2024 Statement from Asia expert operators on transcatheter pulmonary valve replacement.

Transcatheter pulmonary valve replacement (TPVR), also known as percutaneous pulmonary valve implantation, refers to a minimally invasive technique that replaces the pulmonary valve by delivering an artificial pulmonary prosthesis through a catheter into the diseased pulmonary valve under the guidance of X-ray and/or echocardiogram while the heart is still beating not arrested. In recent years, TPVR has achieved remarkable progress in device development, evidence-based medicine proof and clinical experience. To update the knowledge of TPVR in a timely fashion, and according to the latest research and further facilitate the standardized and healthy development of TPVR in Asia, we have updated this consensus statement. After systematical review of the relevant literature with an in-depth analysis of eight main issues, we finally established eight core viewpoints, including indication recommendation, device selection, perioperative evaluation, procedure precautions, and prevention and treatment of complications.

Management of patent foramen ovale in embolic stroke of undetermined source patients: Malaysian experts' consensus.

INTRODUCTION: About 20 to 40% of ischaemic stroke causes are cryptogenic. Embolic stroke of undetermined source (ESUS) is a subtype of cryptogenic stroke which is diagnosed based on specific criteria. Even though patent foramen ovale (PFO) is linked with the risk of stroke, it is found in about 25% of the general population, so it might be an innocent bystander. The best way to treat ESUS patients with PFO is still up for discussion. MATERIALS AND METHODS: Therefore, based on current evidence and expert opinion, Malaysian expert panels from various disciplines have gathered to discuss the management of ESUS patients with PFO. This consensus sought to educate Malaysian healthcare professionals to diagnose and manage PFO in ESUS patients based on local resources and facilities. RESULTS: Based on consensus, the Malaysian expert recommended PFO closure for embolic stroke patients who were younger than 60, had high RoPE scores and did not require long-term anticoagulation. However, the decision should be made after other mechanisms of stroke have been ruled out via thorough investigation and multidisciplinary evaluation. The PFO screening should be made using readily available imaging modalities, ideally contrasttransthoracic echocardiogram (c-TTE) or contrasttranscranial Doppler (c-TCD). The contrast-transesophageal echocardiogram (c-TEE) should be used for the confirmation of PFO diagnosis. The experts advised closing PFO as early as possible because there is limited evidence for late closure. For the post-closure follow-up management, dual antiplatelet therapy (DAPT) for one to three months, followed by single antiplatelet therapy (APT) for six months, is advised. Nonetheless, with joint care from a cardiologist and a neurologist, the multidisciplinary team will decide on the continuation of therapy.

Pulmonary arteriovenous malformations: A case of missed diagnosis in a neonate.

Pulmonary arteriovenous malformation (PAVM) is a congenital vascular abnormality that can cause persistent cyanosis in children. PAVMs can go undetected till adulthood; however, there have been several neonatal cases reported over the years. This case report describes a classical manifestation of a child with isolated PAVM whose diagnosis was likely missed during the neonatal period. A high level of clinical awareness of this condition is crucial as early diagnosis and appropriate treatment can prevent lifethreatening complications and mortality. Diagnosis was confirmed by computed tomography pulmonary angiography and percutaneous transcatheter embolotherapy resulted in complete resolution of symptoms.

Predictors of acute neurological complication following tetralogy of Fallot operation in Serdang Hospital, Malaysia.

