Multileveled Hierarchical Hydrogel with Continuous Biophysical and Biochemical Gradients for Enhanced Repair of Full‐Thickness Osteochondral Defect

Abstract

The repair of hierarchical osteochondral defect requires sophisticated gradient reestablishment; however, few strategies for continuous gradient casting consider the relevance to clinical practice regarding cell adaptability, multiple gradient elements, and precise gradient mirroring native tissue. Here, a hydrogel with continuous gradients in nano‐hydroxyapatite (HA) content, mechanical, and magnetism is developed using synthesized superparamagnetic HA nanorods (MagHA) that easily respond to a brief magnetic field. To precisely reconstruct osteochondral tissue, the optimized gradient mode is calculated according to magnetic resonance imaging (MRI) of healthy rabbit knees. Then, MagHA are patterned to form continuous biophysical and biochemical gradients, consequently generating incremental HA, mechanical, and electromagnetic cues under an external magnetic stimulus. To make such depth‐dependent biocues work, an adaptable hydrogel is developed to facilitate cell infiltration. Furthermore, this approach is applied in rabbit full‐thickness osteochondral defects equipped with a local magnetic field. Surprisingly, this multileveled gradient composite hydrogel repairs osteochondral unit in a perfect heterogeneous feature, which mimics the gradual cartilage‐to‐subchondral transition. Collectively, this is the first study that combines an adaptable hydrogel with magneto‐driven MagHA gradients to achieve promising outcomes in osteochondral regeneration.

Injectable, High Specific Surface Area Cryogel Microscaffolds Integrated with Osteoinductive Bioceramic Fibers for Enhanced Bone Regeneration

“…For immunofluorescence staining, the fixed complexes were permeabilized with 0.1% Triton X-100 and blocked with 3% BSA before being incubated with osteopontin (OPN, Affinity Biosciences, USA) or osteocalcin (OCN, Affinity Biosciences, USA) primary antibodies overnight. The samples were then treated with fluorescent secondary antibodies (Zhongshan Goldenbridge, China) for 1 h, counterstained with DAPI for 5 min, and submitted to CLSM detection and image taking. , The immunofluorescence intensities for these images were semiquantitatively analyzed by ImageJ.…”

“…The samples were then treated with fluorescent secondary antibodies (Zhongshan Goldenbridge, China) for 1 h, counterstained with DAPI for 5 min, and submitted to CLSM detection and image taking. 41,42 The immunofluorescence intensities for these images were semiquantitatively analyzed by ImageJ.…”

Macrostructure and Microenvironment Biomimetic Hydrogel: Design, Properties, and Tissue Engineering Application

“…These challenges primarily encompass the gradient reconstruction of biochemical components, such as collagen, inorganic constituents, and cell types, alongside the integration of biophysical attributes like stiffness and electromagnetic biophysics. , However, the current landscape lacks continuous gradient fabrication strategies that adequately consider cellular adaptability, incorporate multigradient elements, and precisely mirror the relevance of natural tissue architectures in clinical practice. In light of these considerations, Zhang et al have introduced a novel approach employing synthetically engineered superparamagnetic nanohydroxyapatite (MagHA) nanorods to develop hydrogels exhibiting continuous gradients in nanoscale hydroxyapatite (HA) content, mechanical properties, and magnetic responsiveness, as depicted in Figure a . To meticulously emulate bone cartilage tissue, gradient patterns were calculated through magnetic resonance imaging (MRI) of healthy rabbit knee joints.…”

“…(a) Design and utilization of multilevel continuous gradient hydrogel for osteochondral defect repair. Reproduced from ref . Copyright 2023 John Wiley and Sons.…”

Biosynthesis of Zinc Oxide Nanoparticles on l-Carnosine Biofunctionalized Polyacrylonitrile Nanofibers; a Biomimetic Wound Healing Material

“…In this regard, Zn has been previously coupled with CAR to develop a Zn-CAR complex, polaprezinc (PLZ), with various therapeutic potentials for wound healing . Therapeutic ions, including Mg, Ca, and Si, notably contribute to tissue repair and the regulation of cell metabolism. , Additionally, Zn is an essential trace element taking part in the chemistry of different transcription factors or enzymes that contribute to cell proliferation, protein synthesis, and healing upon injury . Additionally, due to its immunomodulatory activity, Zn majorly contributes to wound healing.…”