The Experts below are selected from a list of 261 Experts worldwide ranked by ideXlab platform

Sean I Patterson - One of the best experts on this subject based on the ideXlab platform.

  • sciatic nerve injury a simple and subtle model for investigating many aspects of nervous system damage and recovery
    Journal of Neuroscience Methods, 2014
    Co-Authors: Luis E Savastano, Sergio Laurito, Marcos R Fitt, Jorge A Rasmussen, Virginia Gonzalez Polo, Sean I Patterson
    Abstract:

    Sciatic nerve injury has been used for over a century to investigate the process of nerve damage, to assess the absolute and relative capacity of the central and peripheral nervous systems to recover after axotomy, and to understand the development of chronic pain in many pathologies. Here we provide a historical review of the contributions of this experimental model to our current understanding of fundamental questions in the neurosciences, and an assessment of its continuing capacity to address these and future problems. We describe the different degrees of nerve injury - neurapraxia, Axonotmesis, neurotmesis - together with the consequences of selective damage to the different functional and anatomic components of this nerve. The varied techniques used to model different degrees of nerve injury and their relationship to the development of neuropathic pain states are considered. We also provide a detailed anatomical description of the sciatic nerve from the spinal cord to the peripheral branches in the leg. A standardized protocol for carrying out sciatic nerve axotomy is proposed, with guides to assist in the accurate and reliable dissection of the peripheral and central branches of the nerve. Functional, histological, and biochemical criteria for the validation of the injury are described. Thus, this paper provides a review of the principal features of sciatic nerve injury, presents detailed neuroanatomical descriptions of the rat's inferior limb and spine, compares different modes of injury, offers material for training purposes, and summarizes the immediate and longterm consequences of damage to the sciatic nerve.

Andrea Gartner - One of the best experts on this subject based on the ideXlab platform.

  • corrigendum to use of poly dl lactide e caprolactone membranes and mesenchymal stem cells from the wharton s jelly of the umbilical cord for promoting nerve regeneration in Axonotmesis in vitro and in vivo analysis differentiation 84 2012 355 365
    Differentiation, 2013
    Co-Authors: Andrea Gartner, Tiago Pereira, Paulo Armadadasilva, Miguel Lacueva Franca, Marco G Alves, Irina Amorim, R Gomes, J Ribeiro, C M C Lopes, Rui A Carvalho
    Abstract:

    Corrigendum to “Use of poly(DL-lactide-e-caprolactone) membranes and mesenchymal stem cells from the Wharton's jelly of the umbilical cord for promoting nerve regeneration in Axonotmesis: In vitro and in vivo analysis” [Differentiation 84 (2012) 355–365] A. Gartner , T. Pereira , Marco G. Alves , P.A.S. Armada-da-Silva , I. Amorim , R. Gomes , J. Ribeiro , M.L. Franca , C. Lopes , Rui A. Carvalho , S. Socorro , Pedro F. Oliveira , B. Porto , R. Sousa , A. Bombaci , G. Ronchi , F. Fregnan , A.S.P. Varejao , A.L. Luis , S. Geuna , A.C. Mauricio a,b,n

  • use of poly dl lactide e caprolactone membranes and mesenchymal stem cells from the wharton s jelly of the umbilical cord for promoting nerve regeneration in Axonotmesis in vitro and in vivo analysis
    Differentiation, 2012
    Co-Authors: Andrea Gartner, Tiago Pereira, Paulo Armadadasilva, Miguel Lacueva Franca, Irina Amorim, J Ribeiro, Raquel Zita Gomes, C Lopes, Beatriz Porto, R C Sousa
    Abstract:

