Review preparations about small caliber artificial blood vessels,cell cultivation,nano materials and growth factors in the research of vascular tissue engineering.The main method of keeping small diameter vascular graft patency is to promote the small-diameter artificial vascular cells,using nanometer encapsulated growth factor delivery system which can promote the growth of endothelial cells at the luminal surface adhesion,and using anticoagulant drug delivery system.

Objective To construct a model of small caliber vascular endothelial growth factor(VEGF) in tissue engineering,to investigate the performance of the sustained-release microspheres and vascular stent,and to provide materials and theoretical basis for animal experiment.Methods The sheep carotid arteries were treated with a cellular reagents,the cellular conditions and the stent properties were observed.Preparation of sustained release microspheres containing VEGF,particle size,encapsulation efficiency,drug loading and release curve were measured.The effective combination of the slow release microsphere and the vascular stent was used in the freeze drying technology.The rat vascular endothelial cells grown in tissue engineered blood vessel model release lumen,observe the growth of endothelial cells.Results After the treatment,the original performance of the vascular stent can be maintained.The average particle size of the microspheres was (9.8 ± 6.0) μm,which could be released slowly in 20 days,and the release rate was 70％.Microspheres can effectively with the tissue.engineering blood vessel tight binding.Rat vascular endothelial cells can grow in the vascular stent surface.Conclusion Using Triton X-100,DNA/RNA ribozyme for acellular reagent,stent performance is good.PLGA microspheres have good sustained release performance,and constructing appropriate tissue engineered small caliber vascular release model by using freeze drying technology can make the stent compact structure.

Objective:To conduct a systematic study of the immunologic response of rats to transplanted glutaraldehyde ( GA)-treated porcine blood vessels in vivo.Methods: The experiment was divided into two groups:fresh group and glutaraldehyde-treated group.Twenty cases of fresh and glutaraldehyde-treated porcine pulmonary arteries were subcutaneously embedded in rats.We compared the changes using HE staining and immunohistochemistry.Results:HE staining showed that there were stronger expression on day 12 and day 30 in the fresh group than that in the glutaraldehyde group.There were similar results in morphology in CD68,C3,IgG.The results of integral optical density ( IOD) in immunohistochemistry showed that IOD started rising from day 4 and got the peak on day 12 or day 30 and or fell on day 60.Conclusion: Innate immunity played an important role in the research on xenogenic immunological rejection mechanism.The immunogenicity of glutaraldehyde-treated xenogenic blood vessels is lower than that in fresh blood vessels.However there is still immunogenicity in glutaraldehyde-treated xenogenic blood vessels.We will explore better ways to obviously weaken the rejection.

In some countries and regions,descending branch of lateral circumflex femoral artery(DBLCFA) has been successfully applied to CABG.It is feasible,easy and safe to harvest and apply DBLCFA to CABG.We review the origin,distribution and anatomical features of DBLCFA.And introduce its application,relevant techniques and strategies in CABG.

Objective:To describe the COVID-19 epidemic and its characteristics in Heilongjiang province, and provide evidence for the further prevention and control of COVID-19 in the province.Methods:The information of COVID-19 cases and clusters were collected from national notifiable disease report system and management information system for reporting public health emergencies of China CDC. The Software’s of Excel 2010 and SPSS 23.0 were applied for data cleaning and statistical analysis on the population, time and area distributions of COVID-19 cases.Results:On January 22, 2020, the first confirmed case of COVID-19 was reported in Heilongjiang. By March 11, 2020, a total of 482 cases domestic case of COVID-19, The incidence rate was 1.28/100 000, the mortality rate was 2.70% (13/482) in 13 municipalities in Heilongjiang. There were 81 clusters of COVID-19, The number of confirmed cases accounted for 79.25% (382/482) of the total confirmed cases and 12 cases of deaths. The family clusters accounted for 86.42% (70/81). Compared with the sporadic cases, the mortality rate, proportion of elderly cases aged 60 or above and severe or critical cases of clinical classification were all higher in the clusters especially the family clusters, but the differences were not significant ( P>0.05). There were 34 clusters involving more than 5 confirmed cases accounted for 41.98% (34/81) of the total clusters, the involved cases accounted for 68.31% (261/382) of the total cases of clusters. There were significant differences in age distribution of the cases among the case clusters with different case numbers. In the clusters involving 6-9 cases, the proportion of cases aged 65 years or above was more (26.53%, 39/147). Conclusions:The incidence rate of COVID-19 was relatively high and the early epidemic was serious in Heilongjiang, The number of cases was large in clusters especially family clusters.