一种快速分离纯化小鼠胰岛的方法

目的 介绍一种快速分离纯化小鼠胰岛的方法及进行纯化后胰岛的活性、完整性和胰岛内结构的质量分析.方法 雄性ICR小鼠,采用2 mg/mL胶原酶V灌注和消化,并用Hanks液快速洗涤,用Histopaque（R）-1077和Histopaque（R）-1119密度梯度离心对胰岛进行纯化,用手工方法进行胰岛挑选,DTZ、FD-PI染色鉴定胰岛纯度及其活性,透射电镜观察胰岛内的结构.结果 胰岛开始消化至手工挑选前过程耗时＜ 25 min,每只小鼠得到胰岛数量为：128±36,当量为：145±42,纯度＞90％.透射电镜显示胰岛内部血管仍有损伤.结论 采用此方法可快速得到数量较多、结构较完整的小鼠胰岛,且活性高,为进一步进行胰岛的体外质量研究及体内移植奠定了基础.     

大豆胰蛋白酶抑制剂对大鼠胰岛分离纯化的影响

目的探讨大豆胰蛋白酶抑制剂（STI）在大鼠胰岛分离纯化中对胰岛产量及功能的影响。方法按胶原酶中是否加入STI将大鼠分为实验组和对照组，实验组在胶原酶消化液中按2．0mg／ml加入STI，对照组不添加STI。2组均运用胶原酶原位灌注大鼠胰腺的方法来分离胰岛，使用Ficoll-400用非连续梯度离心法纯化胰岛，将纯化前、后获得的胰岛进行计数，并对纯化后的胰岛进行形态、功能检查。同时进行大鼠同种异体胰岛移植观察其体内功能。结果实验组和对照组在消化后纯化前所得胰岛数量无明显差别[（624±38．2）IEQVS（586±37．7）IEQ，P〉0．053；在纯化后实验组与对照组所得胰岛数量[（408±28．3）IEQVS（189±27．1）IEQ，P〈0．05]和纯度[（93±2．4）％VS（75±2．1）％，P〈0．05；差异有统计学意义。实验组与对照组最终所得胰岛的体外功能差异无统计学意义（P〉0．05），体内功能实验结果差异亦无统计学意义（P〉0．05）。结论使用在胶原酶中加入STI的消化液原位灌注大鼠胰腺，可以明显提高大鼠胰岛的最终产量和纯度，但对胰岛的功能无明显影响。     

几种小鼠胰岛的分离纯化方法比较

目的探讨几种小鼠胰岛的分离纯化方法及进行纯化后胰岛的计数和完整性的分析。方法选用ICR小鼠,采用不同胶原酶消化方法和不同的胶原酶种类,并用Ficoll-PaqueTMPLUS密度梯度离心法对胰岛进行纯化,并对获得的胰岛进行DTZ染色计数和计算当量,扫描电镜考察胰岛的完整性。结果采用胶原酶V和P胰管灌注、内外消化结合,消化需时较短,胶原酶V和P在胰岛纯化前后每只小鼠收获的胰岛细胞数量和当量无差别(P>0.05);扫描电镜结果显示消化较好的胰岛表面被膜完整,消化过度的胰岛导致被膜不完整,易致外层细胞损伤。结论小鼠逆行胰管灌注胶原酶、内外消化相结合的胰岛消化方法所需时间较短,但同时要注意防止消化过度。     

