Open Competition 1 - Biotechnology

Development and Testing of a Coronary, Tubular, Radioactive Stent from a New Ternary Alloy

Sponsor: Bio-Nucleonics, Inc.

• Project Performance Period: 9/1/2001 - 8/31/2004
• Total project (est.): $3,313,085.00
• Requested ATP funds: $1,496,135.00

Bio-Nucleonics proposes a research project to develop a new class of alloys for use in "stents," small metal slotted tubes that are implanted in arteries by surgeons to prevent the vessel walls from collapsing after surgery. Stents are routinely placed in patients' arteries after a procedure called "balloon angioplasty" is used to clear obstructions and blockages. Surgeons insert a stent at the site of the injury to prevent the collapse of the vessel walls. A large percentage of patients still develop restenosis -- a narrowing of the artery -- because of the build-up of excess cells around the stent as part of the healing process. Surgeons have reduced the restenosis rate by using stents coated with phosphorus-32, a radioactive isotope. The low-level radiation inhibits cell proliferation. Unfortunately, restenosis still can occur at the ends of the stent, possibly because the phosphorus is not evenly distributed at the stent edges. In addition, the half-life of phosphorus-32 is longer than necessary for preventing restenosis, the energy of its radiation is stronger than necessary to treat the injured arterial wall, and there is potential for the radioactive phosphorus to leach from the coating and be carried to bone marrow, where blood cells are formed. To solve these problems, Bio-Nucleonics has developed a new class of biocompatible alloys that combine nickel, titanium, and an element that can be made radioactive by irradiation in a nuclear reactor. The alloy is "superelastic" -- it has an almost rubber-like springiness -- which is important for use in stents. When irradiated the added element becomes radioactive and emits shallow-penetrating, low-energy beta radiation with a half-life shorter than phosphorus-32. Since the radionuclide is integral to the alloy, it is expected to be evenly distributed throughout the stent and not leach out. Bio-Nucleonics has demonstrated the ability to make the basic alloy, but there are a number of important unknowns, such as the optimal radioactivity required for the stent to deliver an effective dose to the artery site. Bio-Nucleonics is a small company that requires ATP support to complete the development work in a reasonable time. If successful, the new material could dramatically reduce the number of cases of restenosis that require repeat angioplasty -- a condition that costs the United States over $6 billion annually. The alloy also could prove useful for other medical procedures that require controlled delivery of low-dose radiation. The University of South Florida (Tampa), the University of Central Florida (Orlando), and Vanderbilt University (Nashville, Tenn.) will assist in the research.

For project information:

Rosanne Satz, (305) 576-0996
bionucmed@aol.com

ATP Project Manager

Thomas Wiggins, (301) 975-5416
thomas.wiggins@nist.gov