| 1. |
- Brandhorst, Heide, 1962-, et al.
(författare)
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A new oxygen carrier for improved long-term storage of human pancreata before islet isolation
- 2010
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Ingår i: Transplantation. - 0041-1337 .- 1534-6080. ; 89:2, s. 155-60
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Pancreas oxygenation during cold storage has been established in islet isolation and transplantation to prevent ischemic tissue damage using perfluorodecalin (PFD) as hyperoxygen carrier. However, studies in humans and pigs provided conflicting results about the efficiency of PFD for pancreas oxygenation. The aim of this study was to compare PFD with a newly developed oxygen carrier composed of perfluorohexyloctane and polydimethylsiloxane 5 (F6H8S5) for long-term storage of human pancreata.METHODS: After 24-hr storage in preoxygenated PFD or F6H8S5, pancreata were processed using Liberase HI for pancreas dissociation and a Ficoll gradient for islet purification. Islet quality assessment was performed measuring glucose-stimulated insulin release, viability, islet ATP content, and posttransplant function in diabetic nude mice.RESULTS: Compared with PFD, F6H8S5 significantly increased the intrapancreatic partial oxygen pressure and islet ATP content. This corresponded to an increase of islet yield, recovery after culture, glucose stimulation index, viability, and improved graft function in diabetic nude mice.CONCLUSIONS: The present findings indicate clearly that F6H8S5 improves isolation outcome after prolonged ischemia compared with PFD. This observation seems to be related to the significant lipophilicity and almost pancreas-specific density of F6H8S5. Moreover, these characteristics facilitate pancreas shipment without using custom-made transport vessels as required for PFD.
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| 2. |
- Brandhorst, Heide, et al.
(författare)
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Large-Scale Comparison of Liberase HI and Collagenase NB1 Utilized for Human Islet Isolation
- 2010
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Ingår i: Cell Transplantation. - 0963-6897 .- 1555-3892. ; 19:1, s. 3-8
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Tidskriftsartikel (refereegranskat)abstract
- For more than a decade Liberase HI was commonly used as the standard enzyme blend for clinical human islet isolation until enforced replacement by collagenase NB1 (NB1). This change resulted initially in a reduction in islet isolation outcome and transplant activities worldwide. This retrospective study was initiated to compare the efficiency of NB1 premium grade with Liberase in 197 human islet isolations. All pancreata were processed between January 2006 and June 2008 utilizing the same procedures for isolation and quality assessment except the administration of preselected lots of either Liberase (n = 101) or NB1 (n = 96). Utilizing Liberase significantly more digested tissue and purified islet yield was produced compared to NB1. In contrast, the use of NB1 was associated with significantly higher purity and glucose stimulation index during dynamic perifusion. The expression of proinflammatory markers was almost identical except tissue factor expression that was higher after utilization of Liberase. No difference was found in the percentage of pancreata fulfilling the criteria for clinical islet transplantation. The results suggest that Liberase is more efficient for pancreas dissociation than collagenase NB1 but seems to be more harmful to exocrine cells and islet tissue.
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| 3. |
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| 4. |
- Brandhorst, Heide, 1962-, et al.
(författare)
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The importance of tryptic-like activity in purified enzyme blends for efficient islet isolation
- 2009
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Ingår i: Transplantation. - 0041-1337 .- 1534-6080. ; 87:3, s. 370-5
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The isolation of islets from the human pancreas critically depends on an efficient enzyme blend. Previous studies have solely focused on the presence of collagenase and neutral protease/thermolysin. Despite improved characterization of these components, the lot-related variability in efficacy still persists suggesting that additional so far disregarded enzymes are required for efficient islet cleavage. METHODS: Varying activities of a tryptic-like enzyme were identified within collagenase NB1 lots, which were selected according to a matched ratio between tryptic-like and collagenase activity (TLA-ratio). Rat and human pancreata were processed with current standard procedures. RESULTS: Increasing the TLA-ratio from 1.3% to 10% reduced pancreas dissociation time in rats by 50% without affecting islet yield, viability, or posttransplant function in diabetic nude mice. Enhancing the TLA-ratio from 1.3% to 12.6% for human pancreas processing resulted in a significant reduction of recirculation time and increased incrementally human islet yield without affecting purity, in vitro function or recovery after culture. Optimized pancreas digestion correlated with a higher percentage of islet preparations fulfilling quality criteria for clinical transplantation. CONCLUSIONS: We conclude that TLA is an effective component that should be included in moderate amounts in enzyme blends for human islet isolation to optimize the efficiency and minimize the lot-related variability.