    Cellular systems implanted into an injured nerve may produce growth factors or extracellular matrix molecules, modulate the inflammatory process and eventually improve nerve regeneration. In the present study, we evaluated the therapeutic value of human umbilical cord matrix MSCs (HMSCs) on rat sciatic nerve after Axonotmesis injury associated to Vivosorb® membrane. During HMSCs expansion and differentiation in neuroglial-like cells, the culture medium was collected at 48, 72 and 96 h for nuclear magnetic resonance (NMR) analysis in order to evaluate the metabolic profile. To correlate the HMSCs ability to differentiate and survival capacity in the presence of the Vivosorb® membrane, the [Ca(2+)]i of undifferentiated HMSCs or neuroglial-differentiated HMSCs was determined by the epifluorescence technique using the Fura-2AM probe. The Vivosorb® membrane proved to be adequate and used as scaffold associated with undifferentiated HMSCs or neuroglial-differentiated HMSCs. In vivo testing was carried out in adult rats where a sciatic nerve Axonotmesis injury was treated with undifferentiated HMSCs or neuroglial differentiated HMSCs with or without the Vivosorb® membrane. Motor and sensory functional recovery was evaluated throughout a healing period of 12 weeks using sciatic functional index (SFI), extensor postural thrust (EPT), and withdrawal reflex latency (WRL). Stereological analysis was carried out on regenerated nerve fibers. In vitro investigation showed the formation of typical neuroglial cells after differentiation, which were positively stained for the typical specific neuroglial markers such as the GFAP, the GAP-43 and NeuN. NMR showed clear evidence that HMSCs expansion is glycolysis-dependent but their differentiation requires the switch of the metabolic profile to oxidative metabolism. In vivo studies showed enhanced recovery of motor and sensory function in animals treated with transplanted undifferentiated and differentiated HMSCs that was accompanied by an increase in myelin sheath. Taken together, HMSC from the umbilical cord Wharton jelly might be useful for improving the clinical outcome after peripheral nerve lesion.

  • use of hybrid chitosan membranes and human mesenchymal stem cells from the wharton jelly of umbilical cord for promoting nerve regeneration in an Axonotmesis rat model
    Neural Regeneration Research, 2012
    Co-Authors: Andrea Gartner, Tiago Pereira, Maria J Simoes, Paulo Armadadasilva, Miguel Lacueva Franca, R C Sousa, Simone Bompasso, Stefania Raimondo, Yuki Shirosaki, Yuri Nakamura
    Abstract:

    Many studies have been dedicated to the development of scaffolds for improving post-traumatic nerve regeneration. The goal of this study was to assess the effect on nerve regeneration, associating a hybrid chitosan membrane with non-differentiated human mesenchymal stem cells isolated from Wharton's jelly of umbilical cord, in peripheral nerve reconstruction after crush injury. Chromosome analysis on human mesenchymal stem cell line from Wharton's jelly was carried out and no structural alterations were found in metaphase. Chitosan membranes were previously tested in vitro, to assess their ability in supporting human mesenchymal stem cell survival, expansion, and differentiation. For the in vivo testing, Sasco Sprague adult rats were divided in 4 groups of 6 or 7 animals each: Group 1, sciatic Axonotmesis injury without any other intervention (Group 1-Crush); Group 2, the Axonotmesis lesion of 3 mm was infiltrated with a suspension of 1 250–1 500 human mesenchymal stem cells (total volume of 50 μL) (Group 2-CrushCell); Group 3, Axonotmesis lesion of 3 mm was enwrapped with a chitosan type III membrane covered with a monolayer of non-differentiated human mesenchymal stem cells (Group 3-CrushChitIIICell) and Group 4, Axonotmesis lesion of 3 mm was enwrapped with a chitosan type III membrane (Group 4-CrushChitIII). Motor and sensory functional recovery was evaluated throughout a healing period of 12 weeks using sciatic functional index, static sciatic index, extensor postural thrust, and withdrawal reflex latency. Stereological analysis was carried out on regenerated nerve fibers. Results showed that infiltration of human mesenchymal stem cells, or the combination of chitosan membrane enwrapment and human mesenchymal stem cell enrichment after nerve crush injury provide a slight advantage to post-traumatic nerve regeneration. Results obtained with chitosan type III membrane alone confirmed that they significantly improve post-traumatic axonal regrowth and may represent a very promising clinical tool in peripheral nerve reconstructive surgery. Yet, umbilical cord human mesenchymal stem cells, that can be expanded in culture and induced to form several different types of cells, may prove, in future experiments, to be a new source of cells for cell therapy, including targets such as peripheral nerve and muscle.

