Regulation of Transplanted Cell Homing by FGF1 and PDGFB after Doxorubicin Myocardial Injury

There is no effective treatment for the total recovery of myocardial injury caused by an anticancer drug, doxorubicin (Dox). In this study, using a Dox-induced cardiac injury model, we compared the cardioprotective effects of ventricular cells harvested from 11.5-day old embryonic mice (E11.5) with those from E14.5 embryos. Our results indicate that tail-vein-infused E11.5 ventricular cells are more efficient at homing into the injured adult myocardium, and are more angiogenic, than E14.5 ventricular cells. In addition, E11.5 cells were shown to mitigate the cardiomyopathic effects of Dox. In vitro, E11.5 ventricular cells were more migratory than E14.5 cells, and RT-qPCR analysis revealed that they express significantly higher levels of cytokine receptors Fgfr1, Fgfr2, Pdgfra, Pdgfrb and Kit. Remarkably, mRNA levels for Fgf1, Fgf2, Pdgfa and Pdgfb were also found to be elevated in the Dox-injured adult heart, as were the FGF1 and PDGFB protein levels. Addition of exogenous FGF1 or PDGFB was able to enhance E11.5 ventricular cell migration in vitro, and, whereas their neutralizing antibodies decreased cell migration. These results indicate that therapies raising the levels of FGF1 and PDGFB receptors in donor cells and or corresponding ligands in an injured heart could improve the efficacy of cell-based interventions for myocardial repair.

Engineering human ventricular heart tissue based on macroporous iron oxide scaffolds

Myocardial infarction (MI) is a primary cardiovascular disease threatening human health and quality of life worldwide. The development of engineered heart tissues (EHTs) as a transplantable artificial myocardium provides a promising therapy for MI. Since most MIs occur at the ventricle, engineering ventricular-specific myocardium is therefore more desirable for future applications. Here, by combining a new macroporous 3D iron oxide scaffold (IOS) with a fixed ratio of human pluripotent stem cell (hPSC)-derived ventricular-specific cardiomyocytes and human umbilical cord-derived mesenchymal stem cells, we constructed a new type of engineered human ventricular-specific heart tissue (EhVHT). The EhVHT promoted expression of cardiac-specific genes, ion exchange, and exhibited a better Ca²⁺ handling behaviors and normal electrophysiological activity in vitro. Furthermore, when patched on the infarcted area, the EhVHT effectively promoted repair of heart tissues in vivo and facilitated the restoration of damaged heart function of rats with acute MI. Our results show that it is feasible to generate functional human ventricular heart tissue based on hPSC-derived ventricular myocytes for the treatment of ventricular-specific myocardium damage. STATEMENT OF SIGNIFICANCE: We successfully generated highly purified homogenous human ventricular myocytes and developed a method to generate human ventricular-specific heart tissue (EhVHT) based on three-dimensional iron oxide scaffolds. The EhVHT promoted expression of cardiac-specific genes, ion exchange, and exhibited a better Ca²⁺ handling behaviors and normal electrophysiological activity in vitro. Patching the EhVHT on the infarct area significantly improved cardiac function in rat acute MI models. This EhVHT has a great potential to meet the specific requirements for ventricular damages in most MI cases and for screening drugs specifically targeting ventricular myocardium.

Towards a Tissue-Engineered Contractile Fontan-Conduit: The Fate of Cardiac Myocytes in the Subpulmonary Circulation

