Nerve Gaps (nerve + gap)

Distribution by Scientific Domains


Selected Abstracts


In vitro and in vivo evaluation of a biodegradable chitosan,PLA composite peripheral nerve guide conduit material

MICROSURGERY, Issue 6 2008
Feng Xie M.D., Ph.D.
Chitosan, a nature biodegradable material, has good biocompatibility but poor physical properties to serve as a nerve conduit. In this study, polylactic acid (PLA) was added to chitosan to form a composite material with improved intensity and elasticity, to be used as nerve conduits. The chitosan,PLA nerve conduits were fabricated with a mold casting/infrared dehydration technique. The constituent ratio of PLA and chitosan of 1:5 (v:v) was chosen to give the composite material both good mechanical properties and good biocompatibility. An in vitro cytotoxicity test showed that the chitosan,PLA material was not cytotoxic. The conduits were proved biodegradable and had many micropores to allow permeability. We evaluated chitosan,PLA nerve conduits as a guidance channel to repair 10 mm gaps in rat sciatic nerves. Nerve autograft and silicon conduits were used as the control. After 12 weeks, the regenerating nerves in three groups succeeded in passing through the nerve gap and reinnervating the muscle. Assessments, including ECG, histomorphometric evaluation, and weighing of triceps calf muscle, showed that the functional recovery of sciatic nerve was better in chitosan,PLA conduit group than in the silicon conduit group (P < 0.05), but the differences between the chitosan,PLA conduit group and the nerve autograft group were not significant (P > 0.05). Therefore, the chitosan,PLA guide proved to be a promising nerve conduit. 2008 Wiley-Liss, Inc. Microsurgery, 2008. [source]


Tissue engineering of peripheral nerves: Epineurial grafts with application of cultured Schwann cells

MICROSURGERY, Issue 1 2003
H. Fansa M.D., Ph.D.
After a simple nerve lesion, primary microsurgical suture is the treatment of choice. A nerve gap has to be bridged, with a nerve graft sacrificing a functioning nerve. Alternatively, tissue engineering of nerve grafts has become a subject of experimental research. It is evident that nerve regeneration requires not only an autologous, allogenous, or biodegradable scaffold, but additional interactions with regeneration-promoting Schwann cells. In this study, we compared epineurial and acellularized epineurial tubes with and without application of cultured Schwann cells as alternative grafts in a rat sciatic nerve model. Autologous nerve grafts served as controls. Evaluation was performed after 6 weeks; afterwards, sections of the graft and distal nerve were harvested for histological and morphometrical analysis. Compared to controls, all groups showed a significantly lower number of axons, less well-shaped remyelinizated axons, and a delay in clinical recovery (e.g., toe spread). The presented technique with application of Schwann cells into epineurial tubes did not offer any major advantages for nerve regeneration. Thus, in this applied model, neither the implantation of untreated nor the implantation of acellularized epineurial tubes with cultured Schwann cells to bridge nerve defects was capable of presenting a serious alternative to the present gold standard of conventional nerve grafts for bridging nerve defects in this model. 2003 Wiley-Liss, Inc. MICROSURGERY 23:72,77 2003 [source]


Processed porcine collagen tubulization versus conventional suturing in peripheral nerve reconstruction: An experimental study in rabbits

MICROSURGERY, Issue 3 2001
Guda C.M. Heijke M.D.
In peripheral nerve reconstruction, various procedures are used. One of the procedures that received the most interest in the past decade is the tubulization technique for small nerve gaps. A disadvantage in the use of non-biodegradable tubes is that the material often has to be removed owing to its mechanical properties. Some investigators, in exploring the use of collagen tubes, being a natural biodegradable material, found either allogenicity or xenogenicity and immune responses that may inhibit nerve regeneration. Processed porcine collagen (PPC) is a new inert and biodegradable material that has a favorable effect on wound healing, as demonstrated by experiments on other tissues. The aim of our study was to compare the healing of nerve sutures with PPC tubes with conventional end-to-end sutures. In our experiments, we reconstructed the saphenous nerves of 27 rabbits. In series 1 (n = 12) and 2 (n = 12), PPC tubes were slid over an end-to-end nerve suture without or with a 10-mm nerve gap, respectively. In series 3 (n = 12), conventional suturing was performed in the collateral saphenous nerves of the animals of series 1. Epineurial suturing was performed. Three other non-operated saphenous nerves served as controls. The healing was studied after 3, 6, and 12 months in sections stained by monoclonal antibodies and by conventional histologic staining. Morphometric analysis of the regenerating axons was done by using confocal scanning laser microscopy (CLSM). Data analysis was carried out using a software program especially developed for this purpose. All results were evaluated statistically. Our results showed that during the healing period in the distal nerve stump, the number of axons of the PPC procedure with a 10-mm gap was significantly higher than that in the procedure without a gap. At 12 months, the mean number of axons of all procedures was significantly lower than in the non-operated nerve, and the mean axon diameter in all distal stumps did not differ significantly from that of the non-operated nerve. In the distal nerve stump, the ratio of total axon area to total fascicle area in the PPC procedure with a gap was significantly higher than that in the conventional suturing procedure. After 12 months, there was no significant difference between the percentages of axon outgrowth of the PPC procedure without a gap, the conventional suturing procedure, and the non-operated nerve (100%). The percentage of axon outgrowth in PPC with a gap was significantly higher than in the other procedures. 2001 Wiley-Liss, Inc. Microsurgery 21:84,95 2001 [source]


