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Published October 18, 2016 | public
Journal Article Open

Multiplicity of morphologies in poly (L-lactide) bioresorbable vascular scaffolds


Poly(L-lactide) (PLLA) is the structural material of the first clinically approved bioresorbable vascular scaffold (BVS), a promising alternative to permanent metal stents for treatment of coronary heart disease. BVSs are transient implants that support the occluded artery for 6 mo and are completely resorbed in 2 y. Clinical trials of BVSs report restoration of arterial vasomotion and elimination of serious complications such as late stent thrombosis. It is remarkable that a scaffold made from PLLA, known as a brittle polymer, does not fracture when crimped onto a balloon catheter or during deployment in the artery. We used X-ray microdiffraction to discover how PLLA acquired ductile character and found that the crimping process creates localized regions of extreme anisotropy; PLLA chains in the scaffold change orientation from the hoop direction to the radial direction on micrometer-scale distances. This multiplicity of morphologies in the crimped scaffold works in tandem to enable a low-stress response during deployment, which avoids fracture of the PLLA hoops and leaves them with the strength needed to support the artery. Thus, the transformations of the semicrystalline PLLA microstructure during crimping explain the unexpected strength and ductility of the current BVS and point the way to thinner resorbable scaffolds in the future.

Additional Information

© 2016 National Academy of Sciences. Edited by John A. Rogers, University of Illinois, Urbana, IL, and approved August 12, 2016 (received for review April 22, 2016) This research used resources of the Advanced Photon Source (APS), a US Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract DE-AC02-06CH11357. We thank Dr. Zhonghou Cai at APS for his assistance in collecting x-ray microdiffraction data, and Mr. Troy P. Carter (Abbott Vascular) for sectioning the scaffolds. We appreciate the assistance of Dr. Nobumichi Tamura at the Advanced Light Source, Lawrence Berkeley National Laboratories, for proof-of-concept x-ray microdiffraction measurements. The Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the US Department of Energy under Contract DE-AC02-05CH1123. Funding for this research was provided by Abbot Vascular. A.A and K.R contributed equally to this work. Author contributions: A.A., K.R., and J.A.K. designed research; A.A. and K.R. performed research; M.B.K., J.P.O., and J.A.K. contributed new reagents/analytic tools; A.A., K.R., and J.A.K. analyzed data; and A.A., K.R., and J.A.K. wrote the paper. Conflict of interest statement: M.B.K. and J.P.O. are employees of Abbott Vascular. Funding for this research was provided by Abbott Vascular. This article is a PNAS Direct Submission. This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1602311113/-/DCSupplemental.

Attached Files

Published - PNAS-2016-Ailianou-11670-5.pdf

Supplemental Material - pnas.201602311SI.pdf


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August 22, 2023
August 22, 2023