Noninvasive evaluation of the vascular response to transplantation of alginate encapsulated islets using the dorsal skin-fold model

Krishnan, Rahul; Arora, Rajan; Alexander, Michael P.; White, Sean; Lamb, Morgan; Foster, Clarence E.; Choi, Bernard; Lakey, Jonathan R.T.

doi:10.1016/j.biomaterials.2013.10.012

Cited by 25 publications

(16 citation statements)

References 79 publications

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“…With the speckle technique it is also possible to devise a full-field technique that gives an instantaneous map of velocities in real time. This technique has recently been applied to transplanted islets ( 146 ), but its full potential has not yet been developed.…”

Section: Techniques Used To Study Islet Blood Flowmentioning

confidence: 99%

Pancreatic islet blood flow and its measurement

Jansson

Barbu

Bodin

et al. 2016

Upsala Journal of Medical Sciences

128

104

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Pancreatic islets are richly vascularized, and islet blood vessels are uniquely adapted to maintain and support the internal milieu of the islets favoring normal endocrine function. Islet blood flow is normally very high compared with that to the exocrine pancreas and is autonomously regulated through complex interactions between the nervous system, metabolites from insulin secreting β-cells, endothelium-derived mediators, and hormones. The islet blood flow is normally coupled to the needs for insulin release and is usually disturbed during glucose intolerance and overt diabetes. The present review provides a brief background on islet vascular function and especially focuses on available techniques to measure islet blood perfusion. The gold standard for islet blood flow measurements in experimental animals is the microsphere technique, and its advantages and disadvantages will be discussed. In humans there are still no methods to measure islet blood flow selectively, but new developments in radiological techniques hold great hopes for the future.

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Section: Techniques Used To Study Islet Blood Flowmentioning

confidence: 99%

Pancreatic islet blood flow and its measurement

Jansson

Barbu

Bodin

et al. 2016

Upsala Journal of Medical Sciences

128

104

View full text Add to dashboard Cite

show abstract

“…It would be highly advantageous to be able to bank islets from multiple isolations so that sufficient cells could be accumulated for a single transplant. We hypothesized about the cryoprotective role alginate would have on the islets based on its protective role seen during transportation 12 and in vivo 5,13,14 . To determine the percentage of alginate that would yield the best results, we first did islet yield, viability, and GSIR testing in vitro.…”

Section: Discussionmentioning

confidence: 99%

Cryopreserved Alginate-Encapsulated Islets Can Restore Euglycemia in a Diabetic Animal Model Better than Cryopreserved Non-encapsulated Islets

Kojayan

Flores

et al. 2019

Cell Med

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Islet transplantation has been shown to restore normoglycemia clinically. One of the current limitations to the widespread clinical use of islet transplantation is culturing and preserving more than 1 million islet equivalents in preparation for transplant. One possible solution is to bank frozen islets and use them when needed. Although promising, the standard islet freezing protocol introduces stress and cell death, resulting in high variability of islet quality post thawing. This study aimed to develop an improved cryopreservation protocol using alginate-encapsulated islets to improve islet survival and function for future transplants. Our data showed that encapsulation improved islet survival and function after thawing the frozen islets. Frozen encapsulated islets have an islet yield recovery of 84% when compared to non-encapsulated islets at 72% after thawing. Post-thaw viability was 78% for nonencapsulated islets compared to 88% for encapsulated islets. The stimulation index values after a static glucose test following thawing were 1.9 + 0.5, 2.9 + 0.1, and 3.3 + 0.3 for the non-encapsulated, 1.75% alginate, and 2.5% alginate groups, respectively. In a transplant study, the mice that received 1.75% alginate-encapsulated cryopreserved islets achieved normoglycemia on average 5 days after transplant. In comparison, control mice that received fresh islets took 4 days, while those receiving unencapsulated cryopreserved islets took 18 days. In conclusion, encapsulating islets in 1.75% alginate prior to freezing was shown to improve islet survival, function post thawing, and graft response significantly when compared to islets frozen without encapsulation.

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“…One recent study elaborated on the ability of alginate sheets to promote vascularization and blood flow to areas of implanted sheets in mice due to a robust vascular response in the host. In response to increased blood flow and consequently more oxygen and nutrients reaching the islets, the islets in the alginate sheets maintained high viability and function [38]. In a later attempt to improve the diffusion of nutrients, glucose, and insulin in cells in macroscale devices, a novel macroencapsulation device was developed in which islets were placed in thin, nondegradable, microwell membranes of the device.…”

Section: Biomaterials In Transplantationmentioning

confidence: 99%

Physical Protection of Pancreatic Islets for Transplantation

Lee¹,

Sathialingam²,

Alexander³

et al. 2018

Biomaterials - Physics and Chemistry - New Edition

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Type 1 diabetes is an autoimmune disorder that destroys the insulin producing cells of the pancreas. The mainstay of treatment is replacement of insulin through injectable exogenous insulin. Improvements in islet isolation techniques and immunosuppression regimens have made islet transplants a treatment options for select patients. Islet transplants have improved graft function over the years, however, graft function beyond year two is rare and notably these patients require immunosuppression to prevent rejection. Cell encapsulation has been proposed for numerous cell types but it has found increasing enthusiasm for islets. Since islet transplants have experienced a myriad of success the next step is to improve graft function and avoid systemically toxic immunosuppressive regimens. Cell encapsulation hopes to accomplish this goal. Encapsulation involves encasing cells in a semipermeable biocompatible hydrogel that allows the passage of nutrients and oxygen however blocks immune regulators from destroying the cell thus avoiding systemic drugs. Several advances in encapsulation engineering and cell viability promises to make this a revolutionary discovery. In this chapter, we will provide a review of islet encapsulation as used for the treatment of type 1 diabetes.

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Noninvasive evaluation of the vascular response to transplantation of alginate encapsulated islets using the dorsal skin-fold model

Cited by 25 publications

References 79 publications

Pancreatic islet blood flow and its measurement

Pancreatic islet blood flow and its measurement

Cryopreserved Alginate-Encapsulated Islets Can Restore Euglycemia in a Diabetic Animal Model Better than Cryopreserved Non-encapsulated Islets

Physical Protection of Pancreatic Islets for Transplantation

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