Postoperative intra-abdominal hypertension predicts worse hospital outcomes in children after cardiac surgery: a pilot study†.

OBJECTIVES: Our goal was to determine the incidence and characteristics of postoperative intra-abdominal hypertension (IAH) in paediatric patients undergoing open-heart surgery. METHODS: This single-centre study included consecutive children (aged <16 years) who underwent open-heart surgery between July 2020 and February 2021. Patients who entered the study were followed until in-hospital death or hospital discharge. The study consisted of 2 parts. Part I was a prospective observational cohort study that was designed to discover the association between exposures and IAH. Postoperative intra-abdominal pressure was measured immediately after admission to the intensive care unit and every 6 h thereafter. Part II was a cross-sectional study to compare the hospital-related adverse outcomes between the IAH and the no-IAH cohorts. RESULTS: Postoperatively, 24.7% (38/154) of the patients exhibited IAH, whereas 3.9% (6/154) developed abdominal compartment syndrome. The majority (29/38, 76.3%) of IAH cases occurred within the first 24 h in the intensive care unit. Multivariable analysis showed that the Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery score [odds ratio (OR) = 1.86, 95% confidence interval (CI) 1.23-2.83, P = 0.004], right-sided heart lesion (OR = 5.60, 95% CI 2.34-13.43, P < 0.001), redo sternotomy (OR = 4.35, 95% CI 1.64-11.57, P = 0.003), high baseline intra-abdominal pressure (OR = 1.43, 95% CI 1.11-1.83, P = 0.005), prolonged cardiopulmonary bypass duration (OR = 1.01, 95% CI 1.00-1.01, P = 0.005) and deep hypothermic circulatory arrest (OR = 5.14, 95% CI 1.15-22.98, P = 0.032) were independent predictors of IAH occurrence. IAH was associated with greater inotropic support (P < 0.001), more gastrointestinal complications (P = 0.001), sepsis (P = 0.003), multiple organ dysfunction syndrome (P < 0.001) and prolonged intensive care unit stay (z = -4.916, P < 0.001) and hospitalization (z = -4.710, P < 0.001). The occurrence of a composite outcome (P = 0.009) was significantly increased in patients with IAH. CONCLUSIONS: IAH is common in children undergoing cardiac surgery and is associated with worse hospital outcomes. Several factors may be associated with the development of IAH, including basic cardiac physiology and perioperative factors. TRIAL INFORMATION: This study was registered in the Chinese Clinical Trial Registry (Trial number: ChiCTR2000034322)URL site: https://www.chictr.org.cn/hvshowproject.html?id=41363&v=1.4.

Simplified total arch reconstruction with a stented graft for extended aortic arch dilation.

Background: Reconstruction of the aortic arch and its three supra-aortic vessels remains a great surgical challenge with postoperative complications. We present a simplified total arch reconstruction with a modified stent graft (s-TAR) and compared its operative outcomes with conventional total arch replacement (c-TAR). Methods: This retrospective analysis of prospectively collected data from all consecutive patients who had ascending aortic aneurysm with extended aortic arch dilation and underwent simultaneous ascending aorta replacement and aortic arch reconstruction with the s-TAR or c-TAR between 2018 and 2021. The indication for intervention was maximum diameter of ascending aorta >55 mm and aortic arch in zone II >35 mm. Results: A total of 84 patients were analyzed: 43 in the s-TAR group and 41 in the c-TAR group. No inter-group differences were found for sex, age, comorbidities, or EuroSCORE II results. All patients were successfully treated with s-TAR or c-TAR, and none died intraoperatively. Cardiopulmonary bypass, selective cerebral perfusion, and lower-body circulatory arrest time were significantly shorter in the s-TAR group, which also had a lower incidence of prolonged ventilation and transient neurologic dysfunction. No patient in either group experienced permanent neurologic dysfunction. The incidence of recurrent laryngeal nerve injury and paraplegia was markedly increased in the c-TAR group; however, no such events were observed in the s-TAR group. Both perioperative blood loss and the incidence of reoperation for bleeding were significantly lower in the s-TAR group. The in-hospital mortality rate was 0% in the s-TAR group and 4.9% in the c-TAR group. The s-TAR group had significantly shorter intensive care unit (ICU) stay and lower total hospitalization costs. Conclusions: The s-TAR technique is a safe and effective alternative for total arch reconstruction with shorter operation time, lower rate of postoperative complications and lower total hospitalization costs compared with c-TAR.

