Biology subjects

Cooley, M. B.

Publications and source records attributed to Cooley, M. B..

6 recordsLinked to original sources

bioRxiv2025

Nanobubbles for Precision Oncology: Preclinical Evaluation of Molecular Targeted Ultrasound Contrast Agents in a Rabbit Model

The localization of prostate cancer by ultrasound remains limited by the lack of B-mode conspicuity and the confinement of clinically approved microbubbles (MBs) to the vasculature. This precludes the differentiation of viable tumor tissue, necrotic tissue, and margin-associated disease. We investigate the use of prostate-specific membrane antigen (PSMA)-targeted lipid-shelled perfluorocarbon nanobubbles (PSMA-NBs) in an orthotopic rabbit model using a clinical CEUS system. We implanted PSMA-positive PC3pip-GFP tumors into the prostates of immunosuppressed New Zealand White rabbits and performed transabdominal imaging with PSMA-NBs, MBs, and untargeted nanobubbles (Plain-NB) using the same imaging and analysis protocols. To address tumor heterogeneity and ultrasound boundary ambiguity, ROIs were defined from baseline B-mode images and segmented into the tumor core, rim, and a surrounding peritumoral area. Pixel-wise parametric and decorrelation time (DT) maps were generated and correlated with whole-slide histology (H&E) and PSMA IHC. Compared to MBs, PSMA-NBs exhibited higher peak intensities in the tumor core and rim (1.60-fold and 1.50-fold, respectively) and improved retention (mean transit time: 4.20 to 4.50-fold higher) for up to 10 minutes in the tumor and peritumoral areas. PSMA-NB kinetic and DT parameters also correlated with histology-defined tumor viability and PSMA expression. Compared to Plain-NBs, PSMA-NBs also exhibited improved retention (MTT +21%; AUCwo) in the rim and peritumoral areas. This study demonstrates the capability of PSMA-NBs to characterize prostate cancer by molecular CEUS beyond what is possible with conventional MBs.

bioengineering↗

bioRxiv2023

Assessing Tumor Microenvironment Characteristics and Stratifying EPR with a Nanobubble Companion Nanoparticle via Contrast-Enhanced Ultrasound Imaging

The tumor microenvironment is characterized by dysfunctional endothelial cells, resulting in heightened vascular permeability. Many nanoparticle-based drug delivery systems attempt to use this enhanced permeability combined with impaired lymphatic drainage (a concept known as the enhanced permeability and retention effect or EPR effect) as the primary strategy for drug delivery, but this has not proven to be as clinically effective as anticipated. The specific mechanisms behind the inconsistent clinical outcomes of nanotherapeutics have not been clearly articulated, and the field has been hampered by a lack of accessible tools to study EPR-associated phenomena in clinically relevant scenarios. While medical imaging has tremendous potential to contribute to this area, it has not been broadly explored. This work examines, for the first time, the use of multiparametric dynamic contrast-enhanced ultrasound (CEUS) with a novel nanoscale contrast agent to examine tumor microenvironment characteristics noninvasively and in real-time. We demonstrate that CEUS imaging can: (1) evaluate tumor microenvironment features and (2) be used to help predict the distribution of doxorubicin-loaded liposomes in the tumor parenchyma. CEUS using nanobubbles (NBs) was carried out in two tumor types of high (LS174T) and low (U87) vascular permeability, and time-intensity curve (TIC) parameters were evaluated in both models prior to injection of doxorubicin liposomes. Consistently, LS174T tumors showed significantly different TIC parameters, including area under the rising curve (2.7x), time to peak intensity (1.9x) and decorrelation time (DT, 1.9x) compared to U87 tumors. Importantly, the DT parameter successfully predicted tumoral nanoparticle distribution (r = 0.86 {+/-} 0.13). Ultimately, substantial differences in NB-CEUS generated parameters between LS174T and U87 tumors suggest that this method may be useful in determining tumor vascular permeability and could be used as a biomarker for identifying tumor characteristics and predicting sensitivity to nanoparticle-based therapies. These findings could ultimately be applied to predicting treatment efficacy and to evaluating EPR in other diseases with pathologically permeable vasculature.

