Biology subjects

Hammond, P. T.

Publications and source records attributed to Hammond, P. T..

17 recordsLinked to original sources

bioRxiv2026

Modeling lung adenocarcinoma using layer-by-layer nanoparticles mitigates innate immune cell activation

Lung adenocarcinoma, driven frequently by KRAS and p53 mutations, remains a leading cause of cancer mortality. Current state-of-the-art genetically engineered mouse models often rely on viral delivery of recombinases, such as Cre recombinase, to initiate transformation. However, viral particles can infect and activate innate immune cells, thus potentially impacting studies of tumor-immune dynamics. Here, we develop a layer-by-layer (LbL) polyplex platform using poly({beta}-aminoester) (PBAE) polymers layered with poly-L-aspartic acid (PLD) to deliver Cre mRNA to lungs while avoiding immune cell transfection and activation. PLD-coated nanoparticles (PLD-NPs) exhibit stable mRNA encapsulation and efficient transfection in vitro, even after lyophilization and long-term storage. In KrasLSL-G12D/+;p53flox/flox (KP) mice, PLD-NPs initiate lung adenocarcinomas that mirror human histopathology without infecting or activating dendritic cells and alveolar macrophages, unlike lentiviral (LV) or adenoviral delivery methods. Single-cell transcriptional profiling revealed that LV administration drives long-term upregulation of antigen presentation and costimulatory machinery in lung-resident myeloid populations. This persistent immune activation is avoided by NP delivery. By uncoupling tumor initiation from innate immune activation, this platform enables the high-fidelity interrogation of tumor-immune dynamics, especially for non-inflammation-driven lung cancer.

immunology↗

bioRxiv2026

Phenotypic screens identify biologic regulators of nanoparticle uptake in diffuse midline glioma

Nanoparticle drug delivery systems hold considerable promise for locoregional administration to central nervous system tumors, yet the biological determinants of nanoparticle-cancer cell interactions remain poorly understood. Using patient-derived histone-mutant diffuse midline glioma (DMG) models, we performed a pooled CRISPR-Cas9 perturbation screen to systematically identify regulators of liposomal nanoparticle delivery. The screen identified candidate genes spanning endocytosis, vesicle transport, and metabolic signaling, revealing that nanoparticle delivery is governed by a broader landscape than previously appreciated. Among these, CTNNB1, or {beta}-catenin, emerged as a common negative regulator across two independent DMG models and two distinct nanoparticle surface chemistries. Transcriptomic profiling of CTNNB1-depleted DMG cells revealed upregulation of membrane remodeling and extracellular matrix gene programs, accompanied by reduced cell stiffness measured by a microfluidic acoustic scattering assay. This resulted in a shift in endocytic activity characterized by decreased bulk-phase macropinocytosis and increased receptor-mediated endocytosis. We further identified MAPK and mTOR pathway members as nanoparticle trafficking modulators, and demonstrated concordance between genetic and pharmacologic perturbations in modulating the liposomal nanoparticle interactions in pediatric DMG cells. These findings establish a biology-first screening approach for identifying previously unappreciated regulators with potential relevance to nanoparticle-based therapeutic strategies in pediatric brain tumors.

bioengineering↗

bioRxiv2026

Engineering nanoparticle surface chemistry for antigen-presenting cell targeting improves specificity and safety of TLR3 agonist cancer immunotherapy

