Synthesis and Characterization of Proteoglycan-Mimetic Graft Copolymers with Tunable Glycosaminoglycan Density

Abstract

Proteoglycans (PGs) are important glycosylated proteins found on the cell surface and in the extracellular matrix. They are made up of a core protein with glycosaminoglycan (GAG) side chains. Variations in composition and number of GAG side chains lead to a vast array of PG sizes and functions. Here we present a method for the synthesis of proteoglycan-mimetic graft copolymers (or neoproteoglycans) with tunable GAG side-chain composition. This is done using three different GAGs: hyaluronan, chondroitin sulfate, and heparin. Hyaluronan is functionalized with a hydrazide-presenting linker. Either chondroitin sulfate or heparin is grafted by the reducing end on to the hyaluronan backbone through reductive amination. PG mimics with heparin or chondroitin sulfate side chains and four different ratios of GAG side chain result in graft copolymers with a wide range of sizes. The chemistry is confirmed through attentuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and (1)H NMR. Effective hydrodynamic diameter and zeta potential are determined using dynamic light scattering and electrophoretic mobility measurements. Graft copolymers were tested for their ability to bind and deliver basic fibroblast growth factor (FGF-2) to mesenchymal stem cells (MSCs). The chondroitin sulfate-containing graft copolymers successfully deliver FGF-2 to cells from surfaces. The lowest graft density of heparin-containing PG mimic also performs well with respect to growth factor delivery from a surface. This new method for preparation of GAG-based graft copolymers enables a wide range of graft density, and can be used to explore applications of PG mimics as new biomaterials with tunable biochemical and biomechanical functions.

Glycosaminoglycan and Proteoglycan Biotherapeutics in Articular Cartilage Protection and Repair Strategies: Novel Approaches to Visco‐supplementation in Orthobiologics

“…[206,208] A peptidoglycan lubricin-mimetic, mLUB15 has also been prepared by similar methodology to that of mAGC using HA binding peptide (GAHWQFNALTVRGGGC) and a type II collagen binding peptide (WYRGRL) attached to the CS backbone [209] (Figure 11b). [210] A further GAG copolymer mimetic aggrecan has been developed using HA as a support backbone to which CS or heparin chains were attached using a hydrazide bi-functional reagent [211] (Figure 10i). Summary of the different forms of GAG polymers which have been assembled for tissue engineering applications.…”

Biomimetic proteoglycans diffuse throughout articular cartilage and localize within the pericellular matrix

“…We (Phillips et al, 2018;Prudnikova et al, 2017;Prudnikova et al, 2018;Sarkar, 2011;Sarkar et al, 2017;Sarkar, Lightfoot-Vidal, Schauer, Vresilovic, & Marcolongo, 2012) and others (Bernhard & Panitch, 2012;Place, Kelly, & Kipper, 2014;Sharma, Panitch, & Neu, 2013;Sharma, Vazquez-Portalatin, Calve, & Panitch, 2016) have been investigating mimics to proteoglycans. We designed, synthesized and characterized biomimetic proteoglycans (BPGs) that mimic the molecular architecture and physical properties of natural proteoglycans.…”

Two‐Phase Electrospinning to Incorporate Polyelectrolyte Complexes and Growth Factors into Electrospun Chitosan Nanofibers

“…[ 34,[45][46][47][48][49][50][51][52][53][54][55] We have demonstrated that PCNs and graft copolymers may mimic the size, composition, and growth factor stabilization and delivery properties of proteoglycans found in native ECM. [ 31,56 ] Other groups have also demonstrated growth factor delivery using GAG-based PCNs. [ 57,58 ] While PCNs may mimic the stabilizing and delivery properties of proteoglycans, they must be incorporated into a tissue scaffold for tissue engineering applications.…”