Establishment of induced pluripotent stem cell lines from an ARVC patient carrying a heterozygous variant in LAMA2 gene.

Using peripheral blood mononuclear cell (PBMC) reprogramming technology, a human-induced pluripotent stem cell (iPSC) line was produced from a patient who presents classic clinical features of arrhythmogenic right ventricular cardiomyopathy (ARVA) and carries a de novo laminin subunit alpha 2 (LAMA2) heterozygous mutation (NM_000426.3: c.8842G > A, p.G2948S). This mutation was not inherited from his parents, who also present normal cardiac phenotype. This iPSC line demonstrates a normal karyotype. Pluripotency and differentiation capacity has been confirmed in vitro. This cell line can help in efforts to understand the pathogenic mechanism between LAMA2 mutation and ARVC.

A rare case of arrhythmogenic right ventricular cardiomyopathy associated with LAMA2 mutation: A case report and literature review.

Background: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a heritable heart muscle disorder that predominantly affects the right ventricle. Mutations in genes that encode components of desmosomes, the adhesive junctions that connect cardiomyocytes, are the predominant cause of ARVC. A case with novel heterozygous mutation in the LAMA2 gene is reported here. The protein encoded by LAMA2 gene is the α2 chain of laminin-211 protein, which establishes a stable relationship between the muscle fiber membrane and the extracellular matrix. We explored the potential mechanism and the relationship between the mutation and ARVC. Case Presentation: At the age of 8, the patient developed syncope and palpitation after exercise. Dynamic electrocardiogram recorded continuous premature ventricular beats, and MRI showed the right ventricle was significantly enlarged and there were many localized distensions at the edge of the right ventricular wall. The patient was diagnosed with ARVC and received heart transplantation at the age of 14 due to severe heart dysfunction. The myocardial histological pathological staining revealed a large amount of fibrosis and adipose migration. Whole exome sequencing (WES) identified the heterozygous mutation in the LAMA2 gene [NM_000426.3: c.8842G > A (p.G2948S)]. This is the first report of these variants. Analysis was performed on genetic disorders to reveal splice site changes and damage to protein structure. LAMA2 p.G2948S predicted unstable protein structure and impaired function. Induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) were established. RNA-seq and the western blot were performed on IPSC-CMs to explore the ARVC-related signaling pathway. Conclusion: This is the first case report to describe an ARVC phenotype in patients possessing a novel LAMA2 c.8842G > A (p.G2948S) mutation. Our results aid in understanding of the pathogenesis of ARVC. The molecular mechanism of LAMA2 leading to ARVC disease still needs further study.

Clinical translation of surgical simulated closure of a ventricular septum defect.

OBJECTIVES: To demonstrate that improvement in technical performance of congenital heart surgical trainees during ventricular septum defect (VSD) closure simulation translates to better patient outcomes. METHODS: Seven trainees were divided into 2 groups. Experienced-fellows group included 4 senior trainees who had performed >5 VSD closures. Residents group consisted of 3 residents who had never performed a VSD closure. Experienced-fellows completed 3 VSD closures on real patients as a pretest. Both groups participated in a 4-week simulation requiring each participant to complete 2 VSD closures on three-dimensional printed models per week. One month later, all trainees returned for a post-test operation in real patients. All performances were recorded, blinded and scored independently by 2 cardiac surgeons using the validated Hands-On Surgical Training-Congenital Heart Surgery (HOST-CHS). Predefined surgical outcomes were analysed. RESULTS: The median HOST-CHS score increased significantly from week 1 to 4 [50 (39, 58) vs 73 (65, 74), P < 0.001] during simulation. The improvement in the simulation of experienced-fellows successfully transferred to skill acquisition [HOST-CHS score 72.5 (71, 74) vs 54 (51, 60), P < 0.001], with better patients outcomes including shorter total cross-clamp time [pretest: 86 (70, 99) vs post-test: 60 (53, 64) min, P = 0.006] and reduced incidence of major patch leak requiring multiple pump runs [pretest: 4/11 vs post-test: 0/9, P = 0.043]. After simulation, the technical performance and surgical outcomes of Residents were comparable to Experienced-fellows in real patients, except for significantly longer cross-clamp time [Residents: 76.5 (71.7, 86.8) vs Experienced-fellows: 60 (53, 64) min, P = 0.002]. CONCLUSIONS: Deliberate practice using simulation translates to better performance and surgical outcomes in real patients. Residents who had never completed a VSD closure could perform the procedures just as safely and effectively as their senior colleagues following simulation.

