海藻糖深低温保存外周血造血干细胞的可行性

背景:二甲基亚砜是目前造血干细胞深低温保存的经典保护剂,但其对细胞和患者均有一定的毒副作用。海藻糖是一种稳定的无毒副作用的非还原性双糖,已被广泛应用于红细胞、血小板和胚胎等的冷冻保存中。目的:探讨海藻糖作为低温保存造血干细胞保护剂的可行性。方法:外周血造血干细胞经重组人集落刺激因子动员后,用血细胞分离机采集连续单个核细胞,分为0.5mol/L海藻糖组、1.0mol/L海藻糖组、对照组。采用程序降温法液氮保存,冻存7d后取出,立即置于40℃水浴箱内复苏。锥虫蓝拒染法检测细胞存活率;采用甲基纤维素半固体培养体系进行集落培养,计数粒-巨噬细胞集落形成单位的回收率;采用CD34-PE/CD45-FITC双标法,流式细胞仪检测CD34+细胞回收率。结果与结论:与对照组比较,0.5,1.0mol/L海藻糖组细胞存活率、粒-巨噬细胞集落形成单位回收率、CD34+细胞回收率均明显升高(P0.001),且0.5mol/L海藻糖组升高幅度尤为显著(P0.001或P0.01)。证实海藻糖对于短期内低温冻存的外周血造血干细胞有一定保护作用,浓度为0.5mol/L的海藻糖保护冻存的造血干细胞效果较佳。     

肝细胞低温保存的实验研究

在传统的冻存剂配方的基础上,通过降低DMSO的浓度并且添加不同浓度的葡萄糖、蔗糖或海藻糖,探索一种改善人肝细胞冻存效果的新冻存保护剂配方.在传统的冻存保护剂配方中,将DMSO的浓度降低至2% v/v或5%v/v,加人葡萄糖、蔗糖或海藻糖;两周后将肝细胞快速复温,进行存活率、24 h贴壁率和形态学的检测,并与10%DMSO对照,其中5%DMSO+0.3 mol/mL海藻糖组效果最好,复温后肝细胞的存活率、24 h贴壁率均优于其它冻存液组.结果表明,葡萄糖、蔗糖、海藻糖均对人肝的低温保存有一定的保护作用,5% DMSO+0.3 mol/mL海藻糖组是其中最好的浓度配方;海藻糖与DMSO联合使用降低了冻存保护剂DMSO的浓度,表明两者有协同作用.     

不同冷冻方法对人卵巢组织血管内皮生长因子表达及血管生成的影响

背景:人卵巢组织冷冻已成为一种保存生育能力的手段,卵巢组织移植后必须经过血管重建过程才能恢复血供,冷冻保存和复苏技术是影响移植后卵巢组织血管重建的关键。目的:比较新型玻璃化冷冻和慢速冷冻后人卵巢组织血管内皮生长因子表达情况及微血管密度,探讨不同冷冻方法对人卵巢组织血管重建的影响。方法:8份卵巢组织标本取自子宫内膜癌患者手术切除的正常卵巢组织,将每份卵巢皮质切成1.5mm×1.5mm×1.0mm大小的组织块共12块后,随机数字表法分为3组:对照组(新鲜组)、新型玻璃化冷冻组和慢速冷冻组。将新型玻璃化冷冻组卵巢组织块依次在含体积分数7.5%乙二醇+体积分数7.5%二甲基亚砜+体积分数20%胎牛血清的TCM-199培养液和含体积分数15%乙二醇+体积分数15%二甲基亚砜+0.5mol/L蔗糖的TCM-199培养液中平衡脱水,然后直接浸入液氮并装入冷冻管保存,解冻时按浓度梯度1.0,0.5,0.25mol/L蔗糖和含体积分数20%牛血清的TCM-199培养液依次洗脱冷冻保护剂。将慢速冷冻组人卵巢组织块放入盛有1mL冷冻液(含1.5mol/L二甲基亚砜+体积分数20%牛血清+0.1mol/L蔗糖的TCM-199培养液)的1.8mL冷冻管内平衡,然后放入程序冷冻仪中按设定程序进行冷冻。解冻时按浓度梯度1.0mol/L二甲基亚砜+0.1mol/L蔗糖、0.5mol/L二甲基亚砜+0.1mol/L蔗糖、0.25mol/L二甲基亚砜+0.1mol/L蔗糖和0.1mol/L蔗糖依次洗脱冷冻保护剂。冻融组及对照组均进行体外培养。免疫组织化学观察培养0,2,4,6d各组人卵巢组织血管内皮生长因子和CD34表达情况,并进行微血管计数。结果与结论:3组人卵巢组织培养前后间质细胞中均见血管内皮生长因子成斑片状弱表达,培养2d血管内皮生长因子表达均增加并达到峰值,培养4d均开始减弱,6d时进一步减弱;与慢速冷冻组相比,新型玻璃化冷冻组血管内皮生长因子表达更接近对照组。3组人卵巢组织培养2d微血管密度均增加并达到峰值,对照组和新型玻璃化冷冻组明显高于慢速冷冻组(P0.05);慢速冷冻组培养4d时微血管密度较培养2d时显著下降(P0.05);3组培养6d时微血管密度较培养2d时显著下降(P0.05)。与慢速冷冻法相比,新型玻璃化冷冻法能更好地保存人卵巢组织间质细胞和细胞外基质,对卵巢组织血管内皮生长因子表达及微血管生成的影响更少。     

