Biology subjects

Sohn, S.

Publications and source records attributed to Sohn, S..

9 recordsLinked to original sources

bioRxiv2026

Biodegradable Architected Stents for Endoscopic Internal Drainage

Postoperative gastric leak after bariatric surgery is a serious complication associated with prolonged treatment, repeated interventions, and substantial morbidity. Endoscopic internal drainage using double pigtail stents is widely adopted. However, current stents, originally designed for biliary use and often based on simple cylindrical geometries, are not optimized for post-bariatric gastric leak anatomy, mechanical support, or fluid drainage. Here, we present BRIDGE (Biodegradable aRchitected Internal DrainaGE), a stent concept integrating triply periodic minimal surface (TPMS) architectures to control mechanical compliance, kink resistance, and drainage performance. Using computational modeling, mechanical testing, and benchtop flow studies, we evaluate TPMS designs and identify volume fraction as a key parameter balancing flexibility, structural integrity, and hydraulic performance. TPMS-integrated designs tolerated a 7.1-fold smaller bend radius than a commercial stent without kinking and achieved up to a 2-fold increase in drainage. We also developed a stereolithography-printable biodegradable resin and fabricated a prototype lattice-integrated stent. TeaserA biodegradable, 3D-printed stent with an architected lattice design improves flexibility, kink resistance, and abscess drainage while eliminating the need for device removal.

bioengineering↗

bioRxiv2025

Cell Barcoding Reveals Lineage-dependent Outcomes in hiPSC Cardiac Differentiation

Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) have potential applications in treating cardiovascular disease but are currently limited in their clinical translation. A primary limitation is the poor clinical scalability of hiPSC-CMs, with the heterogeneity of hiPSC cardiac differentiation significantly contributing to this limitation. We hypothesize that clinical scalability can be improved by tracking and controlling hiPSC clonal heterogeneity, a variable often overlooked in current differentiation approaches. "Fate priming", wherein clonal lineage identity determines differentiation fate, has been demonstrated in other stem cell differentiation pathways. We investigated fate priming in hiPSC cardiac differentiation using the ClonMapper cell barcoding platform to label, track, and isolate distinct hiPSC lineages from the same cell line. We show that certain hiPSC lineages preferentially differentiate into hiPSC-CMs or non-CMs. After isolating lineages with apparent fate priming, we found significant differences in cardiac differentiation outcomes between these single-clone populations and heterogeneous, multi-clone hiPSC populations. These findings indicate that lineage identity influences hiPSC cardiac differentiation outcomes. SIGNIFICANCE STATEMENTCardiovascular disease is a significant global health concern that can be addressed by engineering artificial tissues to develop new treatments for heart disease or to directly replace damaged heart tissue. Stem cells are a useful tool for engineering these tissues because of their ability to become cardiomyocytes. However, their clinical translation is limited by variability in the process of differentiating stem cells into cardiomyocytes. This article reports findings that show different lineages of genetically identical human induced pluripotent stem cells have different capacities for differentiating into cardiomyocytes, which may contribute to the variability observed.

bioengineering↗

bioRxiv2025

Modulating Hydrogel Stiffness Through Light-Based 3D Printing to Mimic Cardiac Fibrosis and Cardiomyocyte Dysfunction Using hiPSC-Derived Cells

The human hearts limited regenerative capacity is a significant barrier to addressing cardiovascular disease (CVD). This is particularly true for cardiac fibrosis, a form of CVD wherein the wound healing process has gone awry. In cardiac fibrosis, excessive scar tissue formation due to dysregulated remodeling of the hearts extracellular matrix (ECM) results in increased stiffness that reduces cardiac output and can lead to heart failure. This dysregulated ECM deposition is driven by activated cardiac fibroblasts, where cell substrate stiffness is known to play a role in cardiac fibroblast activation. New preclinical models that accurately recapitulate the behavior of activated cardiac fibroblasts are needed to better understand and treat cardiac fibrosis. To this end, we describe a model wherein human induced pluripotent stem cell (hiPSC)-derived cardiac fibroblasts (HCFs) are cultured on 3D printed hydrogels of tunable stiffness, fabricated using dosage controlled digital light processing (DLP). We demonstrate that our model can induce HCF activation in the absence of TGF{beta}, a key mediator of fibroblast activation, surpassing the activation levels seen with HCFs activated with TGF{beta} on protein-coated tissue culture plates. Furthermore, combining stiffer hydrogels with TGF{beta} recapitulates fibroblast activation similar to what is observed in native cardiac tissue. Lastly, by indirectly coculturing HCFs seeded and activated on these stiff hydrogels with hiPSC-derived cardiomyocytes, we demonstrate that the activated HCFs in our cardiac fibrosis model can impair cardiomyocyte function, mimicking the deleterious effects of cardiac fibrosis.

