Biology subjects

Taubenberger, A. V.

Publications and source records attributed to Taubenberger, A. V..

15 recordsLinked to original sources

bioRxiv2026

Impact of chemotherapy on leukocyte stiffness -A longitudinal RT-DC study in a breast cancer patient

BackgroundThe physical properties of leukocytes, such as cell size and stiffness, are critical for their circulation in microcapillary networks where rapid shape changes are required to squeeze through vascular constrictions. Alterations in the cells physical phenotype can promote venous thromboembolism (VTE), a common cause of death in cancer patients receiving chemotherapy. While biochemical VTE predictors are well studied, physical properties of blood cells receive less attention. MethodsUsing real-time deformability cytometry (RT-DC), we monitored for the first time the physical phenotype of leukocytes in a longitudinal study of a breast cancer patient treated with epirubicin/cyclophosphamide (EC) and paclitaxel (Pax). ResultsThe leukocyte counts extracted from RT-DC were in good agreement with standard clinical leukograms and EC had no immediate effect on leukocyte properties. However, Pax caused a significant softening of granulo/monocytes and a stiffening of lymphocytes immediately after administration. Leukocyte size was constant throughout the therapy, but we observed an overall increase in leukocyte stiffness, which was restored to normal values 45 weeks post treatment. ConclusionTaken together, our data reveal chemotherapy-induced specific alterations of leukocyte stiffness potentially critical for microcirculation. Thus, RT-DC measurements can add important, yet currently not available information to VTE prediction in cancer patients.

biophysics↗

bioRxiv2026

Drosophila sperm carry a dietary sterol that increases offspring development

Diet affects male fitness directly and across generations. The current research focus is on dietary proteins and carbohydrates. Dietary lipids (DL), which are incorporated into cell membranes and affect signaling, were neglected or analyzed at pathological high-fat diet amounts. How fitness variation arises among males consuming healthy amounts of DL remains unknown, as do the fitness parameters being affected, including paternal effects. Contrasting mammal- vs. plant-derived DL, we measure mating rate, sperm count, sperm and seminal fluid quality, fertility and offspring growth in Drosophila melanogaster. We show that i) mammal-derived DL increased male fitness in isolation and competition, but without changing sperm numbers. ii) We discovered that lipid microcarriers in the seminal fluid fused with, and directly provided DL to sperm, changing sperm quality. iii) Dietary cholesterol, precursor of the growth hormone ecdysone, was incorporated into sperm, vectored to the zygote and improved offspring development and survival. This duality of Drosophila sperm function - fertilization and provision of growth hormone precursor - is an elegant, adaptive solution to prevent rival males from exploiting paternal provision. Direct offspring benefits vectored by sperm offer additional and alternative explanations for the evolution of sperm competition, sperm gigantism, and of anisogamy, the driver of sexual selection.

evolutionary biology↗

bioRxiv2025

Cells dynamically adapt their nuclear volumes and proliferation rates during single to multicellular transitions

Tumour development and progression are associated with biophysical alterations that manifest across multiple spatial scales, from the subcellular to multicellular tissue scale. While cells dynamically regulate their biophysical properties like volumes and mechanics in dependence of cell state and function, it is unclear how these properties are controlled in the dense multicellular environment of a developing tumour. Here, we quantified cell and nuclear volumes of single cancer cells, while they grew into multicellular tumour spheroids within well-defined, tuneable biohybrid polymer hydrogels. We quantitatively showed that the formation of multicellular structures is associated with marked reductions of cellular and nuclear volumes, cell cycle delays as well as cell mechanical alterations, and that these changes are coupled. Single-to-multicellular transitions coincided with a drastic decrease in median nuclear volumes by up to 60%, as well as overall cell volume decrease. Nuclear volume decrease could not be explained by compression due to confining microenvironments. Instead, cell cycle adaptions were one significant contributor, with smaller-sized G1 cells accumulating in growing clusters, an effect that was reversed by CDK1 inhibition. Another contributor was nuclear volume decrease in cells within clusters that was associated with higher mass density and stiffness and could be abrogated upon cell release from clusters. In turn, multicellular-to-single cell transitions that happened in cells that invaded from a tumour spheroid into the surrounding matrix, were accompanied by nuclear volume increases and cell softening. Taken together, our study provides insights into how cells dynamically adapt their cellular/nuclear volumes, cell cycle progression and mechanics in dependence of the multicellular state.