BACKGROUND: The long waiting time for Tetralogy of Fallot (TOF) operation may potentially increase the risk of hypoxic insult. Therefore, the objective of this study is to determine the frequency of acute neurological complications following primary TOF repair and to identify the peri-operative risk factors and predictors for the neurological sequelae. METHODS: A retrospective review of the medical and surgical notes of 68 patients who underwent TOF repair in Hospital Serdang, from January 2013 to December 2017 was done. Univariate and multivariate analyses of demographics and perioperative clinical data were performed to determine the risk for the development of acute neurological complications (ANC) among these patients. RESULTS: ANC was reported in 13 cases (19.1%) with delirium being the most common manifestation (10/68, 14.7%), followed by seizures in 4 (5.9%) and abnormal movements in two patients (2.9%). Univariate analyses showed that the presence of right ventricular (RV) dysfunction, prolonged duration of inotropic support (≥7 days), prolonged duration of mechanical ventilation (≥7 days), longer length of ICU stays (≥7 days), and longer length of hospital stay (≥14 days), were significantly associated with the presence of ANCs (p<0.05). However, multivariate analyses did not show any significant association between these variables and the development of ANC (p>0.05). The predictors for the development of postoperative delirium were pre-operative oxygen saturation less than 75% (Odds Ratio, OR=16.90, 95% Confidence Interval, 95%CI:1.36, 209.71) and duration of ventilation of more than 7 days (OR=13.20, 95%CI: 1.20, 144.98). CONCLUSION: ANC following TOF repair were significantly higher in patients with RV dysfunction, in those who required a longer duration of inotropic support, mechanical ventilation, ICU and hospital stay. Low pre-operative oxygen saturation and prolonged mechanical ventilation requirement were predictors for delirium which was the commonest neurological complications observed in this study. Hence, routine screening for delirium using an objective assessment tool should be performed on these high-risk patients to enable accurate diagnosis and early intervention to improve the overall outcome of TOF surgery in this country.

Medical conditions and driving fitness of older Singaporean taxi drivers.

BACKGROUND: Taxi driving has been associated with the risk of various diseases (e.g. cardiovascular disease, hypertension, diabetes, hyperlipaemia, back pain). Little is known about the relationship between health conditions and driving fitness of older taxi drivers who continue to work. AIMS: To investigate the (i) prevalence of medical conditions and (ii) relationship between age and medical conditions, with on-road driving tests in the relicensing process of older taxi drivers aged ≥70 years, prior to the mandatory retirement age of 75 years. METHODS: We analysed retrospectively all relicensing records (N = 855) of taxi drivers aged 70, 73 and 74 years that were submitted from April 2014 to April 2015. RESULTS: All passed their medical fitness screening. Ninety-eight per cent passed their driving tests. Thirty-one per cent, 36% and 24% reported none, one and two medical conditions, respectively. These included hypertension (56%), eye disease (25%; cataracts 19%), diabetes (24%), corrected hearing impairment (14%), hyperlipaemia (12%) and heart disease (9%). Deafness (P < 0.001) was associated with older age. No past medical condition affected driving outcome. CONCLUSION: Older Singaporean taxi drivers were healthy and generally competent drivers. Early effective preventive health screening and modifiable lifestyle intervention are recommended in older taxi drivers.

Donor Heart Treatment With COMP-Ang1 Limits Ischemia-Reperfusion Injury and Rejection of Cardiac Allografts.

The major cause of death during the first year after heart transplantation is primary graft dysfunction due to preservation and ischemia-reperfusion injury (IRI). Angiopoietin-1 is a Tie2 receptor-binding paracrine growth factor with anti-inflammatory properties and indispensable roles in vascular development and stability. We used a stable variant of angiopoietin-1 (COMP-Ang1) to test whether ex vivo intracoronary treatment with a single dose of COMP-Ang1 in donor Dark Agouti rat heart subjected to 4-h cold ischemia would prevent microvascular dysfunction and inflammatory responses in the fully allogeneic recipient Wistar Furth rat. COMP-Ang1 reduced endothelial cell-cell junction disruption of the donor heart in transmission electron microscopy during 4-h cold ischemia, improved myocardial reflow, and reduced microvascular leakage and cardiomyocyte injury of transplanted allografts during IRI. Concurrently, the treatment reduced expression of danger signals, dendritic cell maturation markers, endothelial cell adhesion molecule VCAM-1 and RhoA/Rho-associated protein kinase activation and the influx of macrophages and neutrophils. Furthermore, COMP-Ang1 treatment provided sustained anti-inflammatory effects during acute rejection and prevented the development of cardiac fibrosis and allograft vasculopathy. These results suggest donor heart treatment with COMP-Ang1 having important clinical implications in the prevention of primary and subsequent long-term injury and dysfunction in cardiac allografts.