根据CD4立体构型设计的新型免疫抑制物J2抑制小鼠胰岛移植急性排斥反应的初步观察

目的评价基于CD4立体构型设计的新型免疫抑制物J2对小鼠胰岛移植后急性排斥反应的影响。方法将900～1000个DBA/2（H-2^d）小鼠的胰岛移植在糖尿病模型C57BL/6（H-2^b）小鼠肾被膜下。移植前用台盼蓝和双硫腙染色检测胰岛细胞活性和纯度。将C57BL/6小鼠随机分为5组,每组10只,在胰岛移植后第1～10天腹腔内注射J2,每天一次。对照组注射生理盐水、CsA组注射环孢素A（10 mg/kg）;实验组J2A组（1mg/kg）、J2B组（4 mg/kg）、J2C组（8 mg/kg）。术后监测不同时间各组小鼠的血糖变化及移植胰岛的存活时间,并观察移植胰岛在术后第三天及发生急性排斥反应时的组织病理学及免疫组化表现。结果获得的胰岛细胞的活性＞95%,纯度＞85%。胰岛移植术前各组糖尿病小鼠的血糖平均高于20.0mmol/L,术后前四天各组小鼠的血糖下降明显,均低于11.1 mmol/L,且各组之间比较差异无统计学意义（P＞0.05）。移植第7天以后,对照组、J2A组小鼠的血糖较术后前四天明显升高（P＜0.05）。术后第八天开始,对照组、J2A组小鼠血糖升高平均高于11.1 mmol/L;CsA组、J2B组、J2C组的血糖仍低于11.1 mmol/L,三组之间无明显差异,但明显低于对照组和J2A组（P＜0.05）。病理学检查示移植后第三天各组移植的胰岛细胞轻度水肿,形态大致正常;移植后第八天对照组、J2A组的移植胰岛出现急性排斥反应病理改变,其他组病理未见排斥表现,小鼠胰岛素抗体免疫组化结果显示胰岛素阳性。CsA组（21.6±2.1 d）、J2B组（19.0±2.7d）、J2C组（18.7±2.3d）的移植胰岛存活时间比较差异无统计学意义,但分别较对照组（8.1±0.56d）、J2A组（8.3±0.48d）显著延长（P＜0.01）。结论一定剂量的J2具有和CsA相似的免疫抑制作用,可明显抑制小鼠胰岛移植后排斥反应的发生,显著延长移植物的存活时间。     

小鼠胰岛的分离纯化及体外功能检测的实验研究

目的：探讨获得高质量小鼠胰岛的分离纯化方法，评价其功能。方法：采用胆总管内胶原酶灌注膨胀消化胰腺的方法分离小鼠胰岛，不连续密度梯度离心法纯化胰岛，用双硫腙（Dithizone，DTZ）对胰岛进行特异性染色计算胰岛产量及纯度，以葡萄糖和茶碱刺激胰岛素释放检测胰岛功能。结果：胰岛的产量和活性主要与胰腺均匀膨胀和胶原酶的消化时间有关。平均每个小鼠胰腺能得到150～250个高质量胰岛，活性〉95％，纯度〉90％。葡萄糖及茶碱（carbachol，Cch）刺激后胰岛素释放量明显增加。结论：改良的胆总管内胶原酶灌注膨胀消化小鼠胰腺及不连续密度梯度Ficoll-400纯化胰岛的方法，可获得产量较高、纯度及功能较好的胰岛。     

db/db小鼠胰岛的分离与特征分析

目的 分离db/db小鼠胰岛,并对其特征进行检测和分析。方法 采用胶原酶V对10只db/db小鼠胰岛分离进行逆行胰管灌注和消化,用Ficoll-1077和Ficoll-1119进行胰岛的不连续密度梯度纯化,对分离的胰岛进一步进行手工挑选,并用DTZ进行胰岛和纯度鉴定,用透射电镜观察胰岛内部分泌颗粒等情况。结果 经本方法分离可得到db/db小鼠胰岛数量为（122.4±6.6）个/只,当量为（483.6±82.3）IEQ/只,与ICR小鼠胰岛分离结果差异有统计学意义（P<0.05）;db/db小鼠胰岛DTZ染色后显淡红色;胰岛大小指数为（3.96±0.64）,显著大于ICR小鼠胰岛（P<0.05）;透射电镜下显示β细胞中的胰岛素分泌颗粒减少,分泌颗粒颜色较浅。结论 采用本方法可分离得到db/db小鼠胰岛,为后续开展基于胰岛功能和特征变化的2型糖尿病患者治疗研究提供一种参考。     

低温微重力培养对大鼠胰岛细胞质量影响的实验

目的:研究低温微重力对大鼠胰岛移植质量的影响，以期减少体外培养对胰岛活性和数量的影响，提高胰岛移植质量。方法:将分离纯化的大鼠胰岛分为3组：大鼠新鲜胰岛移植组（于移植前在普通培养基中培养21 d,对照组）；实验1组（大鼠新鲜胰岛在37 ℃ RCCS中培养21 d）；实验2组（新鲜大鼠胰岛在26 ℃ RCCS中培养14 d后复温至37 ℃继续在37 ℃ RCCS中培养7 d）。　观察各种培养液中的胰岛素含量。并将上述3个实验组不同条件培养的胰岛分别以2000IEQ胰岛移植量植入糖尿病大鼠体内，并观察10周。结果:实验2组的胰岛存活率、胰岛素分泌水平及胰岛素刺激指数均高于对照组和实验1组，差异有统计学意义(P＜0.05)。21 d时实验2组胰岛存活率高达(67.4±4.6)%，而对照组和实验1组胰岛存活率分别降至(28.1±3.3)%和(50.3±3.5)%，3组间差异有统计学意义(P＜0.05)。给糖尿病大鼠移植实验1，2组的胰岛后均能控制血糖至正常水平，但实验2组胰岛移植对糖尿病大鼠7 d内血糖控制优于实验1组；对照组血糖控制差，3组间两两比较均有统计学差异（均P＞0.05）。结论:大鼠胰岛经低温微重力培养后移植，可以明显提高1型糖尿病大鼠的治疗效果。     

