Isolated pancreatic islets in three-dimensional matrices are responsive to stimulators and inhibitors of angiogenesis.
The formation of a new microvasculature is essential for the long-term survival and function of the islet graft. In this study we examined endothelium of isolated pancreatic islets by stimulation with growth factors, different culture conditions, and genetic modification. We also inspected the effect of immunosuppressives used in human transplantation on angiogenesis. Isolated islets were embedded in a three-dimensional fibrin or Matrigel matrix. The effect of hyperglycemia, hypoxia, and the addition of VEGF and bFGF was investigated. We exposed islets from transgenic mice expressing the VEGF gene (RIP1VEGF-A) to high glucose (16.7 mmol/L) medium and tested the immunosuppressive agents rapamycin (100 ng/ml) and FK506 (100 ng/ml). To quantify angiogenesis the percentage of sprouting islets was determined. New endothelial capillary-like structures protruded from isolated pancreatic islets. Addition of VEGF to the islets and transgenic RIP-VEGF islets showed a two- to threefold increase of sprouting islets compared to control. Hypoxic culture conditions stimulated angiogenesis, resulting in a twofold increase of capillary sprouting. Rapamycin and FK506 proved to be potent inhibitors of angiogenesis in this system, because a decrease of sprouting islets of more than 20% by both agents was observed. Isolated pancreatic islets are capable of forming new capillary structures and are susceptible to pro- and antiangiogenic stimuli.
Kidszun
André
A
Medical Clinic and Policlinic 3, Justus Liebig University, Rodthohl 6, 35392 Giessen, Germany.
Schneider
Darius
D
Erb
Doris
D
Hertl
Gundula
G
Schmidt
Veronika
V
Eckhard
Michael
M
Preissner
Klaus T
KT
Breier
Georg
G
Bretzel
Reinhard G
RG
Linn
Thomas
T
D043925:Angiogenesis Inducing Agents / Q000494:pharmacology*; D020533:Angiogenesis Inhibitors / Q000494:pharmacology*; D000818:Animals; D002196:Capillaries / Q000187:drug effects; D002417:Cattle; D015687:Cell Hypoxia / Q000187:drug effects; D002469:Cell Separation / Q000379:methods*; D003094:Collagen / Q000378:metabolism*; D004338:Drug Combinations; D005260:Female; D020690:GTPase-Activating Proteins / Q000378:metabolism; D006133:Growth Substances / Q000494:pharmacology; D006801:Humans; D006943:Hyperglycemia / Q000473:pathology; D007150:Immunohistochemistry; D007166:Immunosuppressive Agents / Q000494:pharmacology; D007515:Islets of Langerhans / Q000098:blood supply* / Q000166:cytology / Q000187:drug effects*; D007797:Laminin / Q000378:metabolism*; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D018919:Neovascularization, Physiologic / Q000187:drug effects*; D011509:Proteoglycans / Q000378:metabolism*; D051381:Rats; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis / Q000378:metabolism
D043925:Angiogenesis Inducing Agents; D020533:Angiogenesis Inhibitors; D004338:Drug Combinations; D020690:GTPase-Activating Proteins; D006133:Growth Substances; D007166:Immunosuppressive Agents; D007797:Laminin; D011509:Proteoglycans; C490620:Ralbp1 protein, mouse; D042461:Vascular Endothelial Growth Factor A; C059485:matrigel; D003094:Collagen