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  • 1.
    Jones, Iwan
    et al.
    Umeå universitet, Medicinska fakulteten, Umeå centrum för molekylär medicin (UCMM). Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB).
    Yelhekar, Tushar D.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB).
    Wiberg, Rebecca
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Handkirurgi. Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB).
    Kingham, Paul J.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB).
    Johansson, Staffan
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB).
    Wiberg, Mikael
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Handkirurgi. Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB).
    Carlsson, Leif
    Umeå universitet, Medicinska fakulteten, Umeå centrum för molekylär medicin (UCMM).
    Development and validation of an in vitro model system to study peripheral sensory neuron development and injury2018Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, artikkel-id 15961Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The ability to discriminate between diverse types of sensation is mediated by heterogeneous populations of peripheral sensory neurons. Human peripheral sensory neurons are inaccessible for research and efforts to study their development and disease have been hampered by the availability of relevant model systems. The in vitro differentiation of peripheral sensory neurons from human embryonic stem cells therefore provides an attractive alternative since an unlimited source of biological material can be generated for studies that specifically address development and injury. The work presented in this study describes the derivation of peripheral sensory neurons from human embryonic stem cells using small molecule inhibitors. The differentiated neurons express canonical- and modality-specific peripheral sensory neuron markers with subsets exhibiting functional properties of human nociceptive neurons that include tetrodotoxin-resistant sodium currents and repetitive action potentials. Moreover, the derived cells associate with human donor Schwann cells and can be used as a model system to investigate the molecular mechanisms underlying neuronal death following peripheral nerve injury. The quick and efficient derivation of genetically diverse peripheral sensory neurons from human embryonic stem cells offers unlimited access to these specialised cell types and provides an invaluable in vitro model system for future studies.

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  • 2.
    Jonsson, Samuel
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi.
    Wiberg, Rebecca
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi.
    McGrath, Aleksandra M
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi. Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Handkirurgi.
    Novikov, Lev N
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi.
    Wiberg, Mikael
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi. Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Handkirurgi.
    Novikova, Liudmila N
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi.
    Kingham, Paul J
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi.
    Effect of delayed peripheral nerve repair on nerve regeneration, Schwann cell function and target muscle recovery2013Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, nr 2, artikkel-id e56484Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Despite advances in surgical techniques for peripheral nerve repair, functional restitution remains incomplete. The timing of surgery is one factor influencing the extent of recovery but it is not yet clearly defined how long a delay may be tolerated before repair becomes futile. In this study, rats underwent sciatic nerve transection before immediate (0) or 1, 3, or 6 months delayed repair with a nerve graft. Regeneration of spinal motoneurons, 13 weeks after nerve repair, was assessed using retrograde labeling. Nerve tissue was also collected from the proximal and distal stumps and from the nerve graft, together with the medial gastrocnemius (MG) muscles. A dramatic decline in the number of regenerating motoneurons and myelinated axons in the distal nerve stump was observed in the 3- and 6-months delayed groups. After 3 months delay, the axonal number in the proximal stump increased 2-3 folds, accompanied by a smaller axonal area. RT-PCR of distal nerve segments revealed a decline in Schwann cells (SC) markers, most notably in the 3 and 6 month delayed repair samples. There was also a progressive increase in fibrosis and proteoglycan scar markers in the distal nerve with increased delayed repair time. The yield of SC isolated from the distal nerve segments progressively fell with increased delay in repair time but cultured SC from all groups proliferated at similar rates. MG muscle at 3- and 6-months delay repair showed a significant decline in weight (61% and 27% compared with contra-lateral side). Muscle fiber atrophy and changes to neuromuscular junctions were observed with increased delayed repair time suggestive of progressively impaired reinnervation. This study demonstrates that one of the main limiting factors for nerve regeneration after delayed repair is the distal stump. The critical time point after which the outcome of regeneration becomes too poor appears to be 3-months.

