Elastin-like protein-hyaluronic acid (ELP-HA) hydrogels with decoupled mechanical and biochemical cues for cartilage regeneration

Abstract

Hyaluronic acid (HA) is a major component of cartilage extracellular matrix and is an attractive material for use as 3D injectable matrices for cartilage regeneration. While previous studies have shown the promise of HA-based hydrogels to support cell-based cartilage formation, varying HA concentration generally led to simultaneous changes in both biochemical cues and stiffness. How cells respond to the change of biochemical content of HA remains largely unknown. Here we report an adaptable elastin-like protein-hyaluronic acid (ELP-HA) hydrogel platform using dynamic covalent chemistry, which allows varyiation of HA concentration without affecting matrix stiffness. ELP-HA hydrogels were created through dynamic hydrazone bonds via the reaction between hydrazine-modified ELP (ELP-HYD) and aldehyde-modified HA (HA-ALD). By tuning the stoichiometric ratio of aldehyde groups to hydrazine groups while maintaining ELP-HYD concentration constant, hydrogels with variable HA concentration (1.5%, 3%, or 5%) (w/v) were fabricated with comparable stiffness. To evaluate the effects of HA concentration on cell-based cartilage regeneration, chondrocytes were encapsulated within ELP-HA hydrogels with varying HA concentration. Increasing HA concentration led to a dose-dependent increase in cartilage-marker gene expression and enhanced sGAG deposition while minimizing undesirable fibrocartilage phenotype. The use of adaptable protein hydrogels formed via dynamic covalent chemistry may be broadly applicable as 3D scaffolds with decoupled niche properties to guide other desirable cell fates and tissue repair.

Proteins and Peptides as Important Modifiers of the Polymer Scaffolds for Tissue Engineering Applications—A Review

“…In recent years, biocompatible polymer scaffolds modified with proteins/peptides have been developed for regeneration of skin [192,202,203], nerves [204][205][206], muscles [207,208], tendons [209][210][211], cartilages [212][213][214], and bones [57,58,215]. To fabricate these biomaterials, many different techniques are applied.…”

Genetically Engineered Elastin-based Biomaterials for Biomedical Applications

“…The biomedical applications of NPs have been discussed according to the different structures of the devices, including ELR-based nanoparticles that present growth factors which can interact with cells on their surfaces, some of which have shown promising results for the treatment of chronic skin wounds [98], induction of bone regeneration [121] or treatment of neuronal injuries [100]. Other NPs fused to proteins that are exposed on the surface of the NP and which have been used as therapeutic agents, for example lacritin nanoparticles to promote corneal wound healing and epithelial integrity, have also been discussed [123].…”

“…In addition, hydrogels with a lower HA concentration exhibited more chondrocyte proliferation, whereas higher HA contents resulted in decreased cell proliferation and more cartilage-specific matrix sGAG (sulfated-glycosaminoglycan) deposition. This system was therefore identified as the best scaffold candidate (5% HA hydrogel) as it exhibited the highest expression of cartilage markers, more sGAG deposition, less cell proliferation and less production of type 1 collagen and fibrocartilage phenotype [121].…”

Engineering the Architecture of Elastin‐Like Polypeptides: From Unimers to Hierarchical Self‐Assembly

“…ELPs have also been modified with hydrazide to form hydrogels by allowing dynamic covalent condensation with aldehyde groups of oxidized hyaluronic acid . The ELP‐hyaluronic acid conjugates formed a stiff hydrogel at body temperature that has been applied to regenerating cartilage and delivering stem cells . The stiffness of the hydrogel can be tuned by varying temperature, ELP concentration, and the stoichiometry of the aldehyde and hydrazide groups.…”