The long-term outcome of patients with single ventricles improved over time, but remains poor compared to other congenital heart lesions with biventricular circulation. Main cause for this unfavourable outcome is the unphysiological hemodynamic of the Fontan circulation, such as subnormal systemic cardiac output and increased systemic-venous pressure. To overcome this limitation, we are developing the concept of a contractile extracardiac Fontan-tunnel. In this study, we evaluated the survival and structural development of a tissue-engineered conduit under in vivo conditions. Engineered heart tissue was generated from ventricular heart cells of neonatal Wistar rats, fibrinogen and thrombin. Engineered heart tissues started beating around day 8 in vitro and remained contractile in vivo throughout the experiment. After culture for 14 days constructs were implanted around the right superior vena cava of Wistar rats (n = 12). Animals were euthanized after 7, 14, 28 and 56 days postoperatively. Hematoxylin and eosin staining showed cardiomyocytes arranged in thick bundles within the engineered heart tissue-conduit. Immunostaining of sarcomeric actin, alpha-actin and connexin 43 revealed a well -developed cardiac myocyte structure. Magnetic resonance imaging (d14, n = 3) revealed no constriction or stenosis of the superior vena cava by the constructs. Engineered heart tissues survive and contract for extended periods after implantation around the superior vena cava of rats. Generation of larger constructs is warranted to evaluate functional benefits of a contractile Fontan-conduit.

Bone marrow mesenchymal stem cell transplantation retards the natural senescence of rat hearts

Bone marrow mesenchymal stem cells (BMSCs) have been shown to offer a wide variety of cellular functions including the protective effects on damaged hearts. Here we investigated the antiaging properties of BMSCs and the underlying mechanism in a cellular model of cardiomyocyte senescence and a rat model of aging hearts. Neonatal rat ventricular cells (NRVCs) and BMSCs were cocultured in the same dish with a semipermeable membrane to separate the two populations. Monocultured NRVCs displayed the senescence-associated phenotypes, characterized by an increase in the number of β-galactosidase-positive cells and decreases in the degradation and disappearance of cellular organelles in a time-dependent manner. The levels of reactive oxygen species and malondialdehyde were elevated, whereas the activities of antioxidant enzymes superoxide dismutase and glutathione peroxidase were decreased, along with upregulation of p53, p21(Cip1/Waf1), and p16(INK4a) in the aging cardiomyocytes. These deleterious alterations were abrogated in aging NRVCs cocultured with BMSCs. Qualitatively, the same senescent phenotypes were consistently observed in aging rat hearts. Notably, BMSC transplantation significantly prevented these detrimental alterations and improved the impaired cardiac function in the aging rats. In summary, BMSCs possess strong antisenescence action on the aging NRVCs and hearts and can improve cardiac function after transplantation in aging rats. The present study, therefore, provides an alternative approach for the treatment of heart failure in the elderly population.

Bone marrow mononuclear stem cells transplanted in rat infarct myocardium improved the electrical conduction without evidence of proarrhythmic effects

PURPOSE

The arrhythmogenic effect of stem cells transplantation (SCT) in an infarct myocardium is still unknown. We investigated arrhythmogenicity of SCT in rat cryo-infarct model.

MATERIALS AND METHODS

In rat cryo-infarct model, bone marrow mononuclear stem cells (MNSC, 1 x 10(7) cells) were transplanted into the infarct border zone (BZ) of the LV epicardium. We compared the optical mapping and inducibility of ventricular tachycardia/fibrillation (VT/VF) among normal (n=5), cryo-infarct (n=6), and SCT rats (n=6).

RESULTS

The VT/VF inducibility was higher in the cryo- infarct (47.2%, p=0.001) and SCT groups (34.6%, p=0.01) than in the normal group (12.8%). The induced VT/VF episodes persisted for more than 2 minutes in 4.3%, 26.4% and 17.3% in the normal, cryo-infarct and SCT group, respectively. In the SCT group, the action potential duration at 70% was shorter at the SCT site than the BZ during SR (75.2 +/- 8.1 vs. 145.6 +/- 4.4 ms, p=0.001) and VT (78.2 +/- 13.0 vs. 125.7 +/- 21.0 ms, p= 0.001). Conduction block was observed at the SCT site and BZ during VT. However, no reentry or ectopic foci were observed around the SCT sites.

CONCLUSION

The electrical conduction was improved by SCT without evidence of augmentation of arrhythmia in the rat cryo-infarct model.

Development of a biological ventricular assist device: preliminary data from a small animal model

BACKGROUND

Engineered heart tissue (EHT) can be generated from cardiomyocytes and extracellular matrix proteins and used to repair local heart muscle defects in vivo. Here, we hypothesized that pouch-like heart muscle constructs can be generated by using a novel EHT-casting technology and applied as heart-embracing cardiac grafts in vivo.

