Omentum is better site than kidney capsule for growth, differentiation, and vascularization of immature porcine β-cell implants in immunodeficient rats.
BACKGROUND
Rapid revascularization of islet cell implants is important for engraftment and subsequent survival and function. Development of an adequate vascular network is expected to allow adaptive growth of the β-cell mass. The present study compares omentum and kidney capsule as sites for growth and differentiation of immature β-cell grafts.


METHODS
Perinatal porcine islet cell grafts were implanted in omentum or under kidney capsule of nondiabetic nude rats. Implants were compared over 10 weeks for their respective growth, cellular composition, number and size of β cells, their proliferative activity, and implant blood vessel density.


RESULTS
In both sites, the β-cell volume increased fourfold between weeks 1 and 10 reflecting a rise in β-cell number. In the omental implants, however, the cellular insulin reserves and the percent of proliferating cells were twofold higher than in kidney implants. In parallel, the blood vessel density in omental implants increased twofold, reaching a density comparable with islets in adult pig pancreas. A positive correlation was found between the percent bromodeoxyuridine-positive β cells and the vessel density.


CONCLUSIONS
Growth of the β-cell volume proceeds similarly in the omentum and under the kidney capsule. However, the omentum leads to higher insulin reserves and an increased pool of proliferating cells, which might be related to a more extended vascular network. Our observations support the omentum as an alternative site for immature porcine islet cells, with beneficial effects on proliferation and implant revascularization.
1 Unit Diabetes Pathology and Therapy, Diabetes Research Center, Brussels Free University-VUB, Brussels, Belgium. 2 Department of General and Abdominal Surgery, Universitair Ziekenhuis Brussel, Brussels, Belgium. 3 Department of Endocrinology and Metabolism, Rui-Jin Hospital, Shanghai, China. 4 Address correspondence to: Karine Hellemans, Prof., Dr., Unit Diabetes Pathology and Therapy, Diabetes Research Center, Brussels Free University-VUB, Laarbeeklaan 103, B-1090 Brussels, Belgium.
Kim
K
Bartholomeus
Daniel
D
Jacobs-Tulleneers-Thevissen
Sun
S
Shouyue
Krista
K
Suenens
Peter A
PA
In't Veld
Miriam
M
Pipeleers-Marichal
Daniel G
DG
Pipeleers
Karine
K
Hellemans
D000818:Animals; D001808:Blood Vessels / Q000473:pathology; D001973:Bromodeoxyuridine; D049109:Cell Proliferation; D002470:Cell Survival; D050416:Glucagon-Secreting Cells / Q000166:cytology; D007150:Immunohistochemistry; D007328:Insulin / Q000378:metabolism*; D050417:Insulin-Secreting Cells / Q000166:cytology*; D016381:Islets of Langerhans Transplantation / Q000379:methods*; D007668:Kidney / Q000473:pathology*; D008297:Male; D009852:Omentum / Q000473:pathology*; D051381:Rats; D011923:Rats, Nude; D017208:Rats, Wistar; D013552:Swine
D007328:Insulin; D001973:Bromodeoxyuridine