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Engineered vascular beds provide key signals to pancreatic hormone-producing cells.

ABSTRACT: The mechanisms underlying early islet graft failure are not entirely clear, but are thought to involve ischemic injury due to delayed vascularization. We hypothesize that blood vessels play an active role in cell-cell communications supporting islet survival and engraftment. To test this hypothesis and to uncouple endothelial cell (EC)-generated signaling stimuli from their nutritional and gas exchange functions, we developed three dimensional (3D) endothelial vessel networks in engineered pancreatic tissues prepared from islets, fibroblasts and ECs. The tri-culture setup, seeded on highly porous biocompatible polymeric scaffolds closely mimics the natural anatomical context of pancreatic vasculature. Enhanced islet survival correlating with formation of functional tube-like endothelial vessels was demonstrated. Addition of foreskin fibroblasts to islet-endothelial cultures promoted tube-like structure formation, which further supported islet survival as well as insulin secretion. Gene expression profiles of EC growth factors, extracellular matrix (ECM), morphogenes and differentiation markers were significantly different in 2D versus 3D culture systems and were further modified upon addition of fibroblasts. Implantation of prevascularized islets into diabetic mice promoted survival, integration and function of the engrafted engineered tissue, supporting the suggested role of ECs in islet survival. These findings present potential strategies for preparation of transplantable islets with increased survival prospects.

SUBMITTER: Kaufman-Francis K

PROVIDER: S-EPMC3395696 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

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Engineered vascular beds provide key signals to pancreatic hormone-producing cells.

Kaufman-Francis Keren K Koffler Jacob J Weinberg Noa N Dor Yuval Y Levenberg Shulamit S

PloS one 20120712 7

The mechanisms underlying early islet graft failure are not entirely clear, but are thought to involve ischemic injury due to delayed vascularization. We hypothesize that blood vessels play an active role in cell-cell communications supporting islet survival and engraftment. To test this hypothesis and to uncouple endothelial cell (EC)-generated signaling stimuli from their nutritional and gas exchange functions, we developed three dimensional (3D) endothelial vessel networks in engineered pancr ...[more]

PMID: 22808248

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Project description:Pancreatic cancer is a lethal disease accounting for the fourth leading cause of cancer death in USA. Focal adhesion kinase (FAK) and the insulin-like growth factor-I receptor (IGF-1R) are tyrosine kinases that activate common pathways, leading to increased proliferation and cell survival. Sparse information is available regarding their contribution to the malignant behavior of pancreatic cancer. We analyzed the relationship between FAK and IGF-1R in human pancreatic cancer cells, determined which downstream signaling pathways are altered following kinase inhibition or downregulation and studied whether dual kinase inhibition represents a potential novel treatment strategy in this deadly disease. Using immunoprecipitation and confocal microscopy, we show for the first time that FAK and IGF-1R physically interact in pancreatic cancer cells and that inhibition of tyrosine phosphorylation of either kinase disrupts their interaction. Decreasing phosphorylation of either FAK or IGF-1R alone resulted in little inhibition of cell viability or increased apoptosis. However, dual inhibition of FAK, using either a dominant-negative construct (FAK-CD) or small interfering RNA, and IGF-1R, using a specific small molecule tyrosine kinase inhibitor (AEW-541) or stable expression of a truncated, mutated IGF-1R, led to a synergistic decrease in cell proliferation and phosphorylation of extracellular signal-regulated kinase (ERK) and increase in cell detachment and apoptosis compared with inhibition of either pathway alone. Dual kinase inhibition with FAK-CD and AEW-541 resulted in a marked increase in apoptosis when FAK was displaced from the focal adhesions. Inhibition of both tyrosine kinase activities via a novel single small molecular inhibitor (TAE 226), at low doses specific for FAK and IGF-1R, resulted in significant inhibition of cell viability, decrease in phosphorylation of ERK and Akt and increase in apoptosis accompanied by cleavage of Poly (ADP-ribose) polymerase (PARP) and activation of caspase-3 in pancreatic cancer cells. Thus, simultaneous inhibition of both tyrosine kinases represents a potential novel therapeutic approach in human pancreatic adenocarcinoma.

Project description:Background The purpose of this study was to investigate the association between kidney function and arterial calcification in major vascular beds and to establish whether arterial calcification mediates the relation between kidney function measures and cardiovascular disease ( CVD ) incidence. Methods and Results In 2241 participants from the Rotterdam Study (mean age 69 years, 52% female), kidney function was assessed using the estimated glomerular filtration rate and urine albumin-to-creatinine ratio. All participants underwent noncontrast computed tomography to quantify the amount of arterial calcification in the coronary arteries, aortic arch, extracranial, and intracranial internal carotid arteries. We used linear regression models, adjusted for age, sex, and cardiovascular risk factors, to evaluate the association between kidney function and arterial calcification volume in the 4 vessel beds. Incidence rate of CVD was calculated in 3 groups of participants based on their kidney function and presence of arterial calcification. We conducted mediation analysis to evaluate whether arterial calcification mediates this association. We found that in age- and sex-adjusted models, lower estimated glomerular filtration rate and higher albumin-to-creatinine ratio were associated with larger calcification volumes in all 4 vascular beds. Adjusting for cardiovascular risk factors attenuated the effect estimates. CVD incidence was higher in participants with estimated glomerular filtration rate <60 mL/min per 1.73 m2 and presence of arterial calcification compared with individuals with estimated glomerular filtration rate >60 and no calcification. After adjusting for cardiovascular risk factors, arterial calcification did not mediate the association between kidney function measures and CVD incidence. Conclusions The association of impaired kidney function and larger volumes of arterial calcification is partly explained by cardiovascular risk factors. Arterial calcification does not mediate the association between kidney function and CVD beyond cardiovascular risk factors.

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Engineered vascular beds provide key signals to pancreatic hormone-producing cells.

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Engineered vascular beds provide key signals to pancreatic hormone-producing cells.

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