Tissue Engineering Strategies Designed to Realize the Endogenous Regenerative Potential of Peripheral Nerves

ADVANCED MATERIALS, Issue 46 2009
Vivek Mukhatyar
Abstract http://doi.wiley.com/10.1002/adma.v21:32/33 Bridging peripheral nerve gaps without the use of autografts has significant clinical importance. But in order to rationally design novel scaffolds, a good understanding of the nerve regeneration process is vital. Appropriate amount of structural and chemical cues are required to stimulate the endogenous mechanisms of repair and functional recovery. Synthetic and natural materials present various opportunities to induce the growth of supporting cells as well as promote axon regeneration. An overview of tissue engineering strategies currently being explored that stimulate the different steps of the regenerative sequence is presented. [source]


Improvement of peripheral nerve regeneration in acellular nerve grafts with local release of nerve growth factor

MICROSURGERY, Issue 4 2009
Hailong Yu M.D.
Previous studies have demonstrated the potential of growth factors in peripheral nerve regeneration. A method was developed for sustained delivery of nerve growth factor (NGF) for nerve repair with acellular nerve grafts to augment peripheral nerve regeneration. NGF-containing polymeric microspheres were fixed with fibrin glue around chemically extracted acellular nerve grafts for prolonged, site-specific delivery of NGF. A total of 52 Wister rats were randomly divided into four groups for treatment: autografting, NGF-treated acellular grafting, acellular grafting alone, and acellular grafting with fibrin glue. The model of a 10-mm sciatic nerve with a 10-mm gap was used to assess nerve regeneration. At the 2nd week after nerve repair, the length of axonal regeneration was longer with NGF-treated acellular grafting than acellular grafting alone and acellular grafting with fibrin glue, but shorter than autografting (P < 0.05). Sixteen weeks after nerve repair, nerve regeneration was assessed functionally and histomorphometrically. The percentage tension of the triceps surae muscles in the autograft group was 85.33 5.59%, significantly higher than that of NGF-treated group, acellular graft group and fibrin-glue group, at 69.79 5.31%, 64.46 8.48%, and 63.35 6.40%, respectively (P < 0.05). The ratio of conserved muscle-mass was greater in the NGF-treated group (53.73 4.56%) than in the acellular graft (46.37 5.68%) and fibrin glue groups (45.78 7.14%) but lower than in the autograft group (62.54 8.25%) (P < 0.05). Image analysis on histological observation revealed axonal diameter, axon number, and myelin thickness better with NGF-treated acellular grafting than with acellular grafting alone and acellular grafting with fibrin glue (P < 0.05). There were no significant differences between NGF-treated acellular grafting and autografting. This method of sustained site-specific delivery of NGF can enhance peripheral nerve regeneration across short nerve gaps repaired with acellular nerve grafts. 2009 Wiley-Liss, Inc. Microsurgery, 2009. [source]


Effect of nondepleting anti-CD4 monoclonal antibody (Rib 5/2) plus donor antigen pretreatment in peripheral nerve allotransplantation

MICROSURGERY, Issue 8 2002
Vaishali B. Doolabh M.D.
Peripheral nerve allotransplantation allows the reconstruction of injuries with long nerve gaps that are otherwise unsalvageable. In this study, the efficacy of anti-CD4 monoclonal antibody (mAb) combined with donor antigen pretreatment in prolonging the survival of short peripheral nerve allografts was investigated in a rodent model. Such an approach could potentially avoid the need for systemic immunosuppression and its concomitant morbidities. Buffalo rats received either nerve isografts or nerve allografts from Lewis rats. Untreated isograft and allograft groups were used as controls. Allograft recipients received either a single dose of RIB 5/2, a nondepleting anti-CD4 mAb, a single dose of Lewis splenocytes, or both antigen and RIB 5/2, 7 days prior to transplantation. Flow cytometric analysis verified that the T-lymphocyte population was maintained, while CD4 expression was downregulated by RIB 5/2. Histologic evaluation demonstrated better regeneration in the allograft recipients receiving both donor antigen and antibody, compared to recipients of untreated allografts or treatment with antigen or antibody alone. 2002 Wiley-Liss, Inc. MICROSURGERY 22:329,334 2002 [source]


Nerve regeneration through an epineurial sheath: Its functional aspect compared with nerve and vein grafts