bioengineering↗

bioRxiv2023

Efficient ultrasound-mediated drug delivery to orthotopic liver tumors: Direct comparison of doxorubicin-loaded nanobubbles and microbubbles

Liver metastasis is a major obstacle in treating aggressive cancers, and current therapeutic options often prove insufficient. To overcome these challenges, there has been growing interest in ultrasound-mediated drug delivery using lipid-shelled microbubbles (MBs) and nanobubbles (NBs) as promising strategies for enhancing drug delivery to tumors. Our previous work demonstrated the potential of Doxorubicin-loaded C3F8 NBs (hDox-NB, 280 {+/-} 123 nm) in improving cancer treatment in vitro using low-frequency ultrasound. In this study, we investigated the pharmacokinetics and biodistribution of sonicated hDox-NBs in orthotopic rat liver tumors. We compared their delivery and therapeutic efficiency with size-isolated MBs (hDox-MB, 1104 {+/-} 373 nm). Results showed a similar accumulation of hDox in tumors treated with hDox-MBs and unfocused therapeutic ultrasound (hDox-MB+TUS) and hDox-NB+TUS. However, significantly increased apoptotic cell death in the tumor and fewer off-target apoptotic cells in the normal liver were found upon the treatment with hDox-NB+TUS. The tumor-to-liver apoptotic ratio was elevated 9.4-fold following treatment with hDox-NB+TUS compared to hDox-MB+TUS, suggesting that the therapeutic efficacy and specificity are significantly increased when using hDox-NB+TUS. These findings highlight the potential of this approach as a viable treatment modality for liver tumors. By elucidating the behavior of drug-loaded bubbles in vivo, we aim to contribute to developing more effective liver cancer treatments that could ultimately improve patient outcomes and decrease off-target side effects.

bioengineering↗

bioRxiv2022

Decorrelation Time Mapping as an Analysis Tool for Nanobubble-Based Contrast Enhanced Ultrasound Imaging

Nanobubbles (NBs) are nanoscale ([~]100-500 nm diameter) ultrasound (US) contrast agents that enable new robust applications of contrast enhanced US and US-mediated therapy. Due to their sub-micron size, high particle density, and highly deformable shell, NBs exhibit unique properties. In pathological states of heightened vascular permeability, such as in tumours, NBs can extravasate, enabling extravascular applications not currently possible with clinically available microbubbles ([~]1000-10,000 nm diameter). This ability can be explored to develop imaging biomarkers to improve tumour detection. There is a need for an imaging method that can rapidly and effectively separate intravascular versus extravascular NB signal when imaged using nonlinear dynamic contrast enhanced US. Herein, we demonstrated the use of decorrelation time (DT) mapping to achieve this goal. Two in vitro models were used to explore the roles of NB velocity and diffusion on DTs. Mice bearing prostate specific membrane antigen (PSMA) expressing flank tumours (n = 7) were injected with bubble agents to evaluate the in vivo potential of this technique. The DT was calculated at each pixel of nonlinear contrast videos to produce DT maps. Across all models, long DT correlated with slowly moving or entrapped NBs while short DT correlated with flowing NBs. DT maps were sensitive to NBs in tumour tissue with high average DT in tumour regions ([~]10 s) compared to surrounding normal tissue ([~]1 s). Molecular NB targeting to PSMA extended DT (17 s) compared to non-targeted NBs (12 s), demonstrating sensitivity to NB adherence dynamics. Overall, DT mapping of in vivo NB dynamics produced detailed information of tumour tissue and showed potential for quantifying extravascular NB kinetics. This new NB-contrast enhanced US-based biomarker can be useful in molecular ultrasound imaging, with improved sensitivity and specificity of target tissue detection and potential for use as a predictor of vascular permeability and the enhanced permeability and retention (EPR) effect in tumours.