Innate immune agonists are promising therapeutic agents to induce immune responses against cancer. However, these agents have been limited by toxicity associated with systemic accumulation and activity in off-target cells. In this work, a targeted nanoparticle (NP) platform to encapsulate and protect the Toll-like receptor 3 (TLR3) agonist polyinosinic-polycytidylic acid (poly(I:C)) and promote its specific delivery to antigen presenting cells (APCs), macrophages and dendritic cells, for activation of this cell population was designed. To determine NP physiochemical properties that promote APC delivery, we developed a library of NP surface chemistries formed by electrostatic adsorption of polyanion coatings onto liposomes using layer-by-layer (LbL) assembly and screened the particles on APCs and off-target cells. Dextran sulfate was identified as a promising coating to enhance specific APC delivery. We applied these design parameters to develop a poly(I:C)-loaded NP for an APC-targeted immunotherapy. In a model of metastatic ovarian cancer, the LbL NP prolonged poly(I:C) retention in the peritoneal space--with 2-fold remaining 24-48hr after administration compared to free poly(I:C)--ultimately reducing systemic accumulation and associated toxicities. Compared to free drug, the NP reduced the increase in serum levels of TNF, IL-6, and CXCL10 by 9-, 4-, and 31-fold respectively. NP-treated mice experienced lower weight loss and recovered more quickly at a higher poly(I:C) dose, indicating a widening of the therapeutic window. The NP formulation enhanced accumulation of poly(I:C) in the tumor 2-fold and activation of the target APC population compared to free drug, and ultimately slowed tumor growth and extended survival in combination with doxorubicin chemotherapy. Overall, this work demonstrates a modular NP delivery strategy to improve the delivery, safety, and therapeutic window of a TLR3 agonist.

bioengineering↗

bioRxiv2026

A Multivalent Peptide-Polymer Conjugate Material Mimics STING to Therapeutically Activate Innate Immune Signaling

Stimulator of interferon genes (STING) is a promising therapeutic target for cancer immunotherapy, but agonists are often rendered ineffective by the loss of STING expression in cancer cells. Here we engineer a multivalent peptide-polymer conjugate material that can easily be delivered to the cytosol, where it mimics key protein interactions from the missing STING protein to directly activate downstream innate immune signaling. While previously developed STING mimicking therapeutics use nearly the full STING protein, this material contains only a 39 amino acid peptide from the STING C-terminal tail that includes interaction motifs for downstream kinase TBK1 and transcription factor IRF3. Conjugation of multiple peptide copies to a negatively charged polymer backbone mimics the multivalent protein-protein interactions of the oligomerized STING signaling complex, activating TBK1 and IRF3 as well as the transcription of downstream genes in both STING-proficient and STING-silenced cancer cell lines. We optimize a lipid nanoparticle formulation to deliver this conjugate material intracellularly, allowing for its application as an immunotherapy for ovarian cancer. Treatment with the STING mimicking conjugate material promoted the production of type I interferons, repolarization of myeloid cells to an anti-tumor phenotype, and recruitment of T cells to tumors in mice. This treatment ultimately led to tumor regression and extended survival in multiple mouse models of metastatic ovarian cancer. Overall, this work highlights the potential of peptide-polymer conjugate mimics of STING to therapeutically activate innate immune signaling.

bioengineering↗

bioRxiv2025

Layer-by-Layer Nanoparticle Outer Polyion Impacts Protein Corona Formation

Nanoparticles (NPs) can be engineered to achieve targeted delivery with strategies based on surface modifications. These include layer-by-layer (LbL) NPs, modular electrostatically assembled carriers with tunable surface properties altered by changes to the outer polyion layer. Variations in these polymers dictate intracellular trafficking and biodistribution patterns. As NPs are administered, a layer of protein adsorbs to their surfaces, forming a protein corona that affects NP properties, alters biodistribution, and ultimately, impacts therapeutic efficacy. We hypothesized that some differences in LbL NP performance are due, in part, to variations in the resulting protein coronas. To study them, we first optimized an ultrafiltration method to effectively isolate LbL NPs with their protein corona. Following incubation in conditioned media, anionic homopolypeptide outer layers, such as poly-L-aspartic acid (PLD) and poly-L-glutamic acid (PLE), and LbL NPs with the bioinert polymer poly(acrylic acid) (PAA) had the lowest amount of protein associated, lower than conventional PEG liposomes. While mass spectroscopy revealed changes in the protein composition among LbL NPs; albumin, alpha-2-macroglobulin, and apolipoprotein B were most abundant. In vitro, pre-formed protein coronas reduced uptake in macrophages but increased uptake in ovarian cancer cells for certain LbL NP outer layers. In vivo, LbL NP outer layer influenced both serum half-life and biodistribution. Overall, this work highlights that LbL NPs can be designed to control protein corona formation, and supports that further understanding NP interactions with biological fluids is essential for designing clinically translatable NP platforms. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=181 SRC="FIGDIR/small/670086v1_ufig1.gif" ALT="Figure 1"> View larger version (50K): org.highwire.dtl.DTLVardef@18a2a66org.highwire.dtl.DTLVardef@1e5b755org.highwire.dtl.DTLVardef@676af2org.highwire.dtl.DTLVardef@19e3b34_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2025

