Biology subjects

Grzelak, K. A.

Publications and source records attributed to Grzelak, K. A..

3 recordsLinked to original sources

bioRxiv2026

Image-Guided Injectable Niche for Hepatocyte Transplantation

Liver transplantation remains the standard of care for end-stage liver failure, yet it is constrained by donor scarcity, surgical complexity, and restricted access for many patients. Cell-based therapies offer a potential alternative, yet their translation has been hindered by low engraftment, poor localization, and a lack of delivery strategies that are both effective and minimally invasive. To address these challenges, we developed a new approach termed INSITE (Injected Self-assembled Image-guided Tissue Ensembles), an injectable platform composed of primary human hepatocytes and hydrogel microspheres that can be delivered by image-guided injection and assembled in situ into supportive, vascularizable scaffolds. In vivo, ultrasound-guided delivery into an ectopic site enabled precise graft localization, persistent visibility under noninvasive imaging, and vascular integration. Hepatocytes within these niches remained confined to the scaffold and maintained long-term functional activity. Furthermore, tuning material properties allowed control over scaffold remodeling and vascular recruitment, providing a means to enhance graft function. By integrating image-guided delivery with a modular and supportive scaffold, INSITE establishes a clinically compatible strategy for advancing minimally invasive cell therapies.

bioengineering↗

bioRxiv2025

Electrical stimulation directs formation of perfused vasculature in engineered tissues

Effective, rapid and functionally perfusable vascularization remains a major challenge in tissue engineering. Current approaches to generate vasculature in vitro require multipart fabrication methods or complex and costly media supplements, limiting their scalability. Here, we demonstrate that exogenous electrical stimulation (estim) offers a promising alternative by enhancing 3D vasculogenesis in engineered human tissues. Exposing 3D endothelial-fibroblast cocultures to pulsed estim promoted the formation of dense and branched vascular networks. In a microfluidic device model, we show that estim induces the formation of an interconnected vascular network that can be perfused, whereas unstimulated control networks remained less mature. Importantly, we demonstrate that upon implantation, estim-pretreated vascular grafts exhibit elevated anastomosis with host and perfusion with blood relative to the untreated grafts. In addition, we use estim to promote engraftment of a vascularized 3D liver construct. Mechanistically, we find that estim induces membrane hyperpolarization in endothelial cells via voltage-gated potassium (KV) channels. Inhibiting KV channels abrogated estims pro-vasculogenic effects in endothelial cells. Conversely, pharmacologically activating hyperpolarization induced endothelial responses even without estim, directly linking KV channel-mediated hyperpolarization as a key mechanism by which estim drives vascular assembly and function. Ultimately, our work establishes estim as a new orthogonal approach to promote formation of perfusable vasculature in engineered tissues.

bioengineering↗

bioRxiv2025

A 3D in vitro model of the human hepatobiliary junction

Cholestasis, or disruption in bile flow, is a common yet poorly understood feature of many liver diseases and injuries. Despite this, many engineered human tissue models of liver disease fail to recapitulate physiological bile flow. Here, we present a 3D multicellular spheroid-based model of the human hepatobiliary junction, the interface between hepatocytes and cholangiocytes often disrupted in liver disease that is required for directing bile excreted by hepatocytes into the biliary ductal system. Building on advances in organoid and spheroid engineering, we co-aggregate human hepatocytes and intrahepatic cholangiocytes into adult hepatobiliary organoids (aHBOs) that structurally connect and functionally transport bile. aHBOs directionally transport bile from hepatocyte bile canaliculi to cholangiocyte-lined ductules, which we visualize through a high-throughput imaging assay. Hepatobiliary junction formation and bile flow dynamics are quantified over time using fluorescent bile acid analogs and AI-assisted image analysis. When subjected to hypoxia-reoxygenation, aHBOs recapitulate features of biliary dysfunction that mimics the cholestasis and ischemia-reperfusion injury that complicates liver transplant. Our findings suggest that 1) a reversible reduction in hepatocyte canalicular function under hypoxia, followed by 2) selective cholangiocyte death upon reoxygenation, are processes that potentially contribute to biliary dysfunction upon ischemic injury. This human-derived, scalable platform provides a phenotypically-relevant in vitro model for dissecting biliary pathophysiology and lays the groundwork for a therapeutic discovery platform for post-transplant ischemic cholangiopathy and other cholestatic liver diseases.

bioengineering↗