Biology subjects

Pal, V.

Publications and source records attributed to Pal, V..

8 recordsLinked to original sources

bioRxiv2026

Spheroid surgery: a first-generation micromanipulation platform for extracting viable cell clusters from the outer layers of hydrogel-embedded spheroids

Three-dimensional (3D) cell culture systems have gained attention as in vitro models capable of reproducing the tissue-like architecture, spatial organization, and physiological morphology of in vivo tumors. Their ability to mimic native cell-cell and cell-matrix interactions has positioned 3D cell cultures as powerful models for studying tumor biology and drug responses. However, methods for the localized extraction of viable cells remain limited, as existing approaches often disrupt the original 3D structure, limit access to defined regions, or compromise cell viability, restricting the biological insight that can be achieved. We present a manual, micropipette-based manipulation system designed to extract viable multicellular clusters from the outer layers of compact 3D tumor spheroids, embedded in biocompatible hydrogels. The extracted clusters remained fully functional, demonstrating that the procedure is sufficiently gentle to remove small multicellular units. This technology enables the localized extraction of viable multicellular clusters from 3D in vitro models without complete dissociation of the parent spheroid. The method opens new opportunities for longitudinal studies, spatially targeted sampling and controlled manipulation of living 3D cultures. This capability marks a step toward a new era of 3D model manipulation, where researchers can add, remove, or replace specific regions of living multicellular systems with precision.

bioengineering↗

bioRxiv2026

Bioinstructive Orthogonally-crosslinked Ovoprotein Microgels for Modular Bioprinting

Bioprinting increasingly requires biomaterials that are not only printable, but structurally adaptive and biologically instructive. Here we establish an ovoprotein-derived microgel platform that couples intrinsic protein bioactivity with orthogonal interparticle photocrosslinking for modular bioprinting. Methacrylated ovoproteins yielded a photoresponsive protein-rich hydrogel matrix with retained proteomic complexity, tunable mechanics, and cell-regulatory biofunction. Endogenous tyrosine chemistry drove interparticle dityrosine coupling between ovoprotein microgels, producing cohesive, microporous, and intrinsically autofluorescent granular networks. The resulting systems displayed programmable rheology and broad compatibility across digital light processing, extrusion-based and aspiration-assisted bioprinting. Functionally, the ovoprotein microgel matrices attenuated sustained pro-inflammatory macrophage activation, promoted endothelial organization and host angiogenic invasion, and supported spheroid-mediated vascular morphogenesis with progressive sprouting, lumenization, branching and inosculation. It further enabled bioprinted osteogenic constructs with long-term maturation into bone-like mineralized tissues in vitro. These findings establish ovoprotein microgel-spheroid bioassembly as an adaptive, bioinstructive strategy for engineering vascularized and mineralized tissue constructs.

bioengineering↗

bioRxiv2025

HIV-1 Integration Site Determines the Transcriptional Fate and Persistence of Integrated Proviruses

The mechanisms by which latent HIV-1 reservoirs persist during antiretroviral therapy is incompletely understood. Here, we derive a model system to measure clonal expansion and viral latency in which populations of human memory CD4+ T cells, each bearing a single transcriptionally active HIV-1 provirus are engrafted into immunodeficient mice. Over [~]2 months in vivo, clonal expansion and the establishment of latency occurred in subsets of engrafted infected cells. Clonal expansion in vivo was driven by T-cell receptor identity, but not by proviral insertional mutagenesis. The integration sites of proviruses that became latent in vivo were enriched on chromosome 19, in intergenic and centromeric satellite regions, and genes whose expression is atypically low. Pre-existing repressive epigenetic features were associated with latency for subsets of proviruses. Our findings suggest a confluency of genomic and epigenomic factors predispose certain genomic locations, including ZNF genes, to host proviruses that constitute the latent reservoir.

microbiology↗

bioRxiv2025

Foraging egg parasitoids benefit from the presence of potential competitors

Competition is generally considered a negative interaction that lowers the fitness of individuals. Studies of competition and fitness traits in parasitoids have primarily focused on interference competition, with less attention paid to parasitoids under exploitative competition. Theoretical studies predict that interference competition will decrease the resource utilisation of parasitoids, while exploitative competition will not. In our study, we investigated the impact of intraspecific exploitative competition among parasitoids on fitness traits, including resource utilisation, the percentage of offspring that emerged from parasitised eggs, and the percentage of female offspring produced from parasitised eggs. We investigated whether these fitness traits were influenced by the presence of conspecific foraging females, as well as by parasitoid and resource densities. Since we were studying the effect of exploitative competition, we used Trichogramma chilonis, a non-aggressive egg parasitoid. Corcyra cephalonica, a stored grain pest, was used as the host. We found that T. chilonis resource utilisation increased in the presence of conspecifics. However, the density of those conspecifics and the resource density did not affect resource utilisation. The presence of conspecific foraging females did not affect the rate of offspring survival. However, at a lower resource density, offspring survival was higher than under resource-abundant conditions. We explored this counterintuitive pattern using a simple mathematical model, which shows that superparasitism, occurring at high parasitoid density, can lead to high emergence. This is because, given only some progeny survive, the chance of parasitoid emergence increases with the number of eggs laid in the host. The secondary sex ratio of the progeny was unaffected by the presence of conspecifics or by parasitoid or resource densities. We conclude that for T. chilonis, the presence of competitors has a positive effect. Its high performance under competitive conditions may contribute to its efficiency as a biological control agent.

ecology↗

bioRxiv2025

Interparticle Crosslinked Ion-responsive Microgels for 3D and 4D (Bio)printing Applications