Density of aortopulmonary collaterals predicts in-hospital outcome in tetralogy of Fallot with pulmonary stenosis.

OBJECTIVES: The aim of this study was to characterize the anatomy of aortopulmonary collateral (APC) arteries in tetralogy of Fallot and pulmonary stenosis and to determine whether APC density identified on preoperative multidetector cardiac computed tomography predicts in-hospital outcome. METHODS: The retrospective single-centre study includes consecutive 135 (2015-2019) patients who underwent one-stage repair. Preoperative multidetector cardiac computed tomography, echocardiography and clinical outcomes were reviewed. The cut-off value of indexed total distal APC cross-sectional area (APC-CSA) was identified by receiver operating characteristic curve. Logistic regression was used for predictors analysis. RESULTS: The median age and body weight were 19.7 (10.1-89.7) months and 10 (8.3-18) kg. A total of 337 APCs were detected with only one demonstrating severe stenosis. There was a strong and significant correlation between mean APC diameter per patient and age (r = 0.70, P < 0.001). APCs were imaged but mainly received no interventions. In-hospital mortality was similar between patients with high (indexed APC-CSA ≥3.0 mm2/m2) and low (<3.0 mm2/m2) APC density (P = 0.642). Significantly greater patients with high indexed APC-CSA experienced the in-hospital composite outcome of death, arrest, renal/hepatic injury, lactic acidosis or extracorporeal membrane oxygenation (P = 0.007). High APC density was associated with greater dosing (P = 0.008) and longer (P = 0.01) use of inotropic support, prolonged pleural drainage (P = 0.013), longer ventilation (P = 0.042), intensive care unit (P = 0.014) and hospital (P = 0.027) duration. No reintervention and death occurred in the follow-up with the median duration of 24.4 (11-36.6) months. Multivariable analysis showed the Nakata index (P = 0.05) and high APC density (P = 0.02) independently predicted the composite outcome. CONCLUSIONS: In tetralogy of Fallot and pulmonary stenosis, APCs are likely to be dilated bronchial arteries. Preoperative multidetector cardiac computed tomography-derived APC density was as important as Nakata index in predicting the occurrence of in-hospital composite outcome. The APC-CSA of 3.0 mm2/m2 maybe considered as a threshold for risk stratification.

Enrichment differentiation of human induced pluripotent stem cells into sinoatrial node-like cells by combined modulation of BMP, FGF, and RA signaling pathways.

BACKGROUND: Biological pacemakers derived from pluripotent stem cell (PSC) have been considered as a potential therapeutic surrogate for sick sinus syndrome. So it is essential to develop highly efficient strategies for enrichment of sinoatrial node-like cells (SANLCs) as seed cells for biological pacemakers. It has been reported that BMP, FGF, and RA signaling pathways are involved in specification of different cardiomyocyte subtypes, pacemaker, ventricular, and atrial cells. We aimed to investigate whether combined modulation of BMP, FGF, and RA signaling pathways could enrich the differentiation of SANLC from human pluripotent stem cell (hiPSC). METHODS: During the differentiation process from human induced pluripotent stem cell to cardiomyocyte through small molecule-based temporal modulation of the Wnt signaling pathway, signaling of BMP, FGF, and RA was manipulated at cardiac mesoderm stage. qRT-PCR, immunofluorescence, flow cytometry, and whole cell patch clamp were used to identify the SANLC. RESULTS: qRT-PCR results showed that manipulating each one of bone morphogenetic protein (BMP), fibroblast growth factor (FGF), and retinoid acid (RA) signaling was effective for the upregulation of SANLC markers. Moreover, combined modulation of these three pathways displayed the best efficiency for the expression of SANLC markers, which was further confirmed at protein level using immunofluorescence and flow cytometry. Finally, the electrophysiological characteristics of upregulated SANLC were verified by patch clamp method. CONCLUSION: An efficient transgene-independent differentiation protocol for generating SANLC from hiPSC was developed, in which combined modulating BMP, FGF, and RA signaling at cardiac mesoderm stage generates SANLC at high efficiency. This may serve as a potential approach for biological pacemaker construction.

