Biodegradable Stents Future Solutions

1. Coronary Stents Design
Part C – Biodegradable stents and
Future Solutions
Dr. Amir Kraitzer
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2. Biodegradable Stents (BDS)

3. Rational for Biodegradable stents
Metal stent drawbacks Biodegradable stent advantages
 Cause permanent physical  May eliminate early and late
irritation complications of bare-metal
 Risk of long term endothelial stents
 Restore the vasoreactivity
dysfunction and chronic
 Allow a gradual transfer of the
inflammation
 Metal have thrombogenic
mechanical load to the vessel
 Higher capacity for drug
properties incorporation and complex
 Inability for the vessel to release kinetics
restore its a normal  Facilitate re-intervention
physiology
The need for a permanent prosthesis decreases
dramatically 6 months post-implantation

4. Design considerations
 Overall time and rate of degradation
 a very rapid degradation rate can be associated with
inflammation
 Biocompatibility of degradation products to prevent
toxicity
 Mechanical properties
 Mechanical recoil
 Strut size
 Creep
 Embolization of degraded particles
 Drug load
 Radiopacity

5. Igaki-Tamai BDS
 A bioresorbable zigzag coil design
 PLLA (Initial MW=183KDa)
 Initial clinical trial results proved
efficacy and safety (2000)
 On November 2007 the stent
obtained CE mark indicated for
peripheral artery
 Igaki Tamai Stents loaded with
ST638 (Tranilast) reduced
neointima formation in animals

6. BVS (Abbott) Drug Eluting BDS
 Drug: Everolimus
 Base Polymer: PLLA
 Coating: PDLLA
 Releases 80% of its drug in 28 days
 Maintains radial strength for 3
months
 Mass loss after 6 months, complete
resorption in two years
 Good clinical outcomes with two
years follow-up
 No occurrence of thrombosis
between 6 and 24 months
Source: Abbott Vascular, AP2929018Rev A

7. Stent Functionality phases
Richard J Rapoza, PhD presented at the ICI meeting of 2009, Tel Aviv, Israel

8. REVA Drug Eluting BDS
 Drug: Paclitaxel
 Base polymer: Tyrosine-
derived polycarbonate platform
 Low recoil (<1%)
 Slide and lock design
 Tunable resorption rate
 Radiopacity is achieved by the
incorporation of iodine
molecules

9. Absorbable Magnesium Stent
(Medtronic)
 Radial strength and recoil is
similar to BMS
 4-month clinical results: late
loss is comparable to BMS
 Further improvement in stent
design due to:
 Early recoil
 Fast degradation
 Neointima formation

10. BDS Summary

12. New Concepts
 Pro-healing approach
 Drug eluting balloon

13. Endothelial Progenitor Cells Capture

14. Genous Stent
 Precilinical trials
 1 hour post- deployment:
90% cell coverage
 1st Clinical trial
demonstrated safety
and feasibility
 2nd Clinical trial
demonstrated late loss
is comparable to BMS
Endothelial Progenitor Cell Capture by Stents Coated With
Antibody Against CD34 : The HEALING-FIM Registry, Aoki et
al, J. Am. Coll. Cardiol. 2005;45;1574-1579

15. Drug eluting balloon
SeQuent® Please
 Provides uniform drug dose
 Reduces thrombosis risk and
enables shorter dual anti-
platelet regimen
 Allows significantly lower drug
dose compared with DES
 Two forms of release
 Drug and spacer
 Nanoparticles

16. Core/shell fiber structure concept
I. Good mechanical properties
II. Effective drug release profile
III. Porous structured coating
allows controlled release

17. In-Vitro FTS Release
Effect of coating’s porosity
50/50 PDLGA 75/25 PDLGA
Porous coating
Porous coating
Dense coating
Dense coating

18. References
 Amir Kraitzer, Yoel Kloog, Meital Zilberman, Approaches for
Prevention of Restenosis, J Biomed Mater Res Part B: Appl
Biomater 85B: 583–603, 2008
 Gladius Lewis, Review: Materials, Fluid Dynamics, and Solid
Mechanics Aspects of Coronary Artery Stents: A State-of-the-Art
Review, Biomed Mater Res Part B: Appl Biomater 86B: 569–590,
2008
 Meital Zilberman, Amir Kraitzer, Orly Grinberg and Jonathan J.
Elsner, Drug-Eluting Medical Implants, In : Handbook of European
Pharmacology, 2008
 Update on Bioabsorbable Stents: From Bench to Clinical, RON
WAKSMAN, Journal of Interventional Cardiology, Vol. 19, No. 5,
2006

19. Thank you