- Biochemical and Mechanical Gradients Synergize To Enhance Cartilage Zonal Organization in 3D ACS BIOMATERIALS SCIENCE & ENGINEERING 2018; 4 (10): 3561–69
Mimicking Cartilage Tissue Zonal Organization by Engineering Tissue-scale Gradient Hydrogels as 3D Cell Niche.
Tissue engineering. Part A
Zonal organization plays an important role in cartilage structure and function, whereas most tissue-engineering strategies developed to date have only allowed the regeneration of cartilage with homogeneous biochemical and mechanical cues. To better restore tissue structure and function, there is a strong need to engineer materials with biomimetic gradient niche cues that recapitulate native tissue organization. To address this critical unmet need, here we report a method for rapid formation of tissue-scale gradient hydrogels as a 3D cell niche with tunable biochemical and physical properties. When encapsulated in stiffness gradient hydrogels, both chondrocytes and mesenchymal stem cells demonstrated zonal-specific response and extracellular deposition that mimics zonal organization of articular cartilage. Blocking cell mechanosensing using blebbistatin abolished the zonal response of chondrocytes in 3D hydrogels with a stiffness gradient. Such tissue scale gradient hydrogels can provide a 3D artificial cell niche to enable tissue engineering of various tissue types with zonal organizations or tissue interfaces.
View details for DOI 10.1089/ten.TEA.2016.0453
View details for PubMedID 28385124
Elastin-like protein-hyaluronic acid (ELP-HA) hydrogels with decoupled mechanical and biochemical cues for cartilage regeneration.
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 variation 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.
View details for DOI 10.1016/j.biomaterials.2017.02.010
View details for PubMedID 28268018