AbstractMicrogels offer unique advantages over bulk hydrogels due to their improved diffusion limits for oxygen and nutrients. Particularly, stimuli-responsive microgels with inherently bioactive and self-supporting properties emerge as highly promising biomaterials. This study unveils the development of interparticle-crosslinked, self-supporting, ion-responsive microgels tailored for 3D and 4D (bio)printing applications. A novel strategy was proposed to develop microgels that enabled interparticle crosslinking, eliminating the need for filler hydrogels and preserving essential microscale void spaces to support cell migration and vascularization. Additionally, these microgels possessed unique, ion-responsive shrinking behavior primarily by the Hofmeister effect, reversible upon the removal of the stimulus. Two types of microgels, spherical ({micro}S) and random-shaped ({micro}R), were fabricated, with {micro}R exhibiting superior mechanical properties and higher packing density. Fabricated microgel-based constructs supported angiogenesis with tunable vessel size based on interstitial void spaces while demonstrating excellent shear-thinning and self-healing properties and high print fidelity. Various bioprinting techniques were employed and validated using these microgels, including extrusion-based, embedded, intraembedded, and aspiration-assisted bioprinting, facilitating the biofabrication of scalable constructs. Multi-material 4D printing was achieved by combining ion-responsive microgels with non-responsive microgels, enabling programmable shape transformations upon exposure to ionic solutions. Utilizing 4D printing, complex, dynamic structures were generated such as coiling filaments, grippers, and folding sheets, providing a foundation for the development of advanced tissue models and devices for regenerative medicine and soft robotics, respectively.

bioengineering↗

bioRxiv2023

Nested biofabrication: Matryoshka-inspired Intra-embedded Bioprinting

Engineering functional tissues and organs remains a fundamental pursuit in biofabrication. However, the accurate constitution of complex shapes and internal anatomical features of specific organs, including their intricate blood vessels and nerves, remains a significant challenge. Inspired by the Matryoshka doll, we here introduce a new method called Intra-Embedded Bioprinting (IEB), building upon existing embedded bioprinting methods. We used a xanthan gum-based material, which served a dual role as both a bioprintable ink and a support bath, due to its unique shear-thinning and self-healing properties. We demonstrated IEBs capabilities in organ modelling, creating a miniaturized replica of a pancreas using a photocrosslinkable silicone composite. Further, a head phantom and a Matryoshka doll were 3D printed, exemplifying IEBs capability to manufacture intricate, nested structures. Towards the use case of IEB and employing innovative coupling strategy between extrusion-based and aspiration-assisted bioprinting, we developed a breast tumor model that included a central channel mimicking a blood vessel, with tumor spheroids bioprinted in proximity. Validation using a clinically-available chemotherapeutic drug illustrated its efficacy in reducing the tumor volume via perfusion over time. This method opens a new way of bioprinting enabling the creation of complex-shaped organs with internal anatomical features.

bioengineering↗

bioRxiv2023

A Versatile Photocrosslinkable Silicone Composite for 3D Printing Applications

Embedded printing has emerged as a valuable tool for fabricating complex structures and microfluidic devices. Currently, an ample of amount of research is going on to develop new materials to advance its capabilities and increase its potential applications. Here, we demonstrate a novel, transparent, 3D printable, photocrosslinkable, and tuneable silicone composite that can be utilized as a support bath or an extrudable ink for embedded printing. The proposed silicone composite can be tuned to achieve ideal rheological properties, such as optimal self-recovery and yield stress, for use in 3D printing. When used as a support bath, it facilitated the generation microfluidic devices with circular channels of diameter up to 30 {micro}m. To demonstrate its utility, flow focusing microfluidic devices were fabricated for generation of Janus microrods, which can be easily modified for multitude of applications. When used as an extrudable ink, 3D printing of complex-shaped micro- and macro-constructs were achieved with integrated electronics, which greatly extends its potential applications towards developing complex flexible parts for soft robotics and prosthetics. Further, its biocompatibility was tested with multiple cell types to validate its applicability for medical and tissue engineering use. Altogether, this material offers a myriad of potential applications in material and medical fields by providing a facile approach to develop complicated 3D structures and interconnected channels that can further advance microfluidics and soft-robotics research.

bioengineering↗

bioRxiv2022

High-throughput microgel biofabrication via air-assisted co-axial jetting for cell encapsulation, 3D bioprinting, and scaffolding applications

Microgels have recently received widespread attention for their applications in a wide array of domains such as tissue engineering, regenerative medicine, and cell and tissue transplantation because of their properties like injectability, modularity, porosity, and the ability to be customized in terms of size, form, and mechanical properties. However, it is still challenging to mass produce microgels with diverse sizes and tunable properties. Herein, we developed an air-assisted co-axial device (ACAD) for continuous production of microgels in a high-throughput manner. To test its robustness, microgels of multiple hydrogels and their combination, including alginate (Alg), gelatin methacrylate (GelMA) and Alg-GelMA, were formed at a maximum production rate of 65,000 microgels per sec while retaining circularity and a size range of 50-500 m based on varying air pressure levels. The ACAD platform allowed single and multiple cell encapsulation with around 75% efficiency. These microgels illustrated appealing rheological properties such as yield stress, viscosity, and shear modulus for bioprinting applications. Specifically, Alg microgels have the potential to be used as a sacrificial support bath while GelMA microgels have potential for direct extrusion both on their own or when loaded in a bulk GelMA hydrogel. Generated microgels showed high cell viability (>90%) and proliferation over 7 days with their increased interactions with cells, particularly for GelMA microgels. The developed strategy provides a facile and rapid approach without any complex or expensive consumables and accessories for scalable high-throughput microgel production for cell therapy, tissue regeneration and 3D bioprinting applications.

bioengineering↗