to abutted but also to remote acutely isolated allogenic cardiac myocytes through membranous tunnelling tubes. The beneficial effect of cellular therapy on LVEF and electrical activity was observed in the group of animals injected with Cx43EGFP-expressing SMs. L-type Ca(2+) current amplitude was approximately fivefold smaller in the isolated SMs compared to healthy myocytes suggesting that limited recovery of LVEF may be related to inadequate expression or function of L-type Ca(2+) channels in transplanted differentiating SMs.

Recent developments in cardiovascular stem cells.

Heart failure, a common consequence of ischemic heart disease, is a major cause of morbidity and mortality in the world.1–3 Pharmacological treatment with β-blockers and inhibitors of the renin–angiotensin–aldosterone system has improved the clinical outcomes in patients with heart failure.4–7 Likewise, mechanical unloading with left ventricular assist devices and resynchronization therapy have led to partial reversal of cardiac structural and molecular remodeling and symptomatic improvement.8–10 Despite these remarkable advances, however, mortality and morbidity of patients with heart failure, with or without reduced ejection fraction remains high.1,2 Moreover, heart transplantation, while an effective option, is available only for a selected number of patients and is not without considerable negative consequences.11 Furthermore, gene therapy still remains in early investigational stages and not yet ready for clinical applications.12 The high residual mortality and morbidity of patients with heart failure might be inherent to the shortcomings of the current therapeutic approaches, as none directly targets the underlying causal problem in heart failure, that is, loss of or intrinsically dysfunctional myocytes. Consequently, novel therapeutic approaches are necessary to further improve the clinical outcomes in patients with heart failure. The heart is considered, by and large, a terminally differentiated organ with a limited intrinsic regenerative capacity that alone is insufficient to compensate for the pathological loss of cardiac myocytes during the postnatal period.13–15 The discovery of cardiac progenitor cells (CPCs) in the heart more than a decade ago along with the recent data showing that the existing myocytes undergo a gradual turnover have raised the potentials for regenerative cardiac repair.16,17 Likewise, the discovery of mesenchymal stem cells (MSCs), which was thought to have the potential to differentiate to cardiac myocytes, but yet to proven, or enhance …

Promising Therapeutic Effects of Cell Sheet Implantation with a Pedicle Omentum Flap to Enhance the Angiogenic Response to Ischemic Cardiomyopathy

Introduction: We previously reported that skeletal myoblast (SMB) sheets induced the functional recovery of distressed myocardium in a large or small animal heart failure model via the paracrine effect of cytokines; however, this method was limited by poor vascular network and cell retention. We hypothesized that wrapping the cell sheet with pedicle omentum—a well-vascularized organ delivering different stem cell types and releasing various angiogenic and anti-inflammatory factors—might support retention of the implanted cells and enhance the therapeutic effects of the cell sheet technique on ischemic cardiomyopathy (ICM). Methods and results: The ICM model was generated by inducing anterior myocardial infarction for 4 weeks in mini-pigs; whereas the scaffold-free cell sheets were generated from autologous SMBs in vitro. The cell sheets were placed on the infarct area with or without pedicle omentum wrapping. Mini-pigs that received the omentum flap only or no treatment were used as controls. The quantity of ironoxide-labeled transplanted cells was significantly greater with omentum wrapping than without at 8 weeks after treatment (60 ± 9% vs. 32 ± 4%) as determined by magnetic resonance imaging. Implantation of the cell sheet wrapped with omentum significantly improved the left ventricle systolic function, increased blood perfusion, and accelerated therapeutic vessel growth into the host ischemic myocardium. The inflammatory effect was more attenuated following implantation of the cell sheet wrapped with omentum. Conclusions: Use of the SMB cell sheet wrapped with pedicle omentum flap enhanced cell retention and promoted mature and functional microvasculature in porcine ICM model, thereby improving myocardial function.

Autologous Skeletal Myoblast Sheet Therapy for Porcine Myocardial Infarction Without Increasing Risk of Arrhythmia.

