5,875 research outputs found
The role of mast cells and their proteases in traumatic spinal cord injury
No full textSpinal cord injury (SCI) is a chronic condition that results in functional impairment in locomotion, loss of sensation, and it can cause neuropathic pain, spasticity, and incontinence. SCI has a significant impact on the quality of life and life expectancy;
and it has also several disadvantages from an economical point of view. It is a devastating condition and patients with SCI are lifelong disabled because tissue in the central nervous system (CNS) is unable to regenerate after injury. Last years, there is increasing interest in the development of new therapies that can
improve functional recovery after SCI. The pathology of SCI is characterized by a primary traumatic impact that rapidly destroys neuronal cells and axons, which is followed by secondary injury processes that induce further tissue damage and thereby worsen the neurological deficits. These secondary injury mechanisms consist amongst many other factors out of an inflammatory reaction, which is characterized by the activation and infiltration of various inflammatory cells and release of inflammatory mediators. Later, also scar tissue is formed at the lesion by reactive astrocytes and other cells (such as ependymal cells, pericytes and fibroblasts), which blocks regenerative processes.
Mast cells are specialized cells of the innate immune response that are characterized by the presence of electron dense cytoplasmic granules. In these granules many preformed mediators are stored such as histamine, cytokines and several proteases; and activation of mast cells results in the release of these mediators in the extracellular space. Mast cells are mainly known for their role in
allergic reactions such as asthma and hay fever, but they also play an important role in wound healing and they form a ‘first-line’ defence against pathogens. Mast cells are present in various body tissues, including the CNS. In this dissertation, we investigated the role of mast cells and their proteases on wound healing
processes and repair after traumatic SCI. Our results indicate that mast cells improve functional recovery after SCI by suppressing detrimental inflammatory processes. These actions are mainly mediated by mouse mast cell protease 4 (mMCP4), a mast cell-specific chymase that cleaves inflammatory components after SCI and thereby improving the functional outcome. In addition,
we showed that less scar tissue is formed at the lesion site in mice that have no mast cells. Scar tissue that is formed at the lesion after SCI has a negative impact on axon regeneration and other repair processes. More importantly, degradation or modulation of the scar is a potential therapy for SCI. In our study, we demonstrate that mast cells suppress the formation of the scar via mMCP6, a mast cell-specific tryptase that on one hand directly cleaves matrix components of the scar but on the other hand also can suppress the expression of these factors after injury on the gene level. In contrast to mMCP4, mMCP6 has no strong effect on the inflammatory response after SCI. We also demonstrated
that mMCP4 limits scar formation at the lesion after SCI, but it is not clear yet whether mMCP4 directly cleaves components of the lesion scar after injury. It is plausible that the immunomodulatory effects of mMCP4 play a role in this process since the immune system and the extracellular matrix have a strong influence on each other. As a final step we explored whether mast cell proteases
could be applied therapeutically to improve recovery after SCI. Therefore, we produced recombinant mMCP6 and we applied it in mice, several days after they received a spinal cord lesion. Our data showed that the functional outcome was improved in animals that received recombinant mMCP6 compared to the vehicle control group. This is a first indication that mast cell proteases have a therapeutic effect after SCI. The next step is the application of recombinant mMCP4, either alone or in combination with mMCP6.