不同冷冻保护剂对低温冰箱转液氮阶梯降温冷冻保存造血干细胞效果的影响

背景：非程序降温-80 ℃低温冰箱保存方便快捷,程序降温-196 ℃液氮保存可靠长久,将两者合二为一简化流程已成功用于临床。 目的：观察不同冷冻保护剂对-80 ℃低温冰箱转液氮阶梯降温冷冻保存造血干细胞效果的影响。 方法：分设10%二甲亚砜组、5%二甲亚砜联合3%羟乙基淀粉组、5%二甲亚砜联合0.25 mol/L海藻糖组、5%二甲亚砜联合3%羟乙基淀粉及0.25 mol/L海藻糖组。采用  -80 ℃低温冰箱转液氮阶梯降温法对单采外周造血干细胞进行冷冻保存,通过透射电镜观察细胞超微结构变化,流式细胞仪观察Annexin-V、PI、Caspase-3水平。 结果与结论：4组冷冻保存细胞的存活率、凋亡率和死亡率差异均无显著性意义(P > 0.05)。透射电镜下各组细胞超微结构变化差异不明显。单个核细胞群落冷冻保存后存活率在90%以上,含成熟细胞较多的CD45⁺细胞群落凋亡发生率可达50%左右。造血干祖细胞群落中,早期细胞较晚期细胞更能耐受冷冻损伤。提示在基础冷冻保护剂二甲亚砜的基础上,加入羟乙基淀粉和海藻糖并未显示出对冷冻保存效果的增强作用。     

不同低温保护剂对皮肤组织β1整合素表达影响的比较

目的比较两种不同低温保护剂对皮肤组织β1 integrin低温保存后表达的影响，为寻求皮肤组织低温保护剂的最佳配方提供试验依据。方法获取新鲜成人皮肤组织分为3组．新鲜对照组、海藻糖／二甲基亚砜（T／D）组、二甲基亚砜／丙二醇（D／P）作为低温保护剂保存组，-196℃液氮冻存7d、14d复温，免疫组织化学染色对各组间皮肤进行比较。并在此基础上，进一步采用RT-PCR方法对不同低温保护剂保存后皮肤的β1 integrin基因水平进行了深入的研究。结果通过光镜图象观察和基因水平分析结果说明，0．5M海藻糖／二甲基亚砜能够很好保护皮肤组织，β1 integrin的基因表达量与新鲜皮肤组相似。结论海藻糖与二甲基亚砜联合应用对皮肤组织β1 integrin的保护作用优于传统组。     

