Biology subjects

Skottman, H.

Publications and source records attributed to Skottman, H..

6 recordsLinked to original sources

bioRxiv2026

Mapping heterogeneity drivers in human PSC-derived limbal stem cell differentiation through single-cell multi-modal analysis

Understanding the molecular underpinnings of stem cell differentiation is pivotal for generating appropriate cell types in cell-based therapies. Differentiation of human pluripotent stem cells (PSC) into corneal limbal stem cells offers a promising avenue to regenerate the corneal epithelium. However, current differentiation strategies remain inconsistent in efficiency and yield heterogeneous cell populations that incompletely recapitulate the regenerative properties of donor-derived limbal stem cells. Here, we mapped the molecular landscape of cell states throughout the differentiation process. First, we construct PSC differentiation paths from single-cell RNA sequencing (scRNA-seq) data using the computational framework of optimal transport, identifying on- and off-track cell states toward the limbal stem cell state. Single cell Assay for Transposase-Accessible Chromatin sequencing (scATAC-seq) was performed to profile accessible genomic regions, and subsequently integrated with scRNA-seq data through gene regulatory network analysis to identify key drivers governing the diverse cell states. We showed that genomic enhancers play a major role in cell state determinations. Through this single-cell multi-modal approach, we identified potential transcription factors driving limbal epithelial lineage specification and off-track cell populations. Our findings provide a framework for rational optimization of PSC-derived limbal stem cell generation to advance the development of corneal cell therapies.

molecular biology↗

bioRxiv2026

3D-Printable and Cytocompatible Hydrogel from Acinetobacter baylyi ADP1 Extracellular Matrix

Tissue engineering has advanced significantly, yet multicomponent hydrogels inspired by the compositional complexity of natural extracellular matrices (ECMs) are still underexplored. Most current hydrogels are based on single-component formulations, which can limit their biochemical and mechanical versatility. Developing synthetic multicomponent hydrogels remains challenging because it requires the controlled integration of multiple functional groups within a single material platform. Here, a biologically driven strategy is introduced by leveraging Acinetobacter baylyi ADP1, a bacterium that naturally produces extracellular polymeric substances (EPS) composed of a multicomponent matrix of polysaccharides and proteins. Through three-day cultivation and a simple extraction method, a hydrogel is obtained that can be methacrylated and photocrosslinked using red or blue light. This hydrogel is porous, cytocompatible, 3D-bioprintable, injectable, and undergoes rapid gelation for in situ crosslinking. This work highlights the potential of using bacterial-derived multicomponent hydrogels for biofabrication.

bioengineering↗

bioRxiv2025

Biomimetic hydrogel platform reveals active force transduction from retinal pigment epithelium to photoreceptors

In the eye, the retinal pigment epithelium (RPE) maintains the functionality and welfare of retinal photoreceptors and forms a tight, interlocked structure with photoreceptor outer segments (POSs). The RPE-retina interaction is difficult to recapitulate in vitro, limiting the studies addressing the retinal maintenance functions of the RPE. To overcome this challenge, we constructed a retina-mimicking structure using a soft polyacrylamide hydrogel coated with Matrigel. This structure was introduced to RPE cells apical side to model the RPE-retina interface in vitro. As a result, RPE cells attached to the hydrogels during culture, enabling further studies of cell adhesion and force transduction between the RPE-hydrogel with rheology and traction force microscopy. These methods were applied to a critical interactive process between the retina and the RPE: phagocytosis of the aged tips of POSs enabling their renewal. During phagocytosis, RPE cells imposed considerable traction forces to the POS particles. The force generation was actin-dependent, and the forces were significantly reduced by the disruption of RPEs actin cytoskeleton. These results add another layer to the diverse interaction mechanisms between the RPE and the neural retina and pave the way for further studies of the RPE-retina interplay.

biophysics↗

bioRxiv2024

Microglia from patients with multiple sclerosis display a cell-autonomous immune activation state

