Adaptable Microporous Hydrogels of Propagating NGF‐Gradient by Injectable Building Blocks for Accelerated Axonal Outgrowth

Abstract

Injectable hydrogels in regeneration medicine can potentially mimic hierarchical natural living tissue and fill complexly shaped defects with minimally invasive implantation procedures. To achieve this goal, however, the versatile hydrogels that usually possess the nonporous structure and uncontrollable spatial agent release must overcome the difficulties in low cell‐penetrative rates of tissue regeneration. In this study, an adaptable microporous hydrogel (AMH) composed of microsized building blocks with opposite charges serves as an injectable matrix with interconnected pores and propagates gradient growth factor for spontaneous assembly into a complex shape in real time. By embedding gradient concentrations of growth factors into the building blocks, the propagated gradient of the nerve growth factor, integrated to the cell‐penetrative connected pores constructed by the building blocks in the nerve conduit, effectively promotes cell migration and induces dramatic bridging effects on peripheral nerve defects, achieving axon outgrowth of up to 4.7 mm and twofold axon fiber intensity in 4 days in vivo. Such AMHs with intrinsic properties of tunable mechanical properties, gradient propagation of biocues and effective induction of cell migration are potentially able to overcome the limitations of hydrogel‐mediated tissue regeneration in general and can possibly be used in clinical applications.

Adhesive liposomes loaded onto an injectable, self-healing and antibacterial hydrogel for promoting bone reconstruction

“…S3) 40 . In the first cycle, A-LIP-PEG exhibited elastic and viscous moduli of~3500 Pa and~850 Pa, respectively, indicating that the elastic regime far exceeded the viscous regime at 0.5% oscillatory shear strain, suggesting that the A-LIP-PEG remained intact at low shear strain 40 . In contrast, the elastic modulus (~7 Pa) was slightly lower than the viscous modulus (~16 Pa) at 500% strain of oscillatory shear, suggesting that A-LIP-PEG exists in a liquid state during this time period.…”

“…To examine the lipo-hydrogel's self-healing properties, the elastic modulus and viscous modulus of A-LIP-PEG were validated by multicycle step strain oscillatory measurements at a constant frequency of 5 Hz (Fig. S3) 40 . In the first cycle, A-LIP-PEG exhibited elastic and viscous moduli of~3500 Pa and~850 Pa, respectively, indicating that the elastic regime far exceeded the viscous regime at 0.5% oscillatory shear strain, suggesting that the A-LIP-PEG remained intact at low shear strain 40 .…”

Hyaluronic acid particle hydrogels decrease cerebral atrophy and promote pro-reparative astrocyte/axonal infiltration in the core after ischemic stroke

“…1E). Others and we have utilized MAP scaffolds for cell culture in vitro 24,[29][30][31][32][33][34][35] and support tissue ingrowth in vivo 24,[30][31][32] . HA-MAP scaffolds can be injected into the stroke core at 5-days post wounding without deforming the recipient hemisphere ( Fig.…”

Recent Advances on Magnetic Sensitive Hydrogels in Tissue Engineering

“…Meanwhile, hydrogel-based drug delivery systems for numerous therapeutic agents, with high water content, low interfacial tension with biological fluids, and soft consistency, have been shown to be more stable, economical, and efficient in comparison with conventional delivery systems (Li and Mooney, 2016;Moore and Hartgerink, 2017;Cheng et al, 2019;Fan et al, 2019;Zheng et al, 2019). Considering the above advantages, hydrogels have been conducted into the biomedical application to provide a tunable three-dimensional scaffold for cell adhesion, migration, and/or differentiation, and they could also be designed as the platform for the controlled release of cytokines and drugs in tissue engineering and drug delivery (Huang et al, 2017;Jiang et al, 2017;Hsu et al, 2019;Wei et al, 2019;Zheng et al, 2019).…”