Paulo Armadadasilva - One of the best experts on this subject based on the ideXlab platform.

  • evaluation of pva biodegradable electric conductive membranes for nerve regeneration in Axonotmesis injuries the rat sciatic nerve animal model
    Journal of Biomedical Materials Research Part A, 2017
    Co-Authors: J Ribeiro, Tiago Pereira, Paulo Armadadasilva, Irina Amorim, Ana Rita Caseiro, Sandra Amado, Isabel Pires, Justina Prada, Ines Reis, J D Santos
    Abstract:

    The therapeutic effect of three polyvinyl alcohol (PVA) membranes loaded with electrically conductive materials - carbon nanotubes (PVA-CNTs) and polypyrrole (PVA-PPy) - were tested in vivo for neuro-muscular regeneration after an Axonotmesis injury in the rat sciatic nerve. The membranes electrical conductivity measured was 1.5 ± 0.5 × 10-6 S/m, 579 ± 0.6 × 10-6 S/m, and 1837.5 ± 0.7 × 10-6 S/m, respectively. At week-12, a residual motor and nociceptive deficit were present in all treated groups, but at week-12, a better recovery to normal gait pattern of the PVA-CNTs and PVA-PPy treated groups was observed. Morphometrical analysis demonstrated that PVA-CNTs group presented higher myelin thickness and lower g-ratio. The tibialis anterior muscle, in the PVA-PPy and PVA-CNTs groups showed a 9% and 19% increase of average fiber size area and a 5% and 10% increase of the "minimal Feret's diameter," respectively. No inflammation, degeneration, fibrosis or necrosis were detected in lung, liver, kidneys, spleen, and regional lymph nodes and absence of carbon deposits was confirmed with Von Kossa and Masson-Fontana stains. In conclusion, the membranes of PVA-CNTs and PVA-PPy are biocompatible and have electrical conductivity. The higher electrical conductivity measured in PVA-CNTs membrane might be responsible for the positive results on maturation of myelinated fibers. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1267-1280, 2017.

  • corrigendum to use of poly dl lactide e caprolactone membranes and mesenchymal stem cells from the wharton s jelly of the umbilical cord for promoting nerve regeneration in Axonotmesis in vitro and in vivo analysis differentiation 84 2012 355 365
    Differentiation, 2013
    Co-Authors: Andrea Gartner, Tiago Pereira, Paulo Armadadasilva, Miguel Lacueva Franca, Marco G Alves, Irina Amorim, R Gomes, J Ribeiro, C M C Lopes, Rui A Carvalho
    Abstract:

    Corrigendum to “Use of poly(DL-lactide-e-caprolactone) membranes and mesenchymal stem cells from the Wharton's jelly of the umbilical cord for promoting nerve regeneration in Axonotmesis: In vitro and in vivo analysis” [Differentiation 84 (2012) 355–365] A. Gartner , T. Pereira , Marco G. Alves , P.A.S. Armada-da-Silva , I. Amorim , R. Gomes , J. Ribeiro , M.L. Franca , C. Lopes , Rui A. Carvalho , S. Socorro , Pedro F. Oliveira , B. Porto , R. Sousa , A. Bombaci , G. Ronchi , F. Fregnan , A.S.P. Varejao , A.L. Luis , S. Geuna , A.C. Mauricio a,b,n

  • use of poly dl lactide e caprolactone membranes and mesenchymal stem cells from the wharton s jelly of the umbilical cord for promoting nerve regeneration in Axonotmesis in vitro and in vivo analysis
    Differentiation, 2012
    Co-Authors: Andrea Gartner, Tiago Pereira, Paulo Armadadasilva, Miguel Lacueva Franca, Irina Amorim, J Ribeiro, Raquel Zita Gomes, C Lopes, Beatriz Porto, R C Sousa
    Abstract:

