Matched pair analysis of the effect of longer hypothermic machine perfusion time on kidney transplant outcomes

BACKGROUND Hypothermic machine perfusion(HMP)has demonstrated benefits in terms of early kidney transplant function compared to static cold storage.While longer preservation times have shown detrimental effects,a previous paired study indicated that longer pump times(the second kidney in a pair)might lead to improved outcomes.AIM To revisit the prior paired study's somewhat unexpected results by reviewing our program's experience.METHODS A total of 61 pairs of transplant recipients who received kidneys from the same donor(2012-2021)were analyzed.Patients were divided into two groups depending on whether they were transplanted first(K1)or second(K2).Therefore,the patients in each pair had identical donor characteristics,except for time on the pump.Statistical analyses included Kaplan-Meyer analysis and paired tests,including McNemar's test,student's paired t-test,or Wilcoxon's test,as appropriate.RESULTS The two groups of recipients had similar demographics(age,body mass index,diabetes,time on dialysis,sensit-ization and retransplants).Cold ischemic times for K1 and K2 were 8.9(95%CI:7.9,9.8)and 14.7 hours(13.7,15.8)(P<0.0001),respectively.Overall,K2 had a higher rate of freedom from biopsy-proven acute rejection at 1 year(P=0.015).Delayed graft function was less common in K2,12/61(20%)than in K1,20/61(33%)(P=0.046).Finally,K2 showed a higher graft survival than K1(P=0.023).CONCLUSION Our results agree with a previous study that suggested possible advantages to longer pump times.Both studies should encourage further research into HMP's potential anti-inflammatory effect.

Influence of perfusate on liver viability during hypothermic machine perfusion

AIM: To optimize the perfusates used for hypothermicmachine perfusion(HMP).METHODS: Sprague-Dawley rats were assigned randomly to three groups(n = 12 per group) that received either saline, University of Wisconsin coldstorage solution(UW) or histidine-tryptophan-ketoglutarate solution(HTK) as the perfusate. Each group was divided into two subgroups: static cold storage(SCS) and HMP(n = 6 per subgroup). The liver graft was retrieved according to the method described by Kamada. For the SCS group, the graft was directly placed into cold perfusate(0-4?℃) for 6 h after liver isolation while the portal vein of the graft was connected to the perfusion machine for the HMP group. Then the perfusates were collected at different time points for analysis of aspartate aminotransferase(AST), alanine transaminase(ALT) and lactate dehydrogenase(LDH) levels. Liver tissues were obtained for evaluation of histology, dry/wet weight(D/W) ratio, and malondialdehyde(MDA) and adenosine-triphosphate(ATP) levels. The portal vein pressure and velocity were monitored in real time in all HMP subgroups.RESULTS: Comparison of HMP and SCS: Regardless of the perfusate, HMP improved the architecture of donor graft in reducing the congestion around sinusoids and central vein and maintaining sinusoid lining in morphology; HMP improved liver function in terms of ALT, AST and LDH, especially during the 3-6 h period(SCS vs HMP using saline: ALT3, 225.00 ± 105.62 vs 49.50 ± 18.50, P = 0.047; LDH3, 1362.17 ± 563.30 vs 325.75 ± 147.43, P = 0.041; UW: LDH6, 2880.14 ± 948.46 vs 2135.00 ± 174.27, P = 0.049; HTK, AST6, 307.50 ± 52.95 vs 185.20 ± 20.46, P = 0.041); HMP decreased MDA level(saline, 2.79 ± 0.30 vs 1.09 ± 0.09, P = 0.008; UW, 3.01 ± 0.77 vs 1.23 ± 0.68, P = 0.005; HTK, 3.30 ± 0.52 vs 1.56 ± 0.22, P = 0.006). Comparison among HMP subgroups: HTK showed less portal vein resistance than UW and saline(vs saline, 3.41 ± 0.49 vs 5.00 ± 0.38, P < 0.001; vs UW, 3.41 ± 0.49 vs 4.52 ± 0.63, P = 0.007); UW reduced edema most efficiently(vs saline, 0.68 ± 0.02 vs 0.79 ± 0.05, P = 0.013), while HTK maintained ATP levels best(vs saline, 622.60 ± 29.11 vs 327.43 ± 44.66, P < 0.001; vs UW, 622.60 ± 29.11 vs 301.80 ± 37.68, P < 0.001).CONCLUSION: HMP is superior to SCS in maintaining both architecture and function of liver grafts. Further, HTK was found to be the optimal perfusate for HMP.