METHODS AND RESULTS

Pouch-like EHTs (inner/outer diameter: 10/12 mm) can be generated mainly from neonatal rat heart cells, collagen type I, and serum containing culture medium. They contain a dense network of connexin 43 interconnected cardiomyocytes and an endo-/epicardial surface lining composed of prolylhydroxylase positive cells. Pouch-like EHTs beat spontaneously and show contractile properties of native heart muscle including positive inotropic responses to calcium and isoprenaline. First implantation studies indicate that pouch-like EHTs can be slipped over uninjured adult rat hearts to completely cover the left and right ventricles. Fourteen days after implantation, EHT-grafts stably covered the epicardial surface of the respective hearts. Engrafted EHTs were composed of matrix and differentiated cardiac muscle as well as newly formed vessels which were partly donor-derived.

CONCLUSIONS

Pouch-like EHTs can be generated with structural and functional properties of native myocardium. Implantation studies demonstrated their applicability as cardiac muscle grafts, setting the stage for an evaluation of EHT-pouches as biological ventricular assist devices in vivo.

Mid-term results of reconstruction of the right ventricular outflow tract using cryopreserved homografts

PURPOSE

Homograft benefits include excellent hemodynamics, resistance to infection, decreased thromboembolic events, ease of handling, and lack of need for anticoagulation. We examined the short and mid-term results of right ventricular outflow tract (RVOT) reconstruction using cryopreserved homografts.

PATIENTS AND METHODS

From May 1998 to May 2005, 20 patients (male:female=10:10) underwent RVOT reconstruction using cryopreserved homografts. The median age was 23.8 years (range, 0.9 to 43.3 years) and the median body weight was 57 kg (range, 7.3 to 80 kg). Eighteen patients underwent re-operation after shunt or corrective operations. Homograft failure was defined as either re-operation for homograft replacement or patient death. Homograft dysfunction was defined as grade 3 or more than 3 of graft regurgitation and more than 40 mmHg of transvalvular pressure gradient under echocardiographic examination.

RESULTS

No operative mortality occurred and there were three major complications. Graft failure was observed in one male patient with tetralogy of Fallot. The 8-year freedom from graft failure was 87.5+/-11.7% and the 7-year freedom from graft dysfunction was 62.3+/-17.9%. Multivariable analysis revealed that the independent factor for graft dysfunction was age less than 10 years. In the analysis according to age group, the 7-year freedom from graft dysfunction in the group of patients older than 10 years was 100% and 25.0+/-21.7% in patients age 10 or younger (p= 0.03).

CONCLUSION

Right ventricular outflow reconstruction using cryopreserved homografts provided excellent short and mid-term results in most patients in this study. However, in patients younger than 10 years old, homografts for RVOT reconstruction showed a high dysfunction rate at mid-term.

Orthotopic cardiac transplantation: comparison of outcome using biatrial, bicaval, and total techniques

BACKGROUND

For more than 35 years, the biatrial technique of performing orthotopic cardiac transplantation has been the gold standard, and involves anastomoses of donor and recipient atrial cuffs. More recently, however, bicaval and total techniques have been devised in an attempt to improve cardiac anatomy, physiology, and postoperative outcome. A bicaval approach preserves the donor atria and combines the standard left atrial anastomosis with a separate bicaval anastomosis. Total orthotopic heart transplantation involves complete excision of the recipient atria with separate bicaval end-to-end anastomoses, as well as pulmonary venous anastomoses. The aim of this study was to conduct a literature review of studies that compared the three surgical techniques (biatrial, bicaval, and total) for performing orthotopic cardiac transplantation. Numerous outcome variables were evaluated, and included post-transplant survival, atrial dimensions, atrioventricular valvular insufficiency, arrhythmias, pacing requirements, vasopressor requirements, and hospital stay.

METHODS

We conducted a Medline (Pubmed) search using the terms "biatrial and cardiac transplantation,""bicaval and cardiac transplantation," and "total technique and cardiac transplantation," which yielded 192 entries: 39 of these were studies that compared surgical techniques and were included in the review.