biophysics↗

bioRxiv2025

Mechanical control of tissue growth during limb regeneration

The axolotl is a highly regenerative species, capable of restoring full limbs, regardless of the amputation site. However, the regeneration rate is adjusted with the plane of amputation along the proximo-distal (PD) axis, leading to equivalent regeneration times regardless of the extent of tissue removal. We hypothesized that this phenomenon could be partly explained by differences in tissue mechanical properties. In this work, we describe tissue growth mathematically and evaluate cell cycle parameters of regenerating limbs amputated at different levels along the PD axis, demonstrating a linear correlation between the cell cycle length and the amputation site during early regeneration phases. We show as well, that blastema cells require their endogenous context to retain such proliferation differences. We measured mechanical properties in regenerating limbs with in vivo optical and standard indentation-based techniques and demonstrated that distal blastema cells are stiffer than proximal ones. Accordingly, we demonstrated that axolotl cells decrease their proliferation with increased extracellular matrix stiffness in vitro. Next, we evaluated the activity of the mechanotransducers YAP/TAZ in vivo by using a GTIIC-based reporter line combined with target gene expression data, which indicated that their activity peaks during the blastema stage, with higher activity after proximal amputations. Hence, our findings strongly suggest a mechanical dependence for the position-dependent regulation of cell proliferation during axolotl limb regeneration, where YAP/TAZ likely plays a role in the mechanotransduction mechanism.

biophysics↗

bioRxiv2025

Prostate cancer associated fibroblasts have distinct morphomechanical features that are associated with patient outcome

Tumour development and progression reshape the physical properties of the surrounding tumour microenvironment (TME) including its biomechanical traits. This is driven by a prominent cell type in the TME, cancer associated fibroblasts (CAFs), which increases tissue stiffness via extracellular matrix deposition and remodelling. Currently, it is unclear whether there are also physical changes to CAFs at the cellular level and, if so, how they relate to patient outcome. Here we show that CAFs have distinct morphological and biomechanical features from normal fibroblasts. We examined matched, patient-derived CAFs and non-malignant prostate fibroblasts (NPFs) from 35 patients with primary prostate cancer. Morphologically, CAFs had more aligned stress fibres, and larger and more elongated nuclei, based on quantitative image analysis of confocal microscopy images. In addition, single-cell mechanical measurements using real-time deformability cytometry showed that CAFs are larger and stiffer than NPFs. These changes were consistent across patients and validated with atomic force microscopy. A combined morphomechanical score encompassing these features was significantly associated with patient outcome. In transcriptomic analyses, the score was correlated with microtubule dynamics and a myofibroblast phenotype. Importantly, we also demonstrated that morphomechanical features of prostate fibroblasts are modified by approved treatments for prostate cancer, such as docetaxel, and other small molecular inhibitors, such as axitinib. In summary, changes in cellular morphomechanical properties are a consistent feature of CAFs and associated with patient outcome. Moreover, cellular morphomechanical properties can be therapeutically targeted, potentially providing a new strategy for manipulating the TME to control cancer progression.

cancer biology↗

bioRxiv2024

Manipulation of the Nuclear Envelope-Associated Protein SLAPDuring Mammalian Brain Development Affects Cortical Lamination and Exploratory Behavior

Here we report the first characterization of the effects resulting from the manipulation of Soluble-Lamin Associated Protein (SLAP) expression during mammalian brain development. We found that SLAP localizes to the nuclear envelope and when overexpressed causes changes in nuclear morphology and lengthening of mitosis. SLAP overexpression in apical progenitors of the developing mouse brain altered asymmetric cell division, neurogenic commitment and neuronal migration ultimately resulting in unbalance in the proportion of upper, relative to deeper, neuronal layers. Several of these effects were also recapitulated upon Cas9-mediated knock-down. Ultimately, SLAP overexpression during development resulted in a reduction in subcortical projections of young mice and, notably, reduced their exploratory behavior. Our study shows the potential relevance of the previously uncharacterized nuclear envelope protein SLAP in neurodevelopmental disorders.

