An elastin-like recombinamer-based bioactive hydrogel embedded with mesenchymal stromal cells as an injectable scaffold for osteochondral repair.

Filippo Cipriani,Matilde Alonso Rodrigo,Verónica García Diaz,Angel José Àlvarez Barcia,Blanca Ariño Palao,Ana Sanchez,José Carlos Rodriguez-Cabello,Aurelio Vega Castrillo,Israel Gonzalez De Torre,Héctor José Aguado Hernández,Monica Lopez Peña

doi:10.1093/rb/rbz023

Abstract

The aim of this study was to evaluate injectable, in situ cross-linkable elastin-like recombinamers (ELRs) for osteochondral repair. Both the ELR-based hydrogel alone and the ELR-based hydrogel embedded with rabbit mesenchymal stromal cells (rMSCs) were tested for the regeneration of critical subchondral defects in 10 New Zealand rabbits. Thus, cylindrical osteochondral defects were filled with an aqueous solution of ELRs and the animals sacrificed at 4 months for histological and gross evaluation of features of biomaterial performance, including integration, cellular infiltration, surrounding matrix quality and the new matrix in the defects. Although both approaches helped cartilage regeneration, the results suggest that the specific composition of the rMSC-containing hydrogel permitted adequate bone regeneration, whereas the ELR-based hydrogel alone led to an excellent regeneration of hyaline cartilage. In conclusion, the ELR cross-linker solution can be easily delivered and forms a stable well-integrated hydrogel that supports infiltration and de novo matrix synthesis.

Highlights

Chondral and osteochondral defects in the articular cartilage of the knee and in other joints caused by traumatic and non-traumatic injuries tend to progress to degenerative osteoarthritis over time
From a functional point of view, clinical treatments are not able to promote the proper regeneration of cartilage defects; tissue engineering (TE) represents a new approach for articular cartilage repair [51], it consists in reconstructing living tissue by associating cells with biomaterials
The specific composition of this hydrogel allowed for faster bone regeneration when embedded with rabbit mesenchymal stromal cells (rMSCs) compared to the injection of the hydrogel alone

Summary

Introduction

Chondral and osteochondral defects in the articular cartilage of the knee and in other joints caused by traumatic and non-traumatic injuries tend to progress to degenerative osteoarthritis over time. Several types of cartilage are known, including the articular hyaline cartilage, which is a smooth, pearly bluish layer with a width of 2–4 mm that covers the articular surfaces [2]. Articular hyaline cartilage is a highly specialized tissue characterized by its unique mechanical properties [2]; it has a structural role adsorbing the pressure overload the cartilage, and a functional role allowing the friction-less sliding of the articular surface [3, 4].

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