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- Caballero-Corbalán, José, 1981-, et al.
(författare)
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Predicting the outcome of human islet isolation
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Background. Islet transplantation is currently being explored as a possible treatment to diabetes mellitus. Islet isolation from the human pancreas is a technically demanding process and the success rate even in the most experienced GMP facilities is only about 50%. The aim of this study was to investigate whether isolation outcome can be predicted from a pancreas biopsy taken during organ procurement. Methods. The outcome of 29 human islet isolations was retrospectively studied. Biopsies from the pancreatic head were immunostained for insulin to study islet morphology and size distribution utilizing a digital analysis system. Isolations were categorized as successful if they yielded more than 2000 IE/g. Results. Pellet volume after collagenase digestion and islet purity was higher in the successful group. None of the morphology variables, i.e. islet number (IN/mm2), islet equivalent number (IE/IN) and percentage of insulin positive area in the biopsy, differed significantly between the study groups. Conclusions. No single morphological feature observed in a biopsy taken from the head of pancreas can predict the outcome of islet isolation from the human pancreas, even if using the same enzyme blend in standardized human islet isolation procedure.
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- 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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- Jahan, Mahabuba, et al.
(författare)
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Decreased defluorination by using the novel beta cell imaging agent [18F]FE-DTBZ-d4 in pigs examined by PET
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Introduction: Fluorine-18 DTBZ-analogues, which selectively targets the vesicular monoamine transporter 2 (VMAT2), have been extensively studied for in vivo quantification of beta cell mass by positron emission tomography (PET). This study describes a novel deuterated radioligand [18F]FE-(+)-DTBZ-d4, aimed to increase the stability against in vivo defluorination previously observed for [18F]FE-(+)-DTBZ. Methods: [18F]FE-(+)-DTBZ-d4 was synthesized by alkylation of desmethyl -(+)-DTBZ precursor with deuterated [18F]fluoroethyl bromide ([18F]FCD2CD2Br). Radioligand affinity and specificity to VMAT2 was assessed by an in vitro saturation homogenate binding assay using human endocrine and exocrine pancreatic tissues. In vivo PK/PD was studied in a porcine model by PET/CT. The rate of defluorination was quantified by compartmental modeling and contrasted against defluorination of the non-deuterated analogue. Results: [18F]FE-DTBZ-d4 was produced in good radiochemical yield (3.0-1.7 GBq) in 100 min. Radiochemical purity of the formulated product was > 98% for up to 5h. The in vitro Binding Potential (BP) for VMAT2 in islet tissue was 27.0±8.8. The BP was lower in exocrine tissue (1.7±1.0) in addition to a close to three-fold decrease in specificity. The rate of in vivo defluorination was decreased significantly (kdefluorination= 0.0016±0.0007) compared to the non-deuterated analogue (kdefluorination= 0.012±0.002), resulting in a more than six-fold increase in half-life stability. Conclusion: [18F]FE-(+)-DTBZ-d4 has favorable pharmacokinetic (PK) properties for VMAT2 imaging, in addition to gaining significantly increased stability against defluorination. The in vitro islet BP and specificity was lower compared to a non-deuterated analogue but the islet/exocrine BP ratio was unchanged, potentially allowing for improved target tissue discrimination.
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