Strategies for Treating Traumatic Neuromas with Tissue-Engineered Materials.

Neuroma, a pathological response to peripheral nerve injury, refers to the abnormal growth of nerve tissue characterized by disorganized axonal proliferation. Commonly occurring after nerve injuries, surgeries, or amputations, this condition leads to the formation of painful nodular structures. Traditional treatment options include surgical excision and pharmacological management, aiming to alleviate symptoms. However, these approaches often offer temporary relief without addressing the underlying regenerative challenges, necessitating the exploration of advanced strategies such as tissue-engineered materials for more comprehensive and effective solutions. In this study, we discussed the etiology, molecular mechanisms, and histological morphology of traumatic neuromas after peripheral nerve injury. Subsequently, we summarized and analyzed current nonsurgical and surgical treatment options, along with their advantages and disadvantages. Additionally, we emphasized recent advancements in treating traumatic neuromas with tissue-engineered material strategies. By integrating biomaterials, growth factors, cell-based approaches, and electrical stimulation, tissue engineering offers a comprehensive solution surpassing mere symptomatic relief, striving for the structural and functional restoration of damaged nerves. In conclusion, the utilization of tissue-engineered materials has the potential to significantly reduce the risk of neuroma recurrence after surgical treatment.

Multifunctional wet-adhesive chitosan/acrylic conduit for sutureless repair of peripheral nerve injuries.

The incidence of peripheral nerve injury (PNI) is high worldwide, and a poor prognosis is common. Surgical closure and repair of the affected area are crucial to ensure the effective treatment of peripheral nerve injuries. Despite being the standard treatment approach, reliance on sutures to seal the severed nerve ends introduces several limitations and restrictions. This technique is intricate and time-consuming, and the application of threading and punctate sutures may lead to tissue damage and heightened tension concentrations, thus increasing the risk of fixation failure and local inflammation. This study aimed to develop easily implantable chitosan-based peripheral nerve repair conduits that combine acrylic acid and cleavable N-hydroxysuccinimide to reduce nerve damage during repair. In ex vivo tissue adhesion tests, the conduit achieved maximal interfacial toughness of 705 J m-2 ± 30 J m-2, allowing continuous bridging of the severed nerve ends. Adhesive repair significantly reduces local inflammation caused by conventional sutures, and the positive charge of chitosan disrupts the bacterial cell wall and reduces implant-related infections. This promises to open new avenues for sutureless nerve repair and reliable medical implants.

The Porous Structure of Peripheral Nerve Guidance Conduits: Features, Fabrication, and Implications for Peripheral Nerve Regeneration.

Porous structure is an important three-dimensional morphological feature of the peripheral nerve guidance conduit (NGC), which permits the infiltration of cells, nutrients, and molecular signals and the discharge of metabolic waste. Porous structures with precisely customized pore sizes, porosities, and connectivities are being used to construct fully permeable, semi-permeable, and asymmetric peripheral NGCs for the replacement of traditional nerve autografts in the treatment of long-segment peripheral nerve injury. In this review, the features of porous structures and the classification of NGCs based on these characteristics are discussed. Common methods for constructing 3D porous NGCs in current research are described, as well as the pore characteristics and the parameters used to tune the pores. The effects of the porous structure on the physical properties of NGCs, including biodegradation, mechanical performance, and permeability, were analyzed. Pore structure affects the biological behavior of Schwann cells, macrophages, fibroblasts, and vascular endothelial cells during peripheral nerve regeneration. The construction of ideal porous structures is a significant advancement in the regeneration of peripheral nerve tissue engineering materials. The purpose of this review is to generalize, summarize, and analyze methods for the preparation of porous NGCs and their biological functions in promoting peripheral nerve regeneration to guide the development of medical nerve repair materials.

Tissue-Engineered Nanomaterials Play Diverse Roles in Bone Injury Repair.

Nanomaterials with bone-mimicking characteristics and easily internalized by the cell could create suitable microenvironments in which to regulate the therapeutic effects of bone regeneration. This review provides an overview of the current state-of-the-art research in developing and using nanomaterials for better bone injury repair. First, an overview of the hierarchical architecture from the macroscale to the nanoscale of natural bone is presented, as these bone tissue microstructures and compositions are the basis for constructing bone substitutes. Next, urgent clinical issues associated with bone injury that require resolution and the potential of nanomaterials to overcome them are discussed. Finally, nanomaterials are classified as inorganic or organic based on their chemical properties. Their basic characteristics and the results of related bone engineering studies are described. This review describes theoretical and technical bases for the development of innovative methods for repairing damaged bone and should inspire therapeutic strategies with potential for clinical applications.

Epicardial delivery of a conductive membrane synchronizes conduction to reduce atrial fibrillation.