Hypothermic machine perfusion with metformin-University of Wisconsin solution for ex vivo preservation of standard and marginal liver grafts in a rat model

AIM To compare the effect of University of Wisconsin(UW) solution with or without metformin, an AMP-activated protein kinase(AMPK) activator, for preserving standard and marginal liver grafts of young and aged rats ex vivo by hypothermic machine perfusion(HMP).METHODS Eighteen young(4 mo old) and 18 aged(17 mo old)healthy male SD rats were selected and randomly divided into three groups: control group, UW solution perfusion group(UWP), and UW solution with metformin perfusion group(MUWP). Aspartate aminotransferase(AST), alanine aminotransferase(ALT), lactate dehydrogenase(LDH), interleukin-18(IL-18), and tumor necrosis factor-alpha(TNF-α) in the perfused liquid were tested. The expression levels of AMPK and endothelial nitric oxide synthase(e NOS) in liver sinusoidal endothelial cells were also examined.Additionally, microscopic evaluation of the harvested perfused liver tissue samples was done. RESULTS AST, ALT, LDH, IL-18 and TNF-α levels in the young and aged liver-perfused liquid were, respectively,significantly lower in the MUWP group than in the UWP group(P < 0.05), but no significant differences were found between the young and aged MUWP groups.Metformin increased the expression of AMPK and e NOS protein levels, and promoted the extracellular release of nitric oxide through activation of the AMPK-e NOS mediated pathway. Histological examination revealed that in the MUWP group, the extent of liver cells and tissue damage was significantly reduced compared with the UWP group.CONCLUSION The addition of metformin to the UW preservative solution for ex vivo HMP can reduce rat liver injury during cold ischemia, with significant protective effects on livers, especially of aged rats.

MicroRNA expression in the hippocampal CA1 region under deep hypothermic circulatory arrest

Using deep hypothermic circulatory arrest, thoracic aorta diseases and complex heart diseases can be subjected to corrective procedures. However, mechanisms underlying brain protection during deep hypothermic circulatory arrest are unclear. After piglet models underwent 60 minutes of deep hypothermic circulatory arrest at 14°C, expression of microRNAs(miRNAs) was analyzed in the hippocampus by microarray. Subsequently, TargetScan 6.2, RNA22 v2.0, miRWalk 2.0, and miRanda were used to predict potential targets, and gene ontology enrichment analysis was carried out to identify functional pathways involved. Quantitative reverse transcription-polymerase chain reaction was conducted to verify miRNA changes. Deep hypothermic circulatory arrest altered the expression of 35 miRNAs. Twenty-two miRNAs were significantly downregulated and thirteen miRNAs were significantly upregulated in the hippocampus after deep hypothermic circulatory arrest. Six out of eight targets among the differentially expressed miRNAs were enriched for neuronal projection(cyclin dependent kinase, CDK16 and SLC1 A2), central nervous system development(FOXO3, TYRO3, and SLC1 A2), ion transmembrane transporter activity(ATP2 B2 and SLC1 A2), and interleukin-6 receptor binding(IL6 R)– these are the key functional pathways involved in cerebral protection during deep hypothermic circulatory arrest. Quantitative reverse transcription-polymerase chain reaction confirmed the results of microarray analysis. Our experimental results illustrate a new role for transcriptional regulation in deep hypothermic circulatory arrest, and provide significant insight for the development of miRNAs to treat brain injuries. All procedures were approved by the Animal Care Committee of Xuanwu Hospital, Capital Medical University, China on March 1, 2017(approval No. XW-INI-AD2017-0112).

THE TECHNIQUE OF THE NORMOTHERMIC AND HYPOTHERMIC TOTAL HEPATIC VASCULAR EXCLUSION FOR RESECTION OF THE LIVER TUMORS

The technique for bloodless hepatic resection using the total hepatic vascular isolation under the normothermic or hypothermic perfusion was reported to deal with the large liver tumor involving in the liver hilum,the main hepatic veins or the retrohepatic vena cava.The original Heaney's and Fortner's methods were modified so that the technique could be simpler and more practicable to perform otherwise hazardous liver resection.During the past 4 year,major hepatic resection with the normothermic or hypothermic total vascular exclusion technique was successfully performed on 19 patients with liver tumors in our department.Among the 19 cases,16 underwent hepatic resection with the normothermic selective total vascular exclusion(extended right lobectomy in 5 cases,extended left lobectomy in 3 cases;right lobectomy in 5 cases;central segmentectomy in 3 cases)and 3 with the total vascular isolation and in situ cold perfusion(extended left lobectomy in 2 case,extended right lobectong in 1case).We believe that the technique of normothermic vascular exclusion may be indicated to deal with the lesion close to the hepatic veins and the retrohepatic vena cava.However,for more complicated hepatic resection,the hypothermic perfusion technique should be considered to prolong the safety of ischemic tune of the liver.The preliminary experience in the clinical application using the above technique is reported.

Persistent left superior vena cava in right hemiarch replacement under deep hypothermic circulatory arrest:A case report

BACKGROUND Persistent left superior vena cava(PLSVC),a relatively rare thoracic vascular malformation,can inconvenience perfusionists and operators when encountered during deep hypothermic circulatory arrest(DHCA).CASE SUMMARY Herein,we describe the case of a patient with concurrent giant aortic arch aneurysm,aortic stenosis,and PLSVC.To treat these conditions,we performed right hemiarch and aortic valve replacements under DHCA.Notably,we applied“bilateral superior vena cava retrograde cerebral perfusion(RCP)”for cerebral protection,which significantly optimized the surgical procedure and reduced the risk of postoperative complications.The patient was discharged 14 d after surgery with no complications.CONCLUSION Surgical intervention for PLSVC under DHCA can be performed using the bilateral superior vena cava RCP approach.

Comparative study of the protective effect using hypothermic cardiopulmonary bypass and normothermic cardiopulmonary bypass

Objective To explore the detrimental influence of normothermic and hypothermic cardiopulmonary bypass during open-heart surgery on immunity function,cytokines and complements.Methods Forty patients with congenital or rheumatic heart disease were randomized to receive the two strategies:normothermic CPB(study group)and hypothermic CPB(control group),20 cases in each group.Venous blood samples were collected at each time points of preoperation,end of CPB,day 1,4,7,14 postoperatively to examine the plasma level of IL-2,TNF-α,C3,C4,IgG,IgM,IgA,CD3,CD4,CD8.Results IL-2 in both groups decreased significantly at day 1,4,and returned to normal at day 7 postoperatively.IL-2 in control group was significantly lower than that in study group postoperatively.TNF-α in two groups was all higher at time points of end of CPB,day 1,4 postoperatively;in study group,it returned to normal level at day 7 postoperatively,whereas in control group,it was still higher at day 7 postoperatively than that before operation,and returned to normal at day 14 postoperatively.C3 in study group was significantly lower at time points of end of CPB,day 1,7 postoperatively than that in control group;C3 in both groups was all higher at time points of end of CPB,day 1,4 postoperatively;in study group,it returned to normal level at day 7 postoperatively,whereas in control group,it was still higher at day 7 postoperatively than that before operation and returned to normal at day 14 postoperatively.C4 in study group at time points of end of CPB,day 1 postoperatively was significantly lower than that in control group;C4 in both groups was all lower at time points of end of CPB,day 1,4 postoperatively than that before operation.The results showed that IgA after operation in both groups was significantly lower than that before operation,and returned to normal at day 7 postoperatively;IgA in study group at day 1 postoperatively was higher than that in control group.IgG in both group at time points of end of CPB,day 1,4 postoperatively was significantly lower than that before operation.IgG in control group was significantly higher at time points of end of CPB,day 1,4 postoperatively was significantly higher than that in control group.IgM in study group was significantly lower at time points of end of CPB,day 1,4 postoperatively.In control group,IgM was significantly lower at time points of end of CPB,day 1,4,7 postoperatively and returned to normal at day 14 postoperatively.IgM in study group was significantly higher at day 1,4 postoperatively than that in control group.CD3,CD4 in both groups decreased significantly at time points of end of CPB,day 1,4,and CD3、CD4 in study group and CD3 in control group returned to normal at day 7 postoperatively,CD4 in control group still lower than that before operation at day 7 postoperatively,and returned to normal at day 14 postoperatively.CD3,CD4 in control group was significantly lower at time points of end of CPB,day 1,4 than that in study group.CD8 in both groups increased significantly at day 1 postoperatively;there was no significant difference between the two groups.Conclusions The detrimental influence of open-heart surgery under normothermic CPB on humoral and cellular immunity function,cytokines and complements is less than that under hypothermic CPB,so normothermic CPB is beneficial for the postoperative recovery and anti-inflammation function.

Effect of resuscitation after selective cerebral ultraprofound hypothermia on expressions of nerve growth factor and glial cell line-derived neurotrophic factor in the brain of monkey

Objective To investigate the expression of nerve growth factor （NGF） and glial cell line-derived neurotrophic factor （GDNF） in monkeys of resuscitation after selective cerebral ultraprofound hypothermia and blood flow occlusion. Methods The monkeys were immediately removed brain after death in operation of group A （identical temperature perfusion group） and group B （ultraprofound hypothermia perfusion group）. Immunohistochemical technique was used to determine frontal cellular expression of NGF and GDNF. Statistics were analyzed by ANOVA analyses with significance level at P 〈 0.05. Results The expressions of NGF and GDNF in the group B were significantly higher than those in the group A （P 〈 0.05）. Conclusion NGF and GDNF increased significantly in the monkeys of resuscitation after selective cerebral ultraprofound hypothermia and blood flow occlusion. It may be a protective mechanism for neuron survival and neural function recovery.

The relationship between ENSO cycle and high and low-flow in the upper Yellow River

Firstly, the hydrological and meteorological features of the upper reaches of the Yellow River above Tangnag are analyzed based on observation data, and effects of EI Nino and La Ni na events on the high and low flow in the upper Yellow River are discussed. The results show El Nino and La Nina events possess consanguineous relationship wi th runoff in the upper Yellow River. As a whole, the probability of low fl ow occurrence in the upper Yellow River is relatively great along wit h the occurrence of El Nino event. Moreover, the flood in the upper Yellow River occurs frequently with the occurrence of La Nina event. Besides, the results also show dissimilarity of El Nino event occurri ng time exerts greater impact on high flow and low flow in the uppe r Yellow River, that is, the probability of drought will be greater in the sam e year if El Nino event occurs in spring, the high-flow may happen in this y ear if El Nino occurs in summer or autumn; the longer the continuous period of El Nino is, the lower the runoff in the upper Yellow River is.

Generation of Unfolded DNA in Human Neutrophils Following Hypothermal Treatment

By visualizing DNA with diamidino phenylindole (DAPI), we found that hypothermal incubation followed by rewarming of human neutrophils resulted in an increased number of DAPI-positive objects representative of extensive DNA unfolding seemingly similar to neutrophil extracellular traps (NETs). In contrast to canonical NET formation, diphenylene iodonium (DPI), an NADPH oxidase inhibitor, exhibited negligible effects on formation of the DAPI-positive objects. Moreover, multiple instances of DNA damage were detected in the objects, but not in canonical NETs. Our results thus suggest the potential of hypothermia for triggering DNA structural alteration in neutrophils, which is similar to but distinct from NET formation.

A Cardiac Surgical Perspective on Hypothermia for Protection of Neural Tissues

Background: In clinical and basic science medicine, we often isolate ourselves in silos, unaware of developments in other related disciplines. Our team has had substantial experience, both in the operating room and in the laboratory, with protecting the brain and the spinal cord via hypothermia. Herein, we briefly share this experience with our colleagues in Neurology, eager for comments and advice from the neurologic perspective. Methods: 1) Clinical brain protection via deep hypothermic circulatory arrest (DHCA) for surgery of the aortic arch. For aortic arch replacement (performed for aortic arch aneurysm or aortic dissection), the aortic arch must be opened and native perfusion stopped. We have decades of experience in many hundreds of patients with this technique. This experience is reviewed. 2) Experimental protection of the spinal cord via cooling. We review our laboratory experience with a novel, recirculating cooling catheter for the vulnerable spinal cord. 3) Experimental protection of the brain via an intraventricular cooling catheter. We review our laboratory experience cooling the brain with a balloon-tipped catheter residing the lateral ventricles. Results: 1) Deep hypothermic circulatory arrest for aortic arch surgery provides superb brain protection for periods up to 45 minutes or longer. Clinical neurologic function, and quantitative neurologic tests, show excellent brain preservation. 2) The novel spinal cooling catheter provides excellent cooling of the spinal cord in a large animal model, without apparent injury of any type. 3) The intraventricular brain cooling catheter provides excellent cooling of the brain, documented by both direct temperature probe and high-tech brain imaging. Conclusions: We wish herein (in this article) to share this experience across our disciplines (Cardiac Surgery and Neurology). We welcome advice from the Neurology community on these surgically-directed methods for cooling and protection of neurological tissue in both the brain and the spinal cord.

The Geochemical Characteristics and Minerogenic Model for the Amo Hypothermal Tin Deposit in Ximeng County, Yunnan Province

Through studies on the element geochemistry, alteration of country rocks, ore-forming fluids and isotopegeochemistry of the Arno tin deposit in the metamorphic rocks of the Upper Proterozoic Ximeng Group, theauthors consider that the concentration of the B-F-Li-Rb-Cs-Sn association is related to acidic magmatism inthe study area. The Fe-Mg-Li tourmaline in the ore is the replaced product of the country rocks byhypothermal fluid. The δ^(18)O values of mineral separates are +2.01- +13.16‰ and their δ^(34)S values, +2.6-+7.2‰. The ore-forming materials were derived from hydrothermal fluid of granitic magma. For themineralization, the temperature is 450°-350℃, the pressure, 450-1000×10~5 Pa, and the age, Himalayan(21.5 Ma). According to the geochemical characteristics, a minerogenic model is established: the deposit is ahypothermal cassiterite-quartz vein type tin deposit controlled by the hidden Himalayan granites.

Low-Flow Polysulfone Hemodialysis Alters Lipoprotein Parameters, Paraoxonase Activity and <i>in Vitro</i>Incorporation of Phospholipids

End stage-renal-disease (ESRD) is associated with dyslipidemia and premature atherosclerosis. The study evaluates the effect of hemodialysis (HD) on HDL-remodeling between pre- and post-HD. Was conducted a cross-sectional study with 50 ESRD male patients, undergoing HD at Ana Neri Hospital, Salvador, Brazil. All individuals were on HD for at least 3 months, into a three sessions protocol for 3 - 4 hours per week, with a polysulfone low-flow basic-dialyzing-membrane and unfractionated-heparin. HDL Phospholipid-incorporation was measured by 14C-PL-scintillation-counting, expressed as %14C-PL/mL/hour. Paraoxonase (PON-1) activity was measured by spectrophotometry using paraoxon as substrate. Cardiovascular risk ratios and atherogenic index of plasma were calculated. Total cholesterol, HDL-C and non-HDL-C increased at post-HD on all age groups, but without triglycerides (TG) changes. TG/HDL-C decreased in 30 - 39 and 40 - 49 year (y) at post-HD (p 0.05). LDL-C/apoB increased in >60 y, after HD (p < 0.05). HDL-C/apo-AI increased in 40 - 49 y (p 0.05) and >60 (p 0.01). On the other hand, non-HDL-C/HDL-C reduced in 40 - 49 and >60 y, at post-HD (p 0.05). The linear-correlation between %14C-PL-incorporation and non-HDL-C/HDL-C was negative in 30 - 39 y, both at pre-HD (r = -0.90;p = 0.002) and post-HD (r = -0.78;p = 0.022). Linear-correlation between PON-1 and %14C-PL-incorporation was positive in >60 y, both at pre- (r = 0.63;p = 0.029) and post-HD (r = 0.65;p = 0.022). PON-1 activity increased at pre- (59 ± 30) and post-HD (73 ± 38) in 50 - 59 y (p 0.05). The %14C-PL-incorporation was reduced in >60 y (p 0.05), when compared to pre- and post-HD. ESRD patients undergoing HD shows important changes on lipid-profile, PON-1-activity, cardiac risk ratios and HDL-remodeling. These results demonstrate the influence of HD with a polysulfone low-flow basic-dialyzing-membrane and unfractionated-heparin on lipoprotein metabolism.

深低温停循环发展历史与脑保护策略研究进展

深低温停循环将体外循环与低温保护相结合是体外循环发展过程中的一项里程碑式技术。此技术应用于临床以来,已成为心脏大血管外科手术中必不可少的干预方式。因此,本文就其发展历史及其脑保护策略作一综述,为这一技术更好的应用于临床和未来研究提供参考。

循环旁路技术在肾癌合并下腔静脉癌栓外科治疗中的应用进展

肾细胞癌(renal cell carcinoma,RCC)合并MayoⅢ~Ⅳ级下腔静脉癌栓的外科治疗难度极高,切除此类癌栓常需阻断肝门血管和下腔静脉。体外循环(cardiopulmonary bypass,CPB)和深低温停循环(deep hypothermic circulatory arrest,DHCA)等循环旁路技术能够建立新的循环通路以维持机体循环系统的正常运转,保护机体重要器官,从而保证手术的安全性。使用CPB和DHCA可能出现出血、神经系统功能障碍等并发症,其应用存在一定局限性。本文对以CPB和DHCA为代表的循环旁路技术在肾癌合并下腔静脉癌栓外科治疗中的应用进展进行综述,并讨论其并发症和应对策略。

中国遗体器官捐献供肾体外低温机械灌注保存指南

为促进遗体器官捐献供肾体外低温机械灌注保存技术的规范应用,中华医学会器官移植学分会组织制定了《中国遗体器官捐献供肾体外低温机械灌注保存指南》。该指南整合了肾脏移植学和遗体器官捐献学领域的专家共识,依据现有的临床指南、系统评价、病例研究、专家共识等资料,并结合近年国内外遗体器官捐献供肾体外低温机械灌注保存技术的临床问题。在多次专家研讨和达成一致意见后,完成了该指南的撰写。该指南共包含11个临床问题,14条推荐意见,并按照2009版牛津大学循证医学中心的证据分级与推荐强度标准,对每个临床问题的推荐意见强度与证据级别进行了分级。该指南旨在为临床实践提供指导,提高我国遗体器官捐献供肾保存水平,减少器官弃用率,缓解器官短缺问题。

低温氧合机器灌注在扩展标准供体肝移植中的机制及优势

近年来,由于肝移植供体的短缺问题日益突出,越来越多的机构开始采用扩展标准供体(ECD)的肝脏进行移植,然而,ECD肝脏移植术后并发症发生率较高且预后较差。低温氧合机器灌注(HOPE)作为一种肝移植供体的保存方式,被认为可改善移植患者预后,特别是对于ECD肝脏。HOPE的主要机制包括减轻线粒体损伤、氧化应激损伤、炎症及下调免疫应答。相较于其他灌注方式,HOPE可保护移植物的功能,延长肝脏的保存时间,并减少术后并发症。然而,尽管HOPE在临床上具有许多优势,但其应用仍处于探索阶段,且因其高昂的经济成本使其广泛开展受到限制,未来还需进一步的研究来充分体现和发挥HOPE的临床作用,使其更好地应用于临床。

温度对真空包装大蒜贮藏品质的影响

为探究温度对真空包装大蒜贮藏保鲜效果的影响,以天津宝坻大蒜为实验材料,分别设置了不同温度(0℃、4℃、常温)结合真空包装处理实验组和对照组进行贮存,每7 d进行一次取样,通过测定大蒜贮藏期间失重率、色差、紧实度、硬度、脆性、水分含量等指标,研究不同温度条件结合真空包装对天津宝坻大蒜贮藏品质的影响。结果表明:整个贮藏期间,低温(0℃、4℃)结合真空包装处理大蒜失重率保持较好,仅为0.09%和0.48%;贮藏36 d后,低温(0℃、4℃)结合真空包装处理大蒜的色差值较小,仅为5.589和5.928;低温(0℃、4℃)结合真空包装处理可有效降低大蒜失重率,抑制其腐烂变质,维持其原有色差、紧实度、硬度和脆性,减少水分流失。其中真空包装大蒜在0℃贮藏保鲜效果最好,能显著提高大蒜货架期。

Prevascularized spongy-like hydrogels maintain their angiogenic potential after prolonged hypothermic storage

The chronic shortage of organs and tissues for transplantation represents a dramatic burden on healthcare systems worldwide.Tissue engineering offers a potential solution to address these shortages,but several challenges remain,with prevascularization being a critical factor for in vivo survival and integration of tissue engineering products.Concurrently,a different challenge hindering the clinical implementation of such products,regards their efficient preservation from the fabrication site to the bedside.Hypothermia has emerged as a potential solution for this issue due to its milder effects on biologic systems in comparison with other cold preservation methodologies.Its impact on prevascularization,however,has not been well studied.In this work,3D prevascularized constructs were fabricated using adipose-derived stromal vascular fraction cells and preserved at 4◦C using Hypothermosol or basal culture media(α-MEM).Hypothermosol efficiently preserved the structural and cellular integrity of prevascular networks as compared to constructs before preservation.In contrast,the use ofα-MEM led to a clear reduction in prevascular structures,with concurrent induction of high levels of apoptosis and autophagy at the cellular level.In vivo evaluation using a chorioallantoic membrane model demonstrated that,in opposition toα-MEM,Hypothermosol preservation retained the angiogenic potential of constructs before preservation by recruiting a similar number of blood vessels from the host and presenting similar integration with host tissue.These results emphasize the need of studying the impact of preservation techniques on key properties of tissue engineering constructs such as prevascularization,in order to validate and streamline their clinical application.