Emerging scaffold- and cellular-based strategies for brain tissue regeneration and imaging

Abstract

Stimulating brain tissue regeneration is a major challenge after central nervous system (CNS) injury, such as those observed from trauma or cerebrovascular accidents. Full regeneration is difficult even when a neurogenesis-associated repair response may occur. Currently, there are no effective treatments to stimulate brain tissue regeneration. However, biomaterial scaffolds are showing promising results, where hydrogels are the materials of choice to develop these supportive scaffolds for cell carriers. Their combination with growth factors, such as brain-derived neurotrophic factor (BDNF), basic fibroblast growth factor (bFGF), or vascular endothelial growth factor (VEGF), together with other cell therapy strategies allows the prevention of further neuronal death and can potentially lead to the direct stimulation of neurogenesis and vascularisation at the injured site. Imaging of the injured site is particularly critical to study the reestablishment of neural cell functionality after brain tissue injury. This review outlines the latest key advances associated with different strategies aiming to promote the neuroregeneration, imaging, and functional recovery of brain tissue. Graphical abstract

Application of Conductive Hydrogels on Spinal Cord Injury Repair: A Review

“…Apart from being able to minimize the risks due to surgery, the injectable hydrogels can fill complex irregular cavities and remain localized on the injected region. 18,20 This also enables the hydrogels to directly deliver the loaded molecules to the injury site. Hence, they provide a permissive environment for axonal growth and appropriate structural support to the surrounding tissue, which is important for SCI repair.…”

“…6,31 This event leads to the significant degeneration of transient bioelectrical signals that are responsible for triggering the release of neurotransmitters in the presynaptic terminal. 6,18,32 This occurs through the diffusion of neurotransmitters across the presynaptic neuron and subsequently binding to the receptors on the postsynaptic membrane. However, the impact of neurotransmitters on the postsynaptic neuron can vary based on the type of receptor and the specific neurotransmitter involved.…”

“…Hydrogels synthesized from various biomaterials have been extensively studied for their ability to replicate the intricate structure of the extracellular matrix (ECM). − Their potential in mimicking the three-dimensional ECM microenvironment has effectively promoted cell adhesion, proliferation, and differentiation. , Additionally, due to the hydrogel porosity, biodegradability, and adaptive mechanical properties, it can be used as a multifaceted therapeutic mechanism for reparative SCI tools. For example, refs and mainly reported the use of hydrogel as a physical support for damaged tissue and a matrix for cell adhesion and integration, whereas refs and utilized hydrogel as a therapeutic agent’s carrier that can maintain and release their loading, and also provide biological signals to guide the reparative process.…”

“…Furthermore, one of the important features of hydrogels is their ability to be injectables. Apart from being able to minimize the risks due to surgery, the injectable hydrogels can fill complex irregular cavities and remain localized on the injected region. , This also enables the hydrogels to directly deliver the loaded molecules to the injury site. Hence, they provide a permissive environment for axonal growth and appropriate structural support to the surrounding tissue, which is important for SCI repair. , However, the potential of hydrogels to bridge the lesion gap may be hindered by the excessive formation of glial scars at the injured site, which occurs in response to protecting the surrounding viable neural tissue .…”

Photocrosslinkable and self-healable hydrogels of chitosan and hyaluronic acid

“…The polymerization of monomers or polymers by ultraviolet (UV) and visible light has been investigated as an interesting approach for the development of in situ gelling hydrogels for drug delivery, biosensing and tissue engineering applications [1,2]. Macromers aqueous solutions act as injectable materials, remaining in liquid state before applying the light source and, becoming photopolymerized or photocrosslinked hydrogels after exposure to UV-visible light in a specific wavelength, due to an in situ curing process.…”