Partial resection of large congenital left ventricular diverticulum in an infant: a case report.

BACKGROUND: Congenital left ventricular diverticulum is a rare cardiac malformation usually requiring total resection. CASE PRESENTATION: This report describes an infant presenting with a large apical diverticulum with a wide ventricle connection. Given the vicinity of the left anterior descending coronary artery to the diverticulum and its wide ventricular connection, partial resection was undertaken. The patient remained asymptomatic with good heart function 8 months after surgery. The last follow-up echocardiography did not demonstrate any significant left ventricular outpouching. CONCLUSIONS: We advocate early treatment of left ventricular diverticulum in children given the risk of spontaneous rupture of diverticulum, sudden death, and other serious complications if left untreated. For small patients with a wide connection of diverticulum to ventricle, partial resection is a safe option with favorable short-term outcomes.

[Role of over-expression of TBX3 and TBX18 in the enrichment and differentiation of human induced pluripotent stem cells into sinoatrial node-like cells].

OBJECTIVE: To explore the role of over-expression of TBX3 and TBX18 in inducing human induced pluripotent stem cells (HiPS) to enrich and differentiate into sinoatrial node-like cells. METHODS: The expression of stemness markers OCT3/4, SOX2, and NANOG in HiPS was detected by real-time fluorescence quantitative PCR (qRT- PCR), and compared with human embryonic stem cells (hESCs). Immunofluorescence staining was used to observe the expression of HiPS stemness markers OCT3/4, NANOG, SSEA4, and TRA-1-60. The HiPS were directional differentiated into cardiomyocytes, the expressions of ISL1, NK2 homeobox 5 (NKX2-5), ACTN1, and TNNT2 were detected by qRT-PCR, and human adult cardiomyocytes (hACM) were used as positive control. Immunofluorescence staining was used to observe the expressions of NKX2-5, cardiac troponin (cTnT), α-actinin, atria myosin light chain 2A (MLC-2A), and ventricular myosin light chain 2V (MLC-2V). The positive rate of α-actinin was detected by flow cytometry. On the 3rd day after HiPS were differentiated into cardiomyocytes (mesodermal stage), lentiviral over-expressions of sinoatrial node-related genes TBX3 and TBX18 were carried out for 21 days. The relative expressions of specific markers TBX3, TBX18, SHOX2, NKX2-5, HCN4, and HCN1 in sinoatrial node cells were detected by qRT-PCR, and compared with enhanced green fluorescent protein blank virus. RESULTS: OCT3/4, SOX2, and NANOG were highly expressed in HiPS and ESCs, and there was no significant difference in the relative expression of each gene ( P>0.05); OCT3/4 and NANOG were specifically distributed in the nucleus of HiPS, while SSEA4 and TRA-1-60 were distributed in the cell membrane. The relative expressions of ISL1 gene at 5, 7, 21, and 28 days and NKX2-5 gene at 7, 21, and 28 days of HiPS differentiation into cardiomyocytes were significantly higher than those of hACM ( P<0.05), and the relative expressions of ACTN1 and TNNT2 genes at 3, 5, 7, and 21 days of HiPS differentiation into cardiomyocytes were significantly lower than those of hACM ( P<0.05). NKX2-5 was expressed in most of the nuclei, cTnT and α-actinin, MLC-2A and MLC-2V signals were localized in the cytoplasm, presenting a texture-like structure of muscle nodules. Flow cytometry results showed that HiPS was successfully induced to differentiate into cardiomyocytes. The expressions of TBX18, SHOX2, HCN4, and HCN1 in the over-expression TBX3 group were up-regulated when compared with the control group, and difference in the relative expression of SHOX2 gene was significant ( P<0.05); the relative expression of NKX2-5 gene was lower than that in the control group, but there was no significant difference ( P>0.05). There was no significant difference in the relative expression of each gene between the over-expressed TBX18 group and the control group ( P>0.05). CONCLUSION: HiPS and hESCs have similar pluripotency, and we have established a stable method for maintaining and culturing the stemness of HiPS. A technological platform for the efficient differentiation of HiPS into cardiomyocytes has been successfully established. Although TBX3 and TBX18 do not play a significant role in promoting the enrichment and differentiation of HiPS into sinoatrial node-like cells, TBX3 shows a certain promoting trend, which can be further explored in the future.