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  • 3.
    McGrath, Aleksandra M.
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi. Norrlands Univ Hosp, Sect Hand & Plast Surg, Dept Surg & Perioperat Sci, Umea, Sweden.
    Brohlin, Maria
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi. Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi.
    Wiberg, Rebecca
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi. Norrlands Univ Hosp, Sect Hand & Plast Surg, Dept Surg & Perioperat Sci, Umea, Sweden.
    Kingham, Paul J
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi.
    Novikov, Lev N
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi.
    Wiberg, Mikael
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi. Norrlands Univ Hosp, Sect Hand & Plast Surg, Dept Surg & Perioperat Sci, Umea, Sweden.
    Novikova, Liudmila N
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi.
    Long-Term Effects of Fibrin Conduit with Human Mesenchymal Stem Cells and Immunosuppression after Peripheral Nerve Repair in a Xenogenic Model2018Inngår i: Cell Medicine, ISSN 2155-1790, Vol. 10, s. 1-13Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Introduction: Previously we showed that a fibrin glue conduit with human mesenchymal stem cells (hMSCs) and cyclosporine A (CsA) enhanced early nerve regeneration. In this study long term effects of this conduit are investigated. Methods: In a rat model, the sciatic nerve was repaired with fibrin conduit containing fibrin matrix, fibrin conduit containing fibrin matrix with CsA treatment and fibrin conduit containing fibrin matrix with hMSCs and CsA treatment, and also with nerve graft as control. Results: At 12 weeks 34% of motoneurons of the control group regenerated axons through the fibrin conduit. CsA treatment alone or with hMSCs resulted in axon regeneration of 67% and 64% motoneurons respectively. The gastrocnemius muscle weight was reduced in the conduit with fibrin matrix. The treatment with CsA or CsA with hMSCs induced recovery of the muscle weight and size of fast type fibers towards the levels of the nerve graft group. Discussion: The transplantation of hMSCs for peripheral nerve injury should be optimized to demonstrate their beneficial effects. The CsA may have its own effect on nerve regeneration.

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  • 4.
    Wiberg, Rebecca
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi. Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Handkirurgi.
    An exploration of the mechanisms behind peripheral nerve injury2016Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Despite surgical innovation, the sensory and motor outcome after peripheral nerve injury is incomplete. In this thesis, the biological pathways potentially responsible for the poor functional recoveries were investigated in both the distal nerve stump/target organ, spinal motoneurons and dorsal root ganglia (DRG). The effect of delayed nerve repair was determined in a rat sciatic nerve transection model. There was a dramatic decline in the number of regenerating motoneurons and myelinated axons found in the distal nerve stumps of animals undergoing nerve repair after a delay of 3 and 6 months. RT-PCR of the distal nerve stumps showed a decline in expression of Schwann cells (SC) markers, with a progressive increase in fibrotic and proteoglycan scar markers, with increased delayed repair time. Furthermore, the yield of SC which could be isolated from the distal nerve segments progressively fell with increased delay in repair time. Consistent with the impaired distal nerve stumps the target medial gastrocnemius (MG) muscles at 3- and 6-months delayed repair were atrophied with significant declines in wet weights (61% and 27% compared with contralateral sides). The role of myogenic transcription factors, muscle specific microRNAs and musclespecific E3 ubiquitin ligases in the muscle atrophy was investigated in both gastrocnemius and soleus muscles following either crush or nerve transection injury. In the crush injury model, the soleus muscle showed significantly increased recovery in wet weight at days 14 and 28 (compared with day 7) which was not the case for the gastrocnemius muscle which continued to atrophy. There was a significantly more pronounced up-regulation of MyoD expression in the denervated soleus muscle compared with the gastrocnemius muscle. Conversely, myogenin was more markedly elevated in the gastrocnemius versus soleus muscles. The muscles also showed significantly contrasting transcriptional regulation of the microRNAs miR-1 and miR-206. MuRF1 and Atrogin-1 showed the highest levels of expression in the denervated gastrocnemius muscle. Morphological and molecular changes in spinal motoneurons were compared after L4-L5 ventral root avulsion (VRA) and distal peripheral nerve axotomy (PNA). Neuronal degeneration was indicated by decreased immunostaining for microtubule-associated protein-2 in dendrites and synaptophysin in presynaptic boutons after both VRA and PNA. Immunostaining for ED1-reactive microglia and GFAPpositive astrocytes was significantly elevated in all experimental groups. qRT-PCR analysis and Western blotting of the ventral horn from L4-L5 spinal cord segments revealed a significant upregulation of apoptotic cell death mediators including caspases-3 and -8 and a range of related death receptors following VRA. In contrast, following PNA, only caspase-8 was moderately upregulated. The mechanisms of primary sensory neuron degeneration were also investigated in the DRG following peripheral nerve axotomy, where several apoptotic pathways including those involving the endoplasmic reticulum were shown to be upregulated. In summary, these results show that the critical time point after which the outcome of regeneration becomes too poor appears to be 3-months. Both proximal and distal injury affect spinal motoneurons morphologically, but VRA induces motoneuron degeneration mediated through both intrinsic and extrinsic apoptotic pathways. Primary sensory neuron degeneration involves several different apoptotic pathways, including the endoplasmic reticulum.

