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Muscle recovery after repair of short and long peripheral nerve gaps using fibrin conduits
Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. (Anatomy)
Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Hand Surgery. (Anatomy)
University Hospital of Basel. (Plastic, Reconstructive & Aesthetic Surgery)
Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. (Anatomy)
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2011 (English)In: Neuroscience Letters, ISSN 0304-3940, E-ISSN 1872-7972, Vol. 500, no 1, 41-46 p.Article in journal (Refereed) Published
Abstract [en]

Peripheral nerve injuries with loss of nervous tissue are a significant clinical problem and are currently treated using autologous nerve transplants. To avoid the need for donor nerve, which results in additional morbidity such as loss of sensation and scarring, alternative bridging methods have been sought. Recently we showed that an artificial nerve conduit moulded from fibrin glue is biocompatible to nerve regeneration. In this present study, we have used the fibrin conduit or a nerve graft to bridge either a 10 mm or 20 mm sciatic nerve gap and analyzed the muscle recovery in adult rats after 16 weeks. The gastrocnemius muscle weights of the operated side were similar for both gap sizes when treated with nerve graft. In contrast, muscle weight was 48.32 ± 4.96% of the contra-lateral side for the 10 mm gap repaired with fibrin conduit but only 25.20 ± 2.50% for the 20 mm gap repaired with fibrin conduit. The morphology of the muscles in the nerve graft groups showed an intact, ordered structure, with the muscle fibers grouped in fascicles whereas the 20 mm nerve gap fibrin group had a more chaotic appearance. The mean area and diameter of fast type fibers in the 20 mm gap repaired with fibrin conduits were significantly (P < 0.01) worse than those of the corresponding 10 mm gap group. In contrast, both gap sizes treated with nervegraft showed similar fiber size. Furthermore, the 10 mm gaps repaired with either nerve graft or fibrin conduit showed similar muscle fiber size. These results indicate that the fibrin conduit can effectively treat short nerve gaps but further modification such as the inclusion of regenerative cells may be required to attain the outcomes of nerve graft for long gaps.

Place, publisher, year, edition, pages
Amsterdam, 2011. Vol. 500, no 1, 41-46 p.
Keyword [en]
autograft; biosynthetic conduit; muscle fiber; nerve injury; regeneration
National Category
Neurosciences
Identifiers
URN: urn:nbn:se:umu:diva-42426DOI: 10.1016/j.neulet.2011.06.002OAI: oai:DiVA.org:umu-42426DiVA: diva2:409237
Available from: 2011-04-07 Created: 2011-04-07 Last updated: 2017-12-11Bibliographically approved
In thesis
1. Biosynthetic conduits and cell transplantation for neural repair
Open this publication in new window or tab >>Biosynthetic conduits and cell transplantation for neural repair
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Spinal cord injury results in complete failure of the central neurons to regenerate and is associated with cyst formation and enlargement of the trauma zone. In contrast to the spinal cord, axons in the injured peripheral nerve have the capacity to undergo some spontaneous regeneration. However, significant post-traumatic loss of nervous tissue causing long nerve gap is one of the main reasons for the poor restoration of function following microsurgical repair of injured nerves. The present thesis investigates the effects of biodegradable conduits prepared from fibrin glue and poly-beta-hydroxybutyrate (PHB) in combination with cultured Schwann cells, mesenchymal stem cells and extracellular matrix molecules on regeneration after spinal cord and peripheral nerve injury in adult rats.

At 4-8 weeks after transplantation into the injured spinal cord, the PHB conduit was well integrated into the cavity but regenerating axons were found mainly outside the PHB. When suspension of BrdU-labeled Schwann cells was added to the PHB, regenerating axons filled the conduit and became associated with the implanted cells. Modification of the PHB surface with extracellular matrix molecules significantly increased Schwann cell attachment and proliferation but did not alter axonal regeneration. To improve the labeling technique of the transplanted cells, the efficacy of fluorescent cell tracers Fast Blue, PKH26, Vibrant DiO and Cell Tracker™ Green CMFDA was evaluated. All tested dyes produced very efficient initial labeling of olfactory ensheathing glial cells in culture. The number of Fast Blue-labeled cells remained largely unchanged during the first 4 weeks whereas the number of cells labeled with other tracers was significantly reduced after 2 weeks. After transplantation into the spinal cord, Fast Blue-labeled glial cells survived for 8 weeks but demonstrated very limited migration from the injection sites. Additional immunostaining with glial and neuronal markers demonstrated transfer of the dye from the transplanted cells to the host tissue.

In a sciatic nerve injury model, the extent of axonal regeneration through a 10mm gap bridged with tubular PHB conduit was compared with a fibrin glue conduit. At 2 weeks after injury, the fibrin conduit supported similar axonal regeneration and migration of the host Schwann cells compared with the PHB conduit augmented with a diluted fibrin matrix and GFP-labeled Schwann cells or mesenchymal stem cells. The long-term regenerative response was evaluated using retrograde neuronal labeling. The fibrin glue conduit promoted regeneration of 60% of sensory neurons and 52% of motoneurons when compared with the autologous nerve graft. The total number of myelinated axons in the distal nerve stump in the fibrin conduit group reached 86% of the nerve graft control and the weight of gastrocnemius and soleus muscles recovered to 82% and 89%, respectively. When a fibrin conduit was used to bridge a 20mm sciatic nerve gap, the weight of gastrocnemius muscle reached only 43% of the nerve graft control. The morphology of the muscle showed more chaotic appearance and the mean area and diameter of fast type fibers were significantly worse than those of the corresponding 10mm gap group. In contrast, both gap sizes treated with nerve graft showed similar fiber size.

