Liver as an ideal target for gene therapy: expression of CTLA4Ig by retroviral gene transfer.
OBJECTIVE
Liver has been a target organ for gene therapy as it plays a central role in metabolism and production of serum proteins. Many metabolic disorders result from a deficiency of liver-derived protein products. In transplantation settings, modulation of the immune responses caused by CTLA4Ig protein has been shown to be an attractive direction. In this study, we investigated the efficacy of hepatocyte transduction via introduction of the exogenous CTLA4Ig gene to the rat liver graft by retrovirus vector, and examined the presence of target serum protein after gene transfers.


METHODS
We constructed a replication defective retroviral vector that contained the CTLA4Ig gene. The liver graft regeneration index was first examined by 5-bromo-2-deoxyuridine, Ki-67 and proliferating cell nuclear antigen antibodies to determine the optimal time of gene transduction. The liver graft was then perfused with the retroviral vector, and animals were killed at constant time points to examine for the presence of CTLA4 protein in the graft and peripheral blood.


RESULTS
CTLA4 protein was detected on postoperative days 5, 9 and 14, with liver graft tissue transduction indexes of 7.2, 10.9 and 1.8, respectively. Blood protein levels were at 151.6, 26.5 and 21.4 rhog/mL, respectively. A transduction index reaching 22.1 was observed in the graft with the most rapid liver regeneration.


CONCLUSIONS
We had established the gene delivery model in rat with auxiliary partial liver transplantation. Expression of the exogenous gene delivered by retrovirus was demonstrated in the liver with secretion of diffusible protein in the bloodstream. The present study provides important information for gene transfer using the liver to produce the target protein in situ and as serum protein. This will also be applicable to the treatment of other metabolic diseases.
Cheung
Siu Tim
ST
Department of Surgery and Center for the Study of Liver Disease, The University of Hong Kong Medical Center, Queen Mary Hospital, Hong Kong. stcheung@hkucc.hku.hk
Tsui
Tung Yu
TY
Wang
Wei Lin
WL
Yang
Zhen Fan
ZF
Wong
San Yu
SY
Ip
Ying Chi
YC
Luk
John
J
Fan
Sheung Tat
ST
D000069594:Abatacept; D000818:Animals; D015703:Antigens, CD; D000943:Antigens, Differentiation / Q000235:genetics* / Q000378:metabolism; D060908:CTLA-4 Antigen; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors; D018796:Immunoconjugates; D019394:Ki-67 Antigen / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D008115:Liver Regeneration / Q000502:physiology; D016031:Liver Transplantation; D008297:Male; D023421:Models, Animal; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D051381:Rats; D011917:Rats, Inbred Lew; D011993:Recombinant Fusion Proteins / Q000235:genetics* / Q000378:metabolism; D012190:Retroviridae / Q000235:genetics*; D014162:Transfection
D015703:Antigens, CD; D000943:Antigens, Differentiation; D060908:CTLA-4 Antigen; C556708:Ctla4 protein, rat; D018796:Immunoconjugates; D019394:Ki-67 Antigen; D018809:Proliferating Cell Nuclear Antigen; D011993:Recombinant Fusion Proteins; D000069594:Abatacept