RESULTS

There was overwhelming evidence that the bicaval technique provided anatomic and functional advantages, with improvements in post-transplant survival, atrial geometry, and hemodynamics, as well as decreased valvular insufficiency, arrhythmias, pacing requirements, vasopressor requirements, and hospital stay.

CONCLUSIONS

The bicaval technique was superior to both biatrial and total techniques for numerous outcome variables. To further elucidate this issue, a prospective randomized trial comparing the three techniques, with long-term follow-up, is warranted.

Pediatric arteriovenous extracorporeal membrane oxygenation (ECMO) as a bridge to cardiac transplantation

BACKGROUND

Since 1990, extracorporeal membrane oxygenation (ECMO) has been used as a bridge to cardiac transplantation in 47 patients.

METHODS

A review of the ECMO database, approved by the Arkansas Children's Hospital institutional review board, forms the basis of this report. We made statistical comparison using Fisher's exact probability testing. The ECMO circuitry was a roller occlusion pump with computer-assisted perfusion system technology.

RESULTS

Thirty-two (68%) patients underwent transcatheter septostomy for cardiac decompression. Diagnosis at presentation was either congenital heart disease (CHD, n = 15) or cardiomyopathy (n = 32). Ages ranged from 1 day to 22 years old (median, 18 months old), and weight ranged from 2.9 to 100 kg (median, 10 kg). The average duration of support was 242 hours (range, 22-1078 hours). Overall long-term survival was 47%, with 16 (34%) patients successfully bridged to cardiac transplantation (of which 9 [56%] survived) and 13 (28%) successfully weaned from ECMO. Patients undergoing ECMO after cardiotomy had 31% survival. Survival was improved significantly (p < 0.02) in patients with cardiomyopathy (59%) vs those with CHD (20%). Patients with cardiomyopathy underwent 8 transplantations with 7 survivors (88%), whereas in the CHD group, there were 8 transplantations with only 2 survivors (25%), p < 0.05. Sub-analysis of the cardiomyopathy group revealed that patients with acute cardiomyopathy in association with documented viral illness had a 75% chance of being weaned from ECMO without undergoing transplantation. Complications during ECMO occurred in 45% of survivors and were more frequent in non-survivors. Infectious complications were most frequent, followed by neurologic complications, technical ECMO problems, and renal insufficiency.

CONCLUSIONS

Patients with cardiomyopathy has a better prognosis than did those with CHD when using ECMO as a bridge to transplantation or survival. Complications are significant and increase with the duration of support. Extracorporeal membrane oxygenation for salvage and subsequent transplantation in this high-risk group of patients requires critical review. Alternative support options must be developed in the pediatric population that will allow improved outcomes, comparable with outcomes achieved in the adult population.

Fabrication of pulsatile cardiac tissue grafts using a novel 3-dimensional cell sheet manipulation technique and temperature-responsive cell culture surfaces

Recent progress in cell transplantation therapy to repair impaired hearts has encouraged further attempts to bioengineer 3-dimensional (3-D) heart tissue from cultured cardiomyocytes. Cardiac tissue engineering is currently pursued utilizing conventional technology to fabricate 3-D biodegradable scaffolds as a temporary extracellular matrix. By contrast, new methods are now described to fabricate pulsatile cardiac grafts using new technology that layers cell sheets 3-dimensionally. We apply novel cell culture surfaces grafted with temperature-responsive polymer, poly(N-isopropylacrylamide) (PIPAAm), from which confluent cells detach as a cell sheet simply by reducing temperature without any enzymatic treatments. Neonatal rat cardiomyocyte sheets detached from PIPAAm-grafted surfaces were overlaid to construct cardiac grafts. Layered cell sheets began to pulse simultaneously and morphological communication via connexin43 was established between the sheets. When 4 sheets were layered, engineered constructs were macroscopically observed to pulse spontaneously. In vivo, layered cardiomyocyte sheets were transplanted into subcutaneous tissues of nude rats. Three weeks after transplantation, surface electrograms originating from transplanted grafts were detected and spontaneous beating was macroscopically observed. Histological studies showed characteristic structures of heart tissue and multiple neovascularization within contractile tissues. Constructs transplanted into 3-week-old rats exhibited more cardiomyocyte hypertrophy and less connective tissue than those placed into 8-week-old rats. Long-term survival of pulsatile cardiac grafts was confirmed up to 12 weeks. These results demonstrate that electrically communicative pulsatile 3-D cardiac constructs were achieved both in vitro and in vivo by layering cardiomyocyte sheets. Cardiac tissue engineering based on this technology may prove useful for heart model fabrication and cardiovascular tissue repair. The full text of this article is available at http://www.circresaha.org.