[A preliminary study on the disappearance time of influenza virus antigen].

OBJECTIVE: To investigate the antigen clearance time, time to symptom disappearance, and the association between them using immunofluorescence assay for dynamic monitoring of influenza virus antigen in children with influenza. METHODS: A total of 1 063 children suspected of influenza who visited the Hunan People's Hospital from March to April, 2016 were enrolled. The influenza A/B virus antigen detection kit (immunofluorescence assay) was used for influenza virus antigen detection. The children with positive results were given oseltamivir as the antiviral therapy and were asked to re-examine influenza virus antigen at 5, 5-7, and 7 days after onset. RESULTS: Of all children suspected of influenza, 560 (52.68%) had an influenza virus infection. A total of 215 children with influenza virus infection were followed up. The clearance rate of influenza virus antigen was 9.8% (21 cases) within 5 days after onset. The cumulative clearance rate of influenza virus antigen was 32.1% (69 cases) within 5-7 days, and 98.1% (211 cases) within 7-10 days after onset. Among these children, 6 children (2.8%) achieved the improvement in clinical symptoms within 3 days after onset. The cumulative rate of symptom improvement was 84.7% (182 cases) within 3-5 days after onset, and 100% achieved the improvement after 5 days of onset. CONCLUSIONS: The time to improvement in symptoms after treatment is earlier than antigen clearance time. Almost all of the children achieve influenza virus antigen clearance 7-10 days after onset. Therefore, it is relatively safe for children to go back to school within 7-10 days after onset when symptoms disappear.

Shear stress regulates endothelial cell function through SRB1-eNOS signaling pathway.

AIM: The aim of this study was to explore whether transmembrane flow shear stress could regulate eNOS expression and mediate endothelial cell function via SR-B1 signaling transduction. METHODS: Parallel-plate flow chamber was used to impose laminar shear stress and evaluate the effect of shear stress upon human umbilical vein endothelial cells (HUVECs). The expression of SR-B1 and eNOS at both RNA and protein levels was detected under different dynamic conditions. RNA interference and gene transfection were performed to overexpress and knock down the SRB1 to confirm the role of SR-B1-eNOS signaling pathway. RESULTS: The expression levels of SR-B1 and eNOS were downregulated when HUVECs were treated with 4.2 dyne/cm(2) shear stress compared with those of the control group. However, the expression of SR-B1 and eNOS was upregulated as HUVECs exposed to 8.4 and 15 dyne/cm(2) shear stress. When exposed to 8.4 dyne/cm(2) , SR-B1 and eNOS expression was significantly higher compared with those of the other groups. When SR-B1 was knocked down through RNAi technique, the expression of eNOS was significantly downregulated than those of the other groups. While overexpression of SR-B1 could upregulate eNOS significantly. CONCLUSION: Shear stress regulates endothelial cell function through SR-B1-eNOS signaling pathway. SR-B1 may play a pivotal role in the process of anti-atherosclerosis.

[Research of different expressions of microRNA in sinus node, atrial myocardium, and ventricular myocardium of mouse].