developmental biology↗

bioRxiv2023

Self-propagating wave drives noncanonical antidurotaxis of skull bones in vivo

Cell motility is a key feature of tissue morphogenesis, and it is thought to be driven primarily by the active migration of individual cells or collectives. However, this model is unlikely to apply to cells lacking overt cytoskeletal, stable cell-cell or cell-cell adhesions, and molecular polarity, such as mesenchymal cells. Here, by combining a novel imaging pipeline with biophysical modeling, we discover that during skull morphogenesis, a self-generated collagen gradient expands a population of osteoblasts towards a softer matrix. Biomechanical measurements revealed a gradient of stiffness and collagen along which cells move and divide. The moving cells generate an osteogenic front that travels faster than individual tracked cells, indicating that expansion is also driven by cell differentiation. Through biophysical modeling and perturbation experiments, we found that mechanical feedback between stiffness and cell fate drives bone expansion and controls bone size. Our work provides a mechanism for coordinated motion that does not rely upon the cytoskeletal dynamics of cell migration. We term this self-propagating motion down a stiffness gradient, noncanonical antidurotaxis. Identification of alternative mechanisms of cellular motion will help in understanding how directed cellular motility arises in complex environments with inhomogeneous material properties.

biophysics↗

bioRxiv2022

Adipose cells and tissues soften with lipid accumulation while in diabetes adipose tissue stiffens

Adipose tissue expansion involves both differentiation of new precursors and size increase of mature adipocytes. While the two processes are well balanced in healthy tissues, obesity and diabetes type II are associated with abnormally enlarged adipocytes and excess lipid accumulation. We hypothesised that adipocyte shape and size changes with differentiation and lipid accumulation would be accompanied by changes in the mechanical phenotype at both the cell and tissue level. We quantified by optical diffraction tomography (ODT) that differentiating preadipocytes increased their volumes drastically. Atomic force microscopy (AFM)-indentation and -microrheology revealed that during the early phase of differentiation, human preadipocytes became more compliant and more fluid-like, concomitant with ROCK-mediated F-actin remodelling. Adipocytes that had accumulated large lipid droplets were more compliant, and further promoting lipid accumulation led to an even more compliant phenotype. In line with that, high fat diet-induced obesity was associated with more compliant adipose tissue compared to lean animals, both for drosophila fat bodies and murine gonadal adipose tissue. In contrast, adipose tissue of diabetic mice became significantly stiffer as shown not only by AFM but also magnetic resonance elastography (MRE). Altogether, we dissect relative contributions of the cytoskeleton and lipid droplets to cell and tissue mechanical changes across different functional states, such as differentiation, nutritional state and disease. Since preadipocytes are mechanosensitive, tissue stiffening in diabetes might be critical to the balance between hyperplasia and hypertrophy and moreover present a potential target in the prevention of metabolic disorders.

biophysics↗

bioRxiv2021

Mapping tumor spheroid mechanics in dependence of 3D microenvironment stiffness and degradability by Brillouin microscopy

Altered biophysical properties of cancer cells and of their microenvironment contribute to cancer progression. While the relationship between microenvironmental stiffness and cancer cell mechanical properties and responses has been previously studied using two-dimensional (2D) systems, much less is known about it in a physiologically more relevant 3D context and in particular for multicellular systems. To investigate the influence of microenvironment stiffness on tumor spheroid mechanics, we first generated MCF-7 tumor spheroids within matrix metalloproteinase (MMP)-degradable 3D polyethylene glycol (PEG)-heparin hydrogels, where spheroids showed reduced growth in stiffer hydrogels. We then quantitatively mapped the mechanical properties of tumor spheroids in situ using Brillouin microscopy. Maps acquired for tumor spheroids grown within stiff hydrogels showed elevated Brillouin frequency shifts (hence increased longitudinal elastic moduli) with increasing hydrogel stiffness. Maps furthermore revealed spatial variations of the mechanical properties across the spheroids cross-sections. When hydrogel degradability was blocked, comparable Brillouin frequency shifts of the MCF-7 spheroids were found in both compliant and stiff hydrogels, along with similar levels of growth-induced compressive stress. Under low compressive stress, single cells or free multicellular aggregates showed consistently lower Brillouin frequency shifts compared to spheroids growing within hydrogels. Thus, the spheroids mechanical properties were modulated by matrix stiffness and degradability as well as multicellularity, and also to the associated level of compressive stress felt by tumor spheroids. Spheroids generated from a panel of invasive breast, prostate and pancreatic cancer cell lines within degradable stiff hydrogels, showed higher Brillouin frequency shifts and less cell invasion compared to those in compliant hydrogels. Taken together, our findings contribute to a better understanding of the interplay between cancer cells and microenvironment mechanics and degradability, which is relevant to better understand cancer progression.

