Long Term Gene Expression in Human Induced Pluripotent Stem Cells and Cerebral Organoids to Model a Neurodegenerative Disease.

Human brain organoids (mini-brains) consist of self-organized three-dimensional (3D) neural tissue which can be derived from reprogrammed adult cells and maintained for months in culture. These 3D structures manifest substantial potential for the modeling of neurodegenerative diseases and pave the way for personalized medicine. However, as these 3D brain models can express the whole human genetic complexity, it is critical to have access to isogenic mini-brains that only differ in specific and controlled genetic variables. Genetic engineering based on retroviral vectors is incompatible with the long-term modeling needed here and implies a risk of random integration while methods using CRISPR-Cas9 are still too complex to adapt to stem cells. We demonstrate in this study that our strategy which relies on an episomal plasmid vector derived from the Epstein-Barr virus (EBV) offers a simple and robust approach, avoiding the remaining caveats of mini-brain models. For this proof-of-concept, we used a normal tau protein with a fluorescent tag and a mutant genetic form (P301S) leading to Fronto-Temporal Dementia. Isogenic cell lines were obtained which were stable for more than 30 passages expressing either form. We show that the presence of the plasmid in the cells does not interfere with the mini-brain differentiation protocol and obtain the development of a pathologically relevant phenotype in cerebral organoids, with pathological hyperphosphorylation of the tau protein. Such a simple and versatile genetic strategy opens up the full potential of human organoids to contribute to disease modeling, personalized medicine and testing of therapeutics.

Author Correction: A Small Compound Targeting Prohibitin with Potential Interest for Cognitive Deficit Rescue in Aging mice and Tau Pathology Treatment.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

A Small Compound Targeting Prohibitin with Potential Interest for Cognitive Deficit Rescue in Aging mice and Tau Pathology Treatment.

Neurodegenerative diseases, including Alzheimer's and Parkinson's disease, are characterized by increased protein aggregation in the brain, progressive neuronal loss, increased inflammation, and neurogenesis impairment. We analyzed the effects of a new purine derivative drug, PDD005, in attenuating mechanisms involved in the pathogenesis of neurodegenerative diseases, using both in vivo and in vitro models. We show that PDD005 is distributed to the brain and can rescue cognitive deficits associated with aging in mice. Treatment with PDD005 prevents impairment of neurogenesis by increasing sex-determining region Y-box 2, nestin, and also enhances synaptic function through upregulation of synaptophysin and postsynaptic density protein 95. PDD005 treatment also reduced neuro-inflammation by decreasing interleukin-1ß expression, activation of astrocytes, and microglia. We identified prohibitin as a potential target in mediating the therapeutic effects of PDD005 for the treatment of cognitive deficit in aging mice. Additionally, in the current study, glycogen synthase kinase appears to attenuate tau pathology.

Proof-of-Concept Study of Drug Brain Permeability Between in Vivo Human Brain and an in Vitro iPSCs-Human Blood-Brain Barrier Model.

The development of effective central nervous system (CNS) drugs has been hampered by the lack of robust strategies to mimic the blood-brain barrier (BBB) and cerebrovascular impairments in vitro. Recent technological advancements in BBB modeling using induced pluripotent stem cells (iPSCs) allowed to overcome some of these obstacles, nonetheless the pertinence for their use in drug permeation study remains to be established. This mandatory information requires a cross comparison of in vitro and in vivo pharmacokinetic data in the same species to avoid failure in late clinical drug development. Here, we measured the BBB permeabilities of 8 clinical positron emission tomography (PET) radioligands with known pharmacokinetic parameters in human brain in vivo with a newly developed in vitro iPSC-based human BBB (iPSC-hBBB) model. Our findings showed a good correlation between in vitro and in vivo drug brain permeability (R2 = 0.83; P = 0.008) which contrasted with the limited correlation between in vitro apparent permeability for a set of 18 CNS/non-CNS compounds using the in vitro iPSCs-hBBB model and drug physicochemical properties. Our data suggest that the iPSC-hBBB model can be integrated in a flow scheme of CNS drug screening and potentially used to study species differences in BBB permeation.

Small-molecule induction of Aß-42 peptide production in human cerebral organoids to model Alzheimer's disease associated phenotypes.