人胎脑神经干细胞来源少突胶质前体细胞冻存方法的优化

目的通过改变不同因素条件优化人胎脑神经干细胞来源的少突胶质前体细胞(OPC)冻存方法,进一步提高复苏活率。方法比较使用消化和机械吹打两种方法收集人OPC,采用人多能干细胞(hPSC)无血清冻存液、含930 mL/L胎牛血清(FBS)和70 mL/L二甲基亚砜(DMSO)的冻存液分别冻存细胞,比较两组冻存前后活率。择优后比较4种不同冻存液(含70 mL/L DMSO和930 mL/L FBS的冻存液,含70 mL/L DMSO、 300 mL/L FBS的OPC完全培养基,含70 mL/L DMSO、 300 mL/L FBS、 0.2 mol/mL海藻糖的OPC完全培养基,含70 mL/L DMSO、 100 mL/L FBS、 300 mL/L羟乙基淀粉溶液的OPC完全培养基)、冻存速率(冻存盒慢速降温和液氮气相快速降温)及冷冻保存时间3个因素对复苏活率的影响。在优选后的冻存方案基础上,复苏后7 d,使用免疫荧光细胞化学染色法比较OPC特异性标志物血小板源性生长因子受体α(PDGFRα)、 ST8α-N-乙酰神经酰胺α2, 8-唾液酸转移酶1(ST8SIA1/A2B5)、硫酸软骨素蛋白聚糖4(CSPG4/NG2)、增殖相关KI-67抗原(ki67)表达。结果消化组收集细胞,冻存前后活率明显高于机械组;快速降温4组复苏活率均低于30%且无法继续培养,慢速降温4组复苏活率均较高。使用消化法收集细胞,冻存细胞数为2×10~6/mL;使用含海藻糖的冻存液,慢速降温冻存,复苏活率最高;可达(75.73±6.66)%。与对照组相比,复苏后培养组增殖倍数、 ki67表达无明显差异,两组均表达PDGFRα、 A2B5、 NG2。短期和长期储存组复苏活率无明显差别。结论消化液收集OPC,使用含海藻糖的冻存液慢冻快融的方法,适用于人胎脑神经干细胞诱导OPC冷冻保存,复苏后不影响细胞增殖和标志物表达,储存时间对复苏活率无影响。     

血管冷冻保护剂的临床应用

背景：冷冻保存的同种异体血管在血管移植修复中蕴藏着广泛的临床应用前景。深低温冻存是实现同种异体血管长期保存的常用方法。在低温保存过程中,有效的冷冻保护剂对于防止血管组织低温损伤和保持细胞活力至关重要,但对于最佳保护剂的选择并未达成共识。目的：总结近年来各大血管组织库中使用的冷冻保护剂,比较其临床应用效果,以期为将来深低温冻存同种异体血管的应用提供参考。方法：由第一作者检索中国知网、万方、PubMed和Google Scholar数据库2015-2022年发表的相关文献,中文检索词为“同种异体血管,动脉,静脉,深低温冻存,冷冻保护剂,冷冻损伤,血管移植”,英文检索关键词为“cryopreservation,blood vessels,vascular allografts,arteries,veins,cryoinjury,cryoprotectants,cryoprotective agents”,检索国内外有关应用于临床的血管冷冻保护剂及其近远期结果的相关文献,最终选取54篇文献进行综述。结果与结论：(1)在血管的深低温冻存研究中,常使用包含渗透性和非渗透性的冷冻保护剂组合,通过程序...     

微囊牛肾上腺髓质细胞的冻存及其活性评价

目的　建立一种微囊牛肾上腺髓质细胞 (bovinechromaffincell,BCC)的冻存方法 ,为临床推广微囊人工生物细胞技术移植异种细胞奠定基础。方法　微囊化牛肾上腺髓质细胞冻存以二甲基亚砜为保护剂 ,循序缓慢降温 (4℃ ,1h ,- 2 0℃ 2h ,- 5 0℃过夜 ,液氮 ) ,复苏时迅速将冻存管放入 37℃水浴中。通过检测其基础儿茶酚胺分泌量和在高钾 (5 8mmol/L)、乙酰胆碱 (10 -4mol/L)刺激下的分泌量来观察其功能活性。结果　冻存复苏后微囊BCC保留了儿茶酚胺的分泌功能 ,基础与刺激分泌量分别为 (3.2 0 7± 0 .35 0 )ng/ml和 (12 .4 96± 2 .30 2 )ng/ml,大约为冻存前微囊牛肾上腺髓质细胞分泌量的 80 % ;同时刺激后儿茶酚胺分泌增加 (P <0 .0 1)。结论　建立一种微囊牛肾上腺髓质细胞的冻存方法 ,通过功能检测证明该方法是有效和成功的     

