Injectable Anisotropic Nanocomposite Hydrogels Direct in Situ Growth and Alignment of Myotubes

Abstract

While injectable in situ cross-linking hydrogels have attracted increasing attention as minimally invasive tissue scaffolds and controlled delivery systems, their inherently disorganized and isotropic network structure limits their utility in engineering oriented biological tissues. Traditional methods to prepare anisotropic hydrogels are not easily translatable to injectable systems given the need for external equipment to direct anisotropic gel fabrication and/or the required use of temperatures or solvents incompatible with biological systems. Herein, we report a new class of injectable nanocomposite hydrogels based on hydrazone cross-linked poly(oligoethylene glycol methacrylate) and magnetically aligned cellulose nanocrystals (CNCs) capable of encapsulating skeletal muscle myoblasts and promoting their differentiation into highly oriented myotubes in situ. CNC alignment occurs on the same time scale as network gelation and remains fixed after the removal of the magnetic field, enabling concurrent CNC orientation and hydrogel injection. The aligned hydrogels show mechanical and swelling profiles that can be rationally modulated by the degree of CNC alignment and can direct myotube alignment both in two- and three-dimensions following coinjection of the myoblasts with the gel precursor components. As such, these hydrogels represent a critical advancement in anisotropic biomimetic scaffolds that can be generated noninvasively in vivo following simple injection.

Biphasic Hydrogels Integrating Mineralized and Anisotropic Features for Interfacial Tissue Engineering

“…Alignment of pure CNC can be induced at relatively weak magnetic fields (>0.56 T) above the critical nanoparticle concentration required for nematic liquid crystals formation 36 . However, it has also been recently demonstrated that adsorption of polymers on CNC surface increases its effective volume fraction, leading to increased nematic structuring and therefore increased susceptibility to magnetic alignment 37,38 . These effects are hypothesized to enable the magnetic alignment of CNC at weaker magnetic fields and below the critical concentration required for nematic ordering, such as those explored in this work.…”

Nanocellulose-Based Inks for 3D Bioprinting: Key Aspects in Research Development and Challenging Perspectives in Applications—A Mini Review

“…As reported by K.J. De France et al [ 29 ], the magnetic field-induced alignment of CNCs was successfully translated into a nanocomposite hydrogel based on hydrazone cross-linked poly(oligoethylene glycol methacrylate) (POEGMA) and physically incorporated CNCs after injection, which consequently endowed the hydrogel matrix with anisotropic properties. Meanwhile, the anisotropically mechanical property is directive for the motility and migration of cells, such as skeletal muscle myoblasts in the repair of muscle tissue.…”

“…More interestingly, CNCs form a chiral nematic liquid crystal phase under the circumstance of controlling the ionic strength of suspension or applying a strong magnetic field [ 28 ]. Such features as extremely high stiffness of single nanorod (high crystallinity) and ordered alignment of CNCs in the liquid crystal phase make them attractive nanofillers in preparation of reinforced composite matrices with mechanically anisotropic features [ 29 ]. Meanwhile, the surface of CNCs is activated with carboxylates or sulfates, which result from and are dependent on the acidic process adopted.…”

“…Meanwhile, the anisotropically mechanical property is directive for the motility and migration of cells, such as skeletal muscle myoblasts in the repair of muscle tissue. The nanocomposite hydrogel of POEGMA/CNCs promoted the differentiation of resident skeletal muscle myoblasts into highly oriented myotubes in situ [ 29 , 79 ]. According to J.M.…”

Tripolyphosphate-Crosslinked Chitosan/Gelatin Biocomposite Ink for 3D Printing of Uniaxial Scaffolds

“…Tissue engineering (TE) scaffolds for anisotropic tissues have to satisfy the requirement of creating regional and directional anisotropy in three-dimensional space. To obtain this, the design and obtainment of patterns able to induce cell orientation along one preferential direction is needed, together with the enhancement of the mechanical properties in this direction (De France et al, 2017). The most used techniques to generate anisotropy in vitro are the use of mechanical force (Haque et al, 2010;Nardinocchi and Teresi, 2016), directional freezecasting (Chen et al, 2012;Bai et al, 2013) and micro-patterning (Li et al, 2014).…”