| 1. |
- Bajic, Andrej, et al.
(författare)
-
Physically and Chemically Crosslinked Hyaluronic Acid-Based Hydrogels Differentially Promote Axonal Outgrowth from Neural Tissue Cultures
- 2024
-
Ingår i: Biomimetics. - : MDPI. - 2313-7673. ; 9:3
-
Tidskriftsartikel (refereegranskat)abstract
- Our aim was to investigate axonal outgrowth from different tissue models on soft biomaterials based on hyaluronic acid (HA). We hypothesized that HA-based hydrogels differentially promote axonal outgrowth from different neural tissues. Spinal cord sliced cultures (SCSCs) and dorsal root ganglion cultures (DRGCs) were maintained on a collagen gel, a physically crosslinked HA-based hydrogel (Healon 5®) and a novel chemically crosslinked HA-based hydrogel, with or without the presence of neurotrophic factors (NF). Time-lapse microscopy was performed after two, five and eight days, where axonal outgrowth was assessed by automated image analysis. Neuroprotection was investigated by PCR. Outgrowth was observed in all groups; however, in the collagen group, it was scarce. At the middle timepoint, outgrowth from SCSCs was superior in both HA-based groups compared to collagen, regardless of the presence of NF. In DRGCs, the outgrowth in Healon 5® with NF was significantly higher compared to the rest of the groups. PCR revealed upregulation of NeuN gene expression in the HA-based groups compared to controls after excitotoxic injury. The differences in neurite outgrowth from the two different tissue models suggest that axons differentially respond to the two types of biomaterials.
|
|
| 2. |
- Kontakis, M. G., et al.
(författare)
-
Growing rods in meningomyelocele lead to increased risk for complications in comparison with fusion; a retrospective study of 30 patients treated for at the University Hospital of Uppsala
- 2024
-
Ingår i: European spine journal. - : Springer. - 0940-6719 .- 1432-0932. ; 33, s. 739-745
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose: To compare the complication rates of two different types of posterior instrumentation in patients with MMC, namely, definitive fusion and fusionless surgery (growing rods).Methods: Single-center retrospective study of 30 MMC patients that underwent posterior instrumentation for deformity (scoliosis and/or kyphosis) treatment from 2008 until 2020. The patients were grouped based on whether they received definitive fusion or a growth-accommodating system, whether they had a complication that led to early surgery, osteotomy or non-osteotomy. Number of major operations, Cobb angle correction and perioperative blood loss were the outcomes.Results: 18 patients received a growing system and 12 were fused at index surgery. The growing system group underwent a mean of 2.38 (± 1.03) surgeries versus 1.91 (± 2.27) in the fusion group, p = 0.01. If an early revision was necessitated due to a complication, then the number of major surgeries per patient was 3.37 (± 2.44) versus 1.77 (± 0.97) in the group that did not undergo an early revision, p = 0.01. Four patients developed a superficial and six a deep wound infection, while loosening/breakage occurred in 10 patients. The Cobb angle was improved from a mean of 69 to 22 degrees postoperatively. Osteotomy did not lead to an increase in perioperative blood loss or number of major operations.Conclusion: Growing systems had more major operations in comparison with fusion surgery and early revision surgery led to higher numbers of major operations per patient; these differences were statistically significant. Definitive fusion at index surgery might be the better option in some MMC patients with a high-risk profile.
|
|
| 3. |
- Ossinger, Alexander, et al.
(författare)
-
A rapid and accurate method to quantify neurite outgrowth from cell and tissue cultures : Two image analytic approaches using adaptive thresholds or machine learning
- 2020
-
Ingår i: Journal of Neuroscience Methods. - : Elsevier BV. - 0165-0270 .- 1872-678X. ; 331
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Assessments of axonal outgrowth and dendritic development are essential readouts in many in vitro models in the field of neuroscience. Available analysis software is based on the assessment of fixed immunolabelled tissue samples, making it impossible to follow the dynamic development of neurite outgrowth. Thus, automated algorithms that efficiently analyse brightfield images, such as those obtained during time-lapse microscopy, are needed.NEW METHOD: We developed and validated algorithms to quantitatively assess neurite outgrowth from living and unstained spinal cord slice cultures (SCSCs) and dorsal root ganglion cultures (DRGCs) based on an adaptive thresholding approach called NeuriteSegmantation. We used a machine learning approach to evaluate dendritic development from dissociate neuron cultures.RESULTS: NeuriteSegmentation successfully recognized axons in brightfield images of SCSCs and DRGCs. The temporal pattern of axonal growth was successfully assessed. In dissociate neuron cultures the total number of cells and their outgrowth of dendrites were successfully assessed using machine learning.COMPARISON WITH EXISTING METHODS: The methods were positively correlated and were more time-saving than manual counts, having performing times varying from 0.5-2 minutes. In addition, NeuriteSegmentation was compared to NeuriteJ®, that uses global thresholding, being more reliable in recognizing axons in areas of intense background.CONCLUSION: The developed image analysis methods were more time-saving and user-independent than established approaches. Moreover, by using adaptive thresholding, we could assess images with large variations in background intensity. These tools may prove valuable in the quantitative analysis of axonal and dendritic outgrowth from numerous in vitro models used in neuroscience.
