Natural polysaccharides and their derivatives as potential medical materials and drug delivery systems for the treatment of peripheral nerve injuries

Advanced techniques and innovations in peripheral nerve repair: a comprehensive review for clinical and experimental reference

Peripheral nerve injury, resulting from various physical and chemical causes, has a high incidence and significant functional impact. This injury, affecting both sensory and motor functions, can severely diminish quality of life and cause mental health issues. Consequently, it is a major focus of current research. Recent advancements in peripheral nerve repair technology, including the application of new techniques and materials, have expanded the options for nerve repair methods. A comprehensive article that combines the pathological process of peripheral nerve repair with these methods is needed to advance research in this field. This review aims to provide a comprehensive overview of various techniques for repairing peripheral nerve injuries. Beginning with the histopathology of nerve injury, it evaluates these techniques in detail to offer clinical guidance. This review summarizes the advantages and disadvantages of various peripheral nerve repair methods, including photobiological modulation therapy, suture repair, nerve graft repair, vein graft catheter repair, muscle graft repair, laser welding repair, nerve catheter repair, nerve sliding repair technology, growth factor-assisted repair, stem cell therapy, and exosome therapy. Additionally, it explores future directions in the treatment of peripheral nerve injuries, providing valuable references for experimental research and clinical treatment.

Therapeutic Advances in Peripheral Nerve Injuries: Nerve-Guided Conduit and Beyond

Peripheral nerve injury (PNI), a challenging neurosurgery issue, often leads to partial or complete loss of neuronal functions and even neuropathic pain. Thus far, the gold standard for treating peripheral nerve deficit remains autografts. While numerous reviews have explored PNI and regeneration, this work distinctively synthesizes recent advancements in tissue engineering-particularly four-dimensional (4D) bioprinting and exosome therapies-with an emphasis on their clinical translation. By consolidating findings spanning molecular mechanisms to therapeutic applications, this review proposes an actionable framework for advancing experimental strategies toward clinically viable solutions. Our work critically evaluates emerging innovations such as dynamically adaptive 4D-printed nerve conduits and exosome-based therapies, underscoring their potential to match conventional autografts in achieving functional restoration. Impact Statement Although several previous reviews have been made on describing with great detail the degenerative and regenerative mechanisms of the peripheral nervous systems, as well as the several existing and exploratory treatment strategies, we focus more on the latest advancements of each of those topics.

Advances in biomaterial-based tissue engineering for peripheral nerve injury repair

Peripheral nerve injury is a common clinical disease. Effective post-injury nerve repair remains a challenge in neurosurgery, and clinical outcomes are often unsatisfactory, resulting in social and economic burden. Particularly, the repair of long-distance nerve defects remains a challenge. The existing nerve transplantation strategies show limitations, including donor site morbidity and immune rejection issues. The multiple studies have revealed the potential of tissue engineering strategies based on biomaterials in the repair of peripheral nerve injuries. We review the events of regeneration after peripheral nerve injury, evaluates the efficacy of existing nerve grafting strategies, and delves into the progress in the construction and application strategies of different nerve guidance conduits. A spotlight is cast on the materials, technologies, seed cells, and microenvironment within these conduits to facilitate optimal nerve regeneration. Further discussion was conducted on the approve of nerve guidance conduits and potential future research directions. This study anticipates and proposes potential avenues for future research, aiming to refine existing strategies and uncover innovative approaches in biomaterial-based nerve repair. This study endeavors to synthesize the collective insights from the fields of neuroscience, materials science, and regenerative medicine, offering a multifaceted perspective on the role of biomaterials in advancing the frontiers of peripheral nerve injury treatment.

