SNCA/α-synuclein aggregation plays a crucial role in synucleinopathies such as Parkinson disease and dementia with Lewy bodies. Aggregating and nonaggregating SNCA species are degraded by the autophagy-lysosomal pathway (ALP). Previously, we have shown that the ALP is not only responsible for SNCA degradation but is also involved in the intracellular aggregation process of SNCA. An additional role of extracellular SNCA in the pathology of synucleinopathies substantiating a prion-like propagation hypothesis has been suggested since released SNCA species and spreading of SNCA pathology throughout neural cells have been observed. However, the molecular interplay between intracellular pathways, SNCA aggregation, release, and response of the local microenvironment remains unknown. Here, we attributed SNCA-induced toxicity mainly to secreted species in a cell culture model of SNCA aggregation and in SNCA transgenic mice: We showed that ALP inhibition by bafilomycinA1 reduced intracellular SNCA aggregation but increased secretion of smaller oligomers that exacerbated microenvironmental response including uptake, inflammation, and cellular damage. Low-aggregated SNCA was predominantly released by exosomes and RAB11A-associated pathways whereas high-aggregated SNCA was secreted by membrane shedding. In summary, our study revealed a novel role of the ALP by linking protein degradation to nonclassical secretion for toxic SNCA species. Thus, impaired ALP in the diseased brain not only limits intracellular degradation of misfolded proteins, but also leads to a detrimental microenvironmental response due to enhanced SNCA secretion. These findings suggest that the major toxic role of SNCA is related to its extracellular species and further supports a protective role of intracellular SNCA aggregation.

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We have previously shown that soluble factors derived from mesenchymal stem cells (MSCs) induce oligodendrogenic fate and differentiation in adult rat neural progenitors (NPCs) in vitro. Here, we investigated if this pro-oligodendrogenic effect is maintained after cells have been transplanted onto rat hippocampal slice cultures, a CNS-organotypic environment. We first tested whether NPCs, that were pre-differentiated in vitro by MSC-derived conditioned medium, would generate oligodendrocytes after transplantation. This approach resulted in the loss of grafted NPCs, suggesting that oligodendroglial pre-differentiated cells could not integrate in the tissue and therefore did not survive grafting. However, when NPCs together with MSCs were transplanted in situ into hippocampal slice cultures, the grafted NPCs survived and the majority of them differentiated into oligodendrocytes. In contrast to the prevalent oligodendroglial differentiation in case of the NPC/MSC co-transplantation, naïve NPCs transplanted in the absence of MSCs differentiated predominantly into astrocytes. In summary, the pro-oligodendrogenic activity of MSCs was maintained only after co-transplantation into hippocampal slice cultures. Therefore, in the otherwise astrogenic milieu, MSCs established an oligodendrogenic niche for transplanted NPCs, and thus, co-transplantation of MSCs with NPCs might provide an attractive approach to re-myelinate the various regions of the diseased CNS.

It is commonly accepted that adult neurogenesis and gliogenesis follow the same principles through the mammalian class. However, it has been reported that neurogenesis might differ between species, even from the same order, like in rodents. Currently, it is not known if neural stem/progenitor cells (NSPCs) from various species differ in their cell identity and potential. NSPCs can be expanded ex vivo as neurospheres (NSph), a model widely used to study neurogenesis in vitro. Here we demonstrate that rat (r) and mouse (m) NSph display different cell identities, differentiation fate, electrophysiological function and tumorigenic potential. Adult rNSph consist mainly of oligodendroglial progenitors (OPCs), which after repeated passaging proliferate independent of mitogens, whereas adult mNSph show astroglial precursor-like characteristics and retain their mitogen dependency. Most of the cells in rNSph express OPC markers and spontaneously differentiate into oligodendrocytes after growth factor withdrawal. Electrophysiological analysis confirmed OPC characteristics. mNSph have different electrophysiological properties, they express astrocyte precursor markers and spontaneously differentiate primarily into astrocytes. Furthermore, rNSph have the potential to differentiate into oligodendrocytes and astrocytes, whereas mNSph are restricted to the astrocytic lineage. The phenotypic differences between rNSph and mNSph were not due to a distinct response to species specific derived growth factors and are probably not caused by autocrine mechanisms. Our findings suggest that NSph derived from adult rat and mouse brains display different cell identities. Thus, results urge for caution when data derived from NSph are extrapolated to other species or to the in vivo situation, especially when aimed towards the clinical use of human NSph.

Background:Ozanimod, a sphingosine 1-phosphate receptor 1 and 5 modulator, was approved as a disease-modifying therapy for active relapsing-remitting multiple sclerosis (RRMS) in 2020 and for active ulcerative colitis in 2021. Long-term, real-world studies in a nonselective population are needed. OzEAN is an ongoing study to assess the real-world persistent use, effectiveness, and safety of ozanimod and its impact on quality of life (QoL) in patients with RRMS over a 5-year period.MethodsThis prospective, noninterventional, postmarketing authorization study will enroll ~1,300 patients (≥18 years of age) with active RRMS. The decision to initiate ozanimod must have been made before and independent from study participation. Enrollment began in March 2021. Recruitment is ongoing and will last for 36 months across 140 sites in Germany. Treatment-naive patients or those having prior experience with a disease-modifying therapy receive oral ozanimod 0.92 mg/day after an initial dose escalation, per the summary of product characteristics recommendations, for up to 60 months. Persistence with ozanimod treatment (primary endpoint) is assessed at month 60. Secondary endpoints include additional physician-reported outcomes [persistence at earlier time points, annualized relapse rate, Expanded Disability Status Scale score, cognition (Symbol Digit Modalities Test), and incidence of adverse events], and patient-reported outcomes assessing patient satisfaction, adherence, and treatment modalities (Treatment Satisfaction Questionnaire for Medication, v1.4), disability (United Kingdom Neurological Disability Rating Scale), QoL (MSQOL-54 questionnaire), fatigue (Fatigue Scale for Motor and Cognitive Functions), and health economics [Work Productivity and Activity Impairment Questionnaire for Multiple Sclerosis (German v2.1); Multiple Sclerosis Health Resource Survey, v3.0]. A Multiple Sclerosis Documentation System with an internet-based e-health portal allows patients to view files and complete questionnaires. A safety follow-up will occur 3–8 months after the last ozanimod dose for patients who discontinue treatment early. Long-term results are anticipated after study completion in 2029. Yearly interim analyses are planned after enrollment has reached 25%.ConclusionThis is the first long-term, real-world study of ozanimod in patients with RRMS and, to our knowledge, the first noninterventional study utilizing a patient portal. These data will add to the safety/efficacy profile of ozanimod demonstrated in phase 3 trials.Clinical Trial RegistrationClinicaltrials.gov, identifier: NCT05335031.