|
|
| 4. |
- Pazarlis, Konstantinos A., et al.
(författare)
-
Preoperative MRI and Intraoperative Monitoring Differentially Prevent Neurological Sequelae in Idiopathic Scoliosis Surgical Correction, While Curves >70 Degrees Increase the Risk of Neurophysiological Incidences
- 2022
-
Ingår i: Journal of Clinical Medicine. - : MDPI. - 2077-0383. ; 11:9
-
Tidskriftsartikel (refereegranskat)abstract
- The aim was to investigate the role of preoperative magnetic resonance imaging (MRI) and intraoperative monitoring (IOM) in the prevention of correction-related complications in idiopathic scoliosis (IS). We conducted a retrospective case study of 129 patients with juvenile and adolescent IS. The operations took place between 2005 and 2018 in Uppsala University Hospital. Data from MRI scans and IOM were collected. The patients were divided into groups depending on Lenke's classification, sex, major curve (MC) size, and onset age. Neurophysiological incidences were reported in ten patients (7.8%), while nine of them had no signs of intraspinal pathology. Six patients (4.7%) had transient incidences; however, in four patients (3.1%), an intervention was required for the normalization of action potentials. Three of them had an MC >70 degrees, which was significantly higher than the expected value. Eight patients (6.1%) had intraspinal pathologies, and two of them (1.5%) underwent decompression. We suggest the continuation of MRI screening preoperatively and, most importantly, the use of IOM. In three cases with no signs of pathology in the MRI, IOM prevented possible neurological injuries. MCs >70 degrees should be considered a risk factor for the occurrence of neurophysiological deficiencies that require action to be normalized.
|
|
| 5. |
- Pazarlis, Konstantinos A., et al.
(författare)
-
Study protocol for a randomised controlled trial with clinical, neurophysiological, laboratory and radiological outcome for surgical versus non-surgical treatment for lumbar spinal stenosis : the Uppsala Spinal Stenosis Trial (UppSten)
- 2019
-
Ingår i: BMJ Open. - : BMJ PUBLISHING GROUP. - 2044-6055. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- Introduction: Symptomatic lumbar spinal stenosis is the most common indication for spinal surgery. However, more than one-third of the patients undergoing surgery for lumbar stenosis report dissatisfaction with the results. On the other hand, conservative treatment has shown positive results in some cases. This trial will compare the outcomes of surgical versus non-surgical treatment for lumbar stenosis. The study includes a multidimensional follow-up, aiming to study the association between outcome and other studied parameters, mainly electromyography and nerve conduction. Moreover, it may contribute to a better understanding of the pathophysiology of lumbar stenosis and to the development of future pharmacological treatments.Methods and analysis: UppSten is a single-centre randomised controlled trial in which 150 patients with symptomatic lumbar spinal stenosis will be randomised into one of two treatment arms. The patients in the surgical arm will undergo laminectomy; the patients in the non-surgical arm will be given a structured physical training programme. The primary outcome of the study will be the Oswestry Disability Index. Secondary outcomes will include motor amplitude and degree of denervation activity obtained by means of nerve conduction studies and electromyography. Patient-reported outcome measures will be also used as secondary outcomes. Blood sample analysis and the investigation of potential inflammation markers are the additional secondary outcome parameters. Laboratory evaluation will include blood sample collection before the treatment initiation and after 6 months. Flavum ligament biopsies will be performed in the surgical group. Finally, tertiary outcomes will include neurophysiological measures, the objective walking ability and radiological evaluation.Ethics and dissemination: The study is approved by the Local Ethics Committee (Dnr 2017-506), the Hospital's Clinical Trials Committee (2018-0001) and the National Biobank Council and Uppsala Biobank (BbA-827-2018-025).
|
|
| 6. |
- Pazarlis, Konstantinos, et al.
