Investigation of the potential neuroprotective role of a BDNF analog in Parkinson's disease patient-derived neurons

Η ασθένεια του Πάρκινσον (PD) συνιστά τη δεύτερη πιο συχνή νευροεκφυλιστική ασθένεια μετά την νόσο Αλτσχάιμερ και χαρακτηρίζεται από κινητικές δυσλειτουργίες, που έχουν συσχετιστεί με την προοδευτική απώλεια ντοπαμινεργικών νευρώνων στον μεσεγκέφαλο, αλλά και μη κινητικά συμπτώματα. Η μικρονευροτροφίνη BNN-20 είναι μια συνθετική ένωση που μιμείται τον νευροτροφικό παράγοντα BDNF και παρουσιάζει πλειοτροπική νευροπροστατευτική επίδραση στους ντοπαμινεργικούς νευρώνες της μέλαινας ουσίας του παρκινσονικού ζωικού μοντέλου "weaver". Στη μελέτη αυτή διερευνήσαμε τις πιθανές ευεργετικές επιδράσεις της σε ανθρώπινο κυτταρικό περιβάλλον. Συγκεκριμένα χρησιμοποιήσαμε ένα κυτταρικό μοντέλο της PD βασισμένο σε νευρώνες προερχομενους από επαγόμενα πολυδύναμα βλαστοκύτταρα ασθενών που φέρουν την p.A53T-α-synuclein μεταλλαγή. Το μοντέλο αυτό αναπαράγει μια σειρά από παθολογικούς φαινοτύπους όπως την πρωτεϊνική συσσωρευση, την αξονική παθολογία και την μειωμένη συναπτική συνδεσιμότητα. Η BNN-20 αύξησε ελαφρώς το ποσοστό των διαφοροποιημένων νευρώνων στις PD καλλιέργειες και προστάτεψε ως ένα βαθμό τους PD νευρώνες από απόπτωση προκαλούμενη από κυτταρικό στρες και τους άξονες τους από κατακερματισμό, χωρίς όμως να καταπολεμά την παρατηρούμενη βλάβη στην ανάπτυξη των νευριτών ή να επαναφέρει τα επίπεδα έκφρασης γονιδίων που έχουν απορρυθμιστεί στους PD νευρώνες. Για να επιβεβαιωθεί ο ευεργετικός νευροπροστατευτικός ρόλος της BNN-20 χρειάζεται περαιτέρω διερεύνηση των δράσεων της.Parkinson’s disease (PD) remains an incurable neurodegenerative disorder characterized by motor dysfunction related to the progressive loss of midbrain dopamine neurons while non-motor symptoms are also present. BNN-20 is a synthetic, BDNF-mimicking, microneurotrophin that has been shown to exhibit a pleiotropic neuroprotective effect on dopaminergic neurons of the substantia nigra pars compacta in the “weaver” mouse model of PD. Here, we assessed its potential effects in a unique human setting. In particular, we used an induced pluripotent stem cell (iPSC)-based model of PD from patients bearing the p.A53T-α-synuclein mutation that simulates disease-relevant phenotypes, including protein aggregation, compromised neuritic growth, axonal pathology and reduced synaptic connectivity. Our findings demonstrate that BNN-20 treatment increased slightly the percentage of differentiated neurons in PD cultures and protected partially PD neurons from stress-induced cell death and their axons from fragmentation without quenching neurite outgrowth impairment or restoring expression levels of genes associated with axon guidance and synaptic function, which were significantly dysregulated in PD neurons. Further investigation is needed to identify BNN-20 as a potential neuroprotective agent

Enhancement of endogenous midbrain neurogenesis by microneurotrophin BNN-20 after neural progenitor grafting in a mouse model of nigral degeneration

We have previously shown the neuroprotective and pro-neurogenic activity of microneurotrophin BNN-20 in the substantia nigra of the “weaver” mouse, a model of progressive nigrostriatal degeneration. Here, we extended our investigation in two clinically-relevant ways. First, we assessed the effects of BNN-20 on human induced pluripotent stem cell-derived neural progenitor cells and neurons derived from healthy and parkinsonian donors. Second, we assessed if BNN-20 can boost the outcome of mouse neural progenitor cell intranigral transplantations in weaver mice, at late stages of degeneration. We found that BNN-20 has limited direct effects on cultured human induced pluripotent stem cell-derived neural progenitor cells, marginally enhancing their differentiation towards neurons and partially reversing the pathological phenotype of dopaminergic neurons generated from parkinsonian donors. In agreement, we found no effects of BNN-20 on the mouse neural progenitor cells grafted in the substantia nigra of weaver mice. However, the graft strongly induced an endogenous neurogenic response throughout the midbrain, which was significantly enhanced by the administration of microneurotrophin BNN-20. Our results provide straightforward evidence of the existence of an endogenous midbrain neurogenic system that can be specifically strengthened by BNN-20. Interestingly, the lack of major similar activity on cultured human induced pluripotent stem cell-derived neural progenitors and their progeny reveals the in vivo specificity of the aforementioned pro-neurogenic effect

Early Signs of Molecular Defects in iPSC-Derived Neural Stems Cells from Patients with Familial Parkinson’s Disease

Parkinson’s disease (PD) is the second most common neurodegenerative disorder, classically associated with extensive loss of dopaminergic neurons of the substantia nigra pars compacta. The hallmark of the disease is the accumulation of pathogenic conformations of the presynaptic protein, α-synuclein (αSyn), and the formation of intraneuronal protein aggregate inclusions. Neurodegeneration of dopamine neurons leads to a prominent dopaminergic deficiency in the basal ganglia, responsible for motor disturbances. However, it is now recognized that the disease involves more widespread neuronal dysfunction, leading to early and late non-motor symptoms. The development of in vitro systems based on the differentiation of human-induced pluripotent stem cells provides us the unique opportunity to monitor alterations at the cellular and molecular level throughout the differentiation procedure and identify perturbations that occur early, even at the neuronal precursor stage. Here we aim to identify whether p.A53T-αSyn induced disturbances at the molecular level are already present in neural precursors. Towards this, we present data from transcriptomics analysis of control and p.A53T-αSyn NPCs showing altered expression in transcripts involved in axon guidance, adhesion, synaptogenesis, ion transport, and metabolism. The comparative analysis with the transcriptomics profile of p.A53T-αSyn neurons shows both distinct and overlapping pathways leading to neurodegeneration while meta-analysis with transcriptomics data from both neurodegenerative and neurodevelopmental disorders reveals that p.A53T-pathology has a significant overlap with the latter category. This is the first study showing that molecular dysregulation initiates early at the p.A53T-αSyn NPC level, suggesting that synucleinopathies may have a neurodevelopmental component