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  • 5.
    Wiberg, Rebecca
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Handkirurgi.
    Andersson, Magnus N.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Kirurgi.
    Svensson, Johan
    Umeå universitet, Samhällsvetenskapliga fakulteten, Handelshögskolan vid Umeå universitet, Statistik.
    Rosén, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Onkologi.
    Koch, Freja
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Kirurgi.
    Björkgren, Annika
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Onkologi.
    Sund, Malin
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Kirurgi.
    Prophylactic Mastectomy: Postoperative Skin Flap Thickness Evaluated by MRT, Ultrasound and Clinical Examination2020Inngår i: Annals of Surgical Oncology, ISSN 1068-9265, E-ISSN 1534-4681Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: Women with an increased hereditary risk of breast cancer can undergo prophylactic mastectomy (PM), which provides a significant, but not total, risk reduction. There is an ongoing discussion about how much skin and subcutaneous tissue should be resected to perform an adequate PM while leaving viable skin flaps.

    Methods: Forty-five women who had undergone PM were examined with magnetic resonance tomography (MRT), ultrasound (US) and clinical examination (CE) by a plastic surgeon and a general surgeon to estimate skin flap thickness.

    Results: The estimated mean skin flap thickness after PM was 13.3 (± 9.6), 7.0 (± 3.3), 6.9 (± 2.8) and 7.4 (± 2.8) mm following MRT, US, and CE performed by a plastic surgeon and a general surgeon, respectively. The mean difference in estimated skin flap thickness was significant between MRT and the other measuring methods, while there was no significant difference between US and CE, nor between CE performed by the surgeons. The mean skin flap thickness was significantly affected by the age at PM. Following PM, necrosis was detected in 7/23 (30.4%) of the breasts in skin flaps ≤ 5 mm and in 5/46 (10.9%) of the breasts in skin flaps > 5 mm (OR 6.29; CI 1.20–32.94; p = 0.03).

    Conclusion: The odds of getting postoperative necrosis was > 6 times higher in skin flaps ≤ 5 mm. Thus, if the degree of remaining glandular tissue is acceptably low, it is desirable to create skin flaps thicker than 5 mm to prevent wound healing problems after the PM procedure.

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  • 6.
    Wiberg, Rebecca
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi. Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Handkirurgi.
    Jonsson, Samuel
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi. Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Handkirurgi.
    Novikova, Liudmila N.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi.
    Kingham, Paul J
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi.
    Investigation of the Expression of Myogenic Transcription Factors, microRNAs and Muscle-Specific E3 Ubiquitin Ligases in the Medial Gastrocnemius and Soleus Muscles following Peripheral Nerve Injury2015Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, nr 12, artikkel-id e0142699Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Despite surgical innovation, the sensory and motor outcome after a peripheral nerve injury remains incomplete. One contributing factor to the poor outcome is prolonged denervation of the target organ, leading to apoptosis of both mature myofibres and satellite cells with subsequent replacement of the muscle tissue with fibrotic scar and adipose tissue. In this study, we investigated the expression of myogenic transcription factors, muscle specific microRNAs and muscle-specific E3 ubiquitin ligases at several time points following denervation in two different muscles, the gastrocnemius (containing predominantly fast type fibres) and soleus (slow type) muscles, since these molecules may influence the degree of atrophy following denervation. Both muscles exhibited significant atrophy (compared with the contra-lateral sides) at 7 days following either a nerve transection or crush injury. In the crush model, the soleus muscle showed significantly increased muscle weights at days 14 and 28 which was not the case for the gastrocnemius muscle which continued to atrophy. There was a significantly more pronounced up-regulation of MyoD expression in the denervated soleus muscle compared with the gastrocnemius muscle. Conversely, myogenin was more markedly elevated in the gastrocnemius versus soleus muscles. The muscles also showed significantly contrasting transcriptional regulation of the microRNAs miR-1 and miR-206. MuRF1 and Atrogin-1 showed the highest levels of expression in the denervated gastrocnemius muscle. This study provides further insights regarding the intracellular regulatory molecules that generate and maintain distinct patterns of gene expression in different fibre types following peripheral nerve injury.