乌司他丁在大鼠胰岛分离过程中的保护作用

目的探讨乌司他丁在大鼠胰岛分离中的保护作用。方法用含胶原酶的Hanks溶液灌注大鼠胰腺。根据胶原酶中乌司他丁的含量分为3组。低浓度组:胶原酶中含乌司他丁2500U/ml;高浓度组:胶原酶中含乌司他丁5000U/ml;对照组:胶原酶中不含乌司他丁。将各组分离出的胰岛进行比较。结果加用乌司他丁的两组分离出的胰岛在形态、数量方面均优于对照组(P<0.01)。在无糖、低糖、高糖和茶碱 高糖刺激下,加用乌司他丁的两组胰岛素的释放量优于对照组(P<0.01)。结论用乌司他丁灌注胰腺对大鼠胰岛分离具有保护作用。     

实验大鼠胰岛分离移植技术方法的比较分析

目的 探索高效的大鼠胰岛分离移植技术方法.方法 应用Wistai-Furth大鼠,于体内或体外胶原酶经胰管灌注膨化胰腺,联合不同密度Ficoll液或Histopaque液纯化胰岛细胞,评估胰岛的数量、纯度、胰岛当量以及肾被膜下胰岛移植的有效性.结果 体外经胰管灌注膨化胰腺结合Histopaque液纯化提取胰岛的数量、纯度和胰岛当量值均显著高于体内灌注组各数值(P＜0.01),其提取时间无显著差别.1000个胰岛细胞移植进入左肾被膜下,有效的逆转了糖尿病大鼠高血糖,其远期糖耐受结果优于500和800个胰岛细胞移植组.结论 体外灌注膨化消化胰腺结合Histopaque液纯化胰岛的分离方法是一种满意的分离技术.1000个胰岛细胞是保证肾被膜下胰岛移植成功的最低有效数量.     

生物发光显像技术用于移植胰岛的在体监测

目的 探讨生物发光显像技术用于移植胰岛监测的优势和可行性.方法 成年雄性C57BL/6小鼠腹腔注射链佐星,制成糖尿病模型.取C57BL/6小鼠和Bclb/c小鼠胰腺,消化、分离、纯化,获得胰岛,再将荧光素酶基因转入胰岛.将糖尿病模型小鼠分为同系移植组(n=20)和同种移植组(n=7),同系移植组糖尿病模型小鼠移植不同数量(分别为10、50、100和200个,每个数量移植5只小鼠)的C57BL/6小鼠胰岛,同种移植组糖尿病模型小鼠移植Bclb/c小鼠胰岛,胰岛均移植至左后腿上方皮下脂肪内.在设计时间点对受者进行生物发光扫描成像,观察光密度强弱及变化规律,并监测同种移植组受者的随机血糖变化.结果 移植后第6天,扫描成像可见移植区光密度随移植胰岛数量增多而增高,光密度与植入胰岛数量呈正相关.同种移植组受者的随机血糖在移植后2 d内迅速下降至正常水平,平均于11 d后再度逐渐升高至糖尿病水平,扫描成像显示移植区光密度在移植后6～7 d达到峰值,随后迅速下降;光密度开始下降时间为移植后(6.14±0.90)d,而血糖升高时间发生在移植后(10.00±0.82)d,前者改变时间明显早于后者(P＜0.05).结论 胰岛生物发光显像技术可及时、直观、准确的反映移植胰岛在机体内的存活状况,其成像改变早于血糖变化.     