Screening for cardiovascular disease risk factors at baseline and post intervention among adults with intellectual disabilities in an urbanised Asian society.

BACKGROUND: Adults with intellectual disabilities (ID) face significant barriers to screening participation. We determined predictors for regular cardiovascular health screening at baseline among adults with ID in Singapore, and evaluated the effectiveness of a 3-month screening intervention. METHODS: The study population involved all adults with ID aged ≥40 years receiving services from the Movement for the Intellectually Disabled of Singapore (MINDS), the largest such provider in Singapore. Over 3 months in 2011, adult clients not screened regularly at baseline for hypertension, diabetes and dyslipidaemia were offered free and convenient blood pressure, fasting blood glucose and lipid testing; data on other cardiovascular disease risk factors were also collected. Chi-square and logistic regression identified predictors of regular screening at baseline. RESULTS: Participation was 95.0% (227/239). At baseline, among adults with ID, 61.8% (118/191), 24.8% (52/210) and 18.2% (34/187) had gone for regular hypertension, diabetes and dyslipidaemia screening respectively; post intervention, rates rose to 96.9%, 89.5% and 88.8% respectively. Prevalence of cardiovascular disease risk factors (22.5% with hypertension, 10.6% with diabetes, 34.8% with dyslipidaemia, 10.7% obese and 90.6% lacking regular exercise) was high compared against the general population. While receiving residential services was associated with regular hypertension screening, receiving non-residential services and being independently mobile were associated with regular participation in fasting blood tests (all P < 0.05). CONCLUSION: Cardiovascular disease risk factors are common among adults with ID and clinicians should proactively screen such populations. Provision of free and convenient screening for cardiovascular disease risk improved screening participation.

All-cause and cause-specific mortality after hip fracture among Chinese women and men: the Singapore Chinese Health Study.

UNLABELLED: All-cause mortality risk persisted for 5 years after hip fractures in both men and women. There may be gender-specific differences in effect and duration of excess risk for cause-specific mortality after hip fracture. INTRODUCTION: To determine all-cause and cause-specific mortality risk in the first 5 years after hip fracture in an Asian Chinese population. METHODS: The Singapore Chinese Health Study is a population-based cohort of 63,257 middle-aged and elderly Chinese men and women in Singapore recruited between 1993 and 1998. This cohort was followed up for hip fracture and death via linkage with nationwide hospital discharge database and death registry. As of 31 December 2008, we identified 1,166 hip fracture cases and matched five non-fracture cohort subjects by age and gender for each fracture case. Cox proportional hazards and competing risks regression models with hip fracture as a time-dependent covariate were used to determine all-cause and cause-specific mortality risk, respectively. RESULTS: Increase in all-cause mortality risk persisted till 5 years after hip fracture (adjusted hazard ratio, aHR = 1.58 [95 % CI, 1.35-1.86] for females and aHR = 1.64 [95 % CI, 1.30-2.06] for males). Men had higher mortality risk after hip fracture than women for deaths from stroke and cancer up to 1 year post-fracture but women with hip fracture had higher coronary artery mortality risk than men for 5 years post-fracture. Men had higher risk of death from pneumonia while women had increased risk of death from urinary tract infections. There was no difference in mortality risk by types of hip fracture surgery. CONCLUSIONS: All-cause mortality risk persisted for 5 years after hip fractures in men and women. There are gender-specific differences in effect size and duration of excess mortality risk from hip fractures between specific causes of death.

The impact of diabetes on the pathogenesis of sepsis.

