Return to search

Etude du modèle de rat pour la Sclérose Latérale Amyotrophique; caractérisation de la barrière hémato-encéphalique et applications thérapeutiques - Study of the rat model for Amyotrophic Lateral Sclerosis; characterization of the blood-brain barrier and therapeutical approaches

The selective degeneration of motoneurons in the spinal cord, the brainstem and the brain cortex is the core pathology of amyotrophic lateral sclerosis (ALS), but evidences suggest that the neighbouring non-neuronal cells are also involved in the disease progression. Beside Riluzole, only drug approved to treat this fatal neurodegenerative disease, new pharmaceutical agents or novel strategies including stem cell therapy are currently under development and evaluated preclinically in front line on mutant SOD1 rodents mimicking all hallmarks of the human disease.
Current intravenously delivered drugs tested in ALS therapy assume an intact blood-brain barrier and suppose the passage across the endothelium to hit their targets in the CNS parenchyma. If BBB impairment occurs in ALS, it may lead to revision of planned pharmaceutical treatment. In the first part of the work, we have validated the mutant SOD1 rat model of ALS and we characterized properties and integrity of its BBB. We observed a significant BBB disruption at symptomatic phase of ALS, evidenced by blood protein leakage, IgG accumulation and microhemorrhage. To look for the mechanism of BBB opening, we demonstrated that the expression of key genes involved in the BBB integrity was decreased. At the ultrastructure, the morphology of endothelial cells and vascular astrocyte end-feet was altered. Our results suggest that BBB disruption is a late event in ALS disease course and appears like a consequence of the local degenerative process or neuroinflammation rather than a cause. Since a lot of extracellular oedema and swollen astrocyte end-feet were found in mutant SOD1 rats, we also looked at the expression and localization of aquaporin-4, a key protein involved in CNS water movement. We found that its expression was highly increased in the symptomatic phase of ALS course and we hypothesize that this overexpression might be related to the resolution of oedema after BBB opening.
In the second part of the work, we considered an original, easy, non-invasive and safe therapeutical approach of stem cell delivery in ALS rats. Since ALS affects the motoneurons throughout the CNS, we decided to use the bloodstream to deliver neural stem cells. We studied cell homing, survival, proliferation, integration and differentiation. Interestingly, the highest efficiency of cell delivery to the CNS was found in symptomatic ALS and the lowest in healthy animals. Neural stem cells injected into ALS animals preferentially colonized the motor cortex, hippocampus and spinal cord. We detected their successful differentiation into neural lineages by the appearance of MAP2-, GFAP-positive cells and the decrease of nestin expression.
One of the realistic near-term clinical goals for ALS is the transplantation of stem cells that counteract the loss of motoneurons by secreting neuroprotective factors. Accordingly, we evaluated in vitro the expression of neurotrophic factors released by stem cells after stimulation with tissue extracts from ALS rats. The aim of this paradigm was to determine whether the ALS environment triggers neuroprotective factors release from stem cells. Mesenchymal stem cells and neural stem cells were able to express a wider range of growth factors than fibroblasts. According to the stem cell population stimulated, we obtained differential expression pattern, raising the choice of cell population for appropriate clinical applications in ALS.

Identiferoai:union.ndltd.org:BICfB/oai:ulb.ac.be:ETDULB:ULBetd-12162010-163110
Date22 December 2010
CreatorsNicaise, Charles
ContributorsLebrun, Philippe, Salmon, Isabelle, Bohl, Delphine, Haiech, Jacques, Lotstra, Françoise, Pandolfo, Massimo, Petein, Michel
PublisherUniversite Libre de Bruxelles
Source SetsBibliothèque interuniversitaire de la Communauté française de Belgique
LanguageEnglish
Detected LanguageEnglish
Typetext
Formatapplication/pdf
Sourcehttp://theses.ulb.ac.be/ETD-db/collection/available/ULBetd-12162010-163110/
Rightsunrestricted, J'accepte que le texte de la thèse (ci-après l'oeuvre), sous réserve des parties couvertes par la confidentialité, soit publié dans le recueil électronique des thèses ULB. A cette fin, je donne licence à ULB : - le droit de fixer et de reproduire l'oeuvre sur support électronique : logiciel ETD/db - le droit de communiquer l'oeuvre au public Cette licence, gratuite et non exclusive, est valable pour toute la durée de la propriété littéraire et artistique, y compris ses éventuelles prolongations, et pour le monde entier. Je conserve tous les autres droits pour la reproduction et la communication de la thèse, ainsi que le droit de l'utiliser dans de futurs travaux. Je certifie avoir obtenu, conformément à la législation sur le droit d'auteur et aux exigences du droit à l'image, toutes les autorisations nécessaires à la reproduction dans ma thèse d'images, de textes, et/ou de toute oeuvre protégés par le droit d'auteur, et avoir obtenu les autorisations nécessaires à leur communication à des tiers. Au cas où un tiers est titulaire d'un droit de propriété intellectuelle sur tout ou partie de ma thèse, je certifie avoir obtenu son autorisation écrite pour l'exercice des droits mentionnés ci-dessus.

Page generated in 0.0012 seconds