A grooved conduit combined with decellularized tissues for peripheral nerve regeneration

Bioactive ECM-mimicking nerve guidance conduit for enhancing peripheral nerve repair

Extensive research efforts are being directed towards identifying alternatives to autografts for the treatment of peripheral nerve injuries (PNIs) with engineered nerve conduits (NGCs) identified as having potential for PNI patients. These NGCs, however, may not fulfill the necessary criteria for a successful transplant, such as sufficient mechanical structural support and functionalization. To address the aforementioned limitations of NGCs, the present investigation explored the development of double cross-linked hydrogels (o-CSMA-E) that integrate the biocompatibility of porcine tendon extracellular matrix (ECM) with the antimicrobial and conductive properties of methacrylated quaternary chitosan. The hydrogels had matrices that could promote the growth of axons and the transmission of neural signals. The hydrogels were subsequently incorporated into a nanofibrous PLLA-ZnO sheath scaffold (ZnO@PLLA) to emulate the natural nerve structure, guiding cell growth and facilitating nerve regeneration. The collaboration of core and sheath materials in ZnO@PLLA/o-CSMA-E nerve guidance conduits resulted in enhanced migration of Schwann cells, formation of myelin sheaths, and improved locomotion performance in rats with sciatic nerve defects when in vivo studies were undertaken. Notably, the in vivo studies demonstrated the similarity between the newly developed engineered NGCs and autologous transplants, with the newly engineered NGCs possessing the potential to promote functional recovery by mimicking the tubular structure and ECM of nerves.

PLCL/SF/NGF nerve conduit loaded with RGD-TA-PPY hydrogel promotes regeneration of sciatic nerve defects in rats through PI3K/AKT signalling pathways

Peripheral nerve defect are common clinical problem caused by trauma or other diseases, often leading to the loss of sensory and motor function in patients. Autologous nerve transplantation has been the gold standard for repairing peripheral nerve defects, but its clinical application is limited due to insufficient donor tissue. In recent years, the application of tissue engineering methods to synthesize nerve conduits for treating peripheral nerve defect has become a current research focus. This study introduces a novel approach for treating peripheral nerve defects using a tissue-engineered PLCL/SF/NGF@TA-PPy-RGD conduit. The conduit was fabricated by combining electrospun PLCL/SF with an NGF-loaded conductive TA-PPy-RGD gel. The gel, synthesized from RGD-modified tannic acid (TA) and polypyrrole (PPy), provides growth anchor points for nerve cells. In vitro results showed that this hybrid conduit could enhance PC12 cell proliferation, migration, and reduce apoptosis under oxidative stress. Furthermore, the conduit activated the PI3K/AKT signalling pathway in PC12 cells. In a rat model of sciatic nerve defect, the PLCL/SF/NGF@TA-PPy-RGD conduit significantly improved motor function, gastrocnemius muscle function, and myelin sheath axon thickness, comparable to autologous nerve transplantation. It also promoted angiogenesis around the nerve defect. This study suggests that PLCL/SF/NGF@TA-PPy-RGD conduits provide a conducive environment for nerve regeneration, offering a new strategy for peripheral nerve defect treatment, this study provided theoretical basis and new strategies for the research and treatment of peripheral nerve defect.

Conductive and alignment-optimized porous fiber conduits with electrical stimulation for peripheral nerve regeneration