Investigating Bio-Nano Interactions of PEGylated Cationic Polyamidoamine (PAMAM) Dendrimers within Synovial Joints

Delivering therapeutics directly to synovial joints to treat osteoarthritis (OA) is challenging due to the dense negatively charged cartilage matrix and rapid turnover of synovial fluid, leading to high clearance rates. Our lab has identified polyamidoamine (PAMAM) dendrimers as optimal nanocarriers to overcome delivery challenges to cartilage due to their positive charge and small size, which enables them to bind to cartilage and diffuse through tissue to deliver therapeutics to chondrocytes. Previously, we have developed and characterized dendrimers functionalized with polyethylene glycol (PEG), demonstrating improved biocompatibility and enhanced transport through cartilage matrix. To improve the design of our therapeutic system, in this next phase of work, we characterized dendrimer-protein interactions or protein coronas that form on dendrimers after being immersed in synovial fluid. We also analyzed how synovial fluid protein coronas affect biological outcomes of dendrimers in synovial joints, specifically uptake in cartilage and internalization by chondrocytes. We identified that protein coronas can reduce dendrimer uptake in cartilage and chondrocytes; however, uptake reduction is mitigated by varying PEG chain length and density. Although protein coronas can be perceived as "biological barriers" to uptake, we demonstrate that dendrimers conjugated with insulin-like growth factor 1 (IGF-1) have better engagement with IGF-1 receptors after being pre-coated with a synovial fluid protein corona. Overall, these studies offer further insight into the mechanisms of how positively charged dendrimers target and transport through cartilage, bridging knowledge gaps between ex vivo and in vivo work. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=127 SRC="FIGDIR/small/668990v2_ufig1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@9298ccorg.highwire.dtl.DTLVardef@6d85aeorg.highwire.dtl.DTLVardef@63838dorg.highwire.dtl.DTLVardef@151ca4a_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2025

Surface avidity of anionic polypeptide coatings target nanoparticles to cancer-associated amino acid transporters

Tumor-targeted drug delivery enhances therapeutic efficacy while minimizing toxicity. Layer-by-layer nanoparticles (LbL-NPs) coated with anionic polypeptides selectively bind to cancer cells, though the mechanisms have been unclear. Here, we integrated in silico and in vitro approaches--including gene expression analysis, receptor inhibition, and AI-based protein modeling--to show that poly(L-glutamate) (PLE)-coated LbL-NPs bind with high avidity to SLC1A5, a glutamine transporter overexpressed in cancer. We also discovered that PLE clusters SLC1A5 on the cell membrane, promoting prolonged cell surface retention. Poly(L-aspartate) (PLD)-coated NPs similarly bind SLC1A5 but also interact with faster internalizing transporters of anionic amino acids. Correlation analyses across cancer cell lines confirmed a strong link between transporter expression and nanoparticle association. These findings demonstrate that dense glutamate or aspartate presentation through electrostatically adsorbed polypeptides enables selective targeting of overexpressed transporters, providing a mechanistic framework for receptor-targeted delivery that leverages metabolic characteristics of a range of solid tumor types.

bioengineering↗

bioRxiv2025

Polyamines buffer labile iron to suppress ferroptosis

Polyamines are essential and evolutionarily conserved metabolites present at millimolar concentrations in mammalian cells. Cells tightly regulate polyamine homeostasis through complex feedback mechanisms, yet the precise role necessitating this regulation remains unclear. Here, we show that polyamines contribute to endogenous buffering of redox-active iron, providing a molecular link between polyamine metabolism and ferroptosis. Using a genome-wide CRISPR screen, we identified a synthetic lethal dependency between polyamine depletion and the key ferroptosis suppressor, GPX4. Mechanistically, we show that polyamine deficiency triggers a redistribution of cellular iron, increasing the labile iron pool and upregulating ferritin. To directly visualize this iron buffering in living cells, we developed a genetically encoded fluorescent reporter for redox-active iron. Live-cell analysis revealed a striking inverse correlation between intracellular polyamine levels and redox-active iron at single-cell resolution. These findings reposition polyamines as key regulators of iron homeostasis, with implications for ferroptosis-linked disease states and cellular redox balance.