液氮冻存人同种心脏瓣膜和大动脉免疫原性的对比

目的进行液氮冻存人同种带瓣主、肺动脉(CVH)瓣叶、动脉壁和瓣下心肌组织的免疫原性对比研究。方法采用CVH瓣叶、动脉壁的单细胞悬液分别与相同血型受体的淋巴细胞混合培养法,检测混合培养后不同时点CD25、HLA-DR的表达;并与单纯淋巴细胞培养组(对照组)进行对比研究。结果CVH动脉壁的免疫原性较其瓣叶强,表现为CD25、HLA-DR高水平表达;未能获得CVH瓣下心肌的细胞悬液。结论液氮冻存人CVH动脉壁的免疫原性较其瓣叶的免疫原性强。     

玻璃化冷冻法保存关节软骨

背景：同种异体骨软骨移植技术是治疗关节软骨缺损有效的方法之一,但由于移植物保存方法不理想,明显制约着该技术的临床应用。 目的：探讨玻璃化冷冻法保存关节软骨组织的可行性和优越性。 方法：切取成年猪骨软骨,制成约5 mm×6 mm(直径×长度)大小的圆柱形骨软骨块。以新鲜软骨组为对照,分别采用0.5 mol/L甘油 、1 mol/L二甲基亚砜、1 mol/L玻璃化溶液3种方法预处理软骨块,再行冷冻法保存软骨块8周,采用组织化学染色、免疫荧光染色观察并比较软骨细胞活性的变化。 结果与结论：玻璃化溶液预处理组的关节软骨细胞存活率达到74.5%,明显高于甘油和二甲基亚砜预处理组,软骨基质成分仅少量丢失。3种方法相比较,玻璃化溶液预处理后慢速梯度降温冷冻保存法可以明显提高冻存关节软骨组织的活性。     

海藻糖对低温保存胸骨中bcl-2和bax基因表达的影响

背景:研究已经证实海藻糖对低温保存中的胸骨具有保护作用,但作用途径尚不清楚。 目的：观察海藻糖对低温保存胸骨bcl-2和bax基因表达的影响。 方法：新鲜配置4组保存液：低钾右旋糖酐组、低钾右旋糖酐+二甲基亚砜组、低钾右旋糖酐＋海藻糖组、低钾右旋糖酐＋二甲基亚砜组＋海藻糖组。切取SD大鼠胸骨后立即分别放入含上述4 种溶液的冻存管中低温保存。抽取新鲜大鼠胸骨组织和低温保存120 d的4组标本,采用RT-PCR方法检测不同保存液保存的胸骨及新鲜胸骨bcl-2和bax基因mRNA表达量。 结果与结论：低钾右旋糖酐+海藻糖组bcl-2表达量高于低钾右旋糖酐组、低钾右旋糖酐+二甲基亚砜组(P < 0.01),但bax表达量低于低钾右旋糖酐组、低钾右旋糖酐+二甲基亚砜组(P < 0.01);低钾右旋糖酐+二甲基亚砜组+海藻糖组bcl-2表达量最高,bax表达量最低,基本接近新鲜骨组织(P > 0.05)。结果提示海藻糖可能通过增强bcl-2基因、抑制bax基因的表达保护低温保存中的胸骨细胞活性,其与二甲基亚砜合用保护作用更好。     

Cryopreservation of human granulocytes in liquid nitrogen.

