Improved survival of biolistically transfected mouse islet allografts expressing CTLA4-Ig or soluble Fas ligand.
BACKGROUND
Pancreatic islet transplantation is limited because of immune rejection of the transplanted tissue. Long-term survival of allogeneic pancreatic islet grafts in the absence of systemic immunosuppressive agents should be possible by transfecting the islets directly with DNA encoding immunoregulatory molecules. Localized production of these molecules should affect only the immune cells that come into the vicinity of the foreign tissue. We investigated whether local expression of human CTLA4-Ig or soluble human Fas ligand from biolistically transfected mouse islets would have a protective effect on allograft survival.


METHODS
Isolated CBA (H2k) islets were biolistically transfected using the gene gun. The experimental groups were naked gold particles (n=6), empty vector DNA (n=5), DNA encoding human CTLA4-Ig (n=8), or soluble human Fas ligand (n=5). Secretion of the transfected gene product was confirmed by screening islet culture supernatants for protein production using a sandwich ELISA. The blasted islets were transplanted under the kidney capsule of alloxan-diabetic BALB/c (H2d) recipients.


RESULTS
Control grafts survived for 23 days, on average. CTLA4-Ig-transfected islets showed a bimodal distribution: 50% of cases survived > or = 46 days and 50% were similar to the controls. In the soluble human Fas ligand group, 80% of grafts survived > or = 50 days. There was no correlation between graft survival times and pretransplant levels of protein production.


CONCLUSIONS
Our results indicate that local production of human CTLA4-Ig or soluble human Fas ligand by biolistically transfected islets can promote allograft survival. This approach should be valuable as a potential immunoprotective therapeutic strategy in tissue transplantation.
Surgical-Medical Research Institute and Department of Surgery, University of Alberta, Edmonton, Canada.
A L
AL
Gainer
W L
WL
Suarez-Pinzon
W P
WP
Min
J R
JR
Swiston
C
C
Hancock-Friesen
G S
GS
Korbutt
R V
RV
Rajotte
G L
GL
Warnock
J F
JF
Elliott
D000069594:Abatacept; D000818:Animals; D015703:Antigens, CD; D000943:Antigens, Differentiation / Q000502:physiology*; D060908:CTLA-4 Antigen; D053222:Fas Ligand Protein; D006046:Gold / Q000494:pharmacology; D006085:Graft Survival; D018796:Immunoconjugates; D016381:Islets of Langerhans Transplantation; D008562:Membrane Glycoproteins / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008808:Mice, Inbred CBA; D014162:Transfection; D014184:Transplantation, Homologous
D015703:Antigens, CD; D000943:Antigens, Differentiation; D060908:CTLA-4 Antigen; C556706:CTLA4 protein, human; C556707:Ctla4 protein, mouse; C505661:FASLG protein, human; D053222:Fas Ligand Protein; C505658:Fasl protein, mouse; D018796:Immunoconjugates; D008562:Membrane Glycoproteins; D006046:Gold; D000069594:Abatacept