Abstract: Objective To assess the feasibility of transferring major histocompatibility complex (MHC) gene into the thymus to mitigate xenograft rejection. Methods By molecular cloning technique, we extracted and proliferated the-H-2K d gene from donor mice (MHC class Ⅰ gene of Balb/c mice) and constructed the expression vector plasmid of pCI-H-2K d. Twenty SD rats were selected as receptors, and by using random number table, they were divided into the experimental group and the control group with equal number of rats in each group. By ultrasoundguided puncture and lipofection method, the pCI-H-2Kd was injected into thymus of SD rats in the experimental group and meanwhile, empty vector plasmid of pCIneo was injected into thymus of SD rats in the control group. Subsequently, we transplanted the donor mice myocardium xenografts into the receptor rats, and observed the xenograft rejection in both the two groups. Results The survival time of the xenotransplanted myocardium in the experimental group was significantly longer than that in the control group (14.61±2.98 d vs. 6.40±1.58 d, t=-7.619,Plt;0.05). Microtome section of transplanted myocardium in the control group showed a relatively large amount of lymphocyte infiltration and necrosis occurred to most part of the transplanted myocardium, while microtome section of experiment group showed no lymphocyte infiltration and most of the cells of the transplanted myocardium were still alive. After mixed lymphocyte culture, the reaction of receptors to donor cells in the experiment group was obviously lower than that in the control group (t=4.758, P=0.000).After the count by flow cytometer, the xenoMHC molecules were expressed in the receptors’ thymus with a transfection efficiency of 60.7%. Conclusion Our findings suggest that xenograft rejection can be mitigated substantially by donor’s MHC gene transferring into receptor’s thymus. This may provide theoretical and experimental evidence for inducing xenotransplantation tolerance.
Objective To introduce the method and effect of common cardiop ulmonary bypass(CPB) switched to closed extracorporeal circulation by medtronic extracorporeal membrane oxygenation(ECMO) package. Methods From Junuary 2007 to June 2008, common CPB switched to closed extracorporeal circulation by Medtronic ECMO package adding blood reservoir and artery microembolus filtrator was used to 15 patients with grave heart disease to provide CPB support during operation on heart and cardiac function support after operation. The circulation was built through femoral arteryfemoral veinsuperior vena cava intubation or aortaright auricle intubation. There were 10 male and 5 female aged from 6582 years (74.0±9.3 years) and weighed from 6389 kg (69.0±11.4 kg). There were 11 cases with old myocardial infarction, 1 case with acute myocardial infarction, 1 case with old myocardial infarction complicated with mitral stenosis and mitral incompetence, and 2 cases reopened and undergone double valve replacement. Results For all the 15 patients, the closed circulation time was 31112 min（77.3±21.5 min）. The CPB time was 51-84 min（69.7±9.8 min）. The ostoperative mechanical ventilation time was 414 h（8.3±2.9 h）. The 24 hchest drainage was 110-360 ml（227.3±80.4 ml）. All patients were cured and discharged successfully with cardiac function classification in grade ⅠⅡ. Thirteen cases were followed up. The followup time was 412 months. Their cardiac function recovered well and no complication occurred. Conclusion This method could provide effective support for heart and lung before operation，during operation and after operation. This method could save material cost. The heparin paintcoat could reduce inflammatory reaction and it is good for patients’ recovery.
Objective To observe the changes of inflammatory cytokines in brain protective methods, study the inflammatory mechanism during cerebral protection tissues in different cerebral Methods Eighteen healthy adult dogs were randomly divided into three groups （6 dogs in each group）： normothermic cardiopulmonary bypass （NCPB group）, deep hypothermic circulatory arrest （DHCA group）, and intermittent selective antegrade cerebral perfusion （ISACP） during DHCA（DHCA＋ISACP group）. After operation the water contents in brain tissue were measured ,the hippocampus were removed, and radio-immunity analysis （RIA） was used to measure the content of interleukin-1β（IL-1β） and tumor necrosis factor-alpha （TNF-α） of the hippocampus tissue. The morphology of the hippocampus were examined by transmission electron （TE） microscopy. Results The contents of IL-1β and TNF-α of DHCA group was higher significantly than those of NCPB group and DHCA＋ISACP group （P〈0.01）, there was no significant difference between NCPB group and DHCA＋ISACP group （P〉0.05）. And the contents of TNF-α and IL-1β were positive linear correlated with degree of edema of brain tissues （r = 0. 987, 0.942; P〈 0.01）. TE examination revealed that the damage of the uhrastructure in the DHCA group was more severe than that in NCPB group and DHCA＋ISACP group. Conclusions This experiment revealed that long duration DHCA can bring some damages to the brain and that ISACP during long-term DHCA has brain protective effects to some extent. IL-1β and TNF-α play an effective role in the brain damage of long-term DHCA.