Degraded collagenase deteriorates islet viability

OBJECTIVE: The utilization of purified enzyme blends consisting of collagenase class I (CI) and II (CII) and neutral protease is an essential step for clinical islet isolation. Previous studies suggested that the use of enzyme lots containing degraded CI reduced islet release from human pancreata. The present study sought to assess the effect of degraded collagenase on islet function in vitro and posttransplantation. MATERIALS AND METHODS: Crude collagenase was chromatographically separated into CI, CII, and a mixture of degraded CI and CII isomers. Subsequently, classes were recombined to obtain a CII/CI ratio of 0.5. Rat islets were isolated utilizing neutral protease and 20 units of recombined collagenase containing either intact (Ci) or degraded isomers (Cd). RESULTS: Digestion time was reduced utilizing Cd (P < .001). The highest islet yield and lowest islet fragmentation were obtained with Ci (P < .01). Utilization of Cd corresponded to a reduction in viability and in vitro function (NS). Islet transplantation reversed hyperglycemia in diabetic nude mice, but revealed an absence of weight gain in recipients receiving islets isolated using Cd (P < .01). CONCLUSION: This study suggested that islet function posttransplantation is affected by degraded collagenase isomers. This finding has to be considered for the purification process of collagenase.     

Isolation of islands of Langerhans from the human adult pancreas

Nine of 38 islet isolation experiments, using the duct collagenase technique, were selected for quality checks on isolated islet tissue. Pancreas was harvested, following aortic multi-organ perfusion. The total number of islets isolated amounted to 112,461 +/- 11,828 in 13.7 ml of suspension on average. In vitro secretion of beta cells was increased by a factor of 3.8 in response to glucose stimulation. Isolated islets in morphologically intact condition were detected by histological investigations. A new viability test (MTT, Sigma) for isolated pancreas islets worked well, in that it provided very soon information on islet survival in the wake of collagenase preparation. These results produced evidence to an improvement of technical conditions for clinical use of adult islet transplantation in cases of type I diabetes.     

一种经济高效的SD大鼠胰岛细胞分离技术

目的 建立一种经济高效的大鼠胰岛细胞分离纯化方法,为胰腺的修复重建奠定实验基础.方法 成年雄性SD大鼠25只,体重230～380g,共进行5次实验,每5只大鼠一组进行消化和分离.采用医用复方氯化钠注射液(compound sodium chloride injection, CSCI)经胰总管灌注大鼠胰腺,0.5mg/mL V型胶原酶消化后,分别采用浓度为27.0%、23.0%、20.5%和11.0%的Ficoll 400形成不连续密度梯度介质,离心纯化胰岛细胞.双硫腙(dithizon, DTZ)染色行纯化前后胰岛细胞计数和纯度检测;荧光染料碘化丙啶(propidium iodide, PI)和二乙酸荧光素(fluorescein diacetate, FDA)储存液双染色鉴定胰岛细胞活性;RPMIl640培养基培养3d后,分别用浓度为2.8mmol/L的低糖和25.0mmol/L的高糖行葡萄糖刺激胰岛素释放实验检测胰岛细胞功能.结果 5次实验胰岛细胞消化时间为(13.8±1.6)min.DTZ染色鉴定纯化前胰岛细胞数为(5626±422)个,纯化后为(2914±485)个,纯化后的胰岛细胞数较纯化前明显减少(P<0.01),回收率51.6%±6.0%,每个胰腺收获胰岛细胞数为(583±97)个/只.5次分离获得的胰岛细胞纯度为90.2%±3.4%,活性为81.6%±7.0%.培养3d后,葡萄糖刺激胰岛素释放实验显示:低糖环境下胰岛素水平为(39.7±7.5)EU/L,高糖环境为(116.1±17.4)EU/L,比较差异有统计学意义(P<0.01)刺激指数为3.0±0.4.结论 采用CSCI作为大鼠胰岛细胞分离纯化的主要液体试剂,并采用低浓度V型胶原酶消化,不仅可降低实验成本,同时可获得高质量的胰岛细胞.     

