Biology subjects

Alonso-Martin, S.

Publications and source records attributed to Alonso-Martin, S..

7 recordsLinked to original sources

bioRxiv2026

Tunable neuronal microenvironments drive distinct functional phenotypes in human iPSCs-derived dopaminergic neurons

Neuronal heterogeneity is a defining feature of complex neural circuits, where local differences in firing patterns, activity levels, and temporal dynamics shape information processing and emergent network activity. In adult neurons, this heterogeneity arises from a variety of known and unknown factors including the extracellular environment. Although neurons have been cultured on three-dimensional substrates, the effect of the microenvironments on their firing activity remains poorly understood. Here, we have synthesized two chitosan hydrogel systems seeded with human iPSCs-derived dopaminergic neurons as tunable platforms to control neuronal microenvironments. Both systems were formulated with the ability to incorporate carbon nanotubes (CNT), thus promoting neural interfacing. Calcium imaging combined with computational single-cell analysis demonstrated that supramolecular organization, hydration state, and general physicochemical properties differentially bias neuronal firing dynamics and synchrony leading to the emergence of distinct activity phenotypes despite identical cellular origin. These activity profiles were clustered through K-means and assigned to specific phenotypes including bursting irregular neurons, regular network contributors, or less active/quiescent neurons. Furthermore, CNTs incorporation enhanced local hydrogel compaction, resulting in unique active neuronal phenotypes, highlighting the potential of CNTs to modulate local cellular microenvironments. These findings establish tunable biomaterials as microenvironment contenders for controlling neuronal network state while giving insights on the interplay of different cues in promoting neuronal heterogeneity and functional phenotype relevant to neurodevelopment, neurodegeneration, and disease modelling.

neuroscience↗

bioRxiv2026

Loss of TDP-43 drives premature aging and impairs skeletal muscle stem cell pool restoration

TAR DNA-binding protein 43 (TDP-43) dysfunction is a hallmark of amyotrophic lateral sclerosis (ALS) and related disorders, yet its role in skeletal muscle stem cells, the satellite cells (SC), remains incompletely understood. Here, we investigated ALS-associated gain- and loss-of-function TDP-43 mutations together with inducible SC-specific TDP-43 deletion. While TDP-43Q331K and heterozygous TDP-43F210I mice displayed normal muscle homeostasis, SC abundance, and regenerative capacity, complete TDP-43 loss caused a marked reduction of the SC pool, particularly in females, and shifted SCs from a CD34high stem-like state toward a CD34low primed population. TDP-43-deficient SCs failed to clonally expand, proliferate, and differentiate, resulting in severe regenerative failure following muscle injury. Notably, the SC pool failed to recover after injury and was nearly depleted 30 days post-injury, accompanied by muscle loss, fibrosis and fat infiltration. Transcriptomic analyses revealed activation of stress and aging-associated programs in uninjured TDP-43-deficient SCs, indicating the premature acquisition of an aging-like state. Consistently, chronological aging further exacerbated SC depletion, establishing TDP-43 as a critical regulator of SC stemness, regeneration, and resistance to age-related decline.

cell biology↗

bioRxiv2026

Muscle spatial lipidomics identifies early ALS signatures in presymptomatic SOD1G93A mice

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease whose diagnosis often remains delayed. Skeletal muscle is increasingly recognized as an early contributor to ALS pathology. Using lipid imaging mass spectrometry (LIMS) in Tibialis anterior muscle from hSOD1G93A mice across disease stages, we identified fiber-type-specific and sex-dependent lipid remodeling. Lipid alterations were detected at the presymptomatic stage, preceding motor neuron loss and clinical symptoms. LIMS distinguished fast-twitch oxidative-glycolytic (type IIA) and glycolytic (type IIB/IIX) fibers and revealed their differential vulnerability to disease. Presymptomatic mutant muscles showed loss of physiological lipid signatures alongside disease-specific lipid changes. Although lipid profiles differed between sexes, ALS-associated alterations enabled accurate discrimination of mutant mice before symptom onset. Importantly, similar disease-related lipid changes were detected in serum, enabling accurate classification of presymptomatic animals. These findings establish lipid remodeling as an early ALS event and highlight novel biomarkers with potential for diagnosis and disease monitoring.

neuroscience↗

bioRxiv2026

Comprehensive characterization of skeletal muscle remodeling in hSOD1G93A mice reveals limited functional impact of systemic FOXO1 inhibition

BackgroundAmyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by progressive motor neuron (MN) loss, muscle atrophy and paralysis. Although traditionally considered a MN-specific disease, accumulating evidence supports a crucial contribution of skeletal muscle pathology to disease onset and progression. Except for specific mutations, to date there is no effective treatment for ALS. FOXO transcription factors regulate programs of atrophy, metabolism and stress response in skeletal muscle, and their inhibition has shown beneficial effects in cellular and Drosophila models of ALS. MethodsIn this study, we investigated whether pharmacological FOXO inhibition (iFOXO) could modify disease progression and muscle pathology in female hSOD1G93A mice. Mice received daily oral administration of iFOXO starting at presymptomatic (P50; n=5 per group) or symptomatic (P90; n=9 mice per group) stages until end-stage. Body weight was monitored longitudinally, and motor performance was evaluated using grip strength and hanging-wire tests. Tibialis anterior and soleus muscles, representing fast- and slow-twitch muscles respectively, were analyzed by histology and immunofluorescence to assess fiber atrophy, fibrosis, lipid accumulation, satellite cell pool and fiber type composition. Quadriceps muscles (n=3 per group) were used for RNA-seq analysis. ResultsWhile histological analyses revealed severe fiber atrophy and increased fibrosis in hSOD1G93A mice, satellite cell numbers were preserved or mildly increased in a muscle and treatment onset dependent manner. iFOXO treatment did not improve motor performance, survival or attenuate muscle atrophy. Transcriptomic profiling indicated that genotype was the predominant driver of gene expression changes, while iFOXO produced only subtle, treatment onset dependent effects on pathways related to oxidative stress responses, mitochondrial function and adaptive metabolism. ConclusionOverall, FOXO inhibition alone showed limited therapeutic benefit in the hSOD1G93A ALS mouse model. These findings highlight the dominant influence of ALS driven molecular alterations over pharmacological modulation and emphasize the need for combinatorial therapeutic strategies targeting multiple disease mechanisms, including those preserving nerve health.