Core-shell hydrogel with synergistic super absorption and long-term acid resistance stability: a novel gastric retention drug delivery carrier

Traditional natural polysaccharide-based hydrogels, when used as drug carriers, often struggle to maintain long-term stability in the extremely harsh gastric environment. This results in unstable drug release and significant challenges in bioavailability. To address this issue, this study utilized inexpensive and safe natural polysaccharides-chitosan (CS) and high methoxyl pectin (HM)-as raw materials. Dynamic chemical bonds and anion-cation electrostatic interactions were employed to successfully prepare a super absorbent gel bead substrate (CS-HM), which serves as the "core" structure. Subsequently, another low-density hydrophilic polysaccharide, sodium carboxymethyl cellulose (CMCNa), was used to coat and crosslink the outer layer of the core, increasing the number of ionic groups. This enhancement raises the osmotic pressure inside the gel network, improving its absorption capacity. At the same time, the core-shell structure provides an energy dissipation mechanism, allowing the material to remain more stable in a strong acid environment. Due to its super absorption, high modulus, and continuous floating release properties, CS-HM@CMCNa-as a new type of acid-resistant super absorbent core-shell material-possesses the key characteristics required for gastric retention sustained-release systems. It is expected to become an ideal drug carrier for the treatment of clinical chronic diseases.

Advances in polysaccharide-based materials for biomedical and pharmaceutical applications: A comprehensive review

Polysaccharides, the most abundant biopolymers in nature, have attracted the attention of researchers and clinicians due to its practicality in biomedical and pharmaceutical sciences. These biomaterials have high bioavailability and play structural and functional roles in living organisms. Polysaccharides are classified into several groups based on their origin, including plant polysaccharides and marine polysaccharides (like chitosan, hyaluronic acid, dextran, alginates, etc.) with specific applications. These biopolymers possess unique physicochemical (such as surface functional groups, solubility, and stability), mechanical (like mechanical strength and tensile), and biomedical (such as antioxidant activity, biocompatibility, biodegradability, renewability, and non-immunogenicity) characteristics which have made them excellent platforms for a wide variety of biomedical and pharmaceutical applications. Ease of extraction and different preparation approaches are mentioned as other potential properties of polysaccharides that further improved their practicality in biomedical sciences. They have high drug/bioactive encapsulation capacity and sustained/controlled release manner in in vivo microenvironments. The anti-inflammatory and immunomodulation, stimuli-responsive drug/bioactive release, and passive and active drug/bioactive delivery are considered the potential features of these biopolymers in pharmaceutical sciences. Polysaccharides have indicated practical applications in biomedical sciences, including biosensors, tissue engineering, implantation, wound healing, vascular grafting, and vaccines. This review highlights the advances of polysaccharide-based materials in biomedical and pharmaceutical sciences.

Recent advance for animal-derived polysaccharides in nanomaterials

Inspired by the structure characteristics of natural products, the size and morphology of particles are carefully controlled using a bottom-up approach to construct nanomaterials with specific spatial unit distribution. Animal polysaccharide nanomaterials, such as chitosan and chondroitin sulfate nanomaterials, exhibit excellent biocompatibility, degradability, customizable surface properties, and novel physical and chemical properties. These nanomaterials hold great potential for development in achieving a sustainable bio-economy. This paper provides a summary of the latest research results on the preparation of nanomaterials from animal polysaccharides. The mechanism for preparing nanomaterials through the bottom-up method from different sources of animal polysaccharides is introduced. Furthermore, this paper discusses the potential hazards posed by industrial applications to the environment and human health, as well as the challenges and future prospects associated with using animal polysaccharides in nanomaterials.

Effect of sodium L-lactate on bioactive properties of chitosan-hydroxyapatite/polycaprolactone conduits for peripheral nerve tissue engineering

Biomaterials and synthetic polymers have been widely used to replicate the regenerative microenvironment of the peripheral nervous system. Chitosan-based conduits have shown promise in the regeneration of nerve injuries. However, to mimic the regenerative microenvironment, the scaffold structure should possess bioactive properties. This can be achieved by the incorporation of biomolecules (e.g., proteins, peptides) or trophic factors that should preferably be aligned and/or released with controlled kinetics to activate the process of positive axon chemotaxis. In this study, sodium L-lactate has been used to enhance the bioactive properties of chitosan-hydroxyapatite/polycaprolactone electrodeposits. Next, two methods have been developed to incorporate NGF-loaded microspheres - Method 1 involves entrapment and co-deposition of NGF-loaded microspheres, while Method 2 is based on absorption of NGF-loaded microspheres. The study shows that modification of chitosan-hydroxyapatite/polycaprolactone conduits by sodium L-lactate significantly improves their bioactive, biological, and physicochemical properties. The obtained implants are cytocompatible, enhancing the neurite regeneration process by stimulating its elongation. The absorption of NGF-loaded microspheres into the conduit structure may be considered more favorable for the stimulation of axonal elongation compared to entrapment, as it allows for trophic factor dose-dependent controlled release. The developed conduits possess properties essential for the successful treatment of peripheral nerve discontinuities.

