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Industry's First Reproducible Cloning of Pigs Reported in 'Nature Biotechnology'.

- New Cloning Technique Offers Greater Potential for Use in

Xenotransplantation Than Earlier Reports -

DEFOREST, Wis., Sept. 27 /PRNewswire/ --

Two litters of "cloned" pigs have been successfully produced using nuclear transfer (NT) and more litters are on the way, demonstrating the commercial feasibility of porcine cloning. The NT technique described in the October 2000 issue of "Nature Biotechnology" greatly improves prospects for the genetic manipulation of pigs to provide organs and tissues for transplantation. The report is co-authored by scientists from Infigen, Inc., a privately held biotechnology company in DeForest, WI., and Imutran, Ltd., a UK-based subsidiary of Novartis Pharma AG. The Infigen/Imutran protocol has produced two litters, each of two male piglets, born in July and September.

Somatic cells that were cultured for periods of eight and twenty-two days were fused with enucleated oocytes to produce the embryos that developed into the two litters. In this NT process the genetic material, contained in the nucleus, is transferred from the somatic cell to the oocyte and its developmental potential is "reprogrammed." Currently, multiple pregnancies are ongoing, derived from donor cells that have been cultured for up to ninety days. This ability to culture the donor cells for extended periods is a prerequisite for gene transfer and gene targeting strategies.

"The publication recognizes the industry's first successive litters of cloned pigs, animals which hold enormous promise as a source of new treatments for millions of people suffering from advanced diseases of numerous types," said Michael Bishop, Ph.D., President of Infigen, and corresponding author of the paper.

"Our optimized nuclear transfer approach offers the first reproducible means for producing these valuable animals for xenotransplantation, as well as the production of pharmaceutical proteins, and the enhancement of pig breeding programs worldwide."

Past research has demonstrated that pig organs -- eg, kidneys, hearts, lungs, liver and other tissues -- are immunologically incompatible with humans. A hyperacute rejection reaction is stimulated by certain human antibodies specific for a sugar structure (Gal-alpha-1,3-Gal epitope) on the surface of pig endothelial cells. "Knock-out" or deletion of the gene that creates this epitope has not been possible in pigs to date. It is hoped that the "knock-out" of this epitope, when combined with Imutran's proprietary genetic modifications, will lead to extended survival times for porcine xenotransplants.

Simon Thompson, Ph.D., of Imutran and co-author of the paper, stated that the somatic cell nuclear transfer process described in the "Nature Biotechnology" report is "promising progress towards knocking-out pig genes," enhancing the prospects for overcoming immune rejection in a human recipient.

"In the mouse it is possible to make very precise modifications to the genome, including the inactivation of genes or groups of genes by gene targeting. The nuclear transfer procedure described in this paper is a significant step towards gene targeting in the pig, which can be employed to develop tissues and organs for transplantation," said Dr. Thompson.

Infigen/Imutran researchers anticipate that the extended culture of donor cells for nuclear transfer -- described for the first time in the "Nature Biotechnology" report -- will offer important advantages for the development of porcine xenografts:

* More efficient generation of transgenic pigs, through the evaluation

of the transgene integration site during the cell culture phase,

rather than following establishment of a transgenic line.

* Potential for gene targeting to delete genes that contribute to

organ rejection or to improve safety.

The report, "Production of cloned pigs from in vitro systems," was published in the October 2000 issue of "Nature Biotechnology" (vol. 18). In addition to Drs. Bishop and Thompson, coauthors included J. Betthauser, E. Forsberg, M. Augenstein, L. Childs, K. Eilertsen, J. Enos, T. Forsythe, P. Golueke, G. Jurgella, R. Koppang, T. Lesmeister, K. Mallon, G. Mell, P. Misica, M. Pace, M. Pfister-Genskow, N. Strelchenko, G. Voelker, and S. Watt, all of Infigen, Inc.

Earlier this year, Infigen was issued a fundamental U.S. patent that covered critical processes for cloning any mammal utilizing nuclear transfer technology (NT). The patent, US Patent No. 6,077, 710, covers essential steps for the activation of an enucleated oocyte, once a donor cell has been fused into its cytoplasm -- a final stage of a process that enables a fully grown mammal to be cloned from a single cell. The awarded patent affords Infigen a controlling position for all potential uses of NT-related cloning of mammalian cells, including livestock such as cattle and pigs, for all agricultural and human health applications worldwide.

In 1998, Infigen partnered with Pharming Holding, N.V., of Leiden, the Netherlands, for the development and commercialization of pharmaceutical products produced in the milk of transgenic animals. The goal is to provide safe, unlimited, cost-effective supplies of therapeutic proteins to treat patients with various diseases.

Infigen is the world's leading company for the commercial development of proprietary nuclear transfer cloning in the human health and animal agriculture industries. Recently, the company disclosed it has produced the world's largest herd of transgenic and non-transgenic cloned cattle from different cell lines (adult and fetal types), for the production of varied pharmaceutical protein products, in partnership with Pharming N.V. Located in DeForest, WI, Infigen has formed alliances with such industry leaders as Imutran Ltd. (a wholly owned subsidiary of Novartis Pharma AG) of Cambridge, UK to develop nuclear transfer in pigs for xenotransplantation.

This release contains certain forward-looking statements which involve known and unknown risks, delays, uncertainties and other factors not under the Company's control which may cause actual results, performance or achievements of the Company to be materially different from the results, performance or other expectations implied by these forward-looking statements. These factors include results of current or pending research and development activities, actions by the FDA and other regulatory authorities, and other activities.
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