Injectable Hydrogels in Repairing Central Nervous System Injuries

Abstract

The injured central nervous system (CNS) can hardly regenerate. In vitro engineering of brain tissue hits technical bottlenecks. Also, the compaction and complexity of anatomical structure defy the accurate positioning for lesion sites in intracranial injuries. Therefore, repairing injured CNS remains a significant clinical challenge. Various recent in vivo and in vitro experiments have demonstrated the excellent effect of tissue engineering on repairing central nerve cells and tissues through implanting new materials and engineered cells. Except for porous three-dimensional structures able to pad lesions in various shapes and simulate the natural extracellular matrix with nutrients for cell proliferation, hydrogels incorporate high biocompatibility. Injectable hydrogels with the merits of avoiding complex surgery on large wounds, filling irregular gaps, delivering drugs, and others, are of growing interest. This review focuses on the experimental studies regarding injectable hydrogels, especially applying various injectable hydrogels to repair brain damage.

A Comprehensive Review of Cross-Linked Gels as Vehicles for Drug Delivery to Treat Central Nervous System Disorders

“…Injuries to the CNS can be caused by traumatic brain injury (TBI), neurodegenerative diseases, neurodevelopmental disorders, transient ischaemic attack/stroke, and brain tumors. The poor regeneration of the CNS parenchyma and scar formation at the lesion site make brain damage irreversible, resulting in long-term disability [ 215 ]. Consequently, the application of biomaterial scaffolds to fill brain lesions has grown into a field of focus.…”

“…Consequently, the application of biomaterial scaffolds to fill brain lesions has grown into a field of focus. Cross-linked gels, particularly hydrogels have been proven to be ideal biomaterials for brain tissue regeneration [ 215 ]. Their admirable 3-D cross-linked polymer network with over 90% water content, in addition to their adjustable physical and chemical properties, enables hydrogels to provide a favorable microenvironment for nerve cells’ growth and proliferation.…”

“…The hydrogels applied to repair CNS injuries can be administered via injectable or non-injectable routes. Depending on the site damage whether it’s the spinal area or the brain parenchyma, either injectable or non-injectable cross-linked gels may be administered [ 215 ].…”

Hydrogel, Electrospun and Composite Materials for Bone/Cartilage and Neural Tissue Engineering

“…The hydrogels seem to be excellent candidates for CNS injuries, especially in situ thermosensitive gelling ones that can be injected [104]. The conventional scaffold implantation by complex surgeries leads to blood-brain barrier damage, resulting in fluid and blood cell infiltration into the ventricle and subsequent inflammation and immune response [105].…”

Recent Advances on Electroconductive Hydrogels Used in Heart Repair and Regeneration

“…Along with its ability to cover diverse geometries of damage and resemble the natural extracellular matrix and cell-proliferating nutrients, hydrogels are very biocompatible [7]. Hydrogels, particularly injectable ones, have many bene ts including avoiding complicated surgery on large-sized wounds, lling irregular wounds, and delivering medications and growth factors, which have drawn an increasing amount of attention [8][9][10]. Hydrogels are thus an appealing material for heart repair and regeneration.…”