Functional Recovery of Transected Peripheral Nerve by Means of Microwave Irradiated Collagen Nerve Guides Filled With Chick Embryonic Cerebrospinal Fluid in Rats

Introduction Peripheral nerve injuries are common and often cause long-lasting disability and mainly muscle weakness, sensory loss and painful neuropathy (1). Autologous nerve grafting remains the “gold standard” technique for the peripheral nerve lesions (2). However, autograft is limited with a variety of clinical complications, such as the lack of availability of donor tissue, loss of donor site function, need for a secondary surgery and mismatch in size between the donor nerve and the injured nerve (3). An alternative to autografts engineered nerve guide channels (NGCs) have been explored for the repair of nerve injury. Collagen-based biomaterials are the most common example of a guidance channel designed to create a protective environment for axonal growth across a nerve gap (4). Collagen is resorbable and semipermeable and provides an interface between the nerve and the surrounding tissue (5). Since collagen is a structural component of extracellular matrix it shows excellent advantages over other synthetic and natural polymers (6). Collagen possesses extremely good cell adhesive properties and signaling domains that promote nerve growth and proliferation (7). Recently Ahmed et al (8) studied about effective crosslinking of collagen with microwave irradiation for peripheral nerve repair. Numerous studies have shown that the local presence of growth factors plays an important role in controlling survival, migration, proliferation, and differentiation of the various cell types involved in nerve regeneration (9). It has been confirmed that nerve growth factor (NGF) can protect neurons from death and significantly improve neuronal survival and differentiation (10). Embryo cerebrospinal fluid (ECSF) contains high concentrations of NGF, transforming growth factor-α (TGFα), transforming growth factor-β (TGF-β), epidermal growth factor (EGF), and neurotrophin-3 (NT3) (11) which are important for neural cell survival and proliferation. As a natural medium E-CSF could support viability and proliferation of cortical cells in vitro (12). Gato et al demonstrated that ECSF contributes to the regulation of the survival, proliferation and neurogenesis neuroepithelial stem cell in mesencephalic explants (13). It has been reported that chick CSF at developmental Abstract Objective: The physical properties of nerve guidance channel and components of the regenerating microenvironment can significantly enhance regeneration. The aim of this research was to evaluate the effect of embryo cerebrospinal fluid (ECSF) in nerve regeneration across the microwave irradiated collagen nerve guides in comparison with autograft. Material and Methods: Under general anesthesia, the left sciatic nerve was exposed and 10 mm nerve segment defect was created in 40 adult male Sprague-Dawley rats (250-300 g). Animals were randomly divided into 4 experimental groups: repair with reversed autograft, reconstruction with collagen nerve conduit filled with ECSF, reconstruction with collagen nerve conduit filled with normal saline (NS) and sham surgery. All animals were evaluated by sciatic functional index (SFI), electrophysiology, and histopathological staining at weeks 4 and 12 after surgery. Results: The mean SFI value of group collagen + ECSF and autograft was significantly higher than that of group NS on days 49 and 60 post-operation (P < 0.05). After 90 days after the operation, the mean nerve conduction velocity (NCV) of groups collagen + ECSF and autograft were significantly faster than NS group (P < 0.05). The regenerated nerves of groups collagen + ECSF and autograft were more mature than that of the group NS group at day 90 (P < 0.05). There was no significant difference between groups collagen + ECSF and autograft. Conclusion: These findings showed that chick CSF in collagen guide can enhance nerve regeneration and promote functional recovery in the injured sciatic nerve of rats. Keyword: Cerebrospinal fluid, Sciatic nerve, Collagen, Nerve injury, Microwave Seyyed Mostafa Ghavami1, Gholam Hossein Farjah2, Hamed Shoorei3, Mohammad Amin Dolatkhah3* Open Access Original Article