neuroscience↗

bioRxiv2025

A novel approach for reliable differentiation of lymphatic endothelial progenitor cells in vitro

The lymphatic system plays critical roles in fluid homeostasis, immune regulation, and lipid transport, making its dysfunction a contributor to numerous pathological conditions. Lymphatic tissue engineering aims to develop therapeutic strategies for lymphatic regeneration and repair, depending on the availability of suitable cell sources for lymphatic endothelial cell (LEC) generation. Key cell sources explored for lymphatic tissue engineering include the dermis, bone marrow and stromal vascular fraction. To our knowledge, no existing differentiation protocols can accurately generate lymphatic endothelial progenitor cells (LEPCs). This study presents a novel in vitro differentiation protocol for generating LEPCs from stromal vascular fraction, dermis and bone marrow-derived mesenchymal stem cells (MSCs). The feasibility of using them as tissue sources was first evaluated leading to dermal cells exclusion due to low yield post-isolation, and highlighting the limited differentiation efficiency of bone marrow MSCs. However, the stromal vascular fraction emerged as the optimal source, exhibiting robust LEPCs differentiation and superior scalability. In vitro characterization confirmed that LEPCs maintain a lymphatic endothelial phenotype, exhibiting high migratory ability, robust angiogenic structure formation, and consistent expression of key lymphatic markers in both 2D and 3D cultures, as validated by RNA-Seq analysis. The protocol provides a consistent platform for studying lymphatic endothelial biology and potential applications in regenerative medicine and therapeutic angiogenesis.

bioengineering↗

bioRxiv2025

Unveiling the neuro-vascular interplay in the skeletal muscle in health, injury and disease

Neuromuscular junctions (NMJs) are complex multicellular structures that convey motor neuron-induced responses in the skeletal muscle. Their cellular composition is well characterized, but interactions between the different cell types and with the surrounding microenvironment remain underexplored. Here, by using a panel of newly discovered mouse cell lineage markers, single-cell RNA sequencing analyses and iDisco tissue clarification, we demonstrate the existence of contacts between adjacent NMJs through their kranocytes, assembling kranocyte network-like structures within the muscle interstitium, which is essential for regulating blood flow and supporting muscle regeneration. Indeed, kranocytes do contact with the surrounding microvasculature as well, both of them uncovering a previously unexplored, expansive interactive system. Moreover, unlike the robustness shown by their counterparts, the terminal Schwann cells, we strikingly observed that kranocytes rapidly detected stressful conditions, leading to structural changes and even the loss of their connections in response to acute damage, such as muscle injury or neuromuscular disease-induced denervation. Therefore, we propose kranocytes as the interactive sensory platforms of the NMJs, working in a perpendicular axis of nerve-transmission, as key NMJ-connectors by, interconnecting adjacent NMJs and interacting with the microvasculature and the microenvironment, and also as NMJ-sensors by detecting microenvironmental inputs. Together, our data postulate kranocytes as triple connectors of the nervous, musculoskeletal and vascular systems.

neuroscience↗

bioRxiv2024

Energy scarcity and impaired mitochondrial translation induce perinuclear stress granule clustering

Many proteins linked to amyotrophic lateral sclerosis and fronto-temporal dementia (ALS-FTD) change their cellular location and coalesce in cytoplasmic inclusion bodies in the disease state; yet the factors that govern protein relocation and organization remain unclear. Here, we show that inhibition of glycolysis and mitochondrial protein synthesis causes many proteins involved in ALS-FTD to change location, and form a novel structure comprising a ring of stress granules encircling the aggresome, a focal microtubule-based structure beside the nucleus. A perinuclear ring of stress granules also forms in activated microglia of mice exposed to the glycolytic inhibitor, 2-Deoxy-D-glucose. We propose that the new arrangement increases the risk of the stress granules merging and converting from the liquid phase to the insoluble inclusion characteristic of ALS-FTD. Thus, our findings suggest that that compromised nutrient and energy metabolism can precipitate a molecular cascade that ultimately leads to the pathological hallmark of ALS-FTD the perinuclear inclusion body. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=127 SRC="FIGDIR/small/578399v1_ufig1.gif" ALT="Figure 1"> View larger version (25K): org.highwire.dtl.DTLVardef@b32d48org.highwire.dtl.DTLVardef@161f848org.highwire.dtl.DTLVardef@f35c66org.highwire.dtl.DTLVardef@1375508_HPS_FORMAT_FIGEXP M_FIG C_FIG Inhibition of glycolysis and mitochondrial protein synthesis induces translocation of a swathe of ALS-FTD related proteins in primary human fibroblasts. The relocated proteins form concentric cytoplasmic rings (CCR) comprising stress granules, the Golgi and the aggresome, beside the nucleus. A perinuclear ring of stress granules forms in the mouse brain following intermittent nutrient restriction, with the glucose analog 2DG. The CCR is potentially a key intermediate step in the formation of pathological inclusions and so perturbed nutrient and energy metabolism encompassing impaired mitochondrial translation could precipitate the ALS-FTD disease cascade.

cell biology↗