Ex Vivo and In Vivo Properties of an Injectable Hydrogel Derived From Acellular Ear Cartilage Extracellular Matrix.

Wei Dong,Yao Tan,Meng Zhou,Yang Lu,Yan Yan,Siyi Zhang,Dan Yan,Wei Fu,Bei Feng,Danni Gong,Yao Fu,Huijing Wang,Ying Chen,Fei Yu

doi:10.3389/fbioe.2021.740635

Abstract

Extracellular matrix (ECM) hydrogels provide advantages such as injectability, the ability to fill an irregularly shaped space, and the adequate bioactivity of native matrix. In this study, we developed decellularized cartilage ECM (dcECM) hydrogels from porcine ears innovatively via the main method of enzymatic digestion and verified good biocompatible properties of dcECM hydrogels to deliver chondrocytes and form subcutaneous cartilage in vivo. The scanning electron microscopy and turbidimetric gelation kinetics were used to characterize the material properties and gelation kinetics of the dcECM hydrogels. Then we evaluated the biocompatibility of hydrogels via the culture of chondrocytes in vitro. To further explore the dcECM hydrogels in vivo, grafts made from the mixture of dcECM hydrogels and chondrocytes were injected subcutaneously in nude mice for the gross and histological analysis. The structural and gelation kinetics of the dcECM hydrogels altered according to the variation in the ECM concentrations. The 10 mg/ml dcECM hydrogels could support the adhesion and proliferation of chondrocytes in vitro. In vivo, at 4 weeks after transplantation, cartilage-like tissues were detected in all groups with positive staining of toluidine blue, Safranin O, and collagen II, indicating the good gelation of dcECM hydrogels. While with the increasing concentration, the tissue engineering cartilages formed by 10 mg/ml dcECM hydrogel grafts were superior in weights, volumes, collagen, and glycosaminoglycan (GAG) content compared to the dcECM hydrogels of 1 mg/ml and 5 mg/ml. At 8 weeks after grafting, dcECM hydrogel grafts at 10 mg/ml showed very similar qualities to the control, collagen I grafts. After 12 weeks of in vivo culture, the histological analysis indicated that 10 mg/ml dcECM hydrogel grafts were similar to the normal cartilage from pig ears, which was the source tissue. In conclusion, dcECM hydrogel showed the promising potential as a tissue engineering biomaterial to improve the regeneration and heal injuries of ear cartilage.

Highlights

Cartilage is a flexible connective tissue composed of chondrocytes trapped in extracellular matrix (ECM)
The histological analyses of sheets revealed that the cartilage Extracellular matrix (ECM) remained intact after decellularization and almost all nuclei were absent by DAPI staining (Figure 1F)
We presented the fabrication of hydrogels from porcine decellularized cartilage ECM via a combined detergent and enzymatic method

Summary

INTRODUCTION

Cartilage is a flexible connective tissue composed of chondrocytes trapped in extracellular matrix (ECM). The ECM is mimicked to produce natural and synthetic biomaterials that can support cell viability and functions with respect to cartilage tissue engineering in vitro and/or in vivo (Hunziker, 1999; Vinatier et al, 2009). Several studies have reported that the ECM of decellularized tissues can be solubilized in pepsin and subsequently polymerized into hydrogels under physiological conditions (Lu et al, 2015; Wu et al, 2015; Pouliot et al, 2020) These ECM hydrogels remain a part of the biologically active molecules found in native tissues, showing significant therapeutic potentials in remodeling source tissues after implantation (Young et al, 2011; Wolf et al, 2012; Medberry et al, 2013; Sawkins et al, 2013). The findings demonstrated the feasibility of injectable dcECM hydrogels and provided a promising candidate to facilitate constructive remodeling in cartilage injuries, especially the repair of ear cartilage tissues

Ethic Statement and Experimental Animals

RESULTS

DISCUSSION

ETHICS STATEMENT