Natural polymeric biomaterials for managing peripheral nerve injuries : a novel approach for tissue repair and reconstruction

Peripheral nerve injury serves as a major challenge to clinicians and researchers due to the complexity and functions of peripheral nerves that play the crucial role of transmitting signals between spinal cord and other human body tissues. Biomaterials offer promising solutions for regeneration of nerve tissues owing to their biodegradability, and biocompatibility. They can be fabricated as hydrogels, scaffolds, nanofibrous matrices, and nanoparticles that can facilitate the release of therapeutic molecules to reduce inflammation and promote neuronal growth. Managing peripheral nerve injuries through natural polymeric based biomaterials represents as a novel approach for tissue repair and reconstruction in the field of regenerative medicine. This correspondence will give an insight into the different types of natural polymeric biomaterials that can be efficiently used in managing peripheral nerve injuries.

Nanocellulose in targeted drug delivery: A review of modifications and synergistic applications

Nanocellulose, a versatile biopolymer renowned for its exceptional physicochemical attributes including lightweight, biocompatibility, biodegradability, and higher mechanical strength properties has captured significant attention in biomedical research. This renewable material, extracted from widely abundant biosources including plants, bacteria, and algae, exists in three primary forms: cellulose-based nanocrystals (CNCs), nanofibrils (CNFs), and bacterial nanocellulose (BNC). CNCs are characterized by their highly crystalline, needle-shaped structure, while CNFs possess a blend of amorphous and crystalline regions. BNC stands out as the purest form of nanocellulose. Chemical functionalization enables precise tuning of nanocellulose properties, enhancing its suitability for diverse biomedical applications. In drug delivery systems, nanocellulose's unique structure and surface chemistry offer opportunities for targeted delivery of active molecules. Surface-modified nanocellulose can effectively deliver drugs to specific sites, utilizing its inherent properties to control drug release kinetics and improve therapeutic outcomes. Despite these advantages, challenges such as achieving optimal drug loading capacity and ensuring sustained drug release remain. Future research aims to address these challenges and explore novel applications of nano-structured cellulose in targeted drug delivery, highlighting the continued evolution of this promising biomaterial in biomedicine. Furthermore, the review delves into the impact of chemical, physical, and enzymatic methods for CNC surface modifications, showcasing how these approaches enhance the functionalization of CNCs for targeted delivery of different compounds in biological systems.

Polysaccharides as a promising platform for the treatment of spinal cord injury: A review

Spinal cord injury is incurable and often results in irreversible damage to motor function and autonomic sensory abilities. To enhance the effectiveness of therapeutic substances such as cells, growth factors, drugs, and nucleic acids for treating spinal cord injuries, as well as to reduce the toxic side effects of chemical reagents, polysaccharides have been gained attention due to their immunomodulatory properties and the biocompatibility and biodegradability of polysaccharide scaffolds. Polysaccharides hold potential as drug delivery systems in treating spinal cord injuries. This article aims to present an extensive evaluation of the potential applications of polysaccharide materials in scaffold construction, drug delivery, and immunomodulation over the past five years so that offering new directions and opportunities for the treatment of spinal cord injuries.

Enhancement of Oral Bioavailability of Protein and Peptide by Polysaccharide-based Nanoparticles

Oral drug delivery is a prevalent and cost-effective method due to its advantages, such as increased drug absorption surface area and improved patient compliance. However, delivering proteins and peptides orally remains a challenge due to their vulnerability to degradation by digestive enzymes, stomach acids, and limited intestinal membrane permeability, resulting in poor bioavailability. The use of nanotechnology has emerged as a promising solution to enhance the bioavailability of these vital therapeutic agents. Polymeric NPs, made from natural or synthetic polymers, are commonly used. Natural polysaccharides, such as alginate, chitosan, dextran, starch, pectin, etc., have gained preference due to their biodegradability, biocompatibility, and versatility in encapsulating various drug types. Their hydrophobic-hydrophilic properties can be tailored to suit different drug molecules.