In conclusion, the results of this study indicate that mast cells play a beneficial role in repair processes and recovery after SCI. Moreover, we demonstrated that these mast cell effects were executed, to a great extent, by proteases that are specifically produced by mast cells such as mMCP4 and mMCP6. These proteases
suppress the so called ‘bad’ inflammatory reactions and alternatively they also prevent the formation of scar tissue at the lesion after SCI. Our findings suggest that mast cell proteases are promising therapeutic candidates to improve repair after CNS injury. However, further research is essential to define the optimal therapeutic time window and also dosage of these proteases has to be determined. Also the possibility to apply these proteases together or in combination with other therapeutic compounds has to be investigated.Agentschap voor Innovatie
door Wetenschap en Technologie (IWT
The Effect of Leukocyte- and Platelet-Rich Fibrin on Central and Peripheral Nervous System Neurons-Implications for Biomaterial Applicability
No full textLeukocyte- and Platelet-Rich Fibrin (L-PRF) is a second-generation platelet concentrate that is prepared directly from the patient's own blood. It is widely used in the field of regenerative medicine, and to better understand its clinical applicability we aimed to further explore the biological properties and effects of L-PRF on cells from the central and peripheral nervous system. To this end, L-PRF was prepared from healthy human donors, and confocal, transmission, and scanning electron microscopy as well as secretome analysis were performed on these clots. In addition, functional assays were completed to determine the effect of L-PRF on neural stem cells (NSCs), primary cortical neurons (pCNs), and peripheral dorsal root ganglion (DRG) neurons. We observed that L-PRF consists of a dense but porous fibrin network, containing leukocytes and aggregates of activated platelets that are distributed throughout the clot. Antibody array and ELISA confirmed that it is a reservoir for a plethora of growth factors. Key molecules that are known to have an effect on neuronal cell functions such as brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), vascular endothelial growth factor (VEGF), and platelet-derived growth factor (PDGF) were slowly released over time from the clots. Next, we found that the L-PRF secretome had no significant effect on the proliferative and metabolic activity of NSCs, but it did act as a chemoattractant and improved the migration of these CNS-derived stem cells. More importantly, L-PRF growth factors had a detrimental effect on the survival of pCNs, and consequently, also interfered with their neurite outgrowth. In contrast, we found a positive effect on peripheral DRG neurons, and L-PRF growth factors improved their survival and significantly stimulated the outgrowth and branching of their neurites. Taken together, our study demonstrates the positive effects of the L-PRF secretome on peripheral neurons and supports its use in regenerative medicine but care should be taken when using it for CNS applications
Unraveling the Role of the Apical Papilla During Dental Root Maturation
No full textThe apical papilla is a stem cell rich tissue located at the base of the developing dental root and is responsible for the progressive elongation and maturation of the root. The multipotent stem cells of the apical papilla (SCAP) are extensively studied in cell culture since they demonstrate a high capacity for osteogenic, adipogenic, and chondrogenic differentiation and are thus an attractive stem cell source for stem cell-based therapies. Currently, only few studies are dedicated to determining the role of the apical papilla in dental root development. In this review, we will focus on the architecture of the apical papilla and describe the specific SCAP signaling pathways involved in root maturation. Furthermore, we will explore the heterogeneity of the SCAP phenotype within the tissue and determine their micro-environmental interaction. Understanding the mechanism of postnatal dental root growth could further aid in developing novel strategies in dental root regeneration.TV and PG were postdoctoral researchers, supported by the Research Foundation—Flanders (FWO—Vlaanderen; 12U7718N, 1502120N, 12Z2620N)
Mouse mast cell protease 4 suppresses scar formation after traumatic spinal cord injury
No full textSpinal cord injury (SCI) triggers the formation of a glial and fibrotic scar, which creates a major barrier for neuroregenerative processes. Previous findings indicate that mast cells (MCs) protect the spinal cord after mechanical damage by suppressing detrimental inflammatory processes via mouse mast cell protease 4 (mMCP4), a MC-specific chymase. In addition to these immunomodulatory properties, mMCP4 also plays an important role in tissue remodeling and extracellular matrix degradation. Therefore, we have investigated the effects of mMCP4 on the scarring response after SCI. We demonstrate that the decrease in locomotor performance in mMCP4(-/-) mice is correlated with excessive scar formation at the lesion. The expression of axon-growth inhibitory chondroitin sulfate proteoglycans was dramatically increased in the perilesional area in mMCP4(-/-) mice compared to wild type mice. Moreover, the fibronectin-, laminin-, and collagen IV-positive scar was significantly enlarged in mMCP4(-/-) mice at the lesion center. A degradation assay revealed that mMCP4 directly cleaves collagen IV in vitro. On the gene expression level, neurocan and GFAP were significantly higher in the mMCP4(-/-) group at day 2 and day 28 after injury respectively. In contrast, the expression of fibronectin and collagen IV was reduced in mMCP4(-/-) mice compared to WT mice at day 7 after SCI. In conclusion, our data show that mMCP4 modulates scar development after SCI by altering the gene and protein expression patterns of key scar factors in vivo. Therefore, we suggest a new mechanism via which endogenous mMCP4 can improve recovery after SCI
Do dolphins benefit from nonlinear mathematics when processing their sonar returns?