Human mini-brains (MB) are cerebral organoids that recapitulate in part the complexity of the human brain in a unique three-dimensional in vitro model, yielding discrete brain regions reminiscent of the cerebral cortex. Specific proteins linked to neurodegenerative disorders are physiologically expressed in MBs, such as APP-derived amyloids (Aß), whose physiological and pathological roles and interactions with other proteins are not well established in humans. Here, we demonstrate that neuroectodermal organoids can be used to study the Aß accumulation implicated in Alzheimer's disease (AD). To enhance the process of protein secretion and accumulation, we adopted a chemical strategy of induction to modulate post-translational pathways of APP using an Amyloid-ß Forty-Two Inducer named Aftin-5. Secreted, soluble Aß fragment concentrations were analyzed in MB-conditioned media. An increase in the Aß42 fragment secretion was observed as was an increased Aß42/Aß40 ratio after drug treatment, which is consistent with the pathological-like phenotypes described in vivo in transgenic animal models and in vitro in induced pluripotent stem cell-derived neural cultures obtained from AD patients. Notably in this context we observe time-dependent Aß accumulation, which differs from protein accumulation occurring after treatment. We show that mini-brains obtained from a non-AD control cell line are responsive to chemical compound induction, producing a shift of physiological Aß concentrations, suggesting that this model can be used to identify environmental agents that may initiate the cascade of events ultimately leading to sporadic AD. Increases in both Aß oligomers and their target, the cellular prion protein (PrPC), support the possibility of using MBs to further understand the pathophysiological role that underlies their interaction in a human model. Finally, the potential application of MBs for modeling age-associated phenotypes and the study of neurological disorders is confirmed.

Disruption of phactr-1 pathway triggers pro-inflammatory and pro-atherogenic factors: New insights in atherosclerosis development.

Significant interest has recently emerged for phosphatase and actin regulatory protein (PHACTR1) gene in heart diseases prognosis. However, the functional role of phactr-1 protein remains elusive in heart related-diseases such as atherosclerosis, coronary artery calcification, ischaemic stroke, coronary artery stenosis and early-onset myocardial infarction. Phactr-1 is directly regulated by vascular endothelial growth factor A165 (VEGF-A165) through VEGF receptor 1 (VEGR-1) and Neuropilin-1 (NRP-1). Using an antagonist peptide approach to inhibit the interaction of VEGF-A165 to NRP-1 and VEGF-R1, we highlighted the importance of both cysteine residues located at the end of VEGF-A165 exon-7 and at the exon-8 to generate functional peptides, which decreased Phactr-1 expression. Here, we report original data showing Phactr-1 down-expression induces the expression of Matrix Metalloproteinase (MMP) regulators such as Tissue inhibitor of metalloproteinase (TIMP-1/-2) and Reversion-inducing-cysteine-rich protein with kazal motifs (RECK). Furthermore, focal adhesion kinases (FAK/PYK2/PAXILLIN) and metabolic stress (AMPK/CREB/eNOS) pathways were inhibited in endothelial cells. Moreover, the decrease of phactr-1 expression induced several factors implicated in atherosclerotic events such as oxidized low-density lipoprotein receptors (CD36, Clusterin, Cadherin-13), pro-inflammatory proteins including Thrombin, Thrombin receptor 1 (PAR-1), A Disintegrin And Metalloprotease domain-9/-17 (ADAM-9/-17), Trombospondin-2 and Galectin-3. Besides, Phactr-1 down-expression also induces emerging atherosclerosis biomarkers such as semicarbazide-sensitive amine oxidase (SSAO) and TGF-beta-inducible gene h3 (ßIG-H3). In this report, we show for the first time the direct evidence of the phactr-1 biological function in the regulation of pro-atherosclerotic molecules. This intriguing result strengthened heart diseases PHACTR-1 single-nucleotide polymorphisms (SNP) correlation. Taken together, our result highlighted the pivotal role of phactr-1 protein in the pathogenesis of atherosclerosis.

Structure-based discovery of a small non-peptidic Neuropilins antagonist exerting in vitro and in vivo anti-tumor activity on breast cancer model.

Neuropilin-1/-2 (+33 NRPs), VEGF-A165 co-receptors, are over-expressed during cancer progression. Thus, NRPs targeted drug development is challenged using a multistep in silico/in vitro screening procedure. The first fully non-peptidic VEGF-A165/NRPs protein-protein interaction antagonist (IC50=34 µM) without effect on pro-angiogenic kinases has been identified (compound-1). This hit showed breast cancer cells anti-proliferative activity (IC50=0.60 µM). Compound-1 treated NOG-xenografted mice significantly exerted tumor growth inhibition, which is correlated with Ki-67(low) expression and apoptosis. Furthermore, CD31(+)/CD34(+) vessels are reduced in accordance with HUVEC-tube formation inhibition (IC50=0.20 µM). Taking together, compound-1 is the first fully organic inhibitor targeting NRPs.