Human granulocytes (PMNL) were successfully cryopreserved for up to 14 months. The PMNL (1-2 X 10(7)/ml) were stored in 2-ml ampoules in the gas phase of liquid nitrogen at a temperature between -160 degrees C and -196 degrees C using dimethylsulphoxide (DMSO 10%) as cryoprotectant. Morphology and phagocytic and bactericidal capacity were best preserved by adding fetal calf serum to the freezing mixture, by using an interrupted cooling process, by washing the thawed PMNL in fresh freeze-dried plasma, and centrifuging at 600 g for no more than two minutes. Careful post-thaw handling of the cells was an important factor in preserving function. These preliminary studies indicate that useful numbers of PMNL can be recovered in a functional state after storage for long periods in liquid nitrogen.     

超低温冰箱转液氮阶梯降温法与传统程序降温法保存造血干细胞的比较

背景：在造血干细胞整个冷冻保存过程中,受到降温速率、储存温度深浅、冷冻保护剂组合等因素影响,各国学者在提倡选择何种保存方法上面存在不同的主张。 目的：比较-80 ℃低温冰箱转液氮阶梯降温法与传统程序降温法保存外周造血干细胞的效果。 方法：将采集的造血干细胞分两组,第一组细胞浓度为1×10¹¹ L^-1,加入10%二甲基亚砜,放入程序冷冻仪内程序设置为室温至-4 ℃按1 ℃/min的速率降温,按35 ℃/min快速降至-45 ℃,再以15 ℃/min升至-21 ℃,然后以5 ℃/min降至-90 ℃,取出冷冻管置-196 ℃液氮罐内。第二组细胞浓度为1×10¹¹ L^-1,加入5%二甲基亚砜、3%羟乙基淀粉、4%人血白蛋白,将冷冻管置-80 ℃冰箱过夜后取出,置-196 ℃液氮罐内的气相,再过夜后置液氮罐液相内。 结果与结论：两组冷冻方法保存细胞的锥虫蓝拒染率、回收率、凋亡率和死亡率差异无显著性意义(P > 0.05)。结果显示用5%二甲基亚砜、4%白蛋白、3%羟乙基淀粉组成的冷冻保护剂,通过-80 ℃低温冰箱转液氮阶梯降温法冷冻保存造血干细胞与传统10%二甲基亚砜作为冷冻保护剂用程序降温的方法取得一样效果,操作简便易于临床应用。     

Efficient cryopreservation protocol enables accessibility of a broad range of ammonia-oxidizing bacteria for the scientific community

Long-term storage of the fastidious ammonia-oxidizing bacteria has proven difficult, which limits their public availability and results in a loss of cultured biodiversity. To enable their accessibility to the scientific community, an effective protocol for cryopreservation of ammonia-oxidizing cultures at ?80 °C and in liquid nitrogen was developed. Long-term storage could be achieved using 5% DMSO as cryoprotectant, preferably in a cryoprotective preservation medium containing tenfold-diluted trypticase soy broth and 1% trehalose. As such, successful activity and growth recovery was observed for a diverse set of ammonia-oxidizing cultures.     

Effect of cryoprotectants and their concentration on post-thaw survival and development of rapid frozen-thawed pronudear stage mouse embryos