    Cellular systems implanted into an injured nerve may produce growth factors or extracellular matrix molecules, modulate the inflammatory process and eventually improve nerve regeneration. In the present study, we evaluated the therapeutic value of human umbilical cord matrix MSCs (HMSCs) on rat sciatic nerve after Axonotmesis injury associated to Vivosorb® membrane. During HMSCs expansion and differentiation in neuroglial-like cells, the culture medium was collected at 48, 72 and 96 h for nuclear magnetic resonance (NMR) analysis in order to evaluate the metabolic profile. To correlate the HMSCs ability to differentiate and survival capacity in the presence of the Vivosorb® membrane, the [Ca(2+)]i of undifferentiated HMSCs or neuroglial-differentiated HMSCs was determined by the epifluorescence technique using the Fura-2AM probe. The Vivosorb® membrane proved to be adequate and used as scaffold associated with undifferentiated HMSCs or neuroglial-differentiated HMSCs. In vivo testing was carried out in adult rats where a sciatic nerve Axonotmesis injury was treated with undifferentiated HMSCs or neuroglial differentiated HMSCs with or without the Vivosorb® membrane. Motor and sensory functional recovery was evaluated throughout a healing period of 12 weeks using sciatic functional index (SFI), extensor postural thrust (EPT), and withdrawal reflex latency (WRL). Stereological analysis was carried out on regenerated nerve fibers. In vitro investigation showed the formation of typical neuroglial cells after differentiation, which were positively stained for the typical specific neuroglial markers such as the GFAP, the GAP-43 and NeuN. NMR showed clear evidence that HMSCs expansion is glycolysis-dependent but their differentiation requires the switch of the metabolic profile to oxidative metabolism. In vivo studies showed enhanced recovery of motor and sensory function in animals treated with transplanted undifferentiated and differentiated HMSCs that was accompanied by an increase in myelin sheath. Taken together, HMSC from the umbilical cord Wharton jelly might be useful for improving the clinical outcome after peripheral nerve lesion.

  • use of hybrid chitosan membranes and human mesenchymal stem cells from the wharton jelly of umbilical cord for promoting nerve regeneration in an Axonotmesis rat model
    Neural Regeneration Research, 2012
    Co-Authors: Andrea Gartner, Tiago Pereira, Maria J Simoes, Paulo Armadadasilva, Miguel Lacueva Franca, R C Sousa, Simone Bompasso, Stefania Raimondo, Yuki Shirosaki, Yuri Nakamura
    Abstract:

    Many studies have been dedicated to the development of scaffolds for improving post-traumatic nerve regeneration. The goal of this study was to assess the effect on nerve regeneration, associating a hybrid chitosan membrane with non-differentiated human mesenchymal stem cells isolated from Wharton's jelly of umbilical cord, in peripheral nerve reconstruction after crush injury. Chromosome analysis on human mesenchymal stem cell line from Wharton's jelly was carried out and no structural alterations were found in metaphase. Chitosan membranes were previously tested in vitro, to assess their ability in supporting human mesenchymal stem cell survival, expansion, and differentiation. For the in vivo testing, Sasco Sprague adult rats were divided in 4 groups of 6 or 7 animals each: Group 1, sciatic Axonotmesis injury without any other intervention (Group 1-Crush); Group 2, the Axonotmesis lesion of 3 mm was infiltrated with a suspension of 1 250–1 500 human mesenchymal stem cells (total volume of 50 μL) (Group 2-CrushCell); Group 3, Axonotmesis lesion of 3 mm was enwrapped with a chitosan type III membrane covered with a monolayer of non-differentiated human mesenchymal stem cells (Group 3-CrushChitIIICell) and Group 4, Axonotmesis lesion of 3 mm was enwrapped with a chitosan type III membrane (Group 4-CrushChitIII). Motor and sensory functional recovery was evaluated throughout a healing period of 12 weeks using sciatic functional index, static sciatic index, extensor postural thrust, and withdrawal reflex latency. Stereological analysis was carried out on regenerated nerve fibers. Results showed that infiltration of human mesenchymal stem cells, or the combination of chitosan membrane enwrapment and human mesenchymal stem cell enrichment after nerve crush injury provide a slight advantage to post-traumatic nerve regeneration. Results obtained with chitosan type III membrane alone confirmed that they significantly improve post-traumatic axonal regrowth and may represent a very promising clinical tool in peripheral nerve reconstructive surgery. Yet, umbilical cord human mesenchymal stem cells, that can be expanded in culture and induced to form several different types of cells, may prove, in future experiments, to be a new source of cells for cell therapy, including targets such as peripheral nerve and muscle.