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| 5. |
- Caballero-Corbalán, José, et al.
(författare)
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No beneficial effect of two-layer storage compared with UW-storage on human islet isolation and transplantation
- 2007
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Ingår i: Transplantation. - : Ovid Technologies (Wolters Kluwer Health). - 0041-1337 .- 1534-6080. ; 84:7, s. 864-869
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Tidskriftsartikel (refereegranskat)abstract
- Background. Shipment of pancreata between distant centers is frequently associated with prolonged cold ischemia time (CIT) that leads to poorer outcomes for islet transplantation. Clinical pilot trials have indicated that oxygenation of explanted human pancreata utilizing the two-layer method (TLM) allows the use of marginal donor pancreata for islet transplantation. The present study aimed to clarify whether TLM enhances the ischemic tolerance of human pancreata. Methods. We analyzed retrospectively the outcome of 200 human islet isolations performed after TLM preservation or storage in University of Wisconsin solution (UWS). Results. Donor characteristics and digestion parameters did not vary significantly between TLM-preserved and UWS-stored pancreata. No differences were observed between experimental groups with regard to islet yield, purity, or dynamic glucose stimulation index after either short or prolonged CIT. However, CIT and stimulation index were negatively correlated in each experimental group. The isolation outcome in donors aged ≥60 years was not increased after TLM preservation when compared to UWS storage. No effect was observed regarding islet posttransplant function in recipients with established kidney grafts. Conclusions. The present study suggests that the ischemic tolerance of human pancreata cannot be extended by TLM preservation. In addition, TLM does not seem to improve the isolation outcome for pancreata from elderly donors.
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| 6. |
- Caballero-Corbalán, José, et al.
(författare)
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Using HTK for Prolonged Pancreas Preservation Prior to Human Islet Isolation
- 2012
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Ingår i: Journal of Surgical Research. - : Elsevier BV. - 1095-8673 .- 0022-4804. ; 175:1, s. 163-168
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Tidskriftsartikel (refereegranskat)abstract
- Background. Histidine-tryptophan-ketoglutarate (HTK) has been established as an alternative to University-of-Wisconsin solution (UWS) for abdominal organ preservation, but data about HTK efficiency to preserve pancreata during prolonged cold ischemia time (CIT) are conflicting. In human islet transplantation, HTK provided similar isolation outcomes after short CIT. The present study aimed to investigate whether islets can be successfully isolated from HTK-preserved pancreata after prolonged CIT compared with UWS. Materials and Methods. Sixty-four human pancreata retrieved from donors meeting criteria for kidney donation were perfused utilizing either HTK or UWS and preserved for more or less than 10 h prior to islet isolation. Along with parameters related to isolation and islet quality assessment, the dry-to-wet weight ratio was evaluated. Results. Donor-and procurement-related factors did not vary between HTK- and UWS-perfused pancreata. The dry-to-wet weight ratio was lower in HTK-preserved pancreata indicated tissue edema (21.0% +/- 3.5% versus 24.8% +/- 2.0%, P = 0.007). Isolation-related variables differed between experimental groups after prolonged CIT with respect to purified packed tissue volume (9.1 +/- 5.0 versus 17.2 +/- 8.1 mu L/g, P = 0.004) and islet yield (1910 +/- 980 versus 3150 +/- 1420 IE/g, P = 0.012). Islet purity and survival after culture were similar after HTK or UWS perfusion. The preservation solution did not affect in vitro function and transplantability of isolated islets. Conclusions. Compared with UWS, HTK has similar efficiency to preserve human pancreata for subsequent islet isolation during <10 h CIT but seems to be limited for prolonged cold storage. (C) 2012 Elsevier Inc. All rights reserved.
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