biophysics↗

bioRxiv2020

Combined fluorescence, optical diffraction tomography and Brillouin microscopy

Quantitative measurements of physical parameters become increasingly important for understanding biological processes. Brillouin microscopy (BM) has recently emerged as one technique providing the 3D distribution of viscoelastic properties inside biological samples -- so far relying on the implicit assumption that refractive index (RI) and density can be neglected. Here, we present a novel method (FOB microscopy) combining BM with optical diffraction tomography and epi-fluorescence imaging for explicitly measuring the Brillouin shift, RI and absolute density with specificity to fuorescently labeled structures. We show that neglecting the RI and density might lead to erroneous conclusions. Investigating the nucleoplasm of wild-type HeLa cells, we find that it has lower density but higher longitudinal modulus than the cytoplasm. Thus, the longitudinal modulus is not merely sensitive to the water content of the sample -- a postulate vividly discussed in the field. We demonstrate the further utility of FOB on various biological systems including adipocytes and intracellular membraneless compartments. FOB microscopy can provide unexpected scientific discoveries and shed quantitative light on processes such as phase separation and transition inside living cells.

biophysics↗

bioRxiv2019

Using real-time fluorescence and deformability cytometry and deep learning to transfer molecular specificity to label-free sorting

The identification and separation of specific cells from heterogeneous populations is an essential prerequisite for further analysis or use. Conventional passive and active separation approaches rely on fluorescent or magnetic tags introduced to the cells of interest through molecular markers. Such labeling is time- and cost-intensive, can alter cellular properties, and might be incompatible with subsequent use, for example, in transplantation. Alternative label-free approaches utilizing morphological or mechanical features are attractive, but lack molecular specificity. Here we combine image-based real-time fluorescence and deformability cytometry (RT-FDC) with downstream cell sorting using standing surface acoustic waves (SSAW). We demonstrate basic sorting capabilities of the device by separating cell mimics and blood cell types based on fluorescence as well as deformability and other image parameters. The identification of blood sub-populations is enhanced by flow alignment and deformation of cells in the microfluidic channel constriction. In addition, the classification of blood cells using established fluorescence-based markers provides hundreds of thousands of labeled cell images used to train a deep neural network. The trained algorithm, with latency optimized to below 1 ms, is then used to identify and sort unlabeled blood cells at rates of 100 cells/sec. This approach transfers molecular specificity into label-free sorting and opens up new possibilities for basic biological research and clinical therapeutic applications.

biophysics↗

bioRxiv2019

Zebrafish spinal cord repair is accompanied by transient tissue stiffening

Severe injury to the mammalian spinal cord results in permanent loss of function due to the formation of a glial-fibrotic scar. Both the chemical composition and the mechanical properties of the scar tissue have been implicated to inhibit neuronal regrowth and functional recovery. By contrast, adult zebrafish are able to repair spinal cord tissue and restore motor function after complete spinal cord transection owing to a complex cellular response that includes neurogenesis and axon regrowth. The mechanical mechanisms contributing to successful spinal cord repair in adult zebrafish are, however, currently unknown. Here, we employ AFM-enabled nano-indentation to determine the spatial distributions of apparent elastic moduli of living spinal cord tissue sections obtained from uninjured zebrafish and at distinct time points after complete spinal cord transection. In uninjured specimens, spinal gray matter regions were stiffer than white matter regions. During regeneration after transection, the spinal cord tissues displayed a significant increase of the respective apparent elastic moduli that transiently obliterated the mechanical difference between the two types of matter, before returning to baseline values after completion of repair. Tissue stiffness correlated variably with cell number density, oligodendrocyte interconnectivity, axonal orientation, and vascularization. The presented work constitutes the first quantitative mapping of the spatio-temporal changes of spinal cord tissue stiffness in regenerating adult zebrafish and provides the tissue mechanical basis for future studies into the role of mechanosensing in spinal cord repair.