bioengineering↗

bioRxiv2025

Crosslinker-free in situ hydrogel induces self-aggregation of human dental pulp stem cells with enhanced antibacterial activity

Recently, injectable hydrogels have garnered significant attention in tissue engineering due to their controlled flowability, strong plasticity, adaptability, and good biocompatibility. However, research on readily injectable in situ-forming hydrogels capable of forming functional three-dimensional (3D) tissue condensations remains limited. This study explores the development and evaluation of a carboxymethyl chitosan (CMCTS) / oxidized hyaluronic acid (oHA) hydrogel incorporated with silver sulfadiazine (AgSD) for tissue engineering applications with inherent antibacterial activity. Through physicochemical analysis, the optimal formulation of CMCTS/oHA hydrogels was established. The hydrogel demonstrated excellent injectability, enabling minimally invasive in situ delivery. In vitro cytotoxicity assays identified 0.1% AgSD as the optimal concentration, supporting cell proliferation while exhibiting antimicrobial efficacy against S. mutans and E. faecalis. In vivo studies revealed complete hydrogel degradation and good biocompatibility, with no adverse tissue reactions. The hydrogels ability to form 3D cell aggregates and support tissue regeneration underscores its potential for future 3D tissue engineering applications. Consequently, the injectable CMCTS/oHA/AgSD hydrogel developed in this study holds significant potential for application in a wide range of bioengineering fields, including antibacterial substance delivery systems and 3D tissue engineering, indicating potential for future clinical application.

bioengineering↗

bioRxiv2024

Dynamic Electrical Stimulation Promotes hiPSC-CM Differentiation and Functionality

Human induced pluripotent stem cell differentiated cardiomyocytes (hiPSC-CMs) hold great potential to resolve cardiovascular disease but are stymied by their functional immaturity. The complex electric potentials measured during cardiogenesis point to the potential of exogenous electrical stimulation in improving cardiac differentiation and functionality. Herein, we create, validate, and implement a low-cost electrical stimulation device to stimulate hiPSCs during cardiac differentiation. Notably, our open-source device enables the generation of complex electrical stimulation regimes that may vary in frequency and pulse duration over time. Our results demonstrate that dynamic stimulation during differentiation improves cardiac differentiation efficiency, calcium handling, and flow velocity, and promotes significant transcriptomic pathway enrichment compared to static stimulation or no stimulation controls. Moreover, dynamic stimulation enhances electrochemical coupling and promotes the expression of cardiogenic pathways, potentially via sarcomere development. We anticipate that more complex dynamic electrical stimulation regimens may be generated to further optimize hiPSC-CM functionality and maturity.

bioengineering↗

bioRxiv2022

Development and evaluation of a formulation of probiont Phaeobacter inhibens S4 for themanagement of vibriosis in bivalve hatcheries

Larval eastern oysters (Crassostrea virginica) grown in shellfish hatcheries are susceptible to bacterial diseases, particularly vibriosis. Probiotics are microbes that confer health benefits to the host and have been identified as promising tools to manage diseases in aquaculture. The marine bacterium Phaeobacter inhibens S4 (S4) protects larval eastern oysters against challenge with the bacterial pathogen Vibrio coralliilyticus RE22 (RE22). A concentrated liquid formulation of probiont S4 that maintained high cell viability after long-term storage was developed for commercial use in shellfish hatcheries. The safety and efficacy of the formulation was tested in six different trials in two hatcheries. The S4 formulation was added to C. virginica larvae culture tanks daily at 104 colony forming units (CFU)/mL from day 1 post fertilization until day 6, 12, or 14, depending on the trial. Treatment of larvae in the hatchery with the S4 formulation did not significantly affect the survival and growth of the larvae. Formulated probiont S4 treatment in the hatchery led to a significant increase in Relative Percent Survival (RPS) when larvae were subsequently challenged with the pathogen RE22 (105 CFU/mL) for 24 hours in a laboratory challenge, as compared to probiotic-untreated RE22-challenged larvae (Relative Percent Survival increase of 46 - 74%, p < 0.05). These results suggest that this novel S4 formulation is a safe, easy to use, and effective tool in preventing larval losses due to vibriosis in hatcheries.

