Biology subjects

Kilian, K.

Publications and source records attributed to Kilian, K..

7 recordsLinked to original sources

bioRxiv2026

Expanding Microgel Parameters to Model the Tumor Microenvironment and Examine Temozolomide Resistance in Glioblastoma

Glioblastoma (GBM) is a highly aggressive brain tumor with a five-year survival rate of less than 5%. The current standard of care established 20 years ago includes maximal surgical resection and administration of alkylating agent temozolomide (TMZ). GBM is highly invasive, and GBM cells that evade surgical resection can become resistant to TMZ and develop new aggressive secondary tumors. Post-relapse there are few treatment options available to patients. Tissue engineering approaches suggest the opportunity to develop in vitro models of the GBM tumor microenvironment that may accelerate the discovery of novel therapies for GBM. Here, we report the adaptation of hydrogel microdroplets (microgels) to encapsulate GBM cells in a tailorable 3D matrix to assess patters of growth and to screen TMZ drug response using patient-derived xenograft (PDX) specimens. We exploit a unique aspect of the microgel system to account for the cellular heterogeneity within the tumor microenvironment (TME). We combine cell-laden microgels generated from TMZ-resistant and TMZ responsive variants of the same PDX specimens to create heterogeneous populations with varying levels of drug sensitivity. We demonstrate a range of drug resistance phenotypes as a function of the ratio of TMZ-responsive to resistance cells and identify the population required for TMZ-resistance to overtake take the response. We then investigate the influence of tumor mimetic shifts in hyaluronic acid bioavailability and hypoxia on patterns of TMZ resistance. We show exposure to matrix-bound hyaluronan increases TMZ resistance and the glioma stem cell population in both cell variants. Lastly, we report an increase in TMZ sensitivity but divergent changes in the GSC subfraction for TMZ resistant vs responsive GBM in the presence of hypoxia. Together, we demonstrate the versatility of cell-laden microgel approach to replicate heterogenous tumor populations, model shifts in the tumor microenvironment, and rapidly screen therapeutic response.

bioengineering↗

bioRxiv2026

Engineered 3D hydrogel model reveals divergence of adhesion-migration balance in Glioblastoma under simulated microgravity

Glioblastoma is an aggressive brain cancer whose cells can switch between different modes of invasion in response to their surroundings, making the disease difficult to predict and treat. How physical forces influence this adaptability remains poorly understood. Here, we used simulated microgravity together with engineered hydrogels that independently control adhesion, degradability, and mechanical properties to test how gravity affects glioblastoma invasion. Microgravity strongly reduced invasion and shifted cells from elongated, protrusive behavior to a more cohesive state. Proteomic analysis showed reduced invasive signaling together with increased cell-matrix and cell-cell adhesion, consistent with a redistribution of contractile forces toward the cell edge. Under normal gravity, blocking CD44, integrin {beta}1, or N-cadherin reduced matrix-dependent invasion. In contrast, under microgravity, inhibiting these same adhesion pathways restored invasion, indicating that microgravity traps cells in an overly adhesive, cohesive state that limits movement rather than motility itself. These findings show that gravity is an important regulator of cancer cell plasticity and reveal a mechanically induced vulnerability in glioblastoma invasion. More broadly, combining defined biomaterials with gravitational modulation provides a new way to study how physical forces shape tumor behavior.

cancer biology↗

bioRxiv2025

Capillary constrictions prime cancer cell tumorigenicity through PIEZO1

Metastasis is a hallmark of cancer and is responsible for the majority of cancer-related deaths. Evidence suggests that even a single cancer cell can spread and seed a secondary tumour. However, not all circulating tumour cells have this ability, which implies that dissemination and distal growth require adaptative mechanisms during circulation. Here we report that constriction during microcapillary transit will trigger reprogramming of melanoma cells to a tumorigenic cancer stem cell-like state. Using a microfluidic device mimicking physiological flow rates and gradual capillary narrowing, we showed that compression through narrow channels lead to cell and nuclear deformation, rapid changes in chromatin state and increased calcium handling through the mechanosensor PIEZO1. Within minutes of microcapillary transit, cells show increased regulation of transcripts associated with metabolic reprogramming and metastatic processes, which culminates in the adoption of cancer stem cell-like properties. Squeezed cells displayed elevated melanoma stem cell markers, increased propensity for trans-endothelium invasion, and characteristics of enhanced tumorigenicity in vitro and in vivo. Pharmacological disruption of channel activity inhibited the stem cell-like state, while the selective PIEZO1 activator Yoda1 primed this state irrespective of constriction. Finally, deletion of PIEZO1 led to complete abrogation of the constriction-induced stem cell-like state. Together, this work demonstrates that compressive forces during circulation can reprogram circulating cancer cells to tumorigenic stem cell-like states that are primed for extravasation and metastatic colonization.

cancer biology↗

bioRxiv2021

Defined microenvironments trigger in vitro gastrulation in human pluripotent stem cells