Diabetes is associated with an increased susceptibility to infection and sepsis. Conflicting data exist on whether the mortality of patients with sepsis is influenced by the presence of diabetes, fuelling the ongoing debate on the benefit of tight glucose regulation in patients with sepsis. The main reason for which diabetes predisposes to infection appears to be abnormalities of the host response, particularly in neutrophil chemotaxis, adhesion and intracellular killing, defects that have been attributed to the effect of hyperglycaemia. There is also evidence for defects in humoral immunity, and this may play a larger role than previously recognised. We review the literature on the immune response in diabetes and its potential contribution to the pathogenesis of sepsis. In addition, the effect of diabetes treatment on the immune response is discussed, with specific reference to insulin, metformin, sulphonylureas and thiazolidinediones.

Transcatheter Closure of Patent Ductus Arteriosus: The Penang Hospital's Experience.

Transcatheter closure of small and moderate sizes of Patent Ductus Arteriosus (PDA) is a standard and well accepted form of treatment. The aim of this study is to describe the experience of transcatheter closure of PDA in Penang Hospital. All patients who underwent transcatheter closure of PDA at our institution between 20th January 2006 and 27th June 2008 were retrospectively identified and studied. There were a total of 66 patients who had undergone transcatheter closure of PDA during this period which comprised of 24 male and 42 female. The PDA was closed by Amplatzer Duct Occluder (ADO) in 31 patients, Gianturco coil in 29 patients and other types of devices in 6 patients. There were 4 patients (6%) who had developed acute complication during the procedure (3 of them developed coil embolization and 1 had bleeding from puncture site). The PDA was successfully close in 95.5% of the study population without any residual PDA shunting. All the patients were alive but 5 of them (4.5%) have some abnormalities (2 has mild left pulmonary stenosis, 3 has small residual). Comparison between ADO and Gianturco coil revealed no significant difference in the outcome. Transcatheter closure of PDA has proven to be safe and effective with good midterm outcome. There was no significant difference between Amplatzer Ductal Occluder and Gianturco coil in term of the outcome.

Association of Pain and Impact of Dual-Task Exercise on Function, Cognition and Quality of Life.

PURPOSE: This study aimed to assess the factors associated with pain and evaluate the impact of dual-task exercise on pain improvement, quality of life (QOL), cognition and function in older adults. PATIENTS AND METHODS: This study is a secondary data analysis of the HAPPY (Healthy Ageing Promotion Program for You) study. At risk older adults ≥ 60 years old were enrolled in a community dual-task exercise program. Assessments for frailty, sarcopenia, falls, quality of life (QOL) and perceived health, depression, cognition and physical function were performed at baseline and 3 months. Pain intensity was derived from EQ-5D and stratified into no pain, slight pain and moderate to extreme pain. RESULTS: Out of 296 participants, 37.2% had slight pain and 11.1% had moderate to severe pain. Both slight and moderate to extreme pain compared with no pain group were significantly associated with lower perceived health (68.2,63.6 vs 76.0) and QOL index (0.70,0.59 vs 0.93); moderate to extreme pain was also significantly associated with depression, low mental vitality, frailty, sarcopenia and poorer physical performance. After 3 months of dual-task exercise, pain improved in 70.8% of the moderate to extreme pain group and 50.8% of slight pain group. Significant improvement in perceived health, QOL, physical function and cognition were also observed. CONCLUSION: Proactive efforts are required to screen for pain and manage frailty, sarcopenia and depression. Dual-task exercise proved safe and possibly effective in reducing pain and improving QOL, physical and cognitive function in older adults. Prospective randomized studies are needed to validate the effectiveness of dual-task vs single-task exercise, including impact of reversal of frailty and sarcopenia in pain management.

Income disparity in school readiness and the mediating role of perinatal maternal mental health: a longitudinal birth cohort study.