cell biology↗

bioRxiv2024

A Modular Layer-by-Layer Nanoparticle Platform for Hematopoietic Progenitor and Stem Cell Targeting

Effective delivery of drug and gene cargos to hematopoietic stem and progenitor cells (HSPCs) is a major challenge. Current therapeutic strategies in genetic disorders or hematological malignancies are hindered by high costs, low accessibility, and high off-target toxicities. Layer-by-Layer nanoparticles (LbL NPs) are modular systems with tunable surface properties to enable highly specific targeting. In this work, we developed LbL NPs that target HSPCs via antibody functionalization with reduced off-target uptake by circulating myeloid cells. NPs layered with poly(acrylic acid), a bioinert polymer, provided more stealth properties in vivo than other tested bioactive polyanions. The additional conjugation of anti-cKit and anti-CD90 antibodies improved NP uptake by 2-to 3-fold in non-differentiated bone marrow cells in vitro. By contrast, anti-CD105 functionalized NPs showed the highest association to HSPCs in vivo, ranging from 3.0-8.5% in progenitor subpopulations. This LbL NP platform was then adapted to target human HSPC receptors, with similar targeting trends in healthy CD34+ human cells. By contrast, anti-CXCR4 functionalization demonstrated the greatest targeting to human B-cell lymphoma and leukemia cells. Taken together, these results underscore the therapeutic potential of this modular LbL NP platform with the capacity to target HSPCs in a disease-dependent context.

bioengineering↗

bioRxiv2024

Pooled nanoparticle screening using a chemical barcoding approach

We report the development of a small molecule-based barcoding platform for pooled screening of nanoparticle delivery. Using aryl halide-based tags (halocodes), we achieve high-sensitivity detection via gas chromatography coupled with mass spectrometry or electron capture. This enables barcoding and tracking of nanoparticles with minimal halocode concentrations and without altering their physicochemical properties. To demonstrate the utility of our platform for pooled screening, we synthesized a halocoded library of polylactide-co-glycolide (PLGA) nanoparticles and quantified uptake in ovarian cancer cells in a pooled manner. Our findings correlate with conventional fluorescence-based assays. Additionally, we demonstrate the potential of halocodes for spatial mapping of nanoparticles using mass spectrometry imaging (MSI). Halocoding presents an accessible and modular nanoparticle screening platform capable of quantifying delivery of pooled nanocarrier libraries in a range of biological settings.

bioengineering↗

bioRxiv2024

'Target-and-release' nanoparticles for effective immunotherapy of metastatic ovarian cancer

Immunotherapies such as checkpoint inhibitors (CPI) are effective in treating several advanced cancers, but these treatments have had limited success in metastatic ovarian cancer (OC). Here, we engineered liposomal nanoparticles (NPs) carrying a layer-by-layer (LbL) polymer coating that promotes their binding to the surface of OC cells. Covalent anchoring of the potent immunostimulatory cytokine interleukin-12 (IL-12) to phospholipid headgroups of the liposome core enabled the LbL particles to concentrate IL-12 in disseminated OC tumors following intraperitoneal administration. Shedding of the LbL coating and serum protein-mediated extraction of IL-12-conjugated lipids from the liposomal core over time enabled IL-12 to disseminate in the tumor bed following rapid NP localization in tumor nodules. Optimized IL-12 LbL-NPs promoted robust T cell accumulation in ascites and tumors in mouse models, extending survival compared to free IL-12 and remarkedly sensitizing tumors to CPI, leading to curative treatments and immune memory.

