Advanced Tissue Sciences Inc. (ATS) announced Monday that ithas entered into an agreement with St. Jude Medical Inc. tostudy the feasibility of human tissue-engineered heart valves.St. Jude of St. Paul, Minn., has made a $5 million equityinvestment in ATS, gaining the exclusive right to license anytechnologies arising from the initial discovery phase.

St. Jude's purchase of 563,380 shares of ATS's stock representsonly the first stage of the collaboration, ATS's executivedirector of corporate development, Alana Wheeler, toldBioWorld. After conducting feasibility studies, which willcontinue for about one year, the companies may negotiate aresearch and development agreement. This could take the formof royalty and milestone payments to ATS of La Jolla, Calif.,from St. Jude or it could be a joint venture, she said.

ATS will take two approaches in its development of a tissue-engineered heart valve, Wheeler explained. The company willstudy the feasibility of seeding porcine heart valves withhuman skin cells, essentially growing human skin over a pig-derived valve. ATS will also attempt to apply its DermaGrafttechnology to heart valves, seeding a bioabsorbable polymerwith human skin cells. Under this approach, the polymershould eventually be entirely absorbed, leaving a fully humanvalve, said Wheeler.

Most heart valves currently on the market are mechanical, butpatients with mechanical valves are susceptible to bloodclotting and must remain permanently on anti-coagulantmedication. St. Jude also sells porcine heart valves, but thesegluteraldehyde-fixed valves are essentially embalmed as apreservative measure and as a means of avoiding transplantrejection problems by cross-linking proteins. After this processthe valves consist of non-viable tissue, Wheeler said. Inaddition, fully-porcine valves tend to attract calcium depositsand must eventually must be replaced, she said.

The agreement will allow St. Jude to explore a new approach toheart valve technology while offering ATS the opportunity toenter a new area of tissue engineering. ATS may eventuallyexplore the development of tissue-engineered replacements forblood vessels, Wheeler said. The companies estimated 1993worldwide sales of heart valves at $490 million, with St. Judecontrolling about a 48 percent share of this market, she noted.

ATS's stock (NASDAQ:ATIS) closed unchanged at $8.13 a shareon Monday. Last month the company completed a $20 millionstock offering to fund development of DermaGraft products.

-- Karl A. Thiel Associate Editor

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