Mechanical properties and cellular response of novel electrospun nanofibers for ligament tissue engineering: Effects of orientation and geometry

Hannah M Pauly; Daniel J Kelly; Ketul C Popat; Nathan A Trujillo; Nicholas J Dunne; Helen O McCarthy; Tammy L Haut Donahue

doi:10.1016/j.jmbbm.2016.03.022

Mechanical properties and cellular response of novel electrospun nanofibers for ligament tissue engineering: Effects of orientation and geometry

J Mech Behav Biomed Mater. 2016 Aug:61:258-270. doi: 10.1016/j.jmbbm.2016.03.022. Epub 2016 Mar 31.

Authors

Hannah M Pauly¹, Daniel J Kelly², Ketul C Popat³, Nathan A Trujillo⁴, Nicholas J Dunne⁵, Helen O McCarthy⁶, Tammy L Haut Donahue⁷

Affiliations

¹ School of Biomedical Engineering, Colorado State University, Fort Collins, CO, USA.
² Trinity Centre for Bioengineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland; Department of Mechanical and Manufacturing Engineering, School of Engineering, Trinity College Dublin, Dublin, Ireland; Department of Anatomy, Royal College of Surgeons in Ireland, Dublin 2, Ireland; Advanced Materials and Bioengineering Research Centre, Royal College of Surgeons in Ireland and Trinity College Dublin, Dublin, Ireland.
³ School of Biomedical Engineering, Colorado State University, Fort Collins, CO, USA; Department of Mechanical Engineering, Colorado State University, 1374 Campus Delivery, Fort Collins, CO 80523, USA.
⁴ Department of Mechanical Engineering, Colorado State University, 1374 Campus Delivery, Fort Collins, CO 80523, USA.
⁵ School of Mechanical and Aerospace Engineering, Queen׳s University of Belfast, UK; School of Mechanical and Manufacturing Engineering, Dublin City University, Dublin 9, Ireland.
⁶ School of Pharmacy, Queen׳s University of Belfast, UK.
⁷ School of Biomedical Engineering, Colorado State University, Fort Collins, CO, USA; Department of Mechanical Engineering, Colorado State University, 1374 Campus Delivery, Fort Collins, CO 80523, USA. Electronic address: Tammy.Donahue@ColoState.edu.

PMID: 27082129
DOI: 10.1016/j.jmbbm.2016.03.022

Abstract

Electrospun nanofibers are a promising material for ligamentous tissue engineering, however weak mechanical properties of fibers to date have limited their clinical usage. The goal of this work was to modify electrospun nanofibers to create a robust structure that mimics the complex hierarchy of native tendons and ligaments. The scaffolds that were fabricated in this study consisted of either random or aligned nanofibers in flat sheets or rolled nanofiber bundles that mimic the size scale of fascicle units in primarily tensile load bearing soft musculoskeletal tissues. Altering nanofiber orientation and geometry significantly affected mechanical properties; most notably aligned nanofiber sheets had the greatest modulus; 125% higher than that of random nanofiber sheets; and 45% higher than aligned nanofiber bundles. Modifying aligned nanofiber sheets to form aligned nanofiber bundles also resulted in approximately 107% higher yield stresses and 140% higher yield strains. The mechanical properties of aligned nanofiber bundles were in the range of the mechanical properties of the native ACL: modulus=158±32MPa, yield stress=57±23MPa and yield strain=0.38±0.08. Adipose derived stem cells cultured on all surfaces remained viable and proliferated extensively over a 7 day culture period and cells elongated on nanofiber bundles. The results of the study suggest that aligned nanofiber bundles may be useful for ligament and tendon tissue engineering based on their mechanical properties and ability to support cell adhesion, proliferation, and elongation.

Keywords: ACL; Knee; Material properties; Polymer; Scaffold; Tissue engineering.

MeSH terms

Biomechanical Phenomena
Humans
Ligaments / physiology*
Nanofibers*
Tendons / physiology*
Tissue Engineering*
Tissue Scaffolds*

Grants and funding

MC_PC_12021/MRC_/Medical Research Council/United Kingdom