Safety concerns of ventricular tachyarrhythmia have arisen from some clinical trials of autologous skeletal myoblast (SkM) injection therapy. This study examined the effect and safety of SkM sheet therapy in a pig model of chronic myocardial infarction. Minipigs underwent LAD occlusion using a balloon catheter for 2 h, followed by reperfusion. After 28 days, 12 SkM sheets were transplanted onto the infarcted myocardium (sheet group n = 8); the same number of cells was also injected into the myocardium (injection group n = 7), and sham operations were performed as a control (sham group n = 7). Implantable ECG loop recorders (ILR) were placed subcutaneously on the left thorax. At 28 days after transplantation, we assessed cardiac function with MDCT, interrogated ILR, and performed programmed ventricular stimulation (PVS), after which organs were harvested for histopathology. To assess the inflammatory and injury response, inflammation factors and high-sensitive CRP and troponin I were measured at 1, 3, 7, and 28 days after transplantation by the cytokine array method and ELISA, respectively. The sheet group showed an improvement in cardiac function compared with both the injection and sham groups (LVEF change: 5.8 ± 2.7%, -1.0 ± 2.6%, and -3.8 ± 1.8% in the sheet, injection, and sham groups, respectively, p < 0.05). VF was not detected in any group using ILR, while VT was detected in one pig from the injection group. VF was induced in 25.0%, 71.4%, and 28.6% of animals in the sheet, injection, and sham groups, respectively. In the injection group, anti-macrophage-positive cells were observed around the injected cells within the myocardium. Transmission electron microscopic images showed differentiated myofilaments, collagen layers, and a characteristic extracellular matrix surrounding the SkMs in the sheet group. Toroponin I and IL-6 levels were higher in the injection group compared with both the sheet and sham groups. SkM sheets transplanted onto infarcted myocardium improved cardiac function over SkM injection without increasing arrhythmogenicity.

Long-term follow-up after autologous skeletal myoblast transplantation in ischaemic heart disease

Short-term follow-up after autologous skeletal myoblasts (ASM) transplantation (Tx) (Myoblast Autologous Grafting in Ischaemic Cardiomyopathy (MAGIC) Phase II Study) for the treatment of ischaemic cardiomyopathy revealed improved left ventricular (LV) remodelling. Our study reports the longest long-term worldwide follow-up of a single-centre cohort, focusing on the safety and efficacy of ASM-Tx. The multicentre MAGIC Phase II Study involved 120 patients and was conducted between 2004 and 2006. Out of the 120 patients involved in the entire study, the cohort treated at our institution contained 7 patients only. These 7 patients received ASM-Tx (injection volume: 400 million cells, n = 2 low dosage; 800 million cells, n = 2 high dosage) or placebo (n = 3) injections, in addition to coronary artery bypass grafting (CABG). After closure of the MAGIC registry, we conducted a long-term follow-up for our 7-patient cohort. The mean follow-up was 72.0 ± 5.3 months. The follow-up was complete for echo data, implanted cardioverter defibrillator (ICD) report, clinical investigation and New York Heart Association (NYHA) class. At final follow-up, all the patients were alive, and 5 were in NYHA class 1 or 2. There were 6 hospitalizations for congestive heart failure during the follow-up (1 patient from each group). One patient (placebo group) was treated twice for ventricular fibrillation by the ICD. The LV ejection fraction remained stable in all the three groups (31.1 ± 3.9% preoperative vs 29.4 ± 4.4% at final follow-up). The LV volumes were reduced in the high-dosage group, remained unchanged in the low-dosage group and deteriorated in the placebo group. Our long-term data confirm the findings of the MAGIC study. The LV function did not improve, but the long-term LV volumes in the high-dosage group were reduced. During the follow-up, there were also no additional arrhythmogenic incidences. Our data could imply that CABG in combination with ASM-Tx is safe and has beneficial therapeutic effects in the long-term. However, due to the small patient number, the clinical impact is limited.