Biology subjects

Tibbitt, M. W.

Publications and source records attributed to Tibbitt, M. W..

7 recordsLinked to original sources

bioRxiv2026

Hydrogel confinement enables subcutaneous delivery of vesicant antibody-drug conjugates

Antibody-drug conjugates (ADCs) deliver cytotoxic payloads to tumors with antibody selectivity, yet all approved ADCs are administered by intravenous (IV) infusion despite a strong patient and clinical preference for subcutaneous (SC) delivery. SC administration would reduce treatment burden, but many ADC payloads are vesicants that cause tissue necrosis upon local release, a liability amplified, not mitigated, by the dispersion-enhancing excipients used for SC antibody formulations. We developed an injectable diacetyl-L-tartaric anhydride-functionalized chitosan hydrogel (TACT) that addresses this conflict by confining ADCs within a protective SC depot. TACT is compatible with clinically approved ADC formulations without drug-product modification and provides drug-to-antibody ratio (DAR)-dependent release kinetics that support a quantitative relationship with in vivo absorption timing. In direct comparison, recombinant human hyaluronidase (rHuPH20) co-formulated with vesicant ADCs caused severe tissue necrosis, whereas TACT prevented macroscopic injury while preserving antitumor efficacy comparable to intravenous dosing. TUNEL staining of injection sites showed that TACT attenuated peri-depot apoptotic injury 3-fold relative to T-DM1 alone and 2-fold relative to rHuPH20 co-formulation. In non-human primates, SC TACT achieved 78% relative bioavailability for total trastuzumab, reduced peak circulating T-DM1 catabolite (free DM1) exposure 7.6-fold compared to IV administration and produced only transient, self-resolving cutaneous reactions. These results identify depot-mediated confinement as a viable alternative to excipient-mediated dispersion for SC delivery of vesicant ADCs, demonstrated here for trastuzumab-based conjugates across two approved ADC drug products (T-DM1 and T-DXd, with non-cleavable MCC and cleavable peptide linkers), with supporting validation in a custom cleavable monomethyl auristatin E (MMAE) series. Additional validation with enfortumab vedotin (EV), a Nectin-4-targeting MMAE ADC, supported the applicability of this strategy beyond trastuzumab-based conjugates.

cancer biology↗

bioRxiv2025

HydroMEA: A 3D Hydrogel Based Microfluidic Device to Study Electrophysiology for Myelinated Nerve-on-Chip

Engineered in vitro platforms are powerful systems to study information flow in the nervous system. While existing polydimethylsiloxane (PDMS)-based microfluidic platforms offer precise architectures, the cultured neurons grow on two-dimensional (2D) planar multielectrode arrays (MEA). To mimic the native microenvironment, where neurons grow in three-dimensional (3D) extracellular matrices (ECM), 3D hydrogels can be designed to encapsulate cells and enable physiologically-mimicked behaviors. Here, we describe hydroMEA, a 3D platform fabricated by placing PDMS microstructures on a high-density MEA and filled with a desired hydrogel, to offer controlled topologies, physiologically-relevant microenvironments, and real-time electrophysiological measurements. First, we developed a gelatin methacryloyl (GelMA) hydrogel with incorporated ECM components and tuned the mechanical properties to match those of nerve tissue. The hydrogel was able to support: 1) the growth of iPSC-derived sensory neurons (hSNs) for >100 days; 2) co-cultures of hSN with human embryonic stem cell-derived Schwann cells (hSCs), to enable reliable 3D myelination. Next, hydroMEA were prepared for topologically- defined 3D growth and myelination in designated compartments. Finally, electrophysiological evaluation of hSN-hSCs co-cultures revealed increased conduction speeds indicating functional myelin. This platform is a promising tool to study cell-cell interactions and to functionally evaluate the effect of pharmacological compounds in a more translational manner.

bioengineering↗

bioRxiv2025

Acoustofluidic patterning for improved microtissue histology

Microtissues (such as organoids or spheroids) are useful to model healthy or diseased human tissues and organs, with application in drug testing, tissue engineering, and personalized medicine. To characterize their morphology and phenotype, microtissues are often monitored using histology and high-resolution imaging. While this technique is well-established and standard for macroscopic tissue sections, it remains challenging to execute and has low throughput in the context of these sub-millimeter structures, mainly due to the fact that their size makes them difficult to locate within the embedding medium. To enhance the efficiency of microtissue histology, we developed an acoustofluidic device that arranges microtissues in a coplanar arrangement within HistoGel, a widely used embedding medium. Pre-patterning microtissues within HistoGel streamlines downstream processing by positioning the centers of mass of the microtissues at a pre-defined plan in the sample, simplifying sectioning, labeling, and imaging. We validated the method using differently sized HepG2 microtissues and tumor microtissues from osteosarcoma cells (Saos-2, MG-63, HOS), demonstrating that this method can be applied to different microtissue shapes, sizes, and types, without modifying established post-processing techniques. Our approach substantially enhances the microtissue histology workflow and broadens possibilities for microtissue analysis.

bioengineering↗

bioRxiv2024

Reinforced polymer-nanoparticle hydrogels for subcutaneous and sustained delivery of trastuzumab