AIMS: There is compelling evidence for gradient effects of household income on school readiness. Potential mechanisms are described, yet the growth curve trajectory of maternal mental health in a child's early life has not been thoroughly investigated. We aimed to examine the relationships between household incomes, maternal mental health trajectories from antenatal to the postnatal period, and school readiness. METHODS: Prospective data from 505 mother-child dyads in a birth cohort in Singapore were used, including household income, repeated measures of maternal mental health from pregnancy to 2-years postpartum, and a range of child behavioural, socio-emotional and cognitive outcomes from 2 to 6 years of age. Antenatal mental health and its trajectory were tested as mediators in the latent growth curve models. RESULTS: Household income was a robust predictor of antenatal maternal mental health and all child outcomes. Between children from the bottom and top household income quartiles, four dimensions of school readiness skills differed by a range of 0.52 (95% Cl: 0.23, 0.67) to 1.21 s.d. (95% CI: 1.02, 1.40). Thirty-eight percent of pregnant mothers in this cohort were found to have perinatal depressive and anxiety symptoms in the subclinical and clinical ranges. Poorer school readiness skills were found in children of these mothers when compared to those of mothers with little or no symptoms. After adjustment of unmeasured confounding on the indirect effect, antenatal maternal mental health provided a robust mediating path between household income and multiple school readiness outcomes (χ2 126.05, df 63, p < 0.001; RMSEA = 0.031, CFI = 0.980, SRMR = 0.034). CONCLUSIONS: Pregnant mothers with mental health symptoms, particularly those from economically-challenged households, are potential targets for intervention to level the playing field of their children.

Formation of nascent intercalated disks between grafted fetal cardiomyocytes and host myocardium.

Fetal cardiomyocytes isolated from transgenic mice carrying a fusion gene of the alpha-cardiac myosin heavy chain promoter with a beta-galactosidase reporter were examined for their ability to form stable intracardiac grafts. Embryonic day 15 transgenic cardiomyocytes delivered directly into the myocardium of syngeneic hosts formed stable grafts, as identified by nuclear beta-galactosidase activity. Grafted cardiomyocytes were observed as long as 2 months after implantation, the latest date assayed. Intracardiac graft formation did not induce overtly negative effects on the host myocardium and was not associated with chronic immune rejection. Electron microscopy revealed the presence of nascent intercalated disks connecting the engrafted fetal cardiomyocytes and the host myocardium. These results suggest that intracardiac grafting might provide a useful approach for myocardial repair, provided that the grafted cells can contribute to myocardial function.

An association between floor vacuuming and dust-mite and serum eosinophil cationic protein in young asthmatics.

UNLABELLED: Although vacuum cleaning is recommended to reduce allergen levels and improve asthma and allergic rhinitis symptoms, some studies suggest it may increase allergen load in homes. We conducted a cross-sectional study to determine if home floor vacuuming was associated with sensitization to dust-mites and cockroaches, and serum eosinophil cationic protein (ECP), a biomarker for atopy, in 102 physician-diagnosed spirometry-confirmed asthmatics. We collected data on floor type, floor cleaning method and frequency, asthma severity, allergy medications used, serum ECP and skin prick tests (SPT) to three dust-mites [Dermatophagoides pteronyssisinus (Der p), Dermatophagoides farinae (Der f) and Blomia tropicalis (Blo t)] and two cockroaches [Periplanata americana (Per a) and Blatella germanica (Bla g)]. Those who vacuumed had increased sensitization to three dust-mites [adjusted ORs (95%CI) = Der p: 26.6 (1.8-405.2); Der f: 44.8 (3.2-620.9); Blo t: 14.1 (1.8-108.1)] but not to cockroaches, adjusted for cleaning frequency and other methods of floor cleaning. Subjects who vacuumed their floor had higher levels of serum ECP than those who did not [adjusted median difference (95%CI): 9.4 (1.1-17.7)], adjusted for use of nasal corticosteroids among those with allergic rhinitis. Vacuuming is associated with increased sensitization to dust-mite allergens and higher serum ECP. PRACTICAL IMPLICATIONS: We found an association between floor vacuuming and increased sensitization to dust-mite allergens and higher levels of an atopy biomarker. Current recommendations to use vacuuming to control allergen exposure and allergic conditions may need to be reconsidered until further studies are performed.

The Long-Term Impact of Functional Disability on Hospitalization Spending in Singapore.