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  • 7.
    Wiberg, Rebecca
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi. Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Handkirurgi.
    Kingham, Paul J
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi.
    Novikova, Liudmila
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi.
    A Morphological and Molecular Characterization of the Spinal Cord after Ventral Root Avulsion or Distal Peripheral Nerve Axotomy Injuries in Adult Rats2017Inngår i: Journal of Neurotrauma, ISSN 0897-7151, E-ISSN 1557-9042, Vol. 34, nr 3, s. 652-660Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Retrograde cell death in sensory dorsal root ganglion cells following peripheral nerve injury is well established. However, available data regarding the underlying mechanism behind injury induced motoneuron death are conflicting. By comparing morphological and molecular changes in spinal motoneurons after L4-L5 ventral root avulsion (VRA) and distal peripheral nerve axotomy (PNA) 7 and 14 days postoperatively, we aimed to gain more insight about the mechanism behind injury-induced motoneuron degeneration. Morphological changes in spinal cord were assessed by using quantitative immunohistochemistry. Neuronal degeneration was revealed by decreased immunostaining for microtubuleassociated protein-2 in dendrites and synaptophysin in presynaptic boutons after both VRA and PNA. Significant motoneuron atrophy was already observed at 7 days post-injury, independently of injury type. Immunostaining for ED1 reactive microglia was significantly elevated in all experimental groups, as well as the astroglial marker glial fibrillary acidic protein (GFAP). Quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis of the ventral horn from L4-L5 spinal cord segments revealed a significant upregulation of genes involved in programmed cell death including caspase-3, caspase-8, and related death receptors TRAIL-R, tumor necrosis factor (TNF)-R, and Fas following VRA. In contrast, following PNA, caspase-3 and the death receptor gene expression levels did not differ from the control, and there was only a modest increased expression of caspase-8. Moreover, the altered gene expression correlated with protein changes. These results show that the spinal motoneurons reacted in a similar fashion with respect to morphological changes after both proximal and distal injury. However, the increased expression of caspase-3, caspase-8, and related death receptors after VRA suggest that injury- induced motoneuron degeneration is mediated through an apoptotic mechanism, which might involve both the intrinsic and the extrinsic pathways.

  • 8.
    Wiberg, Rebecca
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap. Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi.
    Novikova, Liudmila N
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi.
    Kingham, Paul J.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi.
    Evaluation of apoptotic pathways in dorsal root ganglion neurons following peripheral nerve injury2018Inngår i: NeuroReport, ISSN 0959-4965, E-ISSN 1473-558X, s. 779-785Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Peripheral nerve injuries induce significant sensory neuronal cell death in the dorsal root ganglia (DRG); however, the role of specific apoptotic pathways is still unclear. In this study, we performed peripheral nerve transection on adult rats, after which the corresponding DRGs were harvested at 7, 14, and 28 days after injury for subsequent molecular analyses with quantitative reverse transcription-PCR, western blotting, and immunohistochemistry. Nerve injury led to increased levels of caspase-3 mRNA and active caspase-3 protein in the DRG. Increased expression of caspase-8, caspase-12, caspase-7, and calpain suggested that both the extrinsic and the endoplasmic reticulum (ER) stress-mediated apoptotic pathways were activated. Phosphorylation of protein kinase R-like ER kinase further implied the involvement of ER-stress in the DRG. Phosphorylated protein kinase R-like ER kinase was most commonly associated with isolectin B4 (IB4)-positive neurons in the DRG and this may provide an explanation for the increased susceptibility of these neurons to die following nerve injury, likely in part because of an activation of the ER-stress response.

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