Aberrant and sustained activation of microglia is implicated in the progression and severity of multiple sclerosis (MS). However, whether intrinsic alterations in microglial function impact the pathogenesis of this disease remains unclear. We conducted transcriptomic and functional analyses of microglia-like cells (iMGLs) differentiated from induced pluripotent stem cells (iPSCs) from patients with MS (pwMS) to answer this question. We generated iPSCs from six pwMS showing increased microglial activity via translocator protein (TSPO)-PET imaging. We demonstrated that the differentiated iMGL transcriptional profile resembled the microglial signature found in MS lesions. Importantly, compared with healthy controls, MS iMGLs presented cell-autonomous differences in their regulation of inflammation, both in the basal state and following inflammatory lipopolysaccharide challenge. Through transcriptomic profiling, we showed that MS iMGLs display increased expression of genes known to be upregulated in MS microglia. Furthermore, upregulated genes in MS iMGLs were associated with immune receptor activation, antigen presentation, and the complement system, with known MS implications. Finally, functional analyses indicated that the transcriptional changes in MS iMGLs corresponded with alterations in the secretion of inflammatory cytokines and chemokines and increased phagocytosis. Together, our results provide evidence of putative cell-autonomous microglial activation in pwMS and identify transcriptomic and functional changes that recapitulate the phenotypes observed in vivo in microglia from pwMS. These findings indicate that MS disease-specific iPSCs are valuable tools for studying disease-specific microglial activation in vitro and highlight microglia as potential therapeutic targets in MS.

neuroscience↗

bioRxiv2023

Deciphering the heterogeneity of differentiating hPSC-derived corneal limbal stem cells through single-cell RNA-sequencing

A comprehensive understanding of the human pluripotent stem cell (hPSC) differentiation process stands as a prerequisite for the development hPSC-based therapeutics. In this study, single-cell RNA-sequencing (scRNA-seq) was performed to decipher the heterogeneity during differentiation of three hPSC lines towards corneal limbal stem cells (LSCs). The scRNA-seq data revealed nine clusters encompassing the entire differentiation process, among which five followed the anticipated differentiation path of LSCs. The remaining four clusters were previously undescribed cell states that were annotated as either mesodermal-like or undifferentiated subpopulations, and their prevalence was hPSC line-dependent. Distinct cluster-specific marker genes identified in this study were confirmed by immunofluorescence analysis and employed to purify hPSC-derived LSCs, which effectively minimized the variation in the line-dependent differentiation efficiency. In summary, scRNA-seq offered molecular insights into the heterogeneity of hPSC-LSC differentiation, allowing a data-driven strategy for consistent and robust generation of LSCs, essential for future advancement toward clinical translation. HighlightsO_LIhPSCs to LSCs spans epithelial, mesodermal, and undifferentiated cell states. C_LIO_LIscRNA-seq reveals the cell line-dependent differentiation heterogeneity. C_LIO_LIITGA6 and AREG can be used to select pure LSC-like subpopulation. C_LI

cell biology↗

bioRxiv2017

Fast voltage sensitivity in retinal pigment epithelium: sodium channels and their novel role in phagocytosis

Despite the discoveries of voltage-gated sodium channels (Nav) from a number of non-excitable cell types, the presence of Nav-mediated currents in cells of the retinal pigment epithelium (RPE) has been dismissed as a cell culture artifact. Here, we challenge this notion by demonstrating functional Nav1.4-Nav1.6 and Nav1.8 channels in human embryonic stem cell derived and mouse RPE. Importantly, we show that Navs are involved in photoreceptor outer segment phagocytosis: blocking their activity significantly reduces the efficiency of this process. Consistent with this role, Nav1.8 co-localizes with the endosomal marker Rab7 and, during phagocytosis, with opsin. Nav1.4 localizes strongly to the cell-cell junctions together with the gap junction protein Connexin 43. During phagocytosis, both are localized to the phagosomes with a concurrent decrease in the junctional localization. Our study demonstrates that Navs give the capacity of fast electrical signaling to RPE and that Navs play a novel role in photoreceptor outer segment phagocytosis.

physiology↗