Incorporation of a Decorin Biomimetic Enhances the Mechanical Properties of Electrochemically Aligned Collagen Threads

Damaged tendons often do not heal completely and lack full functionality. Tissue engineering employing collagen based biomaterials is a viable option to repair damaged tendons. However, most existing constructs lack the desired mechanical strength needed to reconstruct such load bearing tissues. We have previously reported a novel methodology to synthesize highly ordered electrochemically aligned collagen (ELAC) threads that are mechanically stronger and more amenable to cell migration compared to randomly oriented collagen constructs. While the ELAC mimics the orientational anisotropy of tendon it can be further improved by the incorporation of small leucine rich proteoglycans like decorin. Decorin consists of a protein core that binds to collagen and a glycosaminoglycan (GAG) chain. The GAG chains of adjacent collagen fibrils associate with one another to form crosslinks and are suggested to enhance the mechanical properties of tendon by allowing fibrillar slippage. Based on the structure of natural decorin, we have previously synthesized a novel peptidoglycan (DS-SILY) containing a collagen binding peptide (SILY) and a dermatan sulfate (DS) GAG chain. DS-SILY mimics decorin both structurally and functionally. In this study, we investigated the effects of the incorporation of DS-SILY on the mechanical properties and structural organization of ELAC threads by monotonic mechanical testing, swelling ratio and differential scanning calorimetry.