ABSTRACT
BACKGROUND: Hyperpolarization-activated cyclic nucleotide-gated (HCN) current plays an important role in regulating heart spontaneous pulsation.OBJECTIVE: To observe target gene expression and electrophysiological characteristics of pig bone marrow mesenchymal stem cells (BMSCs) transfected with hyperpolarization-activated cyclic nucleotide-gated channel 2 (HCN2) gene recombinant adenovirus.DESIGN, TIME AND SETTING: Cell-gene in vitro study was performed at the Laboratory of Thoracic and Cardiovascular Surgery,Second Military Medical University of Chinese PLA from July 2007 to March 2008.MATERIALS: Yorkshire pig was supplied by Animal Institute, Second Military Medical University of Chinese PLA. HCN2 plasmid was presented by Professor Dario DiFrancesco from Italy. Recombinant adenovirus Ad.HCN2 was constructed and stored using Ad5 in this laboratory.METHODS: Pig BMSCs were isolated with combination of gradient centrifugation of Percoll and adherent treatment in vitro.Ad.HCN2 was transfected at multiplicity of infection=50. We also set non-transfection and transfected Ad.Null groups.MAIN OUTCOME MEASURES: Expression of HCN2 mRNA was detected with RT-PCR, and expression of HCN2 channel protein was examined with immunofluorescent staining. Electrophysiology of HCN2 channel protein was measured with whole-cell patch clamp.RESULTS: No amplified fragments were found in the non-transfection and transfected Ad.Null groups, but amplified fragments were determined at 250-500 bp following Ad.HCN2 amplification, which was the same as plasmid carrying HCN2 gene. Staining strength of cell nuclei following transfection was significantly weaken compared with cell membrane and plasma, which showed identical distribution as HCN2 protein. No HCN2 protein was detected in the non-transfection and transfected Ad.Null groups.Pacemaker current could be recorded with a whole-cell patch clamp. It was fully activated around -140 mV with an activation threshold of -60 mV, presenting voltage dependence. CsCI (4 mmol/L) reversibly blocked the inward currents. No pacemaker current was detected in the non-transfection and transfected Ad.Null groups.CONCLUSION: The HCN2 recombinant adenovirus carrier was transferred into serial subcultivation porcine bone marrow mesenchymal stem cells. HCN2 channel protein has been expressing. Pacemaker current could be recorded with a whole-cell patch clamp.
ABSTRACT
Objective To develop a novel method for treating complete heart block by autotransplantation of simus node node cells to right ventricular anterior wall.Methods Twenty healthy mongrel dogs were involved in the present study.The dogs were randomly assigned to transplant group or control group(n=10).The sinus node (SN)was harvested and isolated in vitro after an electronic pacemaker was implanted and complete heart bolck was introduced.The SN cells from dogs of transplant group were injected to autogenic right ventricular wall.Commensurable culture medium was implanted to ghe same position of dogs in control group.Two weeks later,detailed electropohysiological study was performed.For investigating the variation of the rhythm,epinephrine was administrated through femoral vein to dogs of transplant group.Results Most of isolated SN cells from dogs were thin-spindle shape,and cell activity was fine.The SNs by VG stained displayed typical structural feature.2 weeks after cell autotransplantation,higher heart rates were achieved from transplant group than that in control group(P＜0.05).This rhythm was stable in 4 weeks and became faster remarkably after administration of eninephrine(P＜0.05).Conclusion SN cell of dogs tutorgrfted into right ventricular anterior wall can form new pacemaker site in ventrcle and improve ventricular rate of complete heart bolck.This pacemaker site can also be regulated by epinephrine.