Pig embryonic pancreatic tissue as a source for transplantation in diabetes: transient treatment with anti-LFA1, anti-CD48, and FTY720 enables long-term graft maintenance in mice with only mild ongoing immunosuppression.
OBJECTIVE
Defining an optimal costimulatory blockade-based immune suppression protocol enabling engraftment and functional development of E42 pig embryonic pancreatic tissue in mice.


METHODS
Considering that anti-CD40L was found to be thrombotic in humans, we sought to test alternative costimulatory blockade agents already in clinical use, including CTLA4-Ig, anti-LFA1, and anti-CD48. These agents were tested in conjunction with T-cell debulking by anti-CD4 and anti-CD8 antibodies or with conventional immunosuppressive drugs. Engraftment and functional development of E42 pig pancreatic tissue was monitored by immunohistology and by measuring pig insulin blood levels.


RESULTS
Fetal pig pancreatic tissue harvested at E42, or even as early as at E28, was fiercely rejected in C57BL/6 mice and in Lewis rats. A novel immune suppression comprising anti-LFA1, anti-CD48, and FTY720 afforded optimal growth and functional development. Cessation of treatment with anti-LFA1 and anti-CD48 at 3 months posttransplant did not lead to graft rejection, and graft maintenance could be achieved for >8 months with twice-weekly low-dose FTY720 treatment. These grafts exhibited normal morphology and were functional, as revealed by the high pig insulin blood levels in the transplanted mice and by the ability of the recipients to resist alloxan induced diabetes.


CONCLUSIONS
This novel protocol, comprising agents that simulate those approved for clinical use, offer an attractive approach for embryonic xenogeneic transplantation. Further studies in nonhuman primates are warranted.
Tchorsh-Yutsis
Dalit
D
Department of Immunology, The Weizmann Institute of Science, Rehovot, Israel.
Hecht
Gil
G
Aronovich
Anna
A
Shezen
Elias
E
Klionsky
Yael
Y
Rosen
Chava
C
Bitcover
Rivka
R
Eventov-Friedman
Smadar
S
Katchman
Helena
H
Cohen
Sivan
S
Tal
Orna
O
Milstein
Oren
O
Yagita
Hideo
H
Blazar
Bruce R
BR
Reisner
Yair
Y
D000818:Animals; D015703:Antigens, CD / Q000276:immunology; D000071178:CD48 Antigen; D000068876:Fingolimod Hydrochloride; D006084:Graft Rejection / Q000276:immunology; D006085:Graft Survival / Q000276:immunology; D007165:Immunosuppression Therapy / Q000379:methods; D016169:Lymphocyte Function-Associated Antigen-1 / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D010179:Pancreas / Q000196:embryology; D016035:Pancreas Transplantation; D011409:Propylene Glycols / Q000276:immunology / Q000627:therapeutic use; D051381:Rats; D011917:Rats, Inbred Lew; D013110:Sphingosine / Q000031:analogs & derivatives / Q000276:immunology / Q000627:therapeutic use; D013552:Swine; D014183:Transplantation, Heterologous / Q000276:immunology*
D015703:Antigens, CD; D000071178:CD48 Antigen; C000604065:CD48 protein, human; C000604066:Cd48 protein, mouse; C000604067:Cd48 protein, rat; D016169:Lymphocyte Function-Associated Antigen-1; D011409:Propylene Glycols; D000068876:Fingolimod Hydrochloride; D013110:Sphingosine