A novel small animal model of left ventricular tissue engineering

BACKGROUND

Complex congenital cardiac anomalies involving ventricular hypoplasia require either staged palliative reconstruction, converting the circulatory system to a single ventricle based pump, or allogeneic transplantation. Tissue engineering offers the potential for complete reconstruction of these defects, but is limited by the inability to model myocardial tissue engineering in a small animal. Our goal was to develop a small animal model for ventricular tissue engineering using rat heterotopic heart transplantation.

METHODS

Donor hearts were explanted after cardioplegic arrest and the left ventricular volume was augmented by the implantation of a biodegradable engineered construct. The heart was then transplanted heterotopically into syngeneic recipients creating either a volume loaded, functioning left ventricle, or a non-functioning left ventricle. Some of the engineered constructs were seeded with multipotent bone marrow-derived mesenchymal progenitor cells before implantation. Animals were evaluated by echocardiography, morphology, histology, and immunohistochemistry after 1 month.

RESULTS

A scaffolding constructed from polytetrafluoroethylene, polylactide mesh, and type I and IV collagen hydrogel resulted in minimal intracardiac inflammation without aneurysmal dilatation. Successful transplantation and differentiation of mesenchymal progenitor cells was accomplished using this scaffolding. No ventricular arrhythmias resulted from this surgical manipulation and echocardiography revealed both end systolic and diastolic volume augmentation with ventricular expansion.

CONCLUSION

We have developed an in vivo model of ventricular tissue engineering using heterotopic heart transplantation. Future work will focus on construction of ventricular tissue around pre-fabricated vascular networks in order increase cellular engraftment for ventricular reconstruction.

Treatment of a saphenous vein graft to right ventricle fistula with a PTFE-covered stent: a case report

This report demonstrates the use of a covered stent for the correction of a fistula from a saphenous vein graft to the right ventricle. The use of this stent resulted in complete obliteration of the fistulous tract and restoration of flow into the sequential limb of the graft.

Heart cell transplantation improves heart function in dilated cardiomyopathic hamsters

BACKGROUND

Little is known about the effect of heart cell transplantation into the dilated cardiomyopathic myocardium. This study was designed to evaluate the effect of heart cell transplantation into dilated cardiomyopathic hamsters.

METHODS AND RESULTS

Ventricular heart cells were isolated from 4-week-old BIO 53. 58 hamsters and cultured for 2 weeks before transplantation. The cells were labeled with bromodeoxyuridine (BrdU) before transplantation for identification. Adult hamsters (17 weeks old) were used as recipients. Heart cells (4 x 10(6) cells) or culture medium was transplanted into the left ventricular free wall (transplantation and control groups, respectively, n=12 each). Sham-operated hamsters (n=12) underwent the surgery but not the transplantation. Cyclosporine A was administered subcutaneously to all hamsters daily after the operation. Four weeks after the transplantation, heart function was evaluated with the use of a Langendorff preparation. Histology showed severe focal myocardial necrosis in all groups. BrdU-stained tissue was found at the cell transplantation sites. The transplanted hearts had greater (P:<0. 001) developed pressures at all balloon volumes and improved dP/dt (transplantation 915+/-253 versus control 453+/-120 and sham 530+/-187 mm Hg/s, P:<0.001, balloon volume of 15 microL). No differences in ventricular function were found between control and sham-operated hamsters.

