Comparing Processed Nerve Allografts and Assessing Their Capacity to Retain and Release Nerve Growth Factor

End-to-side neurorrhaphy in the reconstruction of peripheral segmental neural loss: an experimental study

PURPOSE

To evaluate the effects on peripheral neural regeneration of the end-to-side embracing repair technique compared to the autograft repair technique in Wistar rats.

METHODS

Fifteen male Wistar rats were divided into three groups with five animals each: denervated group (GD), autograft group (GA), and embracing group (EG). For the evaluation, the grasping test, electroneuromyography (ENMG), and muscle weight assessment were used.

RESULTS

Muscle weight assessment and ENMG did not show significant neural regeneration at the end of 12 weeks in the DG and GE groups, but only in GA. The grasping test showed an increase in strength between the surgery and the fourth week in all groups, and only the GA maintained this trend until the 12th week.

CONCLUSIONS

The present study indicates that the neural regeneration observed in the end-to-side embracing neurorrhaphy technique, in the repair of segmental neural loss, is inferior to autograft repair in Wistar rats.

Evidence-Based Approach to Nerve Gap Repair in the Upper Extremity: A Review of the Literature and Current Algorithm for Surgical Management

The upper extremity is the most common site for nerve injuries. In most cases, direct repair can be performed, but when a critical gap occurs, special techniques must be used to enhance nerve regeneration and allow recovery of sensory and motor functions. These techniques include the use of autografts, processed nerve allografts, and conduits. However, surprisingly few studies have compared outcomes from the different methods of nerve gap repair in a rigorous fashion. There is a lack of evidence-based guidelines for the management of digital and motor and mixed nerve injuries with a nerve gap. The purpose of this study is to perform a comprehensive literature review and propose a rational algorithm for management of nerve injuries with a critical gap.

Decellularized nerve matrix hydrogel and glial-derived neurotrophic factor modifications assisted nerve repair with decellularized nerve matrix scaffolds

Nerve defects are challenging to address clinically without satisfactory treatments. As a reliable alternative to autografts, decellularized nerve matrix scaffolds (DNM-S) have been widely used in clinics for surgical nerve repair. However, DNM-S remain inferior to autografts in their ability to support nerve regeneration for long nerve defects. In this study, we systematically and clearly presented the nano-architecture of nerve-specific structures, including the endoneurium, basement membrane and perineurium/epineurium in DNM-S. Furthermore, we modified the DNM-S by supplementing decellularized nerve matrix hydrogel (DNMG) and glial-derived neurotrophic factor (GDNF) and then bridged a 50-mm sciatic nerve defect in a beagle model. Fifteen beagles were randomly divided into three groups (five per group): an autograft group, DNM-S group and GDNF-DNMG-modified DNM-S (DNM-S/GDNF@DNMG) group. DNM-S/GDNF@DNMG, as optimized nerve grafts, were used to bridge nerve defects in the same manner as in the DNM-S group. The repair outcome was evaluated by behavioural observations, electrophysiological assessments, regenerated nerve tissue histology and reinnervated target muscle examinations. Compared with the DNM-S group, limb function, electrophysiological responses and histological findings were improved in the DNM-S/GDNF@DNMG group 6 months after grafting, reflecting a narrower gap between the effects of DNM-S and autografts. In conclusion, modification of DNM-S with DNMG and GDNF enhanced nerve regeneration and functional recovery, indicating that noncellular modification of DNM-S is a promising method for treating long nerve defects.

Decellularization techniques and their applications for the repair and regeneration of the nervous system

A variety of surgical and non-surgical approaches have been used to address the impacts of nervous system injuries, which can lead to either impairment or a complete loss of function for affected patients. The inherent ability of nervous tissues to repair and/or regenerate is dampened due to irreversible changes that occur within the tissue remodeling microenvironment following injury. Specifically, dysregulation of the extracellular matrix (i.e., scarring) has been suggested as one of the major factors that can directly impair normal cell function and could significantly alter the regenerative potential of these tissues. A number of tissue engineering and regenerative medicine-based approaches have been suggested to intervene in the process of remodeling which occurs following injury. Decellularization has become an increasingly popular technique used to obtain acellular scaffolds, and their derivatives (hydrogels, etc.), which retain tissue-specific components, including critical structural and functional proteins. These advantageous characteristics make this approach an intriguing option for creating materials capable of stimulating the sensitive repair mechanisms associated with nervous system injuries. Over the past decade, several diverse decellularization methods have been implemented specifically for nervous system applications in an attempt to carefully remove cellular content while preserving tissue morphology and composition. Each application-based decellularized ECM product requires carefully designed treatments that preserve the unique biochemical signatures associated within each tissue type to stimulate the repair of brain, spinal cord, and peripheral nerve tissues. Herein, we review the decellularization techniques that have been applied to create biomaterials with the potential to promote the repair and regeneration of tissues within the central and peripheral nervous system.

Repair of long segmental ulnar nerve defects in rats by several different kinds of nerve transposition

Multiple regeneration of axonal buds has been shown to exist during the repair of peripheral nerve injury, which confirms a certain repair potential of the injured peripheral nerve. Therefore, a systematic nerve transposition repair technique has been proposed to treat severe peripheral nerve injury. During nerve transposition repair, the regenerated nerve fibers of motor neurons in the anterior horn of the spinal cord can effectively grow into the repaired distal nerve and target muscle tissues, which is conducive to the recovery of motor function. The aim of this study was to explore regeneration and nerve functional recovery after repairing a long-segment peripheral nerve defect by transposition of different donor nerves. A long-segment (2 mm) ulnar nerve defect in Sprague-Dawley rats was repaired by transposition of the musculocutaneous nerve, medial pectoral nerve, muscular branches of the radial nerve and anterior interosseous nerve (pronator quadratus muscle branch). In situ repair of the ulnar nerve was considered as a control. Three months later, wrist flexion function, nerve regeneration and innervation muscle recovery in rats were assessed using neuroelectrophysiological testing, osmic acid staining and hematoxylin-eosin staining, respectively. Our findings indicate that repair of a long-segment ulnar nerve defect with different donor nerve transpositions can reinnervate axonal function of motor neurons in the anterior horn of spinal cord and restore the function of affected limbs to a certain extent.

Emerging Technologies in Upper Extremity Surgery: Polyvinyl Alcohol Hydrogel Implant for Thumb Carpometacarpal Arthroplasty and Processed Nerve Allograft and Nerve Conduit for Digital Nerve Repairs

In the field of upper extremity surgery there are myriad new and developing technologies. The purpose of this article is to highlight a few of the most compelling new technologies and review their background, indications for use, and most recently reported outcomes in clinical practice.