Progress in methods for evaluating Schwann cell myelination and axonal growth in peripheral nerve regeneration via scaffolds

Peripheral nerve injury (PNI) is a neurological disorder caused by trauma that is frequently induced by accidents, war, and surgical complications, which is of global significance. The severity of the injury determines the potential for lifelong disability in patients. Artificial nerve scaffolds have been investigated as a powerful tool for promoting optimal regeneration of nerve defects. Over the past few decades, bionic scaffolds have been successfully developed to provide guidance and biological cues to facilitate Schwann cell myelination and orientated axonal growth. Numerous assessment techniques have been employed to investigate the therapeutic efficacy of nerve scaffolds in promoting the growth of Schwann cells and axons upon the bioactivities of distinct scaffolds, which have encouraged a greater understanding of the biological mechanisms involved in peripheral nerve development and regeneration. However, it is still difficult to compare the results from different labs due to the diversity of protocols and the availability of innovative technologies when evaluating the effectiveness of novel artificial scaffolds. Meanwhile, due to the complicated process of peripheral nerve regeneration, several evaluation methods are usually combined in studies on peripheral nerve repair. Herein, we have provided an overview of the evaluation methods used to study the outcomes of scaffold-based therapies for PNI in experimental animal models and especially focus on Schwann cell functions and axonal growth within the regenerated nerve.

How Advancing is Peripheral Nerve Regeneration Using Nanofiber Scaffolds? A Comprehensive Review of the Literature

Peripheral nerve injuries present significant challenges in regenerative medicine, primarily due to inherent limitations in the body's natural healing processes. In response to these challenges and with the aim of enhancing peripheral nerve regeneration, nanofiber scaffolds have emerged as a promising and advanced intervention. However, a deeper understanding of the underlying mechanistic foundations that drive the favorable contributions of nanofiber scaffolds to nerve regeneration is essential. In this comprehensive review, we make an exploration of the latent potential of nanofiber scaffolds in augmenting peripheral nerve regeneration. This exploration includes a detailed introduction to the fabrication methods of nanofibers, an analysis of the intricate interactions between these scaffolds and cellular entities, an examination of strategies related to the controlled release of bioactive agents, an assessment of the prospects for clinical translation, an exploration of emerging trends, and thorough considerations regarding biocompatibility and safety. By comprehensively elucidating the intricate structural attributes and multifaceted functional capacities inherent in nanofiber scaffolds, we aim to offer a prospective and effective strategy for the treatment of peripheral nerve injury.

Nanofibrous polycaprolactone/amniotic membrane facilitates peripheral nerve regeneration by promoting macrophage polarization and regulating inflammatory microenvironment

Appropriate levels of inflammation are an important part of functional repair of nerve damage. However, excessive inflammation can cause the continuous activation of immune inflammatory cells and degeneration of nerve cells. Regulating the temporal and spatial changes in M1/M2 macrophages can regulate the local inflammatory immune environment of the tissue to promote its transformation to a direction conducive to tissue repair.In the present study, a multi-layer multifunctional nanofiber composite membrane of polycaprolactone(PCL) and amniotic membrane (AM) was constructed using electrospinning. In vitro studies have shown that the PCL/AM composite promoted the axon growth of SH-SY5Y cells and induced their differentiation into neurons. The PCL/AM composite wrapped the nerve stump to form a microenvironment that was conducive to nerve regeneration, blocked the invasion of scar tissue, promoted the recruitment of macrophages and moderate polarization to M2, enhanced the expression of anti-inflammatory factors IL-10 and IL-13, inhibited the expression of pro-inflammatory factors IL-6 and TNF-α, and induced myelin sheath and axon regeneration. By releasing various bioactive substances to regulate the polarization of M2 macrophages and formation of anti-inflammatory factors, the PCL/AM composite can enhance axonal regeneration and improve nerve repair.