CONCLUSIONS

The transplanted ventricular heart cells formed cardiac-like tissue in cardiomyopathic myocardium and improved its contractile function.

A prospective randomized trial of complete atrioventricular transplantation versus ventricular transplantation with atrioplasty

BACKGROUND

The standard technique of ventricular transplantation with atrioplasty (SOHT) distorts atrial anatomy. This may compromise diastolic ventricular function, impair atrioventricular valve competence and elevate resting ANP secretion. In contrast, complete atrioventricular anastomosis (CAVT) preserves atrial geometry.

METHODS

We evaluated long term outcome in a prospective randomized trial of CAVT vs. SOHT. The primary outcome measures were peak oxygen uptake, atrioventricular valve regurgitation and ANP secretion.

RESULTS

58 recipients (median age 49 years; range 21-64) were consecutively randomized (29 CAVT; 29 SOHT). There were no differences in total ischaemic time, cardiopulmonary bypass time, postoperative bleeding or immunosuppression. Cardiopulmonary exercise tolerance testing was performed by 29 recipients at 742 to 1825 days. Pulmonary function was equivalent. Peak oxygen consumption expressed as a percentage of predicted maximum was 53.5% with CAVT and 63.8% with SOHT (p = 0.14). Echocardiography was performed on 41 recipients at 944 to 1665 days. There was less tricuspid regurgitation with CAVT (3/22 [13.6%] CAVT vs. 10/19 [52.6%] SOHT; p = 0.019). The incidence of mitral regurgitation was similar (5/22 [22.7%] CAVT vs. 4/19 [21.1%] SOHT; p = 0.803). Resting ANP secretion was assessed in 17 recipients at 1013 to 1812 days. All were hemodynamically stable and none had concurrent rejection. Resting ANP secretion was less with CAVT (CAVT: 283 pg/ml; SOHT: 521.4; p = 0.041).

CONCLUSIONS

Peak oxygen consumption was not influenced by implantation technique. However, CAVT reduced the incidence of tricuspid regurgitation and attenuated the elevation in resting ANP secretion.

Polyploidization of transplanted cardiac myocytes

Pieces of cardiac ventricular tissue of late embryonic or 1-day postnatal rats, implanted beneath the kidney capsule of adult syngeneic hosts, formed viable, beating transplants. These transplants were investigated over a 40-day postoperative course. In the transplants, cellular binucleation and nuclear polyploidization occurred according to the same schedule as in the heart in situ. The composition of the classes of myocytes was identical both in the hearts in situ and in transplants, but the number of non-diploid myocytes in the intact heart reached 90%, whereas in transplants it varied from 30 to 60%. In contrast to the heart in situ, myocytes in transplants grew feebly after the phase of polyploidization. From these data one can conclude that under conditions of transplantation the temporal sequence of cellular binucleation and nuclear polyploidization follows the normal course, but that a greater number of myocytes remain in a diploid state than is the case in the normal heart. The growth of cardiac myocytes seems to be related to their level of function.

Orthotopic cardiac transplantation for univentricular heart

The technical aspects of orthotopic cardiac transplantation for univentricular heart in a 22-year-old man are discussed. Abnormal pulmonary artery anatomy resulted in right ventricular failure, which was successfully treated.

Long-term expression of isomyosins and myoendocrine functions in ectopic grafts of atrial tissue

Tissue fragments of newborn rat atria were transplanted under the dorsal skin or into the bed of the anterior tibial muscle of nude mice. After 5-11 weeks, the grafts, which had reorganized into beating atrium-like structures, were analyzed and compared to ventricular tissue transplanted the same way. As revealed by monoclonal antibodies against alpha- and beta-type myosin heavy chains, atrial grafts retained a typical pattern of myosin expression distinct from that of ventricular grafts. The majority of ectopic atrial myocytes contained specific atrial granules in which cardiodilatin-immunoreactive material has been localized. Specific granules and cardiodilatin immunoreactivity were not found in myocytes of ventricular grafts. We conclude that the long-term maintenance of isomyosin expression and of the myoendocrine function of atrial tissue is largely independent of the anatomical environment.