Tiago Pereira - One of the best experts on this subject based on the ideXlab platform.

  • evaluation of pva biodegradable electric conductive membranes for nerve regeneration in Axonotmesis injuries the rat sciatic nerve animal model
    Journal of Biomedical Materials Research Part A, 2017
    Co-Authors: J Ribeiro, Tiago Pereira, Paulo Armadadasilva, Irina Amorim, Ana Rita Caseiro, Sandra Amado, Isabel Pires, Justina Prada, Ines Reis, J D Santos
    Abstract:

    The therapeutic effect of three polyvinyl alcohol (PVA) membranes loaded with electrically conductive materials - carbon nanotubes (PVA-CNTs) and polypyrrole (PVA-PPy) - were tested in vivo for neuro-muscular regeneration after an Axonotmesis injury in the rat sciatic nerve. The membranes electrical conductivity measured was 1.5 ± 0.5 × 10-6 S/m, 579 ± 0.6 × 10-6 S/m, and 1837.5 ± 0.7 × 10-6 S/m, respectively. At week-12, a residual motor and nociceptive deficit were present in all treated groups, but at week-12, a better recovery to normal gait pattern of the PVA-CNTs and PVA-PPy treated groups was observed. Morphometrical analysis demonstrated that PVA-CNTs group presented higher myelin thickness and lower g-ratio. The tibialis anterior muscle, in the PVA-PPy and PVA-CNTs groups showed a 9% and 19% increase of average fiber size area and a 5% and 10% increase of the "minimal Feret's diameter," respectively. No inflammation, degeneration, fibrosis or necrosis were detected in lung, liver, kidneys, spleen, and regional lymph nodes and absence of carbon deposits was confirmed with Von Kossa and Masson-Fontana stains. In conclusion, the membranes of PVA-CNTs and PVA-PPy are biocompatible and have electrical conductivity. The higher electrical conductivity measured in PVA-CNTs membrane might be responsible for the positive results on maturation of myelinated fibers. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1267-1280, 2017.

  • corrigendum to use of poly dl lactide e caprolactone membranes and mesenchymal stem cells from the wharton s jelly of the umbilical cord for promoting nerve regeneration in Axonotmesis in vitro and in vivo analysis differentiation 84 2012 355 365
    Differentiation, 2013
    Co-Authors: Andrea Gartner, Tiago Pereira, Paulo Armadadasilva, Miguel Lacueva Franca, Marco G Alves, Irina Amorim, R Gomes, J Ribeiro, C M C Lopes, Rui A Carvalho
    Abstract:

    Corrigendum to “Use of poly(DL-lactide-e-caprolactone) membranes and mesenchymal stem cells from the Wharton's jelly of the umbilical cord for promoting nerve regeneration in Axonotmesis: In vitro and in vivo analysis” [Differentiation 84 (2012) 355–365] A. Gartner , T. Pereira , Marco G. Alves , P.A.S. Armada-da-Silva , I. Amorim , R. Gomes , J. Ribeiro , M.L. Franca , C. Lopes , Rui A. Carvalho , S. Socorro , Pedro F. Oliveira , B. Porto , R. Sousa , A. Bombaci , G. Ronchi , F. Fregnan , A.S.P. Varejao , A.L. Luis , S. Geuna , A.C. Mauricio a,b,n

