Biochemical Gradients to Generate 3D Heterotypic‐Like Tissues with Isotropic and Anisotropic Architectures

Abstract

Anisotropic 3D tissue interfaces with functional gradients found in nature are replicated in vitro for drug development and tissue engineering. Even though different fabrication techniques, based on material science engineering and microfluidics, are used to generate such microenvironments, mimicking the native tissue gradient is still a challenge. Here, the fabrication of 3D structures are described with linear/random porosity and gradient distribution of hydroxyapatite microparticles which are combined with a gradient of growth factors generated by a dual chamber for the development of heterotypiclike tissues. The hydroxyapatite gradient is formed by applying a thermal ramp from the first to the second gel layer, and the porous architecture is controlled through ice templating. A 3D osteochondral (OC) tissue model is developed by codifferentiating fat pad adipose-derived stem cells. Osteogenic and chondrogenic markers expression is spatially controlled, as it occurs in the native osteochondral unit. Additionally, a prevasculature is spatially induced by the perfusion of proangiogenic medium in the bone-like region, as observed in the native subchondral bone. Thus, in this study, precise spatial control is developed over cell/tissue phenotype and formation of prevasculature which opens up possibilities for the study of complex tissues interfaces, with broader applications in drug testing and regenerative medicine.

A Physiology-Inspired Multifactorial Toolbox in Soft-to-Hard Musculoskeletal Interface Tissue Engineering

“…These scaffolds ensure continuity between phases to avoid a barrier in the interface, together with biomaterials integrity, while mimicking the natural hierarchical structure of the osteochondral tissue. Developed functional materials focused on mimicking specific anisotropic orientation of the subchondral bone and calcified cartilage region in single 3D constructs, demonstrating a favorable control of stem cell fate toward osteogenic and chondrogenic-lineages [17,18]. Cartilage-to-bone engineered strategies mainly rely on scaffold-based approaches due to the tunability and versatility of materials to achieve the mechanical and physical requirements of the tissue for proper regeneration.…”

Biphasic Hydrogels Integrating Mineralized and Anisotropic Features for Interfacial Tissue Engineering

“…This dependence has been recently observed with hASCs seeded on biphasic silk fibroin scaffolds showing a porosity anisotropy gradient prepared by the freeze-casting method 50 . Moreover, despite many attempts have been made for the development of monophasic anisotropic hydrogels produced trough ice-templating technique 51,52,52 , few designs have managed to effectively integrate dissimilar features gradients into a single unit 50,50,53 . Additionally, the potential for in vivo injectability and the possibility of the in situ exposure to a magnetic field may help to promote the clinical translation of enzymatically crosslinked hydrogels for interfacial tissue engineering purposes.…”

Biodegradable polymers: an update on drug delivery in bone and cartilage diseases

“…Bone grafts are usually based on biodegradable polymer composites [e.g. silk fibroin [170], PCL [171], gellan-gum [172], chitosan [173] and/or hyaluronic acid] with calcium phosphate materials (e.g. hydroxyapatite and tricalcium phosphate).…”

“…The same polymers are also widely used to produce cartilage scaffolds (Figure 3). Moreover, for osteochondral applications, a gradient osteoconductive phase can be obtained by decreasing the level of porosity and calcium phosphate content from the base (bone side) to the superficial (cartilage side) surface as found in vivo [172]. Advances in tissue engineering were also made by the rational design of 3D structures with adequate structural cues (e.g.…”