OBJECTIVE: To study microRNA (miRNA) involved in the regulation of sinus cell differentiation by comparing sinus node, atrial myocardium, and ventricular myocardium specific miRNA expression profile differences in Kunming mice. METHODS: A total of 180 Kunming mice, aged 60-90 days and weighing 35-45 g, were selected without gender differences after the method of anatomical localization for sinus node had been confirmed by preliminary experiments in another 10 Kunming mice. All the sinus node, atrial myocardium, and ventricular myocardium tissue from 180 mice were dissected and frozen by liquid nitrogen. The structure of tissue was observed by HE staining. Total RNA were extracted and quality-controlled before hybridize with miRNA chip. The chips with miRNA were used to screen specific miRNAs; and correlation analysis of gene function was done. RESULTS: The area of mice sinus node located at juncture of the superior vena cava and the right atrium junction with crista as its longitudinal axis, ranged 2.0 mm x 1.5 mm x 1.0 mm. HE staining showed the sinus cells were less, with no stripes, lightly stained cytoplasm, large and round nucleus, and there were much fibrous connective tissue around cells with a visible sinus node artery. The miRNA microarray results showed that compared with atrial myocardium and ventricular myocardium, there were 39 differentially expressed miRNAs in sinus node, including 12 up-regulated miRNAs and 27 down-regulated miRNAs. Based on the regulatory networks of differential miRNA and target gene, the regulatory miRNA was obtained. CONCLUSION: The differentially expressed miRNA in mice sinus node possibly may be involved in the regulation of sinus cell differentiation.

Differentiation induction of mouse cardiac stem cells into sinus node-like cells by co-culturing with sinus node.

Sinus nodal cells can generate a diastolic or "pacemaker" depolarization at the end of an action potential driving the membrane potential slowly up to the threshold for firing the next action potential. It has been proved that adult cardiac stem cells (CSCs) can differentiate into sinus nodal cells by demethylating agent. However, there is no report about adult CSCs-derived sinus nodal cells with pacemaker current (the funny current, I f). In this study, we isolated the mouse adult CSCs from mouse hearts by the method of tissue explants adherence. The expression of c-kit protein indicated the isolation of CSCs. Then we co-cultured mouse CSCs with mouse sinus node tissue to induce the differentiation of these CSCs into sinus node-like cells, which was proved by identifying the enhanced expression of marker proteins cTnI, cTnT and α-Actinin with Immunofluorescence staining. At the same time, with whole-cell patch-clamp we detected the I f current, which can be blocked by CsCl, in these differentiated cells. In conclusion, by confirming specific I f current in the induced node-like cells, our work shows a method inducing differentiation of CSCs into sinus node-like cells, which can provide helpful information for the further research on sick sinus syndrome.

[Influence of intrauterine hypoxia on the lung blood vessel development in rats after birth and expression of VEGF in the lung].

OBJECTIVE: To observe the effect of intrauterine hypoxia on the development of rat lung after birth under ordinary pressure and normoxia, on the expression of vascular endothelial growth factor (VEGF) in the lung as the age increasing after birth, and to provide experimental basis for the treatment of intrauterine hypoxia after baby was born. METHODS: Intrauterine hypoxia models were established. The rats were divided into an air-control group (the control group) and a hypoxic 6-day group (the hypoxic group). All rats were fed under normal pressure and normoxia after they were born. At postnatal 7, 14, and 21 days, we measured the pulmonary vascular morphometry, detected the expression of VEGF protein with immunohistochemisty, the expression of VEGF mRNA with real-time PCR, and observed the alteration of capillary endothelium in the lung tissues under the electron microscope. RESULTS: The expression of VEGF protein and VEGF mRNA in the 2 groups increased as the rats grew, but the expression increased slower in the hypoxic group than that in the control group. The increase curve of the 2 groups crossed. There was no significant difference between the 2 groups in the pulmonary vascular morphometry at each experiment time point. Hyperplasia of capillary endothelium decreased with age. Cellular edema of capillary endothelium was obvious especially at the 14th day after birth under the electron microscope. CONCLUSION: The expression of VEGF protein and VEGF mRNA has slower increase in the intrauterine hypoxic rats than that in the normal control rats. The expression of VEGF may influence the development of lung vessel after rats was born.

[Experimental research of recombinant lentivirus mediated hyperpolarization-activated cyclic nucleotide-gated cation channel 4 gene transfecting bone mesenchymal stem cells].