Experiments have been conducted to develop a simple rapid-freezingprotocol for pronudear stage mouse embryos. The effect of typeof cryoprotectant (dimethyl-sulphoxide (DMSO) or 1,2-propanediol(PROH)) and concentration (ranging from 3.5 to 8.0 mol/1 with0.5 mol/1 sucrose) on the post-thaw morphological survival rate,on cleavage rate and on development to the blastocyst stagewere studied. Further, in-vivo viability of embryos frozen usingthe most effective cryoprotectant concentration (PROH at 7.0mol/1) was compared with viability of non-frozen embryos. Thetype of cryoprotectant and its concentration influenced thesurvival and development of embryos to the blastocyst stagein vitro. The best development with PROH was achieved at 7.0mol/1 (66%, 128/193), whereas with DMSO the best developmentwas achieved at 6.0 mol/1 (42%, 71/171). The rates of survivaland cleavage did not differ between the two best cryoprotectantconcentrations (P > 0.01) but the proportion of embryos whichdeveloped to blastocyst was higher (P > 0.001) with PROHat 7.0 mol/1 compared with DMSO at 6.0 mol/1. The rates of survivaland development were higher (P < 0.001) with DMSO at 3.5and 6.0 mol/1 compared with similar concentrations of PROH.The cleavage and development, however, was higher (P < 0.001)at 7.0 mol/1 PROH compared with the same concentration of DMSO.At 8.0 mol/1 the survival and development was not different(P > 0.01) between DMSO and PROH. The rate of implantationand the percentage of live fetuses at autopsy of the recipientsreceiving non-frozen embryos was higher (63 and 41% respectively)than in those receiving frozen–thawed embryos (53 and37% respectively), but not significantly different. It may beconcluded that the concentration range of cryoprotectants whichallows acceptable embryo viability after freezing and thawingis very narrow. The rapid protocol using dehydration in 0.25mol/1 and 0.5 mol/1 sucrose followed by exposure to 7.0 mol/1PROH and 0.5 mol/1 sucrose for 45 s was the most effective forcryopreservation of pronudear stage mouse embryos.     

Human oocyte cryopreservation as an adjunct to IVF-embryo transfer cycles

BACKGROUND: The purpose of this work was to develop methods for successful cryopreservation of human oocytes. METHODS: Two cryopreservation procedures were used. Method 1 involved use of 1.5 mol/l propanediol (PrOH)-0.1 mol/l sucrose with medium containing sodium (Na) as cryoprotectant medium, seeding at -7 degrees C, and stepwise dilution of cryoprotectant post-thaw. Method 2 used Na-depleted media with 1.5 mol/l PrOH-0.2 mol/l sucrose for freezing, seeding at -6 degrees C, and use of high sucrose (0.5 and 0.2 mol/l) for cryoprotectant removal. RESULTS: The first method was used in seven patients, and gave poor (12.3%) survival results and no pregnancies. The second method was used in 15 patients (16 cycles), and yielded good survival and fertilization rates (74.4 and 59% respectively), with four pregnancies and five healthy infants born to 11 women receiving an embryo transfer. CONCLUSIONS: Using Na-depleted media along with other alterations in freezing and thawing procedures, human oocyte cryopreservation can provide excellent survival and pregnancy rates.     

Cryopreservation of stem cells using trehalose: evaluation of the method using a human hematopoietic cell line

While stem cell cryopreservation methods have been optimized using dimethylsulfoxide (DMSO), the established techniques are not optimal when applied to unfertilized human embryonic cells. In addition, important questions remain regarding the toxicity and characteristics of DMSO for treatment of stem cells for clinical use. The objective of this study was to establish an optimal method for cryopreservation of stem cells using low concentrations (0.2 M) of trehalose, a nontoxic disaccharide of glucose, which possesses excellent protective characteristics, in place of current methods utilizing high concentrations (1-2 M) of DMSO. A human hematopoietic cell line was used in this investigation as a surrogate for human stem cells. Trehalose was loaded into cells using a genetically engineered mutant of the pore-forming protein alpha-hemolysin from Staphylococcus aureus. This method results in a nonselective pore equipped with a metal-actuated switch that is sensitive to extracellular zinc concentrations, thus permitting controlled loading of trehalose. Preliminary experiments characterized the effects of poration on TF-1 cells and established optimal conditions for trehalose loading and cell survival. TF-1 cells were frozen at 1 degrees C/min to -80 degrees C with and without intra- and extracellular trehalose. Following storage at -80 degrees C for 1 week, cells were thawed and evaluated for viability, differentiation capacity, and clonogenic activity in comparison to cells frozen with DMSO. Predictably, cells frozen without any protective agent did not survive freezing. Colony-forming units (CFU) generated from cells frozen with intra- and extracellular trehalose, however, were comparable in size, morphology, and number to those generated by cells frozen in DMSO. There was no observable alteration in phenotypic markers of differentiation in either trehalose- or DMSO-treated cells. These data demonstrate that low concentrations of trehalose can protect hematopoietic progenitors from freezing injury and support the concept that trehalose may be useful for freezing embryonic stem cells and other primitive stem cells for therapeutic and investigational use.     

