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| 2. |
- Friberg, Andrew S., et al.
(författare)
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Transplanted functional islet mass : donor islet preparation, and recipitent factors influence early graft function in islet-after-kidney patients
- 2012
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Ingår i: Transplantation. - 0041-1337 .- 1534-6080. ; 93:6, s. 632-638
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Tidskriftsartikel (refereegranskat)abstract
- Background.The ability to predict clinical function of a specific islet batch released for clinical transplantation using standardized variables remains an elusive goal.Methods. Analysis of 10 donor, 7 islet isolation, 3 quality control, and 6 recipient variables was undertaken in 110 islet-after-kidney transplants and correlated to the pre- to 28-day posttransplant change in C-peptide to glucose and creatinine ratio ([DELTA]CP/GCr).Results.Univariate analysis yielded islet volume transplanted (Spearman r=0.360, P<0.001) and increment of insulin secretion (r=0.377, P<0.001) as variables positively associated to [DELTA]CP/GCr. A negative association to [DELTA]CP/GCr was cold ischemia time (r=-0.330, P<0.001). A linear, backward-selection multiple regression was used to obtain a model for the transplanted functional islet mass (TFIM). The TFIM model, composed of islet volume transplanted, increment of insulin secretion, cold ischemia time, and exocrine tissue volume transplanted, accounted for 43% of the variance of the clinical outcome in the islet-after-kidney data set.Conclusion.The TFIM provides a straightforward and potent tool to guide the decision to use a specific islet preparation for clinical transplantation.
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| 3. |
- Alvariza, A., et al.
(författare)
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Increasing preparedness for caregiving and death in family caregivers of patients with severe illness who are cared for at home - study protocol for a web-based intervention
- 2020
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Ingår i: BMC Palliative Care. - : Springer Science and Business Media LLC. - 1472-684X. ; 19:1
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Tidskriftsartikel (refereegranskat)abstract
- Background Family caregivers of patients with severe illness and in need for a palliative care approach, face numerous challenges and report having insufficient preparedness for the caregiver role as well as a need for information and psychosocial support. Preparing to care for a severely ill family members also means becoming aware of death. Feelings of being prepared are associated with positive aspects and regarded protective against negative health consequences. Methods The study adheres to the SPIRIT-guidelines (Supplementary 1), uses a pre-post design and include a web-based intervention. Inclusion criteria are; being a family caregiver of a patient with severe illness and in need of a palliative care approach. The intervention which aims to increase preparedness for caregiving and death is grounded in theory, research and clinical experience. The topics cover: medical issues, symptoms and symptom relief; communication within the couple, how to spend the time before death, being a caregiver, planning for the moment of death and; considerations of the future. The intervention is presented through videos and informative texts. The website also holds an online peer-support discussion forum. Study aims are to: evaluate feasibility in terms of framework, content, usage and partners' experiences; explore how the use of the website, influences family caregivers' preparedness for caregiving and death; explore how the use of the website influences family caregivers' knowledge about medical issues, their communication with the patient and their considerations of the future; and to investigate how the family caregivers' preparedness for caregiving and death influences their physical and psychological health and quality of life 1 year after the patient's death. Data will be collected through qualitative interviews and a study-specific questionnaire at four time-points. Discussion This project will provide information about whether support via a website has the potential to increase preparedness for caregiving and death and thereby decrease negative health consequences for family caregivers of patients affected by severe illness. It will provide new knowledge about intervention development, delivery, and evaluation in a palliative care context. Identification of factors before death and their association with family caregivers' preparedness and long-term health may change future clinical work.
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| 4. |
- 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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| 5. |
- 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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| 6. |
- 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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| 7. |
- 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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| 8. |
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| 9. |
- Cabric, Sanja, et al.
(författare)
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Islet Surface Heparinization Prevents the Instant-Blood Mediated Inflammatory Reaction in Islet Transplantation
- 2007
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Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 56:8, s. 2008-2015
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE—In clinical islet transplantation, the instant blood-mediated inflammatory reaction (IBMIR) is a major factor contributing to the poor initial engraftment of the islets. This reaction is triggered by tissue factor and monocyte chemoattractant protein (MCP)-1, expressed by the transplanted pancreatic islets when the islets come in contact with blood in the portal vein. All currently identified systemic inhibitors of the IBMIR are associated with a significantly increased risk of bleeding or other side effects. To avoid systemic treatment, the aim of the present study was to render the islet graft blood biocompatible by applying a continuous heparin coating to the islet surface.RESEARCH DESIGN AND METHODS—A biotin/avidin technique was used to conjugate preformed heparin complexes to the surface of pancreatic islets. This endothelial-like coating was achieved by conjugating barely 40 IU heparin per full-size clinical islet transplant.RESULTS—Both in an in vitro loop model and in an allogeneic porcine model of clinical islet transplantation, this heparin coating provided protection against the IBMIR. Culturing heparinized islets for 24 h did not affect insulin release after glucose challenge, and heparin-coated islets cured diabetic mice in a manner similar to untreated islets.CONCLUSIONS—This novel pretreatment procedure prevents intraportal thrombosis and efficiently inhibits the IBMIR without increasing the bleeding risk and, unlike other pretreatment procedures (e.g., gene therapy), without inducing acute or chronic toxicity in the islets.
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| 10. |
- Friberg, Andrew S, et al.
(författare)
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Transplantable functional islet mass – predictive biomarkers of graft function in islet after kidney transplanted patients
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The ability to predict clinical function of a specific islet batch released for clinical transplantation using standardized variables remains an elusive goal. Analysis of donor, islet isolation, quality control and recipient variables was undertaken in 110 islet after kidney (IAK) transplants and correlated to the pre- to 28-day posttransplant change in C-peptide to glucose and creatinine ratio (ΔCP/GCr). Using backward multiple regression the variables positively associated to ΔCP/GCr were islet volume transplanted (p<0.001) and glucose stimulated insulin secretion (SI) (p=0.009). Factors negatively associated to ΔCP/GCr were cold ischemia time (CIT) (p=0.002) and total tissue volume (p=0.009). Donor age, donor body mass index, number of retrieved organs from the donor, preservation solution, islet insulin content, body weight of the recipient of the islets had no influence on transplant function. The transplantable functional islet mass (TFIM), accounting for islet volume transplanted, SI, CIT, and total tissue volume explained 39% of the variance of the clinical outcome in the IAK data set. Therefore, the TFIM provides a straightforward and potent tool to guide the decision to utilize a specific islet preparation for clinical transplantation.
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