Autologous nerve transplantation (ANT) is currently considered the gold standard for treating long-distance peripheral nerve defects. However, several challenges associated with ANT, such as limited availability of donors, donor site injury, mismatched nerve diameters, and local neuroma formation, remain unresolved. To address these issues comprehensively, we have developed porous poly(lactic-co-glycolic acid) (PLGA) electrospinning fiber nerve guide conduits (NGCs) that are optimized in terms of alignment and conductive coating to facilitate peripheral nerve regeneration (PNR) under electrical stimulation (ES). The physicochemical and biological properties of aligned porous PLGA fibers and poly(3,4-ethylenedioxythiophene):polystyrene sodium sulfonate (PEDOT:PSS) coatings were characterized through assessments of electrical conductivity, surface morphology, mechanical properties, hydrophilicity, and cell proliferation. Material degradation experiments demonstrated the biocompatibility in vivo of electrospinning fiber films with conductive coatings. The conductive NGCs combined with ES effectively facilitated nerve regeneration. The designed porous aligned NGCs with conductive coatings exhibited suitable physicochemical properties and excellent biocompatibility, thereby significantly enhancing PNR when combined with ES. This combination of porous aligned NGCs with conductive coatings and ES holds great promise for applications in the field of PNR.

Surface topologized ovalbumin scaffolds containing YIGSR peptides for modulating Schwann cell behavior

Peripheral nerve injuries (PNI) currently have limited therapeutic efficacy, and functional scaffolds have been shown to be effective for treating PNI. Ovalbumin (OVA) is widely used as a natural biomaterial for repairing damaged tissues due to its excellent biocompatibility and the presence of various bioactive components. However, there are few reports on the repair of PNI by ovalbumin. In this study, a novel bionic functionalized topological scaffold based on ovalbumin and grafted with tyrosine-isoleucine-glycine-serine-arginine (YIGSR) peptide was constructed by micro-molding method and surface-biomodification technology. The scaffolds were subjected to a series of evaluations in terms of morphology, mechanics, hydrophilicity, and biocompatibility, and the related molecular mechanisms were further penetrated. The results showed that the scaffolds prepared in this study had aligned ridge/groove structure, good mechanical properties and biocompatibility, and could be used as carriers to slowly release YIGSR, which effectively promoted the proliferation, migration and elongation of Schwann Cells (SCs), and significantly up-regulated the gene expression related to proliferation, apoptosis, migration and axon regeneration. Therefore, the bionic functional topological scaffold has significant application potential for promoting peripheral nerve regeneration and provides a new therapeutic option for repairing PNI.

Advances in nerve guidance conduits for peripheral nerve repair and regeneration

Peripheral nerve injury (PNI) can cause partial or total motor and sensory nerve function, leading to physical disability and nerve pain that severely affects patients' quality of life. Autologous nerve transplantation is currently the clinically recognized gold standard, but due to its inherent limitations, researchers have been searching for alternative treatments. Nerve guidance conduits (NGCs) have attracted much attention as a favorable alternative to promote the repair and regeneration of damaged peripheral nerves. In this review, we provide an overview of the anatomy of peripheral nerves, peripheral nerve injury and repair, and current treatment methods. Importantly, different design strategies of NGCs used for the treatment of PNI and their applications in PNI repair are highlighted. Finally, an outlook on the future development and challenges of NGCs is presented.

Nerve regeneration using decellularized tissues: challenges and opportunities

In tissue engineering, the decellularization of organs and tissues as a biological scaffold plays a critical role in the repair of neurodegenerative diseases. Various protocols for cell removal can distinguish the effects of treatment ability, tissue structure, and extracellular matrix (ECM) ability. Despite considerable progress in nerve regeneration and functional recovery, the slow regeneration and recovery potential of the central nervous system (CNS) remains a challenge. The success of neural tissue engineering is primarily influenced by composition, microstructure, and mechanical properties. The primary objective of restorative techniques is to guide existing axons properly toward the distal end of the damaged nerve and the target organs. However, due to the limitations of nerve autografts, researchers are seeking alternative methods with high therapeutic efficiency and without the limitations of autograft transplantation. Decellularization scaffolds, due to their lack of immunogenicity and the preservation of essential factors in the ECM and high angiogenic ability, provide a suitable three-dimensional (3D) substrate for the adhesion and growth of axons being repaired toward the target organs. This study focuses on mentioning the types of scaffolds used in nerve regeneration, and the methods of tissue decellularization, and specifically explores the use of decellularized nerve tissues (DNT) for nerve transplantation.