Conductive polymers have been investigated as a medium for the transmission of electrical signals in biological tissues, but their capacity to rewire cardiac tissue has not been evaluated. Myocardial tissue is unique in being able to generate an electrical potential at a fixed rate; this potential spreads rapidly among cells to trigger muscle contractions. Tissue injuries result in myocardial fibrosis and subsequent non-uniform conductivity, leading to arrhythmia. Atrial fibrillation (AF) is the most common sustained arrhythmia, associated with disruption of atrial electrical signaling, which can potentially be restored by the epicardial delivery of conductive polymers. In this work, poly-3-amino-4-methoxybenzoic acid, conjugated to gelatin, is fabricated as a membrane (PAMB-G) to support conductive velocities that are close to that of the myocardium. A cross-linked gelatin membrane (Gelatin) is used as a control. The as-fabricated PAMB-G has similar tensile elasticities, determined using the Young's modulus, as contracting myocardium; it can also transmit electrical signals to initiate cardiac cell and tissue excitation. Delivering PAMB-G onto the atrium of a rat AF model shortens AF duration and improves post-AF recovery for the duration of a 28-day-long study. Atrial tissue in the PAMB-G-implanted group has lower impedance, higher conduction velocity, and higher field potential amplitude than that in the Gelatin-implanted group. Therefore, the as-proposed PAMB-G is a suitable medium for restoring proper cardiac electrical signaling in AF hearts.

Comparison of FP-7 and S-2 Ahmed glaucoma valve implantation in refractory glaucoma patients for short-term follow-up.

BACKGROUND: Ahmed glaucoma valves (AGV) has been used for decades, but there is no detailed report about the efficacy of AGV in Chinese glaucoma patients. This study aimed to compare the intraocular pressure (IOP) lowering efficacy and side effects of S-2 polypropylene and PF-7 silicone AGV implantation in Chinese refractory glaucoma patients. METHODS: Patients were divided into S-2 model AGV group and FP-7 model AGV group. The complete and qualified surgical success rate, change of IOP, number of anti-glaucoma medications used and postoperative complications were recorded and analyzed. RESULTS: Average follow-up time was comparable between two groups. IOP was reduced from (37.9 ± 12.7) mmHg preoperatively to (17.3 ± 5.3) mmHg at the last follow-up in S-2 group and reduced from (39.9 ± 14.4) mmHg to (17.7 ± 4.9) mmHg in FP-7 group. Anti-glaucoma medications were reduced from 3.8 ± 0.2 to 1.5 ± 0.2 in S-2 group, and 3.5 ± 0.2 to 0.7 ± 0.2 in FP-7 groups. The cumulative success rates were comparable in two groups, which were 61.2% and 72.1% in S-2 group and FP-7 group respectively. When IOP reduction criteria was used, complete success rates were 30.6% and 51.2% for S-2 and FP-7 groups, and qualified success rates were 86.1% and 92.7% separately. In both groups, the major complication was hypotony, and the previous trabeculectomy of patients was the major risk factor for surgery failure. CONCLUSIONS: In this short-term retrospective study, S-2 AGV is showed at least as effective as FP-7 AGV in IOP reduction, but associated with higher rate of complications. Previous trabeculectomy is a principle risk factor for AGV implantation failure. These clinical outcomes are important for converting use of the FP-7 silicon AGV in Chinese refractory glaucoma patients.

[Clinical efficacy and safety of FP-7 Ahmed glaucoma valve implantation in neurovascular glaucoma patients].

OBJECTIVE: To evaluate the efficacy and safety of FP-7 Ahmed glaucoma valves (AGV) implantation in neurovascular glaucoma (NVG) as the first choice of surgery. METHODS: This retrospective, comparative case series study collected a total of 36 eyes of 36 patients with neurovascular glaucoma who underwent AGV implantation in Zhongshan Ophthalmic Center from January 2009 to June 2010. Change of intraocular pressure (IOP), the best corrected visual acuity, numbers of anti-glaucoma medication, success rate and postoperative complications were followed up at day 1, week 1, month 1, and every 3 months after surgery. Complete success of surgery was rated as reduction of IOP ≥ 30% without medication and those who failed to meet criteria was rated as partial success. Data were analyzed by paired Student t-test for IOP, rank sum test for paired non-parametric numbers of medication, and repeated measures analysis of variance for comparison of IOP between different time points using SPSS 13.0. RESULTS: Compared with pre-operation, IOP was significant (F = 9.26, P < 0.05) decreased after surgery with FP-7 AGV implantation (39.5 ± 9.7) mm Hg (1 mm Hg = 0.133 kPa) vs (9.2 ± 8.9), (11.8 ± 3.8), (13.7 ± 4.8), (16.9 ± 5.3), (16.9 ± 6.8) mm Hg at day 1, week 1, month 1, month 3 and the last following-up of post-operation, respectively. The numbers of anti-glaucoma medication were significantly (Z = 6.764, P < 0.05) reduced from 4.0 (1-6) of pre-operation to 1.0 (1-3) of post-operation. At the last following up, the complete success rate after FP-7 AGV implantation was 80.6%, and qualified success rate was 91.7%. The postoperative complications including occlusion of the drainage tube, exposure of the drainage tube, shallow anterior chamber and encapsulated cystic blebs around the plate were controlled with additional treatment. CONCLUSIONS: The clinical outcome indicated that the implantation of FP-7 AGV has a stable IOP lowering effect and fewer complications, which can be considered as one of the first choices for management of NVG.