Recombinant DNA Advisory Committee - 5/30-31/91 
assess the phenotypic effect on the patient and to assess engraftment of the transplanted cells. 
He noted that because the clinical issues of this research are difficult to assess, there are a 
series of associated clinical research protocols which will accompany this gene transfer 
protocol and as well a psychosocial protocol to address the difficult issue of informed consent 
which will include an assessment of the informed consent documents by means of a quiz to 
determine if the parents gained knowledge and insight into the procedure via the informed 
consent documents. He also added that a study is underway in which laboratory personnel 
are being screened for the presence of amphotrophic retroviruses and that currently there is 
no evidence to support any adverse exposure to laboratory workers. However, blood from 
laboratory workers is being frozen to ensure this safety issue is addressed. And finally, the 
team is going to suggest a registry be developed so that adverse reactions can be identified 
and the best long-term care can be provided to these patients. 
Dr. Ledley said the primary issue listed in the Federal Renter was to show that human 
hepatocytes could be transduced with the retrovirus. He noted that there were no samples 
of human hepatocytes available until two weeks prior to this meeting and that he had just 
received the data via Federal Express while at the meeting. He noted that Dr. Woo, a co- 
investigator, would present additional data on the hepatocellular transplantation in the mouse 
using a new detection method utilizing a fluorescent stain called dil, as well as an experiment 
performed in a baboon within the last month showing the feasibility of the approach. 
Dr. Ledley presented results of studies on residual liver from reduced orthotopic liver 
transplants which showed that one can prepare hepatocytes, culture them, and transduce them 
with a beta-galactosidase virus to show the right cells are being infected and then detection 
of LNL6 provirus using a PCR assay down to a sensitivity level of 1 in 10^ or possibly even 
1 in 10*^ cells 
Dr. Ledley then called on Dr. Savio Woo to present follow-up information on a dog 
experiment which was previously reported to the HGTS. Dr. Woo said that the dog was 
chosen as an intermediate model because going from the original mouse model to a human 
was too big a jump. He said 10 animals were done during the past 6 months in an attempt 
to learn how to isolate hepatocytes after partial hepatectomy. Initially only 10^ cells were 
isolated from a single lobe from a dog, but that now they can consistently isolate 3 billion 
hepatocytes from a single lobe, which is 20-25% of the liver mass of the animal. 
Dr. Woo said that initially they attempted to transplant non-transduced hepatocytes by direct 
injection into the spleen but that complications arose which forced them to seek another route 
of transplantation. They investigated the feasibility of transplanting the cells directly into the 
mesenteric vein, the splenic vein and the splenic artery by use of a catheter. Via this 
technique they were able to transplant 1 billion cells into each of the routes and are now 
satisfied that they have the technology for transplanting hepatocytes into these larger animals. 
They then used hepatocytes isolated from a dog and transduced with human 
a -1-antitrypsin containing retrovirus and performed autologous transplantation. This produced 
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Recombinant DNA Research, Volume 14 