bioengineering↗

bioRxiv2024

Ether lipids influence cancer cell fate by modulating iron uptake

Cancer cell fate has been widely ascribed to mutational changes within proteincoding genes associated with tumor suppressors and oncogenes. In contrast, the mechanisms through which the biophysical properties of membrane lipids influence cancer cell survival, dedifferentiation and metastasis have received little scrutiny. Here, we report that cancer cells endowed with high metastatic ability and cancer stem celllike traits employ ether lipids to maintain low membrane tension and high membrane fluidity. Using genetic approaches and lipid reconstitution assays, we show that these ether lipid-regulated biophysical properties permit non-clathrin-mediated iron endocytosis via CD44, resulting in significant increases in intracellular redox-active iron and enhanced ferroptosis susceptibility. Using a combination of in vitro threedimensional microvascular network systems and in vivo animal models, we show that loss of ether lipids from plasma membranes also strongly attenuates extravasation, metastatic burden and cancer stemness. These findings illuminate a mechanism whereby ether lipids in carcinoma cells serve as key regulators of malignant progression while conferring a unique vulnerability that can be exploited for therapeutic intervention.

cancer biology↗

bioRxiv2023

Electrophoresis-Based Approach for Characterizing Dendrimer-Protein Interactions: A Proof-of-Concept Study

Improving the clinical translation of nanomedicine requires better knowledge about how nanoparticles interact with biological environments. As researchers are recognizing the importance of understanding the protein corona and characterizing how nanocarriers respond in biological systems, new tools and techniques are needed to analyze nanocarrier-protein interactions, especially for smaller-size (<10nm) nanoparticles like polyamidoamine (PAMAM) dendrimers. Here we developed a streamlined, semi-quantitative approach to assess dendrimer-protein interactions using a non-denaturing electrophoresis technique combined with mass spectrometry. With this protocol, we detect fluorescently tagged dendrimers and proteins simultaneously, enabling us to analyze when dendrimers migrate with proteins. We found PAMAM dendrimers mostly interact with complement proteins, particularly C3 and C4a, which aligns with previously published data, verifying our approach can be used to isolate and identify dendrimer-protein interactions. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=134 SRC="FIGDIR/small/555747v1_ufig1.gif" ALT="Figure 1"> View larger version (29K): org.highwire.dtl.DTLVardef@102bdeeorg.highwire.dtl.DTLVardef@103914corg.highwire.dtl.DTLVardef@138402eorg.highwire.dtl.DTLVardef@1fdbbd2_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2023

A new label-free optical imaging method for the lymphatic system enhanced by deep learning

Our understanding of the lymphatic vascular system lags far behind that of the blood vascular system, limited by available imaging technologies. We present a label-free optical imaging method that visualizes the lymphatic system with high contrast. We developed an orthogonal polarization imaging (OPI) in the shortwave infrared range (SWIR) and imaged both lymph nodes and lymphatic vessels of mice and rats in vivo through intact skin, as well as human mesenteric lymph nodes in colectomy specimens. By integrating SWIR-OPI with U-Net, a deep learning image segmentation algorithm, we automated the lymph node size measurement process. Changes in lymph nodes in response to cancer progression were monitored in two separate mouse cancer models, through which we obtained insights into pre-metastatic niches and correlation between lymph node masses and many important biomarkers. In a human pilot study, we demonstrated the effectiveness of SWIR-OPI to detect human lymph nodes in real time with clinical colectomy specimens. One Sentence SummaryWe develop a real-time high contrast optical technique for imaging the lymphatic system, and apply it to anatomical pathology gross examination in a clinical setting, as well as real-time monitoring of tumor microenvironment in animal studies.

bioengineering↗

bioRxiv2022

Core material and surface chemistry of Layer-by-Layer (LbL) nanoparticles independently direct uptake, transport, and trafficking in preclinical blood-brain barrier (BBB) models