Improved recovery of human islets from young donor pancreases utilizing increased protease dose to collagenase for digesting peri‐islet extracellular matrix

Human islet isolation from young donor pancreases (YDP) utilizing the current purified standard dose of collagenase‐protease enzyme mixtures often results in the release of a high percentage of mantled islets. Mantled islets are those surrounded by exocrine tissue and are difficult to purify by density gradient centrifugation, leading to poor islet recovery. Based on difference in extracellular matrix, and total collagen content between YDP and old donor pancreas (ODP, > 35 Y) led us to compare results from islet isolation using increased collagenase combination (ICC) or increased protease combination (IPC), to the standard enzyme combination (SEC) in a “trisected” pancreas model to overcome the donor‐to‐donor variability. These results showed a reduced percentage of mantled islets (17% ± 7.5%) and higher postpurification islet recovery (83.8% ± 5.6%) with IPC. Furthermore, these results were confirmed in 13 consecutive whole pancreas islet isolations utilizing IPC from VitaCyte, Roche, or SERVA collagenase‐protease enzyme mixtures. Results obtained from in vitro and in vivo islet functional assessment indicated that islets isolated using IPC retained normal islet morphology, insulin secretion, and the ability to reverse diabetes after transplantation in diabetic nude mice. This is the first report utilizing trisected pancreas to assess the effectiveness of different enzyme combinations to improve islet recovery from young donor pancreases.     

Use of trypsin for isolation of islets of Langerhans in the rat.

A new technique for pancreatic islet isolation, based on trypsin administered into the pancreatic duct system and a reduced amount of collagenase for digestion of the removed and chopped pancreatic tissue, yielded viable islets as judged by the metabolic response of 27 inbred, streptozotocin-diabetic rats after intraportal transplantation of the islets: all recipients of greater than 240 islets normalized their blood glucose, plasma insulin, urine volume and urinary glucose. The number of islets isolated was the same as with the conventional collagenase technique.     

小鼠胰岛的分离与纯化

目的 探讨稳定、高效的小鼠胰岛细胞的分离纯化方法.方法 采用胆总管内灌注不同浓度胶原酶(分别为0.5、1.0、1.5 g/L)消化胰腺的方法分离BALB/C小鼠胰岛,Ficoll-400不连续密度梯度离心法纯化胰岛.双硫腙(DTZ)对胰岛进行特异性染色计算胰岛产量及纯度,葡萄糖刺激释放试验体外测胰岛功能.结果 不同浓度的胶原酶在不同时间内消化胰腺后收获的胰岛数量有较大的差异,其中采用0.5 g/L胶原酶V、38 ℃水浴消化20 min组收获量最大为(230±20)个胰岛细胞团,纯度约为90%.DTZ染色后胰岛呈腥红色,形态完整.葡萄糖刺激释放实验示高糖刺激后胰岛素释放量为低糖刺激后的2.3倍.结论 胶原酶浓度、消化时间和温度是影响小鼠胰岛分离结果的重要因素,当胶原酶浓度为0.5 g/L,消化时间20 min时可获得数量较多,纯度较好的胰岛细胞.

Abstract：

Objective To investigate the stable and efficient method of isolation and purification from mice pancreas. Methods BALB/C mouse islets were isolated by different concentrations of collagenase digestion (0. 5, 1. 0, 1. 5 g/L respectively) and purificated by Ficoll density gradient centrifugation.The number, purity and vitality of the islets were analyzed. The production and purity of the islets were checked by Dithizone immunofluorescence staining. The glucose-induced insulin secretion was detected by enzyme linked immunosorbent assay (ELISA) for islet function in vitro. Results Different number of islets was obtained by mice pancreas digestion with different concentrations of collagenase and for different digestion durations.After the mouse pancreata were digested in 38 C and with 0. 5 g/L collagenase V for 20rmin, maximum number of islets was obtained, and the purity of the final preparation was ＞ 95%. After culture in vitro, insulin release of islets under high glucose stimulation was 2. 3 times of that under low glucose stimulation. Conclusion Concentration of collagenase, temperature, and digestion duration were important factors of islet isolation and purification from mice pancreas. More production and higher purity of islets were obtained under the concentration of 0. 5 g/L collagenase Ⅴ for 20 min.     

Optimization of neutral protease to collagenase activity ratio for islet of Langerhans isolation

