Loading...
2 results
Search Results
Now showing 1 - 2 of 2
- Retinoic acid-loaded polymeric nanoparticles induce neuroprotection in a mouse model of Parkinson's diseasePublication . Esteves, Marta Raquel Carrola; Bernardino, Liliana Inácio; Baltazar, Graça Maria FernandesRetinoic acid (RA) plays an important role in the developing mammalian nervous system and has been highlighted as a therapeutic option for some neurodegenerative diseases due to its neuroprotective, anti-inflammatory and pro-neurogenic properties. However, RA presents undesirable properties like poor water solubility and short half-life. Therefore, nanoparticles (NPs) are an excellent alternative to control the undesired side effects and to ensure intracellular transport and controlled release of RA. Thus, the aim of this work was to evaluate the effects of RA-loaded NPs (RA+-NPs) in an in vivo mouse model of Parkinson’s disease (PD) using a MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) neurotoxin, and to compare with effects of soluble RA. Interestingly, in adult mice, RA+-NPs significantly reduced the MPTP lesion by increasing the percentage of tyrosine hydroxylase positive (TH+) dopaminergic neurons in the SN to levels similar to control as well as increasing the intensity and area occupied by TH+ fibers in the striatum. This protective effect mediated by RA+-NPs was more robust than when compared with effect of soluble RA. These effects were accompanied by an increase in mRNA expression in SN and striatum of Nurr1 and Pitx3, both transcription factors involved in dopaminergic survival and specification. The same pattern of Pitx3 mRNA expression was found in the SN of old mice. In conclusion, RA+-NPs show a robust protective effect against dopaminergic injury when compared to soluble RA, suggesting that RA+-NPs could be a good strategy to boost brain repair in PD.
- MicroRNAs-enriched exosomes as a new therapy for Parkinson’s diseasePublication . Esteves, Marta Raquel Carrola; Bernardino, Liliana Inácio; Ferreira, Lino SilvaParkinson’s disease (PD), a progressive and chronic neurological disorder characterized by the selective degeneration of the nigrostriatal dopaminergic pathway, has a huge socioeconomic impact in modern society. Alterations in alpha (α)-synuclein protein expression and aggregation have been regarded as a primary cause of dopaminergic neurons death in the substantia nigra (SN) pars compacta. So far, there are no treatments that halt or reverse the progression of PD. Recent evidence showed that microRNAs (miRNA), small non-coding RNAs that negatively regulate gene expression, are dysregulated in PD patients. In particular, miR-124 levels were found decreased in plasma and postmortem brain parenchyma of PD patients. Thus, miR-124 has become a relevant molecular therapeutic target for PD. Increasing intracellular levels of miR-124 enhances neurogenesis and neuroprotection in PD models. However, the effect of miR- 124 on α-synuclein dynamics has not yet been reported. One of the main goals of this thesis was to evaluate the role of miR-124-3p in the expression and aggregation of α-synuclein protein using the rat model of PD based on the acute administration of paraquat (PQ). The first research work showed that intranigral administration of miR-124-3p significantly reduces the protein levels of α- synuclein and α-synuclein phosphorylated at serine 129 (present in large amounts in Lewy bodies) in the SN of rats exposed to PQ. Moreover, the protein levels of NADPH oxidase 1 (Nox1), responsible for the oxidative stress production and eventually involved in the development of α-synuclein toxicity, and its activator GTPase Rac1, decreased in SN after miR-124-3p administration in PQ-treated rats. Additionally, the reduced levels of Pitx3 in the SN caused by the administration of PQ were found to increase after the administration of miR-124-3p. This work demonstrates for the first time the role of miR- 124-3p in the regulation of α-synuclein toxicity, possibly through the modulation of the Nox1/Rac1 signaling pathway and in the regulation of Pitx3 expression important for the survival and maintenance of dopaminergic neurons. The efficient delivery of miRNA at the intracellular and intracerebral levels has several limitations since they are highly susceptible to degradation by nucleases and are difficult to take up by cells due to their negative charge. Recently, several approaches capable of guaranteeing an efficient delivery of miRNA have been developed. In particular, small extracellular vesicles (sEV), also referred to as exosomes, have been highlighted as efficient delivery systems for miRNA due to their intrinsic ability to interact with cells and tissues. The second main goal of this thesis was to use sEV isolated from human umbilical cord blood-derived mononuclear cells as a biological vehicle of miR-124 and to evaluate the efficiency of these sEV transfected with miR-124-3p (miR-124-3p sEV) in inducing neurogenesis and neuroprotection in 6-hydroxydopamine (6-OHDA) PD model. The second research work showed that in vitro, sEV efficiently deliver miR-124- 3p to subventricular zone (SVZ) neural stem cells (NSC) and to N27 dopaminergic cells. Treatment of NSC with miR-124-3p sEV induced neuronal differentiation of SVZ NSC under physiological conditions and protected N27 dopaminergic cells against 6-OHDAinduced toxicity. In vivo, sEV intracerebroventricularly injected in mice were detected in SVZ lining the lateral ventricles and in striatum and midbrain sections, the brain regions most affected by the disease. Although miR-124-3p sEV did not increase the number of new neurons in the 6-OHDA-lesioned striatum, the formulation protected dopaminergic neurons in the SN and striatal fibers, which fully counteracted motor behavior symptoms in mice administered with 6-OHDA. In conclusion, the results obtained during this thesis provide new evidence on the role of miR-124-3p in α-synuclein protein pathology and evidence supporting the application of sEV as biologic delivery agents for miR-124-3p to promote neuroprotection of dopaminergic neurons. In short, the enrichment of sEV with miR-124-3p may configure a promising therapeutic strategy able to halt or slow-down dopaminergic neuronal death in PD.