MICROSURGERY, Issue 5 2001
Ercan Karacao, lu M.D.
Although nerve graft is still the only reliable choice in repair of defects in peripheral nerve structure, it has the disadvantage of donor nerve morbidity and of sometimes being unavailable. It has long been researched in alternate nerve grafts with other materials. Studies have shown that nerves could regenerate across short nerve gaps through various conduits, such as veins, pseudosheaths, and bioabsorbable tubes. Despite encouraging studies, their functional results remain unclear. The present study used 40 rats, in which nerve grafts, vein grafts, and epineurial tubes were placed into 1-cm gaps in sciatic nerves created by resection. In one group, sciatic nerves were denuded of the surrounding epineurium, to assess the possible morbidity caused by epineurial sheath technique. At 2, 4, 8, 12, 20, and 28 weeks, functional assessment of nerve regeneration was performed using walking track analysis. The number of myelinated fibers and fiber diameters was measured and electron microscopic evaluation performed. Functionally, the index values were very close to each other in nerve graft and epineurial sheath groups. Morphometric analysis showed significance between the groups. The result of denuded sciatic nerve group was the same as the base track values. It was concluded that the ready availability of epineurial sheath as a conduit to span short nerve gaps could eliminate the morbidity associated with nerve graft harvest and capitalize on the potential benefits of neurotrophism in directing nerve regeneration. 2001 Wiley-Liss, Inc. Microsurgery 21:196,201 2001 [source]


Processed porcine collagen tubulization versus conventional suturing in peripheral nerve reconstruction: An experimental study in rabbits

MICROSURGERY, Issue 3 2001
Guda C.M. Heijke M.D.
In peripheral nerve reconstruction, various procedures are used. One of the procedures that received the most interest in the past decade is the tubulization technique for small nerve gaps. A disadvantage in the use of non-biodegradable tubes is that the material often has to be removed owing to its mechanical properties. Some investigators, in exploring the use of collagen tubes, being a natural biodegradable material, found either allogenicity or xenogenicity and immune responses that may inhibit nerve regeneration. Processed porcine collagen (PPC) is a new inert and biodegradable material that has a favorable effect on wound healing, as demonstrated by experiments on other tissues. The aim of our study was to compare the healing of nerve sutures with PPC tubes with conventional end-to-end sutures. In our experiments, we reconstructed the saphenous nerves of 27 rabbits. In series 1 (n = 12) and 2 (n = 12), PPC tubes were slid over an end-to-end nerve suture without or with a 10-mm nerve gap, respectively. In series 3 (n = 12), conventional suturing was performed in the collateral saphenous nerves of the animals of series 1. Epineurial suturing was performed. Three other non-operated saphenous nerves served as controls. The healing was studied after 3, 6, and 12 months in sections stained by monoclonal antibodies and by conventional histologic staining. Morphometric analysis of the regenerating axons was done by using confocal scanning laser microscopy (CLSM). Data analysis was carried out using a software program especially developed for this purpose. All results were evaluated statistically. Our results showed that during the healing period in the distal nerve stump, the number of axons of the PPC procedure with a 10-mm gap was significantly higher than that in the procedure without a gap. At 12 months, the mean number of axons of all procedures was significantly lower than in the non-operated nerve, and the mean axon diameter in all distal stumps did not differ significantly from that of the non-operated nerve. In the distal nerve stump, the ratio of total axon area to total fascicle area in the PPC procedure with a gap was significantly higher than that in the conventional suturing procedure. After 12 months, there was no significant difference between the percentages of axon outgrowth of the PPC procedure without a gap, the conventional suturing procedure, and the non-operated nerve (100%). The percentage of axon outgrowth in PPC with a gap was significantly higher than in the other procedures. 2001 Wiley-Liss, Inc. Microsurgery 21:84,95 2001 [source]


A Novel Approach to Align Adult Neural Stem Cells on Micropatterned Conduits for Peripheral Nerve Regeneration: A Feasibility Study

ARTIFICIAL ORGANS, Issue 1 2009
Shan-hui Hsu
Abstract There is a strong need for nerve-tissue engineering using the guide conduit and Schwann cells or neural stem cells (NSCs) with regeneration potential for injured peripheral nerves. In this study, micropatterned poly(d,l -lactide) (PLA) conduits were fabricated by microlithography and solvent-casting. The PLA conduits were seeded with the novel green fluorescent protein (GFP)-positive adult mouse NSCs obtained using the patented method of one of the authors. About 85% of the seeded NSCs were successfully aligned on the micropatterned conduits within 72 h and expressed the genes related to the production of neurotrophic factors. Gene expressions for the neurotrophic factors, such as nerve growth factor and brain-derived neurotrophic factor were upregulated by the micropatterned conduits at 72 h. The micropatterned PLA conduits seeded with the aligned NSCs were used to bridge the 10-mm sciatic nerve gaps in rats and were found to facilitate nerve repair and functional recovery during a period of 6 weeks compared with the nonseeded group. This model can be used to study the role of adult NSCs in peripheral-nerve regeneration in the future. [source]