This document discusses biodegradable coronary stents and future solutions. It notes that metal stents have drawbacks like permanent irritation and inability to restore normal vessel physiology. Biodegradable stents aim to eliminate these issues by degrading over time and allowing the vessel to heal. Design considerations for biodegradable stents include degradation rate, biocompatibility, mechanical properties, and drug loading. Examples of biodegradable stents discussed include the Igaki-Tamai stent, Abbott's everolimus-eluting stent, and REVA's paclitaxel-eluting stent. New concepts discussed are pro-healing stents coated with endothelial progenitor cells and drug-eluting ballo

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