Biology subjects

Diprima, S.

Publications and source records attributed to Diprima, S..

3 recordsLinked to original sources

bioRxiv2026

A bioprinted silk marrow niche reveals mechanical regulation of human megakaryopoiesis under genotoxic stress

Hematopoietic stem and progenitor cells (HSPCs) reside in a mechanically distinct bone marrow niche, yet how niche biomechanics shape genome stability and stress responses has been difficult to test because conventional two-dimensional (2D) culture lacks marrow viscoelasticity and uses surfaces that activate platelets, confounding hematopoietic readouts. Here, we show that this methodological gap has masked a basic principle: the marrow niche actively constrains genotoxic stress signaling in HSPCs, and 2D culture systematically overstates DNA damage and impairs differentiation in vitro. We engineered silk fibroin, a biologically inert biomaterial that does not activate platelets and recapitulates marrow viscoelasticity, into SilkInk, a 3D-bioprintable bioink, and used it to reconstruct a biomimetic marrow microenvironment. HSPCs encapsulated in SilkInk preserved clonogenic potential and multilineage differentiation, whereas 2D-cultured HSPCs activated cytoskeletal-tension and genome-surveillance programs characteristic of chronic stress, including pathways related to replication stress, DNA damage response, and redox stress. Cell phenotyping and single-cell RNA sequencing during megakaryopoiesis revealed that SilkInk supported coordinated endomitotic progression and terminal maturation, with progression from CD34+CD61-CD41-CD42b- progenitors to CD34-CD61+CD41+CD42b+ megakaryocytes, including increased 8N and >16N populations, whereas 2D culture and conventional 3D hydrogels sustained DNA damage signaling and impaired thrombopoiesis. The same hierarchy held under cytotoxic challenge, as 5-fluorouracil amplified DNA damage and crippled platelet output in 2D, whereas SilkInk-encapsulated HSPCs maintained differentiation, mirroring native marrow resilience. These findings reposition niche mechanics as an active determinant of hematopoietic genome stability and establish SilkInk as a physiologically faithful platform for studying hematopoiesis and predicting marrow responses to chemotherapy.

Cell Biology↗

bioRxiv2025

Early endothelial activation at the blood-nerve barrier defines a hallmark of ALS

Vascular defects are common in Amyotrophic Lateral Sclerosis (ALS). The prevailing view is that breakdown of the blood-brain and blood-spinal cord barriers contributes to neurodegeneration. Here, we reveal that selective and early vulnerability of peripheral nerve endothelium --manifested as endothelial cell activation and interlinked blood-nerve barrier dysfunction-- constitutes a core feature of ALS pathogenesis, arising before vascular alterations in the central nervous system (CNS) and motor neuron pathology. Vascular changes in ALS patients have been largely studied in postmortem samples, limiting insight into their onset, causes, and pathogenic role. Surveying diagnostic motor nerve samples from ALS patients across clinical stages, we observed endothelial damage that preceded axonal loss and demyelination, marking vascular dysfunction as an early disease event. Similar ultrastructural abnormalities were detected in pre-symptomatic ALS mouse models (SOD1 and TARDBP mutants). Notably, endothelial cells became dysfunctional even when not carrying mutant TDP-43, indicating they respond to non-cell autonomous disease signals. Transcriptional, histological, and functional analyses revealed that these alterations were largely confined to peripheral nerves, while spinal cord vessels exhibited delayed and more focal changes. Single-cell sequencing identified ALS-susceptible endothelial cell subsets prone to a pro-inflammatory phenotype and impaired blood-nerve barrier function, increasing permeability via the transcellular route. These changes coincided with reactivity of nerve-resident macrophages and neutrophil infiltration. Neutrophil depletion attenuated endothelial activation and barrier leakiness, mitigating axonopathy in ALS mice. Our work unmasks the greater susceptibility of the peripheral nerve vasculature in ALS relative to the CNS. The early activation of peripheral nerve endothelium, combined with its potential reversibility, identifies a therapeutic window and suggests strategies for targeting the vascular-immune axis to protect the motor system.

neuroscience↗

bioRxiv2025

A neurovascular template guides the spatial and functional compartmentalization of the adrenal gland

The vasculature adapts to tissue demands, but whether it can instruct spatial tissue organization remains unclear. In the developing adrenal gland, we uncover a neurovascular mechanism that actively establishes and preserves compartment boundaries between cortex and medulla. Peripheral nerves secrete Semaphorin3C, signaling through PlexinD1 on endothelial cells to locally antagonize VEGF-driven angiogenesis from cortical cells, sculpting distinct vascular domains that guide hormone-producing cells to their correct territories. Disruption of this balance --via denervation or loss of Semaphorin3C-PlexinD1 signaling-- leads to ectopic vascularization of the medulla, which adopts a cortex-like vascular network. This vascular remodeling enables cortical cells invasion of medullary territories, blurring compartment boundaries and triggering a phagocytic macrophage response that reflects pathological hijacking of a postnatal morphogenesis program. Our findings reveal that region-specific vascular scaffolds, shaped by neurovascular cues, serve as instructive templates for organ architecture. Failure of neurovascular signaling can thus trigger a cascade of structural collapse that undermines tissue integrity and homeostasis, driving pathological remodeling.

developmental biology↗