Appeal No. 2002-1671 Page 13
Application No. 08/993,985
Berg's invention relates to intravascular stents for treatment of injuries to blood
vessels and particularly to stents having a framework onto which a therapeutic
substance or drug is applied. Berg teaches (column 3, lines 29-45) that the underlying
structure of the stent can be virtually any stent design, whether of the self-expanding
type or of the balloon-expandable type. Berg further teaches (column 4, lines 35-53)
that
[t]he polymer chosen [for the stent] must be a polymer that is
biocompatible and minimizes irritation to the vessel wall when the stent is
implanted. The polymer may be either a biostable or a bioabsorbable polymer
depending on the desired rate of release or the desired degree of polymer
stability, but a bioabsorbable polymer is probably more desirable since, unlike a
biostable polymer, it will not be present long after implantation to cause any
adverse, chronic local response. Bioabsorbable polymers that could be used
include poly(L-lactic acid), polycaprolactone, poly(lactide-co-glycolide),
poly(hydroxybutyrate), poly(hydroxybutyrate-co-valerate), polydioxanone,
polyorthoester, polyanhydride, poly(glycolic acid), poly(D,L-lactic acid),
poly(glycolic acid-co-trimethylene carbonate), polyphosphoester,
polyphosphoester urethane, poly(amino acids), cyanoacrylates, poly(trimethylene
carbonate), poly(iminocarbonate), copoly(ether-esters) (e.g. PEO/PLA),
polyalkylene oxalates, polyphosphazenes and biomolecules such as fibrin,
fibrinogen, cellulose, starch, collagen and hyaluronic acid.
In applying the test for obviousness, we reach the conclusion that the combined
teachings of Chaikof and Berg would have made it obvious at the time the invention
was made to a person of ordinary skill in the art to have formed Chaikof's reinforcing
fibers 8 (which constitute the structural support) from a bioabsorbable polymer in view
of (1) Chaikof's teaching that reinforcing fibers 8 can be made from any biocompatable
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