Development of new treatments for neurological disorders, especially brain tumors and neurodegenerative diseases, is hampered by poor accumulation of new therapeutic candidates in the brain. Drug carrying nanoparticles are a promising strategy to deliver therapeutics, but there is a major need to understand interactions between nanomaterials and the cells of the blood-brain barrier (BBB), and to what degree these interactions can be predicted by preclinical models. Here, we use a library of eighteen layer-by-layer electrostatically assembled nanoparticles (LbL-NPs) to independently assess the impact of nanoparticle core stiffness and surface chemistry on in vitro uptake and transport in three common assays, as well as intracellular trafficking in hCMEC/D3 endothelial cells. We demonstrate that nanoparticle core stiffness impacts the magnitude of material transported, while surface chemistry influences how the nanoparticles are trafficked within the cell. Finally, we demonstrate that these factors similarly dictate in vivo BBB transport using intravital imaging through cranial windows in mice, and we discover that a hyaluronic acid surface chemistry provides an unpredicted boost to transport. Taken together, these findings highlight the importance of considering factors such as assay geometry, nanomaterial labelling strategies, and fluid flow in designing preclinical assays to improve nanoparticle screening throughput for drug delivery to the brain.

bioengineering↗

bioRxiv2021

A predictive microfluidic model of human glioblastoma to assess trafficking of blood-brain barrier penetrant nanoparticles

The blood-brain barrier represents a significant challenge for the treatment of high-grade gliomas, and our understanding of drug transport across this critical biointerface remains limited. To advance preclinical therapeutic development for gliomas, there is an urgent need for predictive in vitro models with realistic blood-brain barrier vasculature. Here, we report a vascularized human glioblastoma (GBM) model in a microfluidic device that accurately recapitulates brain tumor vasculature with self-assembled endothelial cells, astrocytes, and pericytes to investigate the transport of targeted nanotherapeutics across the blood-brain barrier and into GBM cells. Using modular layer-by-layer assembly, we functionalized the surface of nanoparticles with GBM-targeting motifs to improve trafficking to tumors. We directly compared nanoparticle transport in our in vitro platform with transport across mouse brain capillaries using intravital imaging, validating the ability of the platform to model in vivo blood-brain barrier transport. We investigated the therapeutic potential of functionalized nanoparticles by encapsulating cisplatin and showed improved efficacy of these GBM-targeted nanoparticles both in vitro and in an in vivo orthotopic xenograft model. Our vascularized GBM model represents a significant biomaterials advance, enabling in-depth investigation of brain tumor vasculature and accelerating the development of targeted nanotherapeutics. Significance StatementThe blood-brain barrier represents a major therapeutic challenge for the treatment of glioblastoma, and there is an unmet need for in vitro models that recapitulate human biology and are predictive of in vivo response. Here we present a new microfluidic model of vascularized glioblastoma featuring a tumor spheroid in direct contact with self-assembled vascular networks comprised of human endothelial cells, astrocytes, and pericytes. This model was designed to accelerate the development of targeted nanotherapeutics, and enabled rigorous assessment of a panel of surface-functionalized nanoparticles designed to exploit a receptor overexpressed in tumor-associated vasculature. Trafficking and efficacy data in the in vitro model compared favorably to parallel in vivo data, highlighting the utility of the vascularized glioblastoma model for therapeutic development.

bioengineering↗

bioRxiv2021

Massively parallel pooled screening reveals genomic determinants of nanoparticle-cell interactions

To accelerate the translation of cancer nanomedicine, we hypothesize that integrated genomic screens will improve understanding of the cellular processes governing nanoparticle trafficking. We developed a massively parallel high-throughput screening method leveraging barcoded, pooled cancer cell lines annotated with multi-omic data to investigate cell association patterns across a nanoparticle library spanning a range of formulations with clinical potential. This approach identified both the materials properties and cell-intrinsic features mediating nanoparticle-cell association. Coupling the data with machine learning algorithms, we constructed genomic nanoparticle trafficking networks and identified nanoparticle-specific biomarkers, including gene expression of SLC46A3. We engineered cell lines to validate SLC46A3 as a biomarker whose expression inversely predicts liposomal nanoparticle uptake both in vitro and in vivo. We further demonstrated the predictive capabilities extend beyond liposomal nanoparticles, regulating both uptake and transfection efficacy of solid lipid nanoparticles. Our work establishes the power of massively parallel pooled cell screens for nanoparticle delivery and enables the identification and utilization of biomarkers to rationally design nanoformulations for specific patient populations.

bioengineering↗