Effects of diabetes and hypoxia on gene markers of angiogenesis (HGF, cMET, uPA and uPAR, TGF-alpha, TGF-beta, bFGF and Vimentin) in cultured and transplanted rat islets.
OBJECTIVE
The vascularisation of newly transplanted islets originates from the recipients. Because islets transplanted into a diabetic do less well than those transplanted into a euglycaemic environment, we examined the hypothesis that gene expression of angiogenic factors in grafts is delayed in diabetes. These factors include hepatocyte growth factor (HGF) and its receptor c-MET, and urokinase plasminogen activator (uPA) and its receptor uPAR, basic fibroblast growth factor (bFGF), TGF-alpha and TGF beta-1.


METHODS
Isolated rat islets were studied in vitro under normoxic and hypoxic culture conditions and gene expression was determined with semi-quantitative multiplex RT-PCR. We found that HGF but not c-MET expression was induced by hypoxia in vitro. Using syngeneic Lewis rats, gene expression was also studied in grafts on days 1, 3, 5, 7 and 14 after transplantation.


RESULTS
In grafts of normoglycaemic rats, HGF expression was enhanced on day 3 and maintained whereas expression of c-MET fell and remained down until day 14. Expression of uPA was up at day 3 and remained high; expression of uPAR was also up at day 3 but then fell to control levels at day 14. Expression of bFGF, TGF-alpha and TGF beta-1 persisted throughout. Vimentin, a marker of fibroblasts, had increased expression at day 1 which was further enhanced in subsequent days. In the grafts of diabetic recipients the expression of HGF, uPA and uPAR were delayed, being clearly expressed at day 5 rather than day 3. Vimentin expression was similarly delayed.


CONCLUSIONS
This apparent delay in angiogenesis provides a potential mechanism for the less favourable outcomes of islets transplanted into diabetic recipients.
Vasir
B
B
Section on Islet Transplantation and Cell Biology, Joslin Diabetes Center, Boston, Massachusetts 02215, USA.
Reitz
P
P
Xu
G
G
Sharma
A
A
Bonner-Weir
S
S
Weir
G C
GC
D000818:Animals; D002478:Cells, Cultured; D003921:Diabetes Mellitus, Experimental / Q000235:genetics / Q000503:physiopathology* / Q000601:surgery; D016222:Fibroblast Growth Factor 2 / Q000032:analysis / Q000235:genetics*; D005819:Genetic Markers; D017228:Hepatocyte Growth Factor / Q000032:analysis / Q000235:genetics*; D007515:Islets of Langerhans / Q000098:blood supply*; D016381:Islets of Langerhans Transplantation / Q000502:physiology*; D008297:Male; D018919:Neovascularization, Physiologic; D019859:Proto-Oncogene Proteins c-met / Q000032:analysis / Q000235:genetics; D051381:Rats; D011917:Rats, Inbred Lew; D017207:Rats, Sprague-Dawley; D011956:Receptors, Cell Surface / Q000032:analysis / Q000235:genetics; D055293:Receptors, Urokinase Plasminogen Activator; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016211:Transforming Growth Factor alpha / Q000032:analysis / Q000235:genetics*; D016212:Transforming Growth Factor beta / Q000032:analysis / Q000235:genetics*; D014184:Transplantation, Homologous; D014568:Urokinase-Type Plasminogen Activator / Q000032:analysis / Q000235:genetics*; D014746:Vimentin / Q000032:analysis / Q000235:genetics
D005819:Genetic Markers; C524900:Plaur protein, rat; D011956:Receptors, Cell Surface; D055293:Receptors, Urokinase Plasminogen Activator; D016211:Transforming Growth Factor alpha; D016212:Transforming Growth Factor beta; D014746:Vimentin; D016222:Fibroblast Growth Factor 2; D017228:Hepatocyte Growth Factor; D019859:Proto-Oncogene Proteins c-met; D014568:Urokinase-Type Plasminogen Activator