OBJECTIVE: To investigate the feasibility of recombinant lentivirus (LVs) mediated hyperpolarization-activated cyclic nucleotide-gated cation channel 4 (HCN4) gene transfecting rat bone mesenchymal stem cells (BMSCs) so as to construct the biological pacemaker cells. METHODS: Sprague Dawley rats at the age of 3-5 weeks were selected to isolate and culture BMSCs using modified whole bone marrow adherent culture method. LVs was used as carrier, and enhanced green fluorescent protein (EGFP) as marker to build LVs-HCN4-EGFP virus liquid. The BMSCs at passage 3 were transfected with LVs-HCN4-EGFP virus liquid (experimental group) and LVs-EGFP null virus liquid (control group). Fluorescence microscope was used to observe the green fluorescent protein expression after 24, 48, and 72 hours of transfection; Western blot method was used to detect the HCN4 protein expression. The electrophysiology was used to detect the pacemaker current in the experimental group. RESULTS: After transfection, BMSCs in the experimental group showed normal morphology and good growth; scattered green fluorescence could be seen at 48 hours under fluorescence microscope, with a transfection efficiency of about 10%; the fluorescence expression increased slightly, with the transfection efficiency of 20% to 25% at 72 hours. While no expression of green fluorescence was seen in the control group. Western blot results showed that the same band expression as a relative molecular mass of HCN4 protein were found at 72 hours after transfection in the experimental group, only weak expression of protein band was seen in the control group; the gray value of the experimental group (33.75 +/- 0.41) was significantly higher than that of the control group (23.39 +/- 0.33) (t=17.524, P=0.013). In the experimental group, the pacemaker current was recorded, and it could be blocked by CsCl, in accordance with the characteristics of pacemaker current. CONCLUSION: The recombinant LVs mediated HCN4 gene is successfully transfected into rat BMSCs, and the expression of HCN4 protein and the pacemaker current can be detected.

[Research progress of myocardial tissue engineering scaffold materials].

OBJECTIVE: To review the current status and problems in the developing scaffolds for the myocardial tissue engineering application. METHODS: The literature concerning the myocardial tissue engineering scaffold in recent years was reviewed extensively and summarized. RESULTS: As one of three elements for tissue engineering, a proper scaffold is very important for the proliferation and differentiation of the seeding cells. The naturally derived and synthetic extracellular matrix (ECM) materials aim to closely resemble the in vivo microenvironment by acting as an active component of the developing tissue construct in myocardial tissue engineering. With the advent and continuous refinement of cell removal techniques, a new class of native ECM has emerged with some striking advantages. CONCLUSION: Through using the principle of composite scaffold, computers and other high-technology nano-polymer technology, surface modification of traditional biological materials in myocardial tissue engineering are expected to provide ideal myocardial scaffolds.

[Roles of platelet and its regulating factors in immune vasculitis in young rabbits].

OBJECTIVE: To study the roles of platelet (PLT) and its regulating factors, megakaryocyte, thrombopoietin (TPO) and transforming growth factor beta1 (TGF-beta1), in immune vasculitis in young rabbits. METHODS: An experimental model of Kawasaki disease (KD) of weanling rabbits was reproduced by bovine serum. PLT count, total number and differentiating count of megakaryocyte, and serum TPO and TGF-beta1 levels were measured 0, 4, 8, 12, 16, 20, 24 and 28 days after KD induction. Pathological analysis of coronary artery, liver, spleen, kidney and brain was performed 17 and 28 days after KD induction. RESULTS: In the KD group, PLT count, the total number of megakaryocyte, and the middle board megakaryocyte percentage increased 12, 16, 20, 24 and 28 days; serum TPO level increased 8, 12, 16, 20, 24 and 28 days; serum TGF-beta1 level increased 16, 20, 24 and 28 days after KD induction compared with those in the normal control group (p<0.05). The pathological examinations of coronary artery, liver, spleen, kidney and brain showed severe inflammatory injuries of tiny arteries and small/medium-sized arteries 17 and 28 days after KD induction, respectively in the KD group. The aortas were showed as mild inflammatory injuries. CONCLUSIONS: PLT, megakaryocyte, TPO and TGF-beta1 participate in the pathogenesis of KD, and they may play an important role in the injuries of immune vasculitis. This suggests that they may serve as markers for the assessment of severity in KD.