  • use of poly dl lactide e caprolactone membranes and mesenchymal stem cells from the wharton s jelly of the umbilical cord for promoting nerve regeneration in Axonotmesis in vitro and in vivo analysis
    Differentiation, 2012
    Co-Authors: Andrea Gartner, Tiago Pereira, Paulo Armadadasilva, Miguel Lacueva Franca, Irina Amorim, J Ribeiro, Raquel Zita Gomes, C Lopes, Beatriz Porto, R C Sousa
    Abstract:

    Cellular systems implanted into an injured nerve may produce growth factors or extracellular matrix molecules, modulate the inflammatory process and eventually improve nerve regeneration. In the present study, we evaluated the therapeutic value of human umbilical cord matrix MSCs (HMSCs) on rat sciatic nerve after Axonotmesis injury associated to Vivosorb® membrane. During HMSCs expansion and differentiation in neuroglial-like cells, the culture medium was collected at 48, 72 and 96 h for nuclear magnetic resonance (NMR) analysis in order to evaluate the metabolic profile. To correlate the HMSCs ability to differentiate and survival capacity in the presence of the Vivosorb® membrane, the [Ca(2+)]i of undifferentiated HMSCs or neuroglial-differentiated HMSCs was determined by the epifluorescence technique using the Fura-2AM probe. The Vivosorb® membrane proved to be adequate and used as scaffold associated with undifferentiated HMSCs or neuroglial-differentiated HMSCs. In vivo testing was carried out in adult rats where a sciatic nerve Axonotmesis injury was treated with undifferentiated HMSCs or neuroglial differentiated HMSCs with or without the Vivosorb® membrane. Motor and sensory functional recovery was evaluated throughout a healing period of 12 weeks using sciatic functional index (SFI), extensor postural thrust (EPT), and withdrawal reflex latency (WRL). Stereological analysis was carried out on regenerated nerve fibers. In vitro investigation showed the formation of typical neuroglial cells after differentiation, which were positively stained for the typical specific neuroglial markers such as the GFAP, the GAP-43 and NeuN. NMR showed clear evidence that HMSCs expansion is glycolysis-dependent but their differentiation requires the switch of the metabolic profile to oxidative metabolism. In vivo studies showed enhanced recovery of motor and sensory function in animals treated with transplanted undifferentiated and differentiated HMSCs that was accompanied by an increase in myelin sheath. Taken together, HMSC from the umbilical cord Wharton jelly might be useful for improving the clinical outcome after peripheral nerve lesion.

  • use of hybrid chitosan membranes and human mesenchymal stem cells from the wharton jelly of umbilical cord for promoting nerve regeneration in an Axonotmesis rat model
    Neural Regeneration Research, 2012
    Co-Authors: Andrea Gartner, Tiago Pereira, Maria J Simoes, Paulo Armadadasilva, Miguel Lacueva Franca, R C Sousa, Simone Bompasso, Stefania Raimondo, Yuki Shirosaki, Yuri Nakamura
    Abstract:

    Many studies have been dedicated to the development of scaffolds for improving post-traumatic nerve regeneration. The goal of this study was to assess the effect on nerve regeneration, associating a hybrid chitosan membrane with non-differentiated human mesenchymal stem cells isolated from Wharton's jelly of umbilical cord, in peripheral nerve reconstruction after crush injury. Chromosome analysis on human mesenchymal stem cell line from Wharton's jelly was carried out and no structural alterations were found in metaphase. Chitosan membranes were previously tested in vitro, to assess their ability in supporting human mesenchymal stem cell survival, expansion, and differentiation. For the in vivo testing, Sasco Sprague adult rats were divided in 4 groups of 6 or 7 animals each: Group 1, sciatic Axonotmesis injury without any other intervention (Group 1-Crush); Group 2, the Axonotmesis lesion of 3 mm was infiltrated with a suspension of 1 250–1 500 human mesenchymal stem cells (total volume of 50 μL) (Group 2-CrushCell); Group 3, Axonotmesis lesion of 3 mm was enwrapped with a chitosan type III membrane covered with a monolayer of non-differentiated human mesenchymal stem cells (Group 3-CrushChitIIICell) and Group 4, Axonotmesis lesion of 3 mm was enwrapped with a chitosan type III membrane (Group 4-CrushChitIII). Motor and sensory functional recovery was evaluated throughout a healing period of 12 weeks using sciatic functional index, static sciatic index, extensor postural thrust, and withdrawal reflex latency. Stereological analysis was carried out on regenerated nerve fibers. Results showed that infiltration of human mesenchymal stem cells, or the combination of chitosan membrane enwrapment and human mesenchymal stem cell enrichment after nerve crush injury provide a slight advantage to post-traumatic nerve regeneration. Results obtained with chitosan type III membrane alone confirmed that they significantly improve post-traumatic axonal regrowth and may represent a very promising clinical tool in peripheral nerve reconstructive surgery. Yet, umbilical cord human mesenchymal stem cells, that can be expanded in culture and induced to form several different types of cells, may prove, in future experiments, to be a new source of cells for cell therapy, including targets such as peripheral nerve and muscle.

Stefania Raimondo - One of the best experts on this subject based on the ideXlab platform.

  • use of hybrid chitosan membranes and human mesenchymal stem cells from the wharton jelly of umbilical cord for promoting nerve regeneration in an Axonotmesis rat model
    Neural Regeneration Research, 2012
    Co-Authors: Andrea Gartner, Tiago Pereira, Maria J Simoes, Paulo Armadadasilva, Miguel Lacueva Franca, R C Sousa, Simone Bompasso, Stefania Raimondo, Yuki Shirosaki, Yuri Nakamura
    Abstract:

    Many studies have been dedicated to the development of scaffolds for improving post-traumatic nerve regeneration. The goal of this study was to assess the effect on nerve regeneration, associating a hybrid chitosan membrane with non-differentiated human mesenchymal stem cells isolated from Wharton's jelly of umbilical cord, in peripheral nerve reconstruction after crush injury. Chromosome analysis on human mesenchymal stem cell line from Wharton's jelly was carried out and no structural alterations were found in metaphase. Chitosan membranes were previously tested in vitro, to assess their ability in supporting human mesenchymal stem cell survival, expansion, and differentiation. For the in vivo testing, Sasco Sprague adult rats were divided in 4 groups of 6 or 7 animals each: Group 1, sciatic Axonotmesis injury without any other intervention (Group 1-Crush); Group 2, the Axonotmesis lesion of 3 mm was infiltrated with a suspension of 1 250–1 500 human mesenchymal stem cells (total volume of 50 μL) (Group 2-CrushCell); Group 3, Axonotmesis lesion of 3 mm was enwrapped with a chitosan type III membrane covered with a monolayer of non-differentiated human mesenchymal stem cells (Group 3-CrushChitIIICell) and Group 4, Axonotmesis lesion of 3 mm was enwrapped with a chitosan type III membrane (Group 4-CrushChitIII). Motor and sensory functional recovery was evaluated throughout a healing period of 12 weeks using sciatic functional index, static sciatic index, extensor postural thrust, and withdrawal reflex latency. Stereological analysis was carried out on regenerated nerve fibers. Results showed that infiltration of human mesenchymal stem cells, or the combination of chitosan membrane enwrapment and human mesenchymal stem cell enrichment after nerve crush injury provide a slight advantage to post-traumatic nerve regeneration. Results obtained with chitosan type III membrane alone confirmed that they significantly improve post-traumatic axonal regrowth and may represent a very promising clinical tool in peripheral nerve reconstructive surgery. Yet, umbilical cord human mesenchymal stem cells, that can be expanded in culture and induced to form several different types of cells, may prove, in future experiments, to be a new source of cells for cell therapy, including targets such as peripheral nerve and muscle.