Singapore is one of the fastest-aging populations due to increased life expectancy and lowered fertility. Lifestyle changes increase the burden of chronic diseases and disability. These have important implications for social protection systems. The goal of this paper is to model future functional disability and healthcare expenditures based on current trends. To project the health, disability and hospitalization spending of future elders, we adapted the Future Elderly Model (FEM) to Singapore. The FEM is a dynamic Markov microsimulation model developed in the US. Our main source of population data was the Singapore Chinese Health Study (SCHS) consisting of 63,000 respondents followed up over three waves from 1993 to 2010. The FEM model enables us to investigate the effects of disability compounded over the lifecycle and hospitalization spending, while adjusting for competing risk of multi-comorbidities. Results indicate that by 2050, 1 in 6 elders in Singapore will have at least one ADL disability and 1 in 3 elders will have at least one IADL disability, an increase from 1 in 12 elders and 1 in 5 elders respectively in 2014. The highest prevalence of functional disability will be in those aged 85 years and above. Lifetime hospitalization spending of elders aged 55 and above is US$24,400 (30.2%) higher among people with functional disability compared to those without disability. Policies that successfully tackle diabetes and promote healthy living may reduce or delay the onset of disability, leading to potential saving. In addition, further technological improvements may reduce the financial burden of disability.

Subthreshold depression and cognitive impairment but not demented in stroke patients during their rehabilitation.

BACKGROUND: Subthreshold depression (sD) and cognitive impairment but not demented (CIND) in stroke patients are associated with poorer rehabilitative outcomes. Their diagnosis can easily be operationalized using validated scales. AIM: The aim of the study was to ascertain the prevalence of depressive symptoms and cognitive impairment in stroke patients during three crucial stages of the rehabilitative process, viz. upon admission, upon planned discharges from rehabilitation hospitals and at 6 months post-stroke, using validated scales like the Geriatric Depression Scale and Abbreviated Mental Test (recommended by the British Geriatric Society). Their baseline risk factors were also ascertained. RESULTS: On admission, the prevalence of depressive symptoms and cognitive impairment was 60% and 54% respectively. The prevalence upon planned discharges and 6 months post-stroke, respectively, of depressive symptoms was 38% and 34% and that of impaired cognition was 33% and 40%. Baseline independent correlates at 6 months post-stroke depressive symptoms were: recurrent stroke (OR 3.34); on admission cognitive impairment (OR 4.78) and ADL dependence (OR 5.28). And that of cognitive impairment were: increasing age (OR 8.07); post-stroke dysphagia (OR 4.58); on admission cognitive impairment (OR 23.95) and on admission depressive symptoms (OR 3.50). CONCLUSIONS: Continuous screening and appropriate intervention, especially at baseline, would significantly decrease the burden posed by stroke patients with such psychological impairments in the community.

Genetically selected cardiomyocytes from differentiating embronic stem cells form stable intracardiac grafts.

This study describes a simple approach to generate relatively pure cultures of cardiomyocytes from differentiating murine embryonic stem (ES) cells. A fusion gene consisting of the alpha-cardiac myosin heavy chain promoter and a cDNA encoding aminoglycoside phosphotransferase was stably transfected into pluripotent ES cells. The resulting cell lines were differentiated in vitro and subjected to G418 selection. Immunocytological and ultrastructural analyses demonstrated that the selected cardiomyocyte cultures (> 99% pure) were highly differentiated. G418 selected cardiomyocytes were tested for their ability to form grafts in the hearts of adult dystrophic mice. The fate of the engrafted cells was monitored by antidystrophin immunohistology, as well as by PCR analysis with primers specific for the myosin heavy chain-aminoglycoside phosphotransferase transgene. Both analyses revealed the presence of ES-derived cardiomyocyte grafts for as long as 7 wk after implantation, the latest time point analyzed. These studies indicate that a simple genetic manipulation can be used to select essentially pure cultures of cardiomyocytes from differentiating ES cells. Moreover, the resulting cardiomyocytes are suitable for the formation of intracardiac grafts. This selection approach should be applicable to all ES-derived cell lineages.