Embryogenesis is orchestrated through local morphogen gradients and endometrial constraints that give rise to the three germ layers in a well-defined assembly. In vitro models of embryogenesis have been demonstrated by treating pluripotent stem cells in adherent or suspension culture with soluble morphogens and small molecules, which leads to tri-lineage differentiation. However, treatment with exogenous agents override the subtle spatiotemporal changes observed in vivo that ultimately underly the human body plan. Here we demonstrate how microconfinement of pluripotent stem cells on hydrogel substrates catalyses gastrulation-like events without the need for supplements. Within six hours of initial seeding, cells at the boundary show elevated cytoskeletal tension and yes-associated protein (YAP) activity, which leads to changes in cell and nuclear morphology, epithelial to mesenchymal transition, and emergence of defined patterns of primitive streak containing SRY-Box Transcription Factor 17 (SOX17)+ T/BRACHYURY+ cells. Immunofluorescence staining, transcript analysis, and the use of pharmacological modulators reveal a role for mechanotransduction-coupled non-canonical wingless-type (WNT) signalling in promoting epithelial to mesenchymal transition and multilayered organization within the colonies. These microscale gastruloids were removed from the substrate and encapsulated in 3D hydrogels, where biomaterials properties correspond to maintenance and spatial positioning of the primitive streak. Together, this approach demonstrates how materials alone can nurture embryonic gastrulation, thereby providing an in vitro model of early development.

bioengineering↗

bioRxiv2019

Neural correlates of response inhibition and performance monitoring in binge watching

With the increasing popularity of internet streaming portals, the question why people develop binge-watching behavior has become a focus of scientific research and its addictive potential is discussed. The current study examined neural correlates of binge-watching during inhibition in a go/nogo task and performance monitoring using electroencephalography. Participants reported high binge-watching behavior (HBW, n = 35) or no binge-watching (NBW, n = 33) episode during the past four weeks. Compared to the NBW group, HBW showed larger P3 during response inhibition and larger error-related negativity (ERN) for errors in the flanker task. Group differences in behavioral measures were not observed. The current results suggest that binge watching may be related to both (1) increased neural recruitment during response inhibition as indicated by the increased P3 to facilitate normal inhibitory performance and (2) enhanced performance monitoring as indicated by the increased ERN. As this neurocognitive profile differs from observations in other addictive and excessive behaviors, implications for this budding field are discussed.

neuroscience↗

bioRxiv2019

Patterned substrates modulate growth and dynamics of 3D cellular systems

The development of 3D cellular architectures during development and pathological processes involves intricate migratory patterns that are modulated by genetics and the surrounding microenvironment. The substrate composition of cell cultures has been demonstrated to influence growth, proliferation, and migration in 2D. Here we study the growth and dynamics of mouse embryonic fibroblast (MEF) cultures patterned in a tissue sheet which then exhibits 3D growth. Using gradient light interference microscopy (GLIM), a label-free quantitative phase imaging approach, we explored the influence of geometry on cell growth patterns and rotational dynamics. We apply, for the first time to our knowledge, dispersion-relation phase spectroscopy (DPS) in polar coordinates to generate the radial and rotational cell mass-transport. Our data show that cells cultured on engineered substrates undergo rotational transport in a radially independent manner and exhibit faster vertical growth than the control, unpatterned cells. The use of GLIM and polar DPS provides a novel quantitative approach to studying the effects of spatially patterned substrates on cell motility and growth.

cell biology↗

bioRxiv2017

Simultaneous cell traction and growth measurements using light

Understanding cell mechanotransduction is important for discerning matrix structure-cell function relationships underlying health and disease. Despite the crucial role of mechanochemical signaling in phenomena such as cell migration, proliferation, and differentiation, measuring the cell-generated forces at the interface with the extracellular matrix during these biological processes remains challenging. An ideal method would provide continuous, non-destructive images of the force field applied by cells, over broad spatial and temporal scales, while simultaneously revealing the cell biological process under investigation. Toward this goal, we present the integration of a new real-time traction stress imaging modality, Hilbert phase dynamometry (HPD), with the technique of spatial light interference microscopy (SLIM) for label free monitoring of cell growth. HPD relies on extracting the displacement field in a deformable substrate, which is chemically patterned with a fluorescent grid. The displacements introduced by the cell are captured by the phase of the periodic signal associated with the grid, borrowing concepts from holography. The displacement field is uniquely converted into forces by solving an elasticity inverse problem. Because the measurement of displacement only uses the epi-fluorescence channel of an inverted microscope, we can simultaneously achieve measurements in transmission. We performed SLIM and extracted cell mass on the same field of view in addition to the measured displacement field. We used this technique to study mesenchymal stem cells and found that cells undergoing osteogenesis and adipogenesis exerted larger and more dynamic stresses than their precursor. Our results indicate that the MSCs develop the smallest forces and growth rates. We anticipate that simultaneous cell growth and traction measurements will improve our understanding of mechanotransduction, particularly during dynamic processes where the matrix properties provide context to guide cells towards a physiological or pathological outcome, e.g., tissue morphogenesis, or cancer metastasis.

cell biology↗