Fariborz Soroush

Adhesion patterns in the microvasculature are dependent on bifurcation angle

Particle adhesion in vivo is highly dependent on the microvascular environment comprising of unique anatomical, geