Collagen for neural tissue engineering: Materials, strategies, and challenges

Stiffness-tunable biomaterials provide a good extracellular matrix environment for axon growth and regeneration

Neuronal growth, extension, branching, and formation of neural networks are markedly influenced by the extracellular matrix-a complex network composed of proteins and carbohydrates secreted by cells. In addition to providing physical support for cells, the extracellular matrix also conveys critical mechanical stiffness cues. During the development of the nervous system, extracellular matrix stiffness plays a central role in guiding neuronal growth, particularly in the context of axonal extension, which is crucial for the formation of neural networks. In neural tissue engineering, manipulation of biomaterial stiffness is a promising strategy to provide a permissive environment for the repair and regeneration of injured nervous tissue. Recent research has fine-tuned synthetic biomaterials to fabricate scaffolds that closely replicate the stiffness profiles observed in the nervous system. In this review, we highlight the molecular mechanisms by which extracellular matrix stiffness regulates axonal growth and regeneration. We highlight the progress made in the development of stiffness-tunable biomaterials to emulate in vivo extracellular matrix environments, with an emphasis on their application in neural repair and regeneration, along with a discussion of the current limitations and future prospects. The exploration and optimization of the stiffness-tunable biomaterials has the potential to markedly advance the development of neural tissue engineering.

Recent research of peptide-based hydrogel in nervous regeneration

Neurological disorders exert significantly affect the quality of life for patients, necessitating effective strategies for nerve regeneration. Both traditional autologous nerve transplantation and emerging therapeutic approaches encounter scientific challenges due to the complex nature of the nervous system and the unsuitability of the surrounding environment for cell transplantation. Tissue engineering techniques offer a promising path for neurotherapy. Successful neural tissue engineering relies on modulating cell differentiation behavior and tissue repair by developing biomaterials that mimic the natural extracellular matrix (ECM) and establish a three-dimensional microenvironment. Peptide-based hydrogels have emerged as a potent option among these biomaterials due to their ability to replicate the structure and complexity of the ECM. This review aims to explore the diverse range of peptide-based hydrogels used in nerve regeneration with a specific focus on dipeptide hydrogels, tripeptide hydrogels, oligopeptide hydrogels, multidomain peptides (MDPs), and amphiphilic peptide hydrogels (PAs). Peptide-based hydrogels offer numerous advantages, including biocompatibility, structural diversity, adjustable mechanical properties, and degradation without adverse effects. Notably, hydrogels formed from self-assembled polypeptide nanofibers, derived from amino acids, show promising potential in engineering neural tissues, outperforming conventional materials like alginate, poly(ε-caprolactone), and polyaniline. Additionally, the simple design and cost-effectiveness of dipeptide-based hydrogels have enabled the creation of various functional supramolecular structures, with significant implications for nervous system regeneration. These hydrogels are expected to play a crucial role in future neural tissue engineering research. This review aims to highlight the benefits and potential applications of peptide-based hydrogels, contributing to the advancement of neural tissue engineering.

Exploring the properties and potential of the neural extracellular matrix for next-generation regenerative therapies

The extracellular matrix (ECM) is a dynamic and complex network of proteins and molecules that surrounds cells and tissues in the nervous system and orchestrates a myriad of biological functions. This review carefully examines the diverse interactions between cells and the ECM, as well as the transformative chemical and physical changes that the ECM undergoes during neural development, aging, and disease. These transformations play a pivotal role in shaping tissue morphogenesis and neural activity, thereby influencing the functionality of the central nervous system (CNS). In our comprehensive review, we describe the diverse behaviors of the CNS ECM in different physiological and pathological scenarios and explore the unique properties that make ECM-based strategies attractive for CNS repair and regeneration. Addressing the challenges of scalability, variability, and integration with host tissues, we review how advanced natural, synthetic, and combinatorial matrix approaches enhance biocompatibility, mechanical properties, and functional recovery. Overall, this review highlights the potential of decellularized ECM as a powerful tool for CNS modeling and regenerative purposes and sets the stage for future research in this exciting field. This article is categorized under: Implantable Materials and Surgical Technologies > Nanotechnology in Tissue Repair and Replacement Therapeutic Approaches and Drug Discovery > Nanomedicine for Neurological Disease Implantable Materials and Surgical Technologies > Nanomaterials and Implants.

Unlocking the Therapeutic Potential of Marine Collagen: A Scientific Exploration for Delaying Skin Aging

Aging is closely associated with collagen degradation, impacting the structure and strength of the muscles, joints, bones, and skin. The continuous aging of the skin is a natural process that is influenced by extrinsic factors such as UV exposure, dietary patterns, smoking habits, and cosmetic supplements. Supplements that contain collagen can act as remedies that help restore vitality and youth to the skin, helping combat aging. Notably, collagen supplements enriched with essential amino acids such as proline and glycine, along with marine fish collagen, have become popular for their safety and effectiveness in mitigating the aging process. To compile the relevant literature on the anti-aging applications of marine collagen, a search and analysis of peer-reviewed papers was conducted using PubMed, Cochrane Library, Web of Science, and Embase, covering publications from 1991 to 2024. From in vitro to in vivo experiments, the reviewed studies elucidate the anti-aging benefits of marine collagen, emphasizing its role in combating skin aging by minimizing oxidative stress, photodamage, and the appearance of wrinkles. Various bioactive marine peptides exhibit diverse anti-aging properties, including free radical scavenging, apoptosis inhibition, lifespan extension in various organisms, and protective effects in aging humans. Furthermore, the topical application of hyaluronic acid is discussed as a mechanism to increase collagen production and skin moisture, contributing to the anti-aging effects of collagen supplementation. The integration of bio-tissue engineering in marine collagen applications is also explored, highlighting its proven utility in skin healing and bone regeneration applications. However, limitations to the scope of its application exist. Thus, by delving into these nuanced considerations, this review contributes to a comprehensive understanding of the potential and challenges associated with marine collagen in the realm of anti-aging applications.

Environment-Friendly Preparation and Characterization of Multilayered Conductive PVP/Col/CS Composite Doped with Nanoparticles as Potential Nerve Guide Conduits

Tissue engineering constitutes the most promising method of severe peripheral nerve injuries treatment and is considered as an alternative to autografts. To provide appropriate conditions during recovery special biomaterials called nerve guide conduits are required. An ideal candidate for this purpose should not only be biocompatible and protect newly forming tissue but also promote the recovery process. In this article a novel, multilayered biomaterial based on polyvinylpyrrolidone, collagen and chitosan of gradient structure modified with conductive nanoparticles is presented. Products were obtained by the combination of electrospinning and electrospraying techniques. Nerve guide conduits were subjected to FT-IR analysis, morphology and elemental composition study using SEM/EDS as well as biodegradation. Furthermore, their effect on 1321N1 human cell line was investigated by long-term cell culture. Lack of cytotoxicity was confirmed by XTT assay and morphology study. Obtained results confirmed a high potential of newly developed biomaterials in the field of nerve tissue regeneration with a special focus on injured nerves recovery.

Injectable Hydrogels for Nervous Tissue Repair-A Brief Review

The repair of nervous tissue is a critical research field in tissue engineering because of the degenerative process in the injured nervous system. In this review, we summarize the progress of injectable hydrogels using in vitro and in vivo studies for the regeneration and repair of nervous tissue. Traditional treatments have not been favorable for patients, as they are invasive and inefficient; therefore, injectable hydrogels are promising for the treatment of damaged tissue. This review will contribute to a better understanding of injectable hydrogels as potential scaffolds and drug delivery system for neural tissue engineering applications.

