Extracellular vesicles (EVs) are membrane-enclosed bio-nanoparticles secreted by cells and naturally evolved to transport various bioactive molecules between cells and even organisms. These cellular objects are considered one of the most promising bio-nanovehicles for the delivery of native and exogenous molecular cargo. However, many challenges with state-of-the-art EV-based candidates as drug carriers still exist, including issues with scalability, batch-to-batch reproducibility, and cost-sustainability of the final therapeutic formulation. Microalgal extracellular vesicles, which we named nanoalgosomes, are naturally released by various microalgal species. Here, we evaluate the innate biological properties of nanoalgosomes derived from cultures of the marine microalgae Tetraselmis chuii, using an optimized manufacturing protocol. Our investigation of nanoalgosome biocompatibility in preclinical models includes toxicological analyses, using the invertebrate model organism Caenorhabditis elegans, hematological and immunological evaluations ex vivo and in mice. We evaluate nanoalgosome cellular uptake mechanisms in C. elegans at cellular and subcellular levels, and study their biodistribution in mice with accurate space-time resolution. Further examination highlights the antioxidant and anti-inflammatory bioactivities of nanoalgosomes. This holistic approach to nanoalgosome functional characterization demonstrates that they are biocompatible and innate bioactive effectors with unique bone tropism. These findings suggest that nanoalgosomes have significant potential for future therapeutic applications.

Spinal muscular atrophy (SMA) is a motoneuron disease caused by deletions of the Survival of Motoneuron 1 gene (SMN1) and low SMN protein levels. SMN restoration is the concept behind a number of recently approved drugs which result in impressive yet limited effects. Since SMN has already been enhanced in treated patients, complementary SMN-independent approaches are needed. Previously, a number of altered signaling pathways which regulate motoneuron degeneration have been identified as candidate targets. However, signaling pathways form networks, and their connectivity is still unknown in SMA. Here, we used presymptomatic SMA mice to elucidate the network of altered signaling in SMA. The SMA network is structured in two clusters with AKT and 14-3-3 ζ/δ in their centers. Both clusters are connected by B-Raf as a major signaling hub. The direct interaction of B-Raf with 14-3-3 ζ/δ is important for an efficient neurotrophic activation of the MEK/ERK pathway and crucial for motoneuron survival. Further analyses in SMA mice revealed that both proteins were down-regulated in motoneurons and the spinal cord with B-Raf being reduced at presymptomatic stages. Primary fibroblasts and iPSC-derived motoneurons from SMA patients both showed the same pattern of down-regulation. This mechanism is conserved across species since a Caenorhabditis elegans SMA model showed less expression of the B-Raf homolog lin-45. Accordingly, motoneuron survival was rescued by a cell autonomous lin-45 expression in a C. elegans SMA model resulting in improved motor functions. This rescue was effective even after the onset of motoneuron degeneration and mediated by the MEK/ERK pathway. Significance The mechanisms of neurodegeneration are important targets for future treatments of the devastating motoneuron disease spinal muscular atrophy (SMA). Here, we show an altered signaling network in SMA models and patient cells with a reduced B-Raf expression in the network center. B-Raf is crucial for motoneuron survival, and we present data that B-Raf restoration ameliorates motoneuron loss and symptoms in SMA models.

Monogenic diseases are well-suited paradigms for the causal analysis of disease-driving molecular patterns. Spinal Muscular Atrophy (SMA) is one such monogenic model caused by mutation or deletion of the Survival of motor neuron 1 (SMN1) gene. Although several functions of the SMN protein have been studied, single functions and pathways alone do not allow to identify critical disease-driving molecules. Here, we analyzed the systemic characteristics of SMA employing proteomics, phosphoproteomics, translatomics and interactomics from two mouse models with different disease-severities and genetics. This systems approach revealed sub-networks and proteins characterizing commonalities and differences of both models. To link the identified molecular networks with the disease-causing SMN protein, we combined SMN-interactome data with both proteomes creating a comprehensive representation of SMA. By this approach, disease hubs and bottlenecks between SMN and downstream pathways could be identified. Linking a disease-causing molecule with widespread molecular dysregulations via multiomics is a concept for analyses of monogenic diseases.

Purpose: Dimethyl fumarate (DMF), the first-line oral therapy for relapsing-remitting multiple sclerosis, is rapidly metabolized into monomethyl fumarate. The DMF oral administration provokes gastrointestinal discomfort causing treatment withdrawal. The present study aimed to develop an innovative formulation for DMF nasal administration. Lipid-polymer hybrid nanoparticles (LPNs) were developed to improve DMF stability, limiting gastrointestinal side effects and increasing brain bioavailability by nose-to-brain targeting application. Methods: DMF-loaded and unloaded LPNs with or without hyaluronic acid (HA) were prepared using the nanoprecipitation via magnetic/mechanical stirring technique. Particle morphology and surface properties were evaluated; drug content, viscosity, and mucoadhesion were determined. Physico-chemical stability of LPNs and DMF in the LPNs was also explored. In vitro DMF permeation experiments were performed utilizing the PermeaPad^®. The cytotoxicity and cellular uptake studies were performed using RPMI 2650 and SK-N-BE2 cell lines. DMF nose-to–brain delivery was evaluated by intranasally administering DMF-loaded LPNs to rats. Results: LPNs with average sizes of 120– 250 nm and a negative zeta potential − 17.3 to − 43 mV were obtained, primarily influenced by the presence of HA. HA assured drug stability up to 60 days and promoting the in vitro permeation of DMF compared to the free-DMF. HA greatly improved the viscosity and mucoadhesive properties. LPNs with and without HA did not exhibit any cytotoxicity and showed a rapid cell uptake starting from 15 min to 2 h with a best internalization after 1 h of treatment in both epithelial and neuronal cell lines. Nasal administration of DMF-loaded LPNs allowed to quantify up to about 12 μg/mL of DMF in the rat cerebrospinal fluid. Conclusion: The results highlight the role of HA in improving LPNs properties and performance as carrier of DMF for nasal administration. In particular, LPNs appear able to enter neurons and monolayers of epithelial cells, allowing to promote the nose-to-brain DMF delivery.

Trimethylguanosine synthase 1 (TGS1) is a highly conserved enzyme that converts the 5′-monomethylguanosine cap of small nuclear RNAs (snRNAs) to a trimethylguanosine cap. Here, we show that loss of TGS1 in Caenorhabditis elegans, Drosophila melanogaster and Danio rerio results in neurological phenotypes similar to those caused by survival motor neuron (SMN) deficiency. Importantly, expression of human TGS1 ameliorates the SMN-dependent neurological phenotypes in both flies and worms, revealing that TGS1 can partly counteract the effects of SMN deficiency. TGS1 loss in HeLa cells leads to the accumulation of immature U2 and U4atac snRNAs with long 3′ tails that are often uridylated. snRNAs with defective 3′ terminations also accumulate in Drosophila Tgs1 mutants. Consistent with defective snRNA maturation, TGS1 and SMN mutant cells also exhibit partially overlapping transcriptome alterations that include aberrantly spliced and readthrough transcripts. Together, these results identify a neuroprotective function for TGS1 and reinforce the view that defective snRNA maturation affects neuronal viability and function.