biophysics↗

bioRxiv2019

3D microenvironment stiffness regulates tumor spheroid growth and mechanics via p21 and ROCK

Mechanical properties of cancer cells and their microenvironment contribute to breast cancer progression. While mechanosensing has been extensively studied using two-dimensional (2D) substrates, much less is known about it in a physiologically more relevant 3D context. Here we demonstrate that breast cancer tumor spheroids, growing in 3D polyethylene glycol-heparin hydrogels, are sensitive to their environment stiffness. During tumor spheroid growth, compressive stresses of up to 2 kPa built up, as quantitated using elastic polymer beads as stress sensors. Atomic force microscopy (AFM) revealed that tumor spheroid stiffness increased with hydrogel stiffness. Also, constituent cell stiffness increased in a ROCK- and F-actin-dependent manner. Increased hydrogel stiffness correlated with attenuated tumor spheroid growth, a higher proportion of cells in G0/G1 phase and elevated levels of the cyclin-dependent kinase inhibitor p21. Drug-mediated ROCK inhibition reversed not only cell stiffening upon culture in stiff hydrogels but also increased tumor spheroid growth. Taken together, we reveal here a mechanism by which the growth of a tumor spheroid can be regulated via cytoskeleton rearrangements in response to its mechanoenvironment. Thus, our findings contribute to a better understanding of how cancer cells react to compressive stress when growing under confinement in stiff environments and provide the basis for a more in-depth exploration of the underlying mechanosensory response.

bioengineering↗

bioRxiv2019

Oncogenic signaling alters cell shape and mechanics to facilitate cell division under confinement.

When cells enter mitosis, they become spherical and mechanically stiffen. We used MCF10A cell lines as a model system in which to investigate the effect of induced oncogene expression on mitotic entry. We find that activation of oncogenic RasV12, for as little as five hours, changes the way cells divide. RasV12-dependent activation of the MEK-ERK signalling cascade alters acto-myosin contractility to enhance mitotic rounding. RasV12 also affects cell mechanics, so that RasV12 expressing cells are softer in interphase but stiffen more upon entry into mitosis. As a consequence, RasV12 expression augments the ability of cells to round up and divide faithfully when confined underneath a stiff hydrogel. Conversely, inhibition of the Ras-ERK pathway reduces mitotic rounding under confinement, resulting in chromosome segregation defects. These data suggest a novel mechanism by which oncogenic Ras-ERK signalling can aid division in stiff environments like those found in tumours.

cell biology↗

bioRxiv2018

Acute but not inherited demyelination in mouse models leads to brain tissue stiffness changes

The alteration or decrease of axonal myelination is an important hallmark of aging and disease. Demyelinated axons are impaired in their function and degenerate over time. Oligodendrocytes, the cells responsible for myelination of axons, are sensitive to mechanical properties of their environment. Growing evidence indicates that mechanical properties of demyelinating lesions are different from the healthy state and thus have the potential to affect myelinating potential of oligodendrocytes. We performed a high-resolution spatial mapping of the mechanical heterogeneity of demyelinating lesions using Atomic Force Microscope enabled indentation. Our results indicate that the stiffness of specific regions of mouse brain tissue is influenced by age and degree of myelination. Here we specifically demonstrate that acute but not inherited demyelination leads to decreased tissue stiffness, which could lower remyelination potential of oligodendrocytes. We also demonstrate that specific brain regions have unique ranges of stiffness in white and grey matter. Our ex vivo findings may help the design of future in vitro models to mimic mechanical environment of the brain in healthy and disease state. Reported here, mechanical properties of demyelinating lesions may facilitate novel approaches in treating demyelinating diseases such as multiple sclerosis.

biophysics↗