No full textAn interview with author Tim Leighton about the paper
Altered lysosomal abundance and activity in Charcot-Marie-Tooth disease type 1A (late breaking abstract)
No full textOpportunities for linking young surveyors across professional surveying member organisations and FIG
No full textProteostasis plays an important role in demyelinating Charcot Marie Tooth disease
No full textType 1 Charcot-Marie-Tooth disease (CMT1) is the most common demyelinating peripheral neuropathy. Patients suffer from progressive muscle weakness and sensory problems. The underlying disease mechanisms of CMT1 are still unclear and no therapy is currently available, hence patients completely rely on supportive care. Balancing protein levels is a complex multistep process fundamental to maintain cells in their healthy state and a disrupted proteostasis is a hallmark of several neurodegenerative diseases. When protein misfolding occurs, protein quality control systems are activated such as chaperones, the lysosomal-autophagy system and proteasomal degradation to ensure proper degradation. However, in pathological circumstances, these mechanisms are overloaded and thereby become inefficient to clear the load of misfolded proteins. Recent evidence strongly indicates that a disbalance in proteostasis plays an important role in several forms of CMT1. In this review, we present an overview of the protein quality control systems, their role in CMT1, and potential treatment strategies to restore proteostasis.KL is PhD fellow funded by “Fonds Wetenschappelijk Onderzoek” (FWO: “Research Foundation Flanders”; 11A4120N & 11A4122N) and by the “Special Research Fund” (BOF) of Hasselt University (R-10491). TVG is a Junior postdoc fellow funded by “Fonds Wetenschappelijk Onderzoek” (FWO: “Research Foundation Flanders”; 12Z2620N)
The Influence of Lysosomal Stress on Dental Pulp Stem Cell-Derived Schwann Cells
No full textBackground: Dysregulation of the endo-lysosomal-autophagy pathway has been identified as a critical factor in the pathology of various demyelinating neurodegenerative diseases, including peripheral neuropathies. This pathway plays a crucial role in transporting newly synthesized myelin proteins to the plasma membrane in myelinating Schwann cells, making these cells susceptible to lysosome-related dysfunctions. Nevertheless, the specific impact of lysosomal dysfunction in Schwann cells and its contribution to neurodegeneration remain poorly understood. Methods: We aim to mimic lysosomal dysfunction in Schwann cells using chloroquine, a lysosomal dysfunction inducer, and to monitor lysosomal leakiness, Schwann cell viability, and apoptosis over time. Additionally, due to the ethical and experimental issues associated with cell isolation and the culturing of human Schwann cells, we use human dental pulp stem cell-derived Schwann cells (DPSC-SCs) as a model in our study. Results: Chloroquine incubation boosts lysosomal presence as demonstrated by an increased Lysotracker signal. Further in-depth lysosomal analysis demonstrated an increased lysosomal size and permeability as illustrated by a TEM analysis and GAL3-LAMP1 staining. Moreover, an Alamar blue assay and Caspase-3 staining demonstrates a reduced viability and increased apoptosis, respectively. Conclusions: Our data indicate that prolonged lysosomal dysfunction leads to lysosomal permeability, reduced viability, and eventually apoptosis in human DPSC-SCs.Funding:
This research is partly funded by the Hasselt University “interuniversity Special Research Fund” iBOF (IBOF/23/021) and the “Research Foundation Flanders” (Fonds Wetenschappelijk Onderzoek, FWO G040220N), which was awarded to E.W. K.L. is a PhD fellow funded by the FWO (11A4120N and 11A4122N) and by the Hasselt University BOF (R-10491). T.V. is a postdoctoral fellow
funded by the FWO (12Z2620N) and the Hasselt University BOF program (R-14084).
Acknowledgments:
The authors are grateful to Marc Jans for the excellent tissue processing for the transmission electron microscopy and Joeri Meyns (Ziekenhuis Oost Limburg, Genk, Belgium) for providing the dental pulp tissue
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