(författare)
-
Clinical and Neurophysiological Outcome of a Randomized Controlled Trial for the Treatment of Lumbal Spinal Stenosis : The Uppsala Spinal Stenosis Trial (UppSten)
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Study Design: Randomized Controlled TrialAims: To compare surgical vs non-surgical treatment for lumbar spinal stenosis (LSS) in terms of clinical and neurophysiological outcome. Introduction: LSS is the most common indication for spinal surgery. The evidence based surgical treatment is posterior direct decompression of the affected levels, whereas non-surgical treatment varies. Up to now, there is no clear evidence that the surgical treatment is superior compared to the non-surgical one. Methods: We randomized 155 patients with LSS into two arms; surgery with decompression or structured physical therapy (PT). Clinical and neurophysiological data were collected at baseline and six months after treatment. In the PT group, the patients could cross (CO) over to surgery at any time and then receive follow-up (FU) as in the surgical group. Results. Seventy-nine patients were included in the surgical and 76 in the PT group. At six months there was a clear improvement for all clinical outcomes in favor of surgery. The ODI mean improvement was 12.4 units greater than in the PT group and the improvement of the quality of life was higher after surgery. The odds for improvement in back and leg pain and overall satisfaction was greater in the surgical arm as well. The improvement in six-minute walking test was also higher after surgery. There were no COs before six months. After six months, 30 PT patients chose CO. Six months after CO surgery and collection of new data, they were analyzed separately. These patients did not improve in ODI to the six-month FU after PT, but 6 months after the CO surgery there was an improvement in ODI to the same extent as in the surgery group. The electrophysiological (EDX) evaluation included 134 patients, 67 from the surgical; and another 67 from the PT group. The degree of neurogenic involvement measured with EDX techniques was rather modest and the data did not indicate that EDX could be used as selection tool in LSS surgery. The degree of peripheral motor neuron involvement and presence of active denervation at baseline related to short walking distance; however, neither improved walking distance nor reduced back pain had any clear correlation to EDX improvement. Conclusion: Surgery for LSS has better short-term clinical outcome when compared to PT. Delay in surgery did not affect this outcome. There is no clear indication that EDX could be used as surgery selection tool.
|
|
| 7. |
- Pazarlis, Konstantinos, et al.
(författare)
-
Decompression Improves the Sagittal Balance in Patients with Lumbar Spinal Stenosis. A Randomized Controlled Trial : The Uppsala Spinal Stenosis Trial (UppSten)
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Objective: Lumbar spinal stenosis (LSS) is caused by narrowing of the spinal canal resulting in compression of the nerve roots. It is the most common indication for spinal surgery and a posterior direct decompression is the golden standard surgery. Spine extension increases the LSS symptoms by narrowing more the canal and thus typical LSS patients flex forward to compensate. This study aimed to compare the radiological outcome for surgical vs non-surgical treatment for LSS.Methods: The trial randomized LSS patients into two arms; surgery with decompression and structured physical therapy (PT). Lumbar lordosis (LL), sagittal vertebral axis (SVA) and degenerative spondylolisthesis (DS) were collected at baseline and six months after treatment by means of standing whole spine plain radiographies. The patients of the PT group had option to cross-over (CO) to the surgical group at six months and then received follow-up as in the surgical group. Results: We randomized 155 patients; 79 patients in the surgical and 76 in the PT group. At six months, the surgical group had better LL and tendency towards better SVA results compared to the PT group, where there was no improvement. The DS subgroup comprised of 60 patients; 33 in the surgical and 27 in the PT arm. We found an improvement for LL in the surgical group and an increase of the DS in the PT group. After six months, 30 patients from PT group chose CO to surgery. Six months after the CO surgery, the CO subgroup had less LL compared to the patients who were allocated to surgery from the beginning. Conclusions: Surgery with decompression for LSS improves the spinal sagittal balance in terms of LL and SVA, independently of preoperative DS.
