cytes in culture, and human PAH mRNA accumu- 
lated in the infected cells to a level comparable 
with that in normal human liver. The next area to 
be investigated is the reintroduction of such hepa- 
tocytes into living animals to determine their surviv- 
ability, as well as functionality, in vivo. To investi- 
gate the efficacy of hepatocyte transplants and to 
avoid complications of immunological rejection of 
engrafted cells, Dr. Woo and his colleagues used a 
transgenic mouse model expressing high levels of 
human a^-antitrypsin. This human protein is syn- 
thesized in the transgenic liver and secreted into 
blood, where it can be detected by a radioimmuno- 
assay utilizing an antibody preparation that is spe- 
cific for the human protein. Furthermore, the trans- 
genic mouse was created in C57 black mice, and 
hepatocytes from these animals can be trans- 
planted into nontransgenic C57 black mice, so that 
there will be no immunological rejections in vivo. 
A. Transplantation of hepatocytes in neovessels. A 
variety of inert carriers have recently been reported 
in the literature that may serve as support for he- 
patocyte transplants. Cytodex 3 is a collagen bead 
onto which primary hepatocytes can be attached 
and injected into the peritoneal cavity. Alternatively, 
hepatocytes can be seated into a collagen/gelatin 
matrix that has previously been coated with an an- 
giogenesis factor, and the gel foam can then be im- 
planted onto the liver. Impressive vascularization 
into the neovessel occurs within days of transplant. 
PUBLICATIONS 
With both methods, human a^-antitrypsin can 
be readily detected in plasma of the transplanted 
mice. Unfortunately the level of the human protein 
in mouse plasma underwent a steady decline 
with time and became undetectable after several 
weeks. Retrieval of the neovessel and staining for 
glucose-6-phosphatase demonstrated that there 
were few hepatocytes left at that stage. Thus the 
neovessel does not appear to be a promising means 
of reintroducing primary hepatocytes into living 
animals. 
B. Transplantation of hepatocytes through the 
portal vein. Primary transgenic hepatocytes were 
injected directly into the portal vein of congenic 
mice, and the production of human a^-antitrypsin 
in plasma was observed within a day. The level con- 
tinues to increase and reaches a plateau after about 
a week. This level is maintained after three months 
of transplantation, suggesting the transplanted he- 
patocytes must have established themselves in 
vivo. Furthermore, the level of human a^-anti- 
trypsin accumulation in mouse plasma suggests 
that 20% of the transplanted hepatocytes remain 
functional after transplantation. Although these re- 
sults are preliminary, engraftment of virally infected 
hepatocytes may be explored as a means of somatic 
gene therapy for hepatic deficiencies such as PKU. 
Dr. Woo is also Professor of Cell Biology and Mo- 
lecular Genetics at Baylor College of Medicine. 
Books and Chapters of Books 
Scriver, C.R., Kaufman, S., and Woo, S.L.C. 1989. Hyperphenylalaninemia. In The Metabolic Basis of Inher- 
ited Disease (Scriver, C.R., Beaudet, A.L. , Sly WS., and Valle, P. , Eds.). New York: McGraw-Hill, pp 495- 
533. 
Woo, S.L.C. 1989. Phenylketonuria: molecular basis and clinical applications. In Molecular Genetics in Dis- 
eases of Brain, Nerve, and Muscle (Rowland, L.R, Wood, D.S., Schon, E.A., and DiMauro, S., Eds.). New 
York: Oxford University Press, pp 221-234. 
Articles 
Carlson, J.A., Rogers, B.B., Sifers, R.N., Finegold, M.J., Clift, S.M., DeMayo, F.J., Bullock, D.W, and Woo, S.L.C. 
1989. Accumulation of PiZ a^-antitrypsin causes liver damage in transgenic mice. / Clin Invest 83:1183- 
1190. 
Carlson, J.A., Rogers, B.B., Sifers, R.N., Hawkins, H.K., Finegold, M.J., and Woo, S.L.C. 1988. Multiple tissues 
express alpha ^-antitrypsin in transgenic mice and man. / Clin Invest 82:26-36. 
Cheng, S.Y, Martin, G.R., Nadeau, J.H., Haines, J.L., Bucan, M., Kozak, C.A., MacDonald, M.E., Lockyer, J.L., 
Ledley F.D. , Woo, S.L.C , Lehrach, H., Gilliam, T.C., and Gusella, J.F. 1989. Synteny on mouse chromosome 
5 of homologs for human DNA loci linked to the Huntington disease gene. Genomics 4:419-426. 
Continued 
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