Differentiation and long-term survival of C2C12 myoblast grafts in heart.

We have assessed the ability of skeletal myoblasts to form long-term, differentiated grafts in ventricular myocardium. C2C12 myoblasts were grafted directly into the heart of syngeneic mice. Viable grafts were observed as long as 3 mo after implantation. Immunohistological analyses revealed the presence of differentiated myotubes that stably expressed the skeletal myosin heavy chain isoform. Thymidine uptake studies indicated that virtually all of the grafted skeletal myocytes were withdrawn from the cell cycle by 14 d after grafting. Graft myocytes exhibited ultrastructural characteristics typical of differentiated myotubes. Graft formation and the associated myocardial remodeling did not induce overt cardiac arrhythmia. This study indicates that the myocardium can serve as a stable platform for skeletal myoblast grafts. The long-term survival, differentiated phenotype, and absence of sustained proliferative activity observed in myoblast grafts raise the possibility that similar grafting approaches may be used to replace diseased myocardium. Furthermore, the genetic tractability of myoblasts could provide a useful means for the local delivery of recombinant molecules to the heart.

Targeted expression of transforming growth factor-beta 1 in intracardiac grafts promotes vascular endothelial cell DNA synthesis.

Intracardiac grafts comprised of genetically modified skeletal myoblasts were assessed for their ability to effect long-term delivery of recombinant transforming growth factor-beta (TGF-beta) to the heart. C2C12 myoblasts were stably transfected with a construct comprised of an inducible metallothionein promoter fused to a modified TGF-beta 1 cDNA. When cultured in medium supplemented with zinc sulfate, cells carrying this transgene constitutively secrete active TGF-beta 1. These genetically modified myoblasts were used to produce intracardiac grafts in syngeneic C3Heb/FeJ hosts. Viable grafts were observed as long as three months after implantation, and immunohistological analyses of mice maintained on water supplemented with zinc sulfate revealed the presence of grafted cells which stably expressed TGF-beta 1. Regions of apparent neovascularization, as evidenced by tritiated thymidine incorporation into vascular endothelial cells, were observed in the myocardium which bordered grafts expressing TGF-beta 1. The extent of vascular endothelial cell DNA synthesis could be modulated by altering dietary zinc. Similar effects on the vascular endothelial cells were not seen in mice with grafts comprised of nontransfected cells. This study indicates that genetically modified skeletal myoblast grafts can be used to effect the local, long-term delivery of recombinant molecules to the heart.

Stable fetal cardiomyocyte grafts in the hearts of dystrophic mice and dogs.

This report documents the formation of stable fetal cardiomyocyte grafts in the myocardium of dystrophic dogs. Preliminary experiments established that the dystrophin gene product could be used to follow the fate of engrafted cardiomyocytes in dystrophic mdx mice. Importantly, ultrastructural analyses revealed the presence of intercalated discs consisting of fascia adherens, desmosomes, and gap junctions at the donor-host cardiomyocyte border. To determine if isolated cardiomyocytes could form stable intracardiac grafts in a larger species, preparations of dissociated fetal canine cardiomyocytes were delivered into the hearts of adult CXMD (canine X-linked muscular dystrophy) dogs. CXMD dogs, like Duchenne muscular dystrophy patients and mdx mice, fail to express dystrophin in both cardiac and skeletal muscle. Engrafted fetal cardiomyocytes, identified by virtue of dystrophin immunoreactivity, were observed to be tightly juxtaposed with host cardiomyocytes as long as 10 wk after engraftment, the latest date analyzed. Confocal laser scanning microscopy revealed the presence of connexin43, a major constituent of the gap junction, at the donor-host cardiomyocyte border. The presence of intracardiac grafts was not associated with arrhythmogenesis in the CXMD model. These results indicate that fetal cardiomyocyte grafting can successfully augment cardiomyocyte number in larger animals.