|
|
| 8. |
- Pazarlis, Konstantinos, MD, 1983-
(författare)
-
On the Diagnosis and Treatment of Lumbar Spinal Stenosis
- 2023
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Lumbar spinal stenosis (LSS) is the most common indication for spinal surgery. The aging global population is increasing the demand for strategies that promote physical activity among the elderly. As the prevalence of LSS rises, the condition gains constantly demographic and socioeconomic attention. Until recently, there has been no clear consensus regarding LSS treatment. Further, using electrodiagnostic examinations (EDX) as predictive tools to identify surgical candidates, could lead to a more tailored medical approach. Methodological issues in previous studies have left some questions unanswered. The necessity of extensive surgery for LSS remains a topic of debate among spinal surgeons, which this work addressed by analyzing data from 723 patients. Parts of the work aimed to compare surgery and structured non-surgical treatment for LSS (Paper I, II, III). Furthermore, it aimed to investigate, by means of EDX, whether the degree of neurological affection correlates to the surgical outcome of LSS (Paper I, II). Additionally, this work evaluated the radiological outcome for surgical vs non-surgical treatment for LSS in terms of sagittal balance parameters (Paper III, V). Finally, parts of this thesis aimed to confirm findings from previous studies regarding DA and DF for LSS with DS (Paper IV, V). The current thesis is based on two randomized controlled trials and a cohort study: the Uppsala Spinal Stenosis Trial, the Swedish Spinal Stenosis Study, and the Cohort Study on LSS with DS. Patient reported outcome measures from the Swedish National Quality Registry for Spine Surgery (Swespine) were used to collect follow-up data. We concluded that at six months, surgery with decompression leads to superior clinical outcome, compared to structured physical therapy. The improvement is not affected by delay of surgery (Paper II). EDX does not add predictive value when assessing the patients for eligibility before surgery (Paper II). DA improves the spinal sagittal balance, regardless of preoperative DS (Paper III) and provides good two-year clinical outcome in LSS with DS with low rate of complications, and low need for subsequent surgery (Paper IV). New radiological stenosis was less common two years after DA than after DF, in LSS with or without preoperative DS (Paper V).
|
|
| 9. |
- Schizas, Nikos, 1979-, et al.
(författare)
-
Neural crest stem cells protect spinal cord neurons from excitotoxic damage and inhibit glial activation by secretion of brain-derived neurotrophic factor
- 2018
-
Ingår i: Cell and Tissue Research. - : Springer Science and Business Media LLC. - 0302-766X .- 1432-0878. ; 372:3, s. 493-505
-
Tidskriftsartikel (refereegranskat)abstract
- The acute phase of spinal cord injury is characterized by excitotoxic and inflammatory events that mediate extensive neuronal loss in the gray matter. Neural crest stem cells (NCSCs) can exert neuroprotective and anti-inflammatory effects that may be mediated by soluble factors. We therefore hypothesize that transplantation of NCSCs to acutely injured spinal cord slice cultures (SCSCs) can prevent neuronal loss after excitotoxic injury. NCSCs were applied onto SCSCs previously subjected to N-methyl-d-aspartate (NMDA)-induced injury. Immunohistochemistry and TUNEL staining were used to quantitatively study cell populations and apoptosis. Concentrations of neurotrophic factors were measured by ELISA. Migration and differentiation properties of NCSCs on SCSCs, laminin, or hyaluronic acid hydrogel were separately studied. NCSCs counteracted the loss of NeuN-positive neurons that was otherwise observed after NMDA-induced excitotoxicity, partly by inhibiting neuronal apoptosis. They also reduced activation of both microglial cells and astrocytes. The concentration of brain-derived neurotrophic factor (BDNF) was increased in supernatants from SCSCs cultured with NCSCs compared to SCSCs alone and BDNF alone mimicked the effects of NCSC application on SCSCs. NCSCs migrated superficially across the surface of SCSCs and showed no signs of neuronal or glial differentiation but preserved their expression of SOX2 and Krox20. In conclusion, NCSCs exert neuroprotective, anti-apoptotic and glia-inhibitory effects on excitotoxically injured spinal cord tissue, some of these effects mediated by secretion of BDNF. However, the investigated NCSCs seem not to undergo neuronal or glial differentiation in the short term since markers indicative of an undifferentiated state were expressed during the entire observation period.
|
|
| 10. |
- Schizas, Nikos, 1979-, et al.
