An Injectable Enzymatically Crosslinked Carboxymethylated Pullulan/Chondroitin Sulfate Hydrogel for Cartilage Tissue Engineering.

Feng Chen,Yunzhou Ni,Yongfeng Zhou,Bing Liu,Xiaowei Yu,Yue Su,Xinyuan Zhu,Songrui Yu,Chunyang Yu,Deyue Yan

doi:10.1038/srep20014

Abstract

In this study, an enzymatically cross-linked injectable and biodegradable hydrogel system comprising carboxymethyl pullulan-tyramine (CMP-TA) and chondroitin sulfate-tyramine (CS-TA) conjugates was successfully developed under physiological conditions in the presence of both horseradish peroxidase (HRP) and hydrogen peroxide (H2O2) for cartilage tissue engineering (CTTE). The HRP crosslinking method makes this injectable system feasible, minimally invasive and easily translatable for regenerative medicine applications. The physicochemical properties of the mechanically stable hydrogel system can be modulated by varying the weight ratio and concentration of polymer as well as the concentrations of crosslinking reagents. Additionally, the cellular behaviour of porcine auricular chondrocytes encapsulated into CMP-TA/CS-TA hydrogels demonstrates that the hydrogel system has a good cyto-compatibility. Specifically, compared to the CMP-TA hydrogel, these CMP-TA/CS-TA composite hydrogels have enhanced cell proliferation and increased cartilaginous ECM deposition, which significantly facilitate chondrogenesis. Furthermore, histological analysis indicates that the hydrogel system exhibits acceptable tissue compatibility by using a mouse subcutaneous implantation model. Overall, the novel injectable pullulan/chondroitin sulfate composite hydrogels presented here are expected to be useful biomaterial scaffold for regenerating cartilage tissue.

Highlights

Ii) be controllable and suitable physicochemical properties; iii) preferably mimic cartilaginous ECM features and promote chondrogenic potential of cells; iv) be fully biocompatible with cell growth and tissue remodelling; v) fill the defect sites, and strongly adhere and integrate with the surrounding native cartilage tissue[8,9,10,11]
The key materials of this study, the carboxymethyl pullulan-tyramine (CMP-TA) and chondroitin sulfate-tyramine (CS-TA) conjugates were successfully synthesized by the coupling reaction of the amino groups of TA to the carboxylic acid groups of CMP and CS using EDC/NHS activation (Figs 1B and C). 1H NMR results showed that the DS of CMP-TA and CS-TA were about 6.0 and 7.0, respectively (Figs S1A and B)
CMP-TA/CS-TA hydrogels were rapidly formed by mixing CMP-TA and CS-TA conjugates with horseradish peroxidase (HRP) and H2O2 in PBS under mild conditions, which was a highly efficient method to prepare in situ forming hydrogel

Summary

Introduction

Ii) be controllable and suitable physicochemical properties; iii) preferably mimic cartilaginous ECM features and promote chondrogenic potential of cells; iv) be fully biocompatible with cell growth and tissue remodelling; v) fill the defect sites, and strongly adhere and integrate with the surrounding native cartilage tissue[8,9,10,11]. From the above results it was found that the gelation time of CMP-TA/CS-TA hydrogel could be controlled by adjusting the weight ratio of polymer as well as the concentrations of polymer and HRP, which made the system highly suitable as injectable hydrogel for CTTE.

Results

Conclusion