Biology subjects

Giacomoni, J.

Publications and source records attributed to Giacomoni, J..

3 recordsLinked to original sources

bioRxiv2026

Transient matrix remodeling during direct cell-fate reprogramming enables self-assembly of dense neuronal niches

Native tissues are characterized by high cellular density and continuous reciprocal interactions between cells and the extracellular matrix (ECM), yet recreating these features in vitro remains a major challenge. Current three-dimensional (3D) culture systems typically capture either dense cell-cell interactions or a defined ECM environment, but rarely both. Here, we introduce a strategy that exploits direct fibroblast-to-neuron reprogramming to decouple microenvironment formation from final cell identity. Human dermal fibroblasts were embedded in collagen microgels, where their intrinsic matrix-remodeling capacity drove rapid ECM compaction. Concurrently, the contractile fibroblasts were converted into induced neurons (iN), generating densely packed neuronal microcultures within a remodeled collagen matrix. This approach transforms a defining function of the starting cell type into a mechanism for engineering the microenvironment of the target cell type. The resulting iN-microgels combine high cell density, defined ECM composition, and tunable biophysical properties in a scalable microscale format. By coupling matrix remodeling with cell-fate conversion, our platform establishes a general framework for engineering tissue-like microenvironments and reveals how dynamic 3D extracellular contexts can be integrated into direct cell reprogramming.

bioengineering↗

bioRxiv2025

Long-lasting structural and functional maturation in transplanted human neurons reprogrammed from glial progenitor cells

Direct reprogramming of brain-resident glial progenitor cells (GPCs) into induced neurons (iN) shows great promise for future regenerative therapies for brain diseases. This type of cell conversion is facilitated by introducing lineage-specific transcription factors or small molecules to somatic cells, and can even be achieve in vivo, targeting resident glia cells in the brain for in vivo conversion. While this have shown promising results in animal models, a crucial step is to show the long-term survival and maturation of human reprogrammed cells in vivo. However, this remains largely unexplored partly due to the inaccessible cell source of GPC and difficulty in transplanting converted neurons. In this study, we assessed human GPCs derived iNs for their long-term structural and functional neuronal maturation after transplantation to the immunodeficient mouse brain. GPCs were transduced with established transcription factor cocktail and transplanted to the medial prefrontal cortex as three-dimensional cultures to improve survival and integration upon transplantation. Our results reveal survival of hiNs, for up to 10 months post-transplantation (MPT) and wide distribution across local and proximal functionally connected brain regions. Morphological analysis revealed a gradual neuronal maturation over time, characterized by increase in cellular complexity and expression of neuronal markers. Supporting these findings, electrophysiological recordings demonstrated progressive functional maturation up to 5 MPT with increase in sodium and potassium currents, and the ability to generate multiple evoked and spontaneous action potentials, validating a neuronal phenotype. Importantly, these changes were absent in control grafts of non-converted hGPCs that retained their glia identity. Our findings indicate that hGPCs derived iNs maintain a stable neuronal phenotype that persist in the mouse brain for extended periods. These cells exhibit survival and remarkable adaptability to the host environment, enabling both structural and functional maturation over time. These results highlight their potential as a promising strategy for neural replacement therapies aimed at restoring damaged circuits and promoting brain repair. Highlights* Human neurons reprogrammed from glia progenitor cells survive long term upon transplantation in the immunodeficient mouse brain. * The human induced neurons migrate to local and distal connected brain regions within prefrontal cortex circuitry. * Grafted neurons gradually develop neuronal complex morphology and electrophysiological functional properties in the mouse brain.

neuroscience↗

bioRxiv2024

Generating human parvalbumin interneurons through 3D glia reprogramming

Parvalbumin (PV) interneurons are crucial for synaptic plasticity, and their damage or loss is linked to various neurological disorders. Yet, generating these cells of human source in vitro is challenging, limiting advancements in cell repair and disease modelling. We introduce a novel approach to derive human PV neurons through direct reprogramming of glial precursor cells (GPCs). Using ectopic expression of GABAergic neuronal genes, GPCs efficiently convert into GABAergic interneurons in 3D culture environment within weeks and achieve functional neuronal maturity. Single-nuclei RNA sequencing identified a distinct PV neuronal cluster with high maturity and characteristics of PV chandelier subclass that are equivalent to bona fide human interneurons. Trajectory analysis revealed a distinct glia-to-PV interneuron conversion pathway, involving several new transitory genes, with potential for functional importance for PV derivation. Our data introduces a new strategy for generating human PV interneurons, promising significant implications for future generation of patient-specific PV neurons both in vitro and in vivo. HighlightsO_LIA novel approach to derive human PV interneurons by direct glia reprogramming. C_LIO_LIFirst comprehensive transcriptomic profiling of induced human PV interneurons. C_LIO_LIInduced PV interneurons are of chandelier subtype with transcriptional similarity to bona fide interneurons. C_LIO_LISuccessful glia-to-PV interneuron conversion passes through a specific reprogramming trajectory and involves key genes with functional potential. C_LI

neuroscience↗