(författare)
-
Neural Crest Stem Cells protect Spinal Cord Slice Cultures from Excitotoxic Neuronal Damage and Inhibit Glial Activation
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Neural Crest Stem Cells (NCSC) possess anti-inflammatory properties and they could therefore have protective effects on neurons after spinal cord injury (SCI). We investigated if NCSCs reduce neuronal loss and glial activation after excitotoxic injury in spinal cord slice cultures (SCSCs). SCSCs subjected to N-Methyl-D-Aspartate (NMDA)-induced injury were either treated by transplantation of NCSC or with interleukin-1 receptor antagonist (IL1RA). Immunohistochemistry for Neuronal Nuclei (NeuN), glial fibrillary acidic protein (GFAP) and MacII were used to study neuronal and glial populations, and TUNEL staining to visualize apoptotic cells. Migration and differentiation of NCSCs on SCSCs, laminin or a hyaluronic acid hydrogel were investigated by immunohistochemistry. NCSCs counteracted the neuronal loss observed after NMDA-induced excitotoxicity and reduced the proportion of apoptotic cells. Transplantation of NCSCs also reduced the number of activated microglial cells in the white matter and the number of activated astrocytes in the grey matter of NMDA-injured SCSCs. The majority of NCSCs migrated superficially across the surface of SCSCs with some of them penetrating into the tissue. NCSCs did not show signs of neuronal or glial differentiation, however, the markers SOX2 and Krox20 were expressed which indicated an undifferentiated state of NCSCs. In conclusion, NCSCs have neuroprotective, anti-apoptotic and anti-inflammatory effects on SCSCs subjected to excitotoxicity, similar to the effects of IL1RA. Since the majority of NCSCs did not migrate through SCSCs they are likely to exert their actions through the secretion of soluble factors.
|
|
| 11. |
- Schizas, Nikos, 1979-
(författare)
-
Neuroprotection in the Injured Spinal Cord : Novel Strategies using Immunomodulation, Stem cell Transplantation and Hyaluronic acid Hydrogel carriers
- 2015
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The overall aim of this thesis was to establish strategies to minimize secondary damage to the injured spinal cord. Secondary damage that follows spinal cord injury (SCI) involves inflammatory and excitotoxic pathways. Regulation of these pathways using immunomodulatory and neuroprotective substances potentially protects the injured spinal cord from further damage. We also developed and studied resorbable biomaterials to be used as carriers for potential neuroprotectants to the injured spinal cord.We used transversal spinal cord slice cultures (SCSCs) derived from postnatal mice as a model. SCSCs were maintained on different biomaterials and were studied after treatment with immunomodulatory and/or neurotrophic factors. They were further excitotoxically injured and subsequently treated with interleukin-1 receptor antagonist (IL1RA) or by neural crest stem cell (NCSC)-transplantation.The results show that biocompatible and resorbable hydrogels based on hyaluronic acid (HA) preserved neurons in SCSCs to a much higher extent than a conventional collagen-based biomaterial or standard polyethylene terephthalate (PET) membrane inserts. Glial activation was limited in the cultures maintained on HA-based hydrogel. The anti-inflammatory factor IL1RA protected SCSCs from degenerative mechanisms that occur during in vitro incubation, and IL1RA also protected SCSCs from excitotoxic injury induced by N-Methyl-d-Aspartate (NMDA). IL1RA specifically protected neurons that resided in the ventral horn, while other neuronal populations such as dorsal horn neurons and Renshaw cells did not respond to treatment. Finally, transplantation of NCSCs onto excitotoxically injured SCSCs protected from neuronal loss, apoptosis and glial activation, while NCSCs remained undifferentiated.The results presented in this thesis indicate that carriers based on HA seem to be more suitable than conventional collagen-based biomaterials since they enhance neuronal survival per se. The observed neuroprotection is likely due to biomechanical properties of HA. IL1RA protects SCSCs from spontaneous degeneration and from NMDA-induced injury, suggesting that excitotoxic mechanisms can be modulated through anti-inflammatory pathways. Different neuronal populations are affected by IL1RA to various degrees, suggesting that a combination of different neuroprotectants should be used in treatment strategies after SCI. Finally, NCSCs seem to protect SCSCs from excitotoxic injury through paracrine actions, since they remain undifferentiated and do not migrate into the tissue during in vitro incubation.It seems that combinations of neuroprotectants and carrier substances should be considered rather than one single strategy when designing future treatments for SCI. Incorporation of neuroprotectants such as IL1RA combined with stem cells in injectable biocompatible carriers based on HA is the final goal of our group in the treatment of SCI.
|
|