In oncology, the advent of monoclonal antibody (mAbs) therapeutics represents a major breakthrough in various cancer diseases. However, these biotherapies often necessitate iterative hospital visits for intravenous infusion that can alter patients quality of life and contribute to the chronic saturation of hospitals. Interestingly, subcutaneous formulations of various mAbs offer a promising alternative facilitating faster administration compared with traditional intravenous methods, while still maintaining the same dosing schedule and providing time-saving advantages. Here, we developed an injectable mAb delivery platform using -cyclodextrin (CD)-reinforced polymer-nanoparticle hydrogels to perform a subcutaneous injection but also to delay the release of mAbs. By leveraging the versatility of our platform, we formulated hyaluronic acid- and alginate-based injectable drug depots by simply mixing components that are generally regarded as safe (GRAS). We used trastuzumab for the polymer-antibody complexation. The hydrogel depots delayed mAb release up to at least 3 days in both in vitro and in vivo mice models, outperforming clinically approved Herceptin subcutaneous formulation composed of trastuzumab with recombinant human hyaluronidase (rHuPH20).

bioengineering↗

bioRxiv2024

Tunable bicontinuous macroporous cell culture scaffolds via kinetically controlled phase separation

Three-dimensional (3D) scaffolds enable biological investigations with a more natural cell conformation. However, the porosity of synthetic hydrogels is often limited to the nanometer scale, which confines the movement of 3D encapsulated cells and restricts dynamic cell processes. Precise control of hydrogel porosity across length scales remains a challenge and the development of porous materials that allow cell infiltration, spreading, and migration in a manner more similar to natural ECM environments is desirable. Here, we present a straightforward and reliable method for generating kinetically-controlled macroporous systems using liquid-liquid phase separation between poly(ethylene glycol) (PEG) and dextran. Photopolymerization-induced phase separation resulted in macroporous hydrogels with tunable pore size. Varying light intensity and hydrogel composition controlled polymerization kinetics, time to percolation, and complete gelation, which defined the average pore diameter (O = 1- 300 m) and final gel stiffness of the formed hydrogels. Critically, for biological applications, macroporous hydrogels were prepared from aqueous polymer solutions at physiological pH and temperature using visible light, allowing for direct cell encapsulation. We encapsulated human dermal fibroblasts in a range of macroporous gels with different pore sizes. Porosity improved cell spreading with respect to bulk gels and allowed migration in the porous systems.

bioengineering↗

bioRxiv2023

Dual carbon sequestration with photosynthetic living materials

Natural ecosystems offer efficient pathways for carbon sequestration, serving as a resilient approach to remove CO2 from the atmosphere with minimal environmental impact. However, the control of living systems outside of their native environments is often challenging. Here, we engineered a photosynthetic living material for dual CO2 sequestration by immobilizing photosynthetic microorganisms within a printable polymeric network. The carbon concentrating mechanism of the cyanobacteria enabled accumulation of CO2 within the cell, resulting in biomass production. Additionally, the metabolic production of OH- ions in the surrounding medium created an environment for the formation of insoluble carbonates via microbially-induced calcium carbonate precipitation (MICP). Digital design and fabrication of the living material ensured sufficient access to light and nutrient transport of the encapsulated cyanobacteria, which were essential for long-term viability (more than one year) as well as efficient photosynthesis and carbon sequestration. The photosynthetic living materials sequestered approximately 2.5 mg of CO2 per gram of hydrogel material over 30 days via dual carbon sequestration, with 2.2 {+/-} 0.9 mg stored as insoluble carbonates. Over an extended incubation period of 400 days, the living materials sequestered 26 {+/-} 7 mg of CO2 per gram of hydrogel material in the form of stable minerals. These findings highlight the potential of photosynthetic living materials for scalable carbon sequestration, carbon-neutral infrastructure, and green building materials. The simplicity of maintenance, coupled with its scalability nature, suggests broad applications of photosynthetic living materials as a complementary strategy to mitigate CO2 emissions.

bioengineering↗

bioRxiv2021

3D confinement regulates stem cell fate

Biophysical properties of the cellular microenvironment, including stiffness and geometry, influence cell fate. Recent findings have implicated geometric confinement as an important regulator of cell fate determination. Our understanding of how mechanical signals direct cell fate is based primarily on two-dimensional (2D) studies. To investigate the role of confinement on stem cell fate in three-dimensional (3D) culture, we fabricated a single cell microwell culture platform and used it to investigate how niche volume and stiffness affect human mesenchymal stem cell (hMSC) fate. The viability and proliferation of hMSCs in confined 3D microniches were compared with the fate of unconfined cells in 2D culture. Physical confinement biased hMSC fate, and this influence was modulated by the niche volume and stiffness. The rate of cell death increased, and proliferation markedly decreased upon 3D confinement. We correlated the observed differences in hMSC fate to YES-associated protein (YAP) localization. In 3D microniches, hMSCs displayed primarily cytoplasmic YAP localization, indicating reduced mechanical activation upon confinement. These results demonstrate that 3D geometric confinement can be an important regulator of cell fate, and that confinement sensing is linked to canonical mechanotransduction pathways.

bioengineering↗