  • use of hybrid chitosan membranes and n1e 115 cells for promoting nerve regeneration in an Axonotmesis rat model
    Biomaterials, 2008
    Co-Authors: Sandra Amado, Maria J Simoes, Yuki Shirosaki, P Armada A S Da Silva, Ana Lucia Luis, M A Lopes, J D Santos, Federica Fregnan, Giovanna Gambarotta, Stefania Raimondo
    Abstract:

    Many studies have been dedicated to the development of scaffolds for improving post-traumatic nerve regeneration. The goal of this study was to develop and test hybrid chitosan membranes to use in peripheral nerve reconstruction, either alone or enriched with N1E-115 neural cells. Hybrid chitosan membranes were tested in vitro, to assess their ability in supporting N1E-115 cell survival and differentiation, and in vivo to assess biocompatibility as well as to evaluate their effects on nerve fiber regeneration and functional recovery after a standardized rat sciatic nerve crush injury. Functional recovery was evaluated using the sciatic functional index (SFI), the static sciatic index (SSI), the extensor postural thrust (EPT), the withdrawal reflex latency (WRL) and ankle kinematics. Nerve fiber regeneration was assessed by quantitative stereological analysis and electron microscopy. All chitosan membranes showed good biocompatibility and proved to be a suitable substrate for plating the N1E-115 cellular system. By contrast, in vivo nerve regeneration assessment after crush injury showed that the freeze-dried chitosan type III, without N1E-115 cell addition, was the only type of membrane that significantly improved posttraumatic axonal regrowth and functional recovery. It can be thus suggested that local enwrapping with this type of chitosan membrane may represent an effective approach for the improvement of the clinical outcome in patients receiving peripheral nerve surgery.

  • functional and morphological assessment of a standardized rat sciatic nerve crush injury with a non serrated clamp
    Journal of Neurotrauma, 2004
    Co-Authors: Artur S P Varejao, Stefania Raimondo, Antonio M Cabrita, Marcel F Meek, Jose Bulascruz, Pedro Melopinto, Stefano Geuna, Maria G Giacobinirobecchi
    Abstract:

    Peripheral nerve researchers frequently use the rat sciatic nerve crush as a model for Axonotmesis. Unfortunately, studies from various research groups report results from different crush techniques and by using a variety of evaluation tools, making comparisons between studies difficult. The purpose of this investigation was to determine the sequence of functional and morphologic changes after an acute sciatic nerve crush injury with a non-serrated clamp, giving a final standardized pressure of p = 9 MPa. Functional recovery was evaluated using the sciatic functional index (SFI), the extensor postural thrust (EPT) and the withdrawal reflex latency (WRL), before injury, and then at weekly intervals until week 8 postoperatively. The rats were also evaluated preoperatively and at weeks 2, 4, and 8 by ankle kinematics, toe out angle (TOA), and gait-stance duration. In addition, the motor nerve conduction velocity (MNCV) and the gastrocnemius-soleus weight parameters were measured just before euthanasia. Finally, structural, ultrastructural and histomorphometric analyses were carried out on regenerated nerve fibers. At 8 weeks after the crush injury, a full functional recovery was predicted by SFI, EPT, TOA, and gait-stance duration, while all the other parameters were still recovering their original values. On the other hand, only two of the histomorphometric parameters of regenerated nerve fibers, namely myelin thickness/axon diameter ratio and fiber/axon diameter ratio, returned to normal values while all other parameters were significantly different from normal values. The employment of traditional methods of functional evaluation in conjunction with the modern techniques of computerized analysis of gait and histomorphometric analysis should thus be recommended for an overall assessment of recovery in the rat sciatic nerve crush model.