Experimental repair of phrenic nerve using a polyglycolic acid and collagen tube
The feasibility of a nerve guide tube for regeneration of the phrenic nerve with the aim of restoring diaphragmatic function was evaluated in a canine model.
The nerve tube, made of woven polyglycolic acid mesh, had a diameter of 3 mm and was filled with collagen sponge. This polyglycolic acid-collagen tube was implanted into a 10-mm gap created by transection of the right phrenic nerve in 9 beagle dogs. The tubes were implanted without a tissue covering in 5 of the 9 dogs (group I), and the tubes were covered with a pedicled pericardial fat pad in 4 dogs (group II). Chest x-ray films, muscle action potentials, and histologic samples were examined 4 to 12 months after implantation.
All of the dogs survived without any complications. x-ray film examination showed that the right diaphragm was paralyzed and elevated in all dogs until 3 months after implantation. At 4 months, movement of the diaphragm in the implanted side was observed during spontaneous breathing in 1 dog of group I and in 3 dogs of group II. In the dogs showing diaphragm movement, muscle action potentials were evoked in the diaphragm muscle, indicating restoration of nerve function. Regeneration of the phrenic nerve structure was also examined on the reconstructed site using electron microscopy.
The polyglycolic acid-collagen tube induced functional recovery of the injured phrenic nerve and was aided by coverage with a pedicled pericardial fat pad.
Available from: PubMed Central
- "Artificial nerve conduits constructed of numerous polymeric materials such as silicone (Lundborg et al., 1982), collagen (Archibald et al., 1995), chitosan (Freier et al., 2005; Ao et al., 2006), hyaluronic acid (Wang et al., 1998), poly(caprolactone) (PCL), poly(glycolic acid) (PGA), and poly(lactic acid) (PLA) (Nakamura et al., 2004; Yoshitani et al., 2007) have been investigated. Recently, an artificial nerve conduit composed of poly(lactic-co-glycolic acid) (PLGA) mesh filled with animal-derived collagen has been put into clinical use and has shown good performance (Nakamura et al., 2004). "
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ABSTRACT: We developed a microfibrous poly(L-lactic acid) (PLLA) nerve conduit with a three-layered structure to simultaneously enhance nerve regeneration and prevent adhesion of surrounding tissue. The inner layer was composed of PLLA microfiber containing 25% elastin-laminin mimetic protein (AG73-(VPGIG)30) that promotes neurite outgrowth. The thickest middle layer was constructed of pure PLLA microfibers that impart the large mechanical strength to the conduit. A 10% poly(ethylene glycol) was added to the outer layer to prevent the adhesion with the surrounding tissue. The AG73-(VPGIG)30 compositing of an elastin-like repetitive sequence (VPGIG)30 and a laminin-derived sequence (RKRLQVQLSIRT: AG73) was biosynthesized using Escherichia coli. The PLLA microfibrous conduits were fabricated using an electrospinning procedure. AG73-(VPGIG)30 was successfully mixed in the PLLA microfibers, and the PLLA/AG73-(VPGIG)30 microfibers were stable under physiological conditions. The PLLA/AG73-(VPGIG)30 microfibers enhanced adhesion and neurite outgrowth of PC12 cells. The electrospun microfibrous conduit with a three-layered structure was implanted for bridging a 2.0-cm gap in the tibial nerve of a rabbit. Two months after implantation, no adhesion of surrounding tissue was observed, and the action potential was slightly improved in the nerve conduit with the PLLA/AG73-(VPGIG)30 inner layer.
Available from: Ignacio Alcalde
- "Nerve allografts could be useful but immunosuppressive treatment is necessary (Scharpf et al., 2006). Artificial bridges have been made with biological structures such as vein and muscle (Berenholz et al., 2005; Raimondo et al., 2005) or synthetic materials (Gibson et al., 1991; Chen et al., 2005; Ciardelli and Chiono, 2006; Yoshitani et al., 2007; Bettinger et al., 2009). These artificial bridges are frequently seeded with cultured SCs which are autologous in the most common therapeutic models (Ansselin et al., 1997; Sinis et al., 2005; Keilhoff et al., 2006; Li et al., 2006). "
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ABSTRACT: Schwann cells (SCs) are basic elements for cell therapy and tissue engineering in the central and peripheral nervous system. Therefore, the development of a reliable method to obtain SC cultures is required. For possible therapeutic applications the cultures need to produce a sufficiently large number of SCs with a high level of purity in a relatively short period of time. To increase SC yield and purity we pre-degenerated pieces of 1-2 mm of adult rabbit sciatic nerves by incubating them for seven days in Dulbecco's Modified Eagle's Medium supplemented with 10% fetal bovine serum, penicillin/streptomycin and NRG1-β1. Following pre-degeneration the nerve pieces were dissociated and then cultured for 6 or 15 days in the same culture medium. After 6 days of culture we obtained around 9.5x10³ cells/mg with approximately 94% SCs (S-100 positive) purity. After 15 days of culture the yield was about 80x10³ cells/mg and the purity was approximately 75%. Pre-degeneration and subsequent culture of small pieces of adult nerve with NRG1-β1 supplemented medium increased the number of SCs and restricted the overgrowth of fibroblast-like cells.
Available from: hindawi.com
- "225–235  150 k Braiding and dip-coating with collagen      PGC O O O O n m [η] "
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ABSTRACT: Peripheral nerve regeneration is a complicated and long-term medical challenge that requires suitable guides for bridging nerve injury gaps and restoring nerve functions. Many natural and synthetic polymers have been used to fabricate nerve conduits as well as luminal fillers for achieving desired nerve regenerative functions. It is important to understand the intrinsic properties of these polymers and techniques that have been used for fabricating nerve conduits. Previously extensive reviews have been focused on the biological functions and in vivo performance of polymeric nerve conduits. In this paper, we emphasize on the structures, thermal and mechanical properties of these naturally derived synthetic polymers, and their fabrication methods. These aspects are critical for the performance of fabricated nerve conduits. By learning from the existing candidates, we can advance the strategies for designing novel polymeric systems with better properties for nerve regeneration.
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