RGD-functionalized electrospun scaffold for ACL tissue engineering

Abstract

This thesis describes the preparation and evaluation of a biomimetic scaffold for anterior cruciate ligament (ACL) tissue engineering. An electrospun poly(L-lactide-co¬-acrylated trimethylene carbonate) scaffold was functionalized with a peptide containing the arginine-glycine-aspartic acid (RGD) amino acid sequence to increase mechanotransduction and extracellular matrix (ECM) protein production by fibroblasts seeded on the scaffold surface. The peptide was synthesized by solid phase peptide synthesis and conjugated to the polymer via a Michael-type addition, using a cysteine moiety on the peptide and a maleimide functional group on the polymer. The peptide-polymer conjugate was successfully electrospun with the bulk polymer, resulting in an aligned fibre mat that was crimped and crosslinked to mimic the architecture of native ACL tissue. Analysis of scanning electron microscope images demonstrated no difference in fibre diameter or scaffold porosity between scaffolds with and without peptide functionalization. There was also no difference in the Young’s modulus and toe region of the scaffolds prepared with the functionalized and non-functionalized polymer. Therefore, the inclusion of the RGD peptide did not affect the biomimetic architecture of the electrospun polymer scaffolds. ACL fibroblasts (ACLFs) were attached to the scaffolds, to an extent that was independent of peptide functionalization. Further, scaffolds were cultured under dynamic uniaxial tension to examine the effect of mechanotransduction on the cells. The scaffolds, with and without RGD-modification, were exposed to 10% strain at 1 Hz for 1 h per day. After 12 days, ACLFs cultured dynamically proliferated to a lesser extent than those cultured statically, but produced greater amounts of the ECM proteins collagen and glycosaminoglycan per cell.