bioengineering↗

bioRxiv2022

Characterization of the Interaction of Nanobubble Ultrasound Contrast Agents with Human Blood Components

Nanoscale ultrasound contrast agents, or nanobubbles, are being explored in preclinical applications ranging from vascular and cardiac imaging to targeted drug delivery in cancer. These sub-micron particles are approximately 10x smaller than clinically available microbubbles. This allows them to effectively traverse compromised physiological barriers and circulate for extended periods of time. While various aspects of nanobubble behavior have been previously examined, their behavior in human whole blood has not yet been explored. Accordingly, herein we examined, for the first time, the short and long-term effects of blood components on nanobubble acoustic response. We observed differences in the kinetics of backscatter from nanobubble suspensions in whole blood compared to bubbles in phosphate buffered saline (PBS), plasma, or red blood cell solutions (RBCs). Specifically, after introducing nanobubbles to fresh human whole blood, signal enhancement gradually increased by 22.8 {+/-} 13.1% throughout our experiment, with peak intensity reached within 145 seconds. In contrast, nanobubbles in PBS had a stable signal with negligible change in intensity (-1.7 {+/-} 3.2%) over 8 minutes. Under the same conditions, microbubbles made with the same lipid formulation showed a -56.8 {+/-} 6.1% decrease in enhancement. Subsequent confocal, fluorescent, and scanning electron microscopy analysis revealed attachment of the nanobubbles to the surface of RBCs, suggesting that direct interactions, or hitchhiking, of nanobubbles on RBCs in the presence of plasma may be a possible mechanism for the observed effects. This phenomenon could be key to extending nanobubble circulation time and has broad implications in drug delivery, where RBC interaction with nanoparticles could be exploited to improve delivery efficiency.

bioengineering↗

bioRxiv2019

Metagenomic characterization of creek sediment microbial communities from a major agricultural region in Salinas, California

Little is known about the public health risks associated with natural creek sediments that are affected by runoff and fecal pollution from agricultural and livestock practices. For instance, the persistence of foodborne pathogens originating from agricultural activities such as Shiga Toxin-producing E. coli (STEC) in such sediments remains poorly quantified. Towards closing these knowledge gaps, the water-sediment interface of two creeks in the Salinas River Valley was sampled over a nine-month period using metagenomics and traditional culture-based tests for STEC. Our results revealed that these sediment communities are extremely diverse and comparable to the functional and taxonomic diversity observed in soils. With our sequencing effort (~4 Gbp per library), we were unable to detect any pathogenic Escherichia coli in the metagenomes of 11 samples that had tested positive using culture-based methods, apparently due to relatively low pathogen abundance. Further, no significant differences were detected in the abundance of human- or cow-specific gut microbiome sequences compared to upstream, more pristine (control) sites, indicating natural dilution of anthropogenic inputs. Notably, a high baseline level of metagenomic reads encoding antibiotic resistance genes (ARGs) was found in all samples and was significantly higher compared to ARG reads in metagenomes from other environments, suggesting that these communities may be natural reservoirs of ARGs. Overall, our metagenomic results revealed that creek sediments are not a major sink for anthropogenic runoff and the public health risk associated with these sediment microbial communities may be low.\n\nIMPORTANCECurrent agricultural and livestock practices contribute to fecal contamination in the environment and the spread of food and water-borne disease and antibiotic resistance genes (ARGs). Traditionally, the level of pollution and risk to public health is assessed by culture-based tests for the intestinal bacterium, E. coli. However, the accuracy of these traditional methods (e.g., low quantification, and false positive signal when PCR-based) and their suitability for sediments remains unclear. We collected sediments for a time series metagenomics study from one of the most highly productive agricultural regions in the U.S. in order to assess how agricultural runoff affects the native microbial communities and if the presence of STEC in sediment samples can be detected directly by sequencing. Our study provided important information on the potential for using metagenomics as a tool for assessment of public health risk in natural environments.

microbiology↗