Multi-needle blow-spinning technique for fabricating collagen nanofibrous nerve guidance conduit with scalable productivity and high performance

Nerve guidance conduits (NGCs) have been widely accepted as a promising strategy for peripheral nerve regeneration. Fabricating ideal NGCs with good biocompatibility, biodegradability, permeability, appropriate mechanical properties (space maintenance, suturing performance, etc.), and oriented topographic cues is still current research focus. From the perspective of translation, the technique stability and scalability are also an important consideration for industrial production. Recently, blow-spinning technique shows great potentials in nanofibrous scaffolds fabrication, possessing high quality, high fiber production rates, low cost, ease of maintenance, and high reliability. In this study, we proposed for the first time the preparation of a novel NGC via blow-spinning technique to obtain optimized performances and high productivity. A new collagen nanofibrous neuro-tube with the bilayered design was developed, incorporating inner oriented and outer random topographical cues. The bilayer structure enhances the mechanical properties of the conduit in dry and wet, displaying good radial support and suturing performance. The porous nature of the blow-spun collagen membrane enables good nutrient delivery and metabolism. The in vitro and in vivo evaluations indicated the bilayer-structure conduit could promoted Schwann cells growth, neurotrophic factors secretion, and axonal regeneration and motor functional recovery in rat.

Production of Graft Copolymers of Cod Collagen with Butyl Acrylate and Vinyl Butyl Ether in the Presence of Triethylborane-Prospects for Use in Regenerative Medicine

Collagen is a suitable material for regenerative medicine because it is characterized by its good biocompatibility. However, due to its fibrillar structure, it cannot organize itself into three-dimensional porous structures without additional modification. The introduction of synthetic monomer elements into the collagen macromolecules is a technique used to form three-dimensional, collagen-based, branched, and crosslinked structures. New types of graft copolymers made from cod collagen with a butyl acrylate and vinyl butyl ether copolymer in aqueous dispersion were obtained in the presence of triethylborane by a radical mechanism. The process of graft copolymer formation proceeded as usual by radical initiation, through radicals formed during triethylborane oxidation by oxygen residues, collagen borination, and reversible inhibition with the participation of a boroxyl radical. The characteristics of the graft copolymers were determined using methods of physical and chemical analysis (GPC, SEM, IR spectroscopy, etc.), while the cytotoxicity was assessed using the MTT assay method. It is shown that the grafting of alternating blocks of butyl acrylate and vinyl butyl ether to the protein macromolecules results in changes in the morphological pattern of the graft co-polymer in comparison with native collagen. This is manifested in the development of consolidations around the collagen fibers of the structural matrices, with the co-polymer cellular structure consisting of interpenetrating pores of unequal size. Additionally, it is important that the graft co-polymer solutions are not toxic at a certain concentration. The above properties confirm the promising nature of the technique's application as the basis for producing new materials for regenerative medicine.

Nanofiber Scaffolds as Drug Delivery Systems Promoting Wound Healing

Nanofiber scaffolds have emerged as a revolutionary drug delivery platform for promoting wound healing, due to their unique properties, including high surface area, interconnected porosity, excellent breathability, and moisture absorption, as well as their spatial structure which mimics the extracellular matrix. However, the use of nanofibers to achieve controlled drug loading and release still presents many challenges, with ongoing research still exploring how to load drugs onto nanofiber scaffolds without loss of activity and how to control their release in a specific spatiotemporal manner. This comprehensive study systematically reviews the applications and recent advances related to drug-laden nanofiber scaffolds for skin-wound management. First, we introduce commonly used methods for nanofiber preparation, including electrostatic spinning, sol-gel, molecular self-assembly, thermally induced phase separation, and 3D-printing techniques. Next, we summarize the polymers used in the preparation of nanofibers and drug delivery methods utilizing nanofiber scaffolds. We then review the application of drug-loaded nanofiber scaffolds for wound healing, considering the different stages of wound healing in which the drug acts. Finally, we briefly describe stimulus-responsive drug delivery schemes for nanofiber scaffolds, as well as other exciting drug delivery systems.