microbiology↗

bioRxiv2022

Engineering Alignment has Mixed Effects on hiPSC-CM Maturation

The potential of human induced pluripotent stem cell differentiated cardiomyocytes (hiPSC-CMs) is greatly limited by their functional immaturity. Strong relationships exist between CM structure and function, leading many in the field to seek ways to mature hiPSC-CMs by culturing on biomimetic substrates, specifically those that promote alignment. However, these in vitro models have so far failed to replicate the alignment that occurs during cardiac differentiation. We show that engineered alignment, incorporated before and during cardiac differentiation, affects hiPSC-CM electrochemical coupling and mitochondrial morphology. We successfully engineer alignment in differentiating hiPSCs as early as Day 4. We uniquely apply optical redox imaging to monitor the metabolic changes occurring during cardiac differentiation. We couple this modality with cardiac-specific markers, which allows us to assess cardiac metabolism in heterogeneous cell populations. The engineered alignment drives hiPSC-CM differentiation towards the ventricular compact CM subtype and improves electrochemical coupling in the short term. Moreover, we observe glycolysis to oxidative phosphorylation switch throughout differentiation and CM development. On the subcellular scale, we note changes in mitochondrial morphology in the long term. Our results demonstrate that cellular alignment accelerates hiPSC-CM maturity and emphasizes the interrelation of structure and function in cardiac development. We anticipate that combining engineered alignment with additional maturation strategies will result in improved development of mature CMs from hiPSC and strongly improve cardiac tissue engineering. Impact StatementThis work demonstrates the mixed effect of engineered structure in inducing matured function of human induced pluripotent stem cell -derived cardiomyocytes. Isolating the impacts of hiPSC-CM alignment on functionality is a necessary step in optimizing the culture conditions to develop cardiac cell therapies. Furthermore, our work has broader implications concerning how we understand the impact of mechanical microenvironments on stem cell differentiation and development.

bioengineering↗

bioRxiv2020

Chirality-dependent anti-inflammatory effect of glutathione after spinal cord injury

Neuroinflammation forms a glial scar following a spinal cord injury (SCI). The injured axon cannot regenerate across the scar, suggesting permanent paraplegia. In this study, we report that d-chiral glutathione (D-GSH) suppresses the inflammatory response after SCI and leads to axon regeneration of the injured spinal cord to a greater extent than l-chiral glutathione (L-GSH). After SCI, axon regrowth in D-GSH-treated rats was significantly increased compared to that in L-GSH-treated rats (***p < 0.001). Secondary damage and motor function were significantly improved in D-GSH-treated rats compared to those outcomes in L-GSH-treated rats (**p < 0.01). Moreover, D-GSH significantly decreased pro-inflammatory cytokines and glial scar via inhibition of the mitogen-activated protein kinase (MAPK) signaling pathway compared to L-GSH (***p < 0.001). In primary cultured macrophages, we found that D-GSH undergoes more intracellular interaction with activated macrophages than L-GSH (***p < 0.001). These findings reveal a potential new regenerative function of chiral GSH in SCI and suggest that chiral GSH has therapeutic potential as a treatment of other diseases.

neuroscience↗

bioRxiv2019

Dynamic changes in the regulatory T cell heterogeneity and function by murine IL-2 mutein

The therapeutic expansion of Foxp3+ regulatory T cells (Tregs) shows promise for treating autoimmune and inflammatory disorders. Yet, how this treatment affects the heterogeneity and function of Tregs is not clear. Using single-cell RNA-seq analysis, we characterized 31,908 Tregs from the mice treated with a half-life extended mutant form of murine IL-2 (IL-2 mutein, IL-2M) that preferentially expanded Tregs, or mouse IgG Fc as a control. Cell clustering analysis revealed that IL-2M specifically expands multiple sub-states of Tregs with distinct expression profiles. TCR-profiling with single-cell analysis uncovered Treg migration across tissues and transcriptional changes between clonally related Tregs following IL-2M treatment. Finally, we identified IL-2M-expanded Tnfrsf9+Il1rl1+ Tregs with superior suppressive function, highlighting the potential of IL-2M to expand highly suppressive Foxp3+ Tregs.\n\nOne Sentence SummarySingle-cell analysis revealed that IL-2 mutein treatment expanded multiple sub-states of Tregs with a highly suppressive function in mice.

immunology↗