In summary, these results show that a PHB conduit promotes attachment, proliferation and survival of adult Schwann cells and supports marked axonal growth after transplantation into the injured spinal cord. The data suggest an advantage of the fibrin conduit for the important initial phase of peripheral nerve regeneration and demonstrate potential of the conduit to promote long-term neuronal regeneration and muscle recovery.

Place, publisher, year, edition, pages
Umeå: Umeå universitet, 2011. 61 p.
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 1408
Keyword
Spinal cord injury; Peripheral nerve injury; Nerve graft; Biosynthetic conduit; Nerve tissue engineering; Neural prosthesis
National Category
Neurosciences
Research subject
Neurology; Neurosurgery
Identifiers
urn:nbn:se:umu:diva-42440 (URN)978-91-7459-160-6 (ISBN)
Public defence
2011-05-19, BiA201, Biologihuset, Umeå, 13:00 (English)
Opponent
Supervisors
Available from: 2011-04-28 Created: 2011-04-07 Last updated: 2011-04-28Bibliographically approved
2. Development of biosynthetic conduits for peripheral nerve repair
Open this publication in new window or tab >>Development of biosynthetic conduits for peripheral nerve repair
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Peripheral nerve injuries are often associated with significant loss of nervous tissue leading to poor restoration of function following repair of injured nerves. Although the injury gap could be bridged by autologous nerve graft, the limited access to donor material and additional morbidity such as loss of sensation and scarring have prompted a search for biosynthetic nerve transplants.

The present thesis investigates the effects of a synthetic matrix BD™ PuraMatrix™ peptide (BD)hydrogel, alginate/fibronectin gel and fibrin glue combined with cultured rat Schwann cells or human bone marrow derived mesenchymal stem cells (MSC) on neuronal regeneration and muscle recovery after peripheral nerve injury in adult rats.

In a sciatic nerve injury model, after 3 weeks postoperatively, the regenerating axons grew significantly longer distances within the conduits filled with BD hydrogel if compared with the alginate/fibronectin gel. The addition of rat Schwann cells to the BD hydrogel drastically increased regeneration distance with axons crossing the injury gap and entering into the distal nerve stump. However, at 16 weeks the number of regenerating spinal motoneurons was decreased to 49% and 31% in the BD hydrogel and alginate/fibronectin groups respectively. The recovery of the gastrocnemius muscle was also inferior in both experimental groups if compared with the nerve graft. The addition of the cultured Schwann cells did not further improve the regeneration of motoneurons and muscle recovery.

The growth-promoting effects of the tubular conduits prepared from fibrin glue were also studied following repair of short and long peripheral nerve gaps. Retrograde neuronal labeling demonstrated that fibrin glue conduit promoted regeneration of 60% of injured sensory neurons and 52% of motoneurons when compared with the autologous nerve graft. The total number of myelinated axons in the distal nerve stump in the fibrin conduit group reached 86% of the nerve graft control and the weight of gastrocnemius and soleus muscles recovered to 82% and 89%, respectively. When a fibrin conduit was used to bridge a 20 mm sciatic nerve gap, the weight of gastrocnemius muscle reached only 43% of the nerve graft control. The morphology of the muscle showed a more atrophic appearance and the mean area and diameter of fast type fibres were significantly worse than those of the corresponding 10 mm gap group. In contrast, both gap sizes treated with nerve graft showed similar fiber size.

The combination of fibrin conduit with human MSC and daily injections of cyclosporine A enhanced the distance of regeneration by four fold and the area occupied by regenerating axons by three fold at 3 weeks after nerve injury and repair. In addition, the treatment also significantly reduced the ED1 macrophage reaction. At 12 weeks after nerve injury the treatment with cyclosporine A alone or cyclosporine A combined with hMSC induced recovery of the muscle weight and the size of fast type fibres to the control levels of the nerve graft group.

In summary, these results show that a BD hydrogel supplemented with rat Schwann cells can support the initial phase of neuronal regeneration across the conduit. The data also demonstrate an advantage of tubular fibrin conduits combined with human MSC to promote axonal regeneration and muscle recovery after peripheral nerve injury.

Place, publisher, year, edition, pages
Umeå: Umeå University, 2012. 55 p.
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 1518
Keyword
Biosynthetic conduit, Mesenchymal stem cells, Nerve graft, Nerve tissue engineering, Peripheral nerve injury, Schwann cells
National Category
Cell and Molecular Biology
Identifiers
urn:nbn:se:umu:diva-60915 (URN)978-91-7459-476-8 (ISBN)
Public defence
2012-11-27, BiA201, Biologihuset, Umeå Universitet, Umeå, 09:00 (English)
Opponent
Supervisors
Available from: 2012-11-06 Created: 2012-11-02 Last updated: 2012-11-08Bibliographically approved

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