AIM: The optimal neutral protease to collagenase activity ratio has not been determined for islet isolation. We evaluated a new highly purified collagenase that can be blended with predetermined amounts of neutral protease (NP). METHODS: Islets were isolated from 7 groups of Sprague-Dawley rats. In group I, collagenase type XI (Sigma) at 2 mg/mL, and, in group II, Liberase at 0.6 mg/mL (2.4 PZ- U/mL; Roche) were used as controls. In groups III to VII, collagenase NB1 0.6 mg/mL (2.4 PZ-U/mL; Serva Electrophoresis) was used with increasing amounts of added NP. The NP to collagenase activity ratio (DMC-U/PZ-U) increased from 0.5% in group III to 2.0% in group VII. RESULTS: Mean islet equivalent (IE) yields per rat were 1367, 1755, 597, 895, 1712, 1043, and 905 in groups I to VII. IE yields were maximal at DMC-U/PZ-U = 1.2%. Islet morphology was influenced by NP concentration with decreasing numbers of trapped islets and increasing numbers of fragmented islets as NP contents increased. Cytokine release, islet cell apoptosis, and in vitro function were significantly better in groups III to VII as compared with groups I and II. CONCLUSION: NP is a crucial additive to collagenase for islet isolation. Optimization of the NP to collagenase activity ratio (1.2% in this model) improves yields and morphology after islet isolation.     

Portal Venous Oxygen Persufflation of the Donation after Cardiac Death pancreas in a rat model is superior to static cold storage and hypothermic machine perfusion

Success of clinical pancreatic islet transplantation depends on the mass of viable islets transplanted and the proportion of transplanted islets that survive early ischaemia reperfusion injury. Novel pancreas preservation techniques to improve islet preservation and viability can increase the utilization of donation after cardiac death donor pancreases for islet transplantation. Rat pancreases were retrieved after 30 min of warm ischaemia and preserved by static cold storage, hypothermic machine perfusion or retrograde portal venous oxygen persufflation for 6 h. They underwent collagenase digestion and density gradient separation to isolate islets. The yield, viability, morphology were compared. In vitro function of isolated islets was compared using glucose stimulated insulin secretion test. Portal venous oxygen persufflation improved the islet yield, viability and morphology as compared to static cold storage. The percentage of pancreases with good in vitro function (stimulation index > 1.0) was also higher after oxygen persufflation as compared to static cold storage. Retrograde portal venous oxygen persufflation of donation after cardiac death donor rat pancreases has the potential to improve islet yield.     

Successful human islet isolation utilizing recombinant collagenase

The enzymatic dissociation of acinar tissue by collagenase is a substantial step in the isolation of pancreatic islets. Although essential collagenase components have been purified, the variability in the activity of different batches limits long-term reproducibility of isolation success. The utilization of purified recombinant proteases would solve this problem. In the present study, pancreases from multiorgan donors were dissociated by means of digestion-filtration using either Liberase HI (n = 51) or a recombinant collagenase blend (n = 25). No significant differences were found regarding islet yield before and after purification, the percent of exocrine-attached islets, and final purity. However, the ratio between islet equivalents and islet numbers indicated a lesser fragmentation in islets isolated with recombinant collagenase (P < 0.01). In contrast, viability was slightly higher in islets isolated with Liberase (92.3 +/- 0.8 vs. 85.6 +/- 2.9%; P < 0.05). Insulin release during static glucose incubation was not different between experimental groups. Islet transplantation into diabetic nude mice resulted in sustained normoglycemia in either group until the graft was removed. These results demonstrated that viable human islets can be isolated using recombinant collagenase. Final optimization of this enzyme blend would offer continuous reproducibility of isolation success.     

The ratio between collagenase class I and class II influences the efficient islet release from the rat pancreas

BACKGROUND: Previous studies indicated different roles of collagenase class I, class II and neutral protease in the enzymatic islet release from pancreatic tissue. Because no information has been available, this study was aimed to investigate the isolation efficiency of different ratios between collagenase class II and I (C-ratio) in the rat pancreas serving as model for the human pancreas without being restricted by the large variability observed in human donors. METHODS: Rat pancreata were digested using a marginal neutral protease activity and 20 PZ-U of purified collagenase classes recombined to create a C-ratio of 0.5, 1.0, or 1.5. Collagenase efficiency was evaluated in terms of isolation outcome and posttransplantation function in diabetic nude mice. RESULTS: The highest yield of freshly isolated islets was obtained using a C-ratio of 1.0. Purity and fragmentation of freshly isolated islets were not influenced by the C-ratio. After 24-hr culture performed for quality assessment, a marginal but significant reduction of viability was observed in islets isolated by means of a C-ratio of 0.5 and 1.5. Islet in vitro and posttransplantation function revealed no negative effect mediated by different C-ratios. CONCLUSIONS: The present study demonstrates that the C-ratio is of significant relevance for the outcome after enzymatic rat islet isolation. The data indicate further that purified collagenase class I or class II does not damage islet tissue even if used in excess. The present study can serve as a start for subsequent experiments in the human pancreas.