Effect of freezing rate and exposure time to cryoprotectant on the development of mouse pronuclear stage embryos.

BACKGROUND: The effects of exposure time (20 versus 45 s) to a high concentration of cryoprotectant (7.0 mol/l ethylene glycol with 0.5 mol/l sucrose) and freezing rates (1200-10 300 degrees C/min) during rapid freezing of mouse pronuclear stage embryos on survival and development to blastocysts were investigated. Different freezing rates were achieved by directly plunging the straws (rapid freezing) and open pulled straws (OPS) in liquid nitrogen (OPS freezing) and by plunging the straws (super rapid) and OPS (super OPS) in a super cooled liquid nitrogen chamber (at -212 degrees C) before storage in liquid nitrogen. METHODS: Morphologically intact mouse zygotes (n = 891) pre-equilibrated in 1.5 mol/l ethylene glycol for 5 min were either loaded in 0.25 ml straws containing cryoprotectant or loaded in OPS with 2 microl cryoprotectant. After 20 or 45 s of loading the straws or mixing in cryoprotectant and loading in OPS, they were plunged either directly in to liquid nitrogen or were plunged first in to liquid nitrogen in a super cooled chamber and then stored in liquid nitrogen. Zygotes were thawed and intact embryos cultured in vitro. RESULTS: The rate of survival was higher (91%, P < 0.01) when zygotes were frozen with rapid freezing compared with super rapid, OPS and super OPS freezing rates with an exposure time of 20 s (70, 65, and 76% respectively). When zygotes were exposed to cryoprotectant for 45 s and frozen with rapid freezing rates, the survival was higher (86%, P < 0.01) compared with those frozen with OPS (62%) but was not different from those frozen with super rapid and super OPS freezing rates (81 and 75%). A higher rate of survival was observed when zygotes were exposed to cryoprotectant for 45 s and frozen with super OPS than with OPS freezing (75 versus 62%; P < 0.05). The rate of cleavage and development of intact zygotes to blastocysts was not different among the different groups. CONCLUSION: Exposure of zygotes to a high concentration of cryoprotectant (7.0 mol/l ethylene glycol with 0.5 mol/l sucrose) for 20 or 45 s did not influence their survival and development and increasing the freezing rate from 1200-10 300 degrees C/min was of no advantage when using a rapid freezing procedure for freezing mouse pronuclear stage embryos.     

玻璃化保存肌腱的生物力学观察

目的探讨玻璃化保存法对兔肌腱力学性能的影响。方法玻璃化保存组，6条新鲜胫前肌肌腱，以18．64％二甲基亚砜＋13.37％乙酰胺＋9．17％1．2丙二醇＋浓度0．10mmol／L海藻糖＋10％小牛血清为玻璃化冷冻保护剂．将新西兰纯种大白兔肌腱采用三步法预处理．-196℃液氮保存14d；“两步法”深低温冷冻保存组，6条新鲜胫前肌肌腱，以15％二甲基亚砜＋10％小牛血清作为冷冻保护剂，“两步法”处理后-196℃液氮冷冻保存14d；对照组．6条新鲜新西兰纯种大白兔胫前肌肌腱。分别进行肌腱拉伸实验．检测肌腱破坏载荷峰值、最大载荷拉伸位移及杨氏弹性模量。结果肌腱破坏荷载峰值：新鲜肌腱组与玻璃化保存组及“两步法”深低温冷冻保存组间差异均有统计学意义（P=0．002），玻璃化保存组与“两步法”深低温冷冻保存组无统计学意义（P=0．256）；最大载荷拉伸位移：新鲜肌腱组与玻璃化保存组及“两步法”深低温冷冻保存组3组间均无统计学意义（P=0．065）；杨氏弹性模量：新鲜肌腱组与玻璃化保存组及“两步法”深低温冷冻保存组间差异均有统计学意义（P=0．006）．玻璃化保存组与“两步法”深低温冷冻保存组差异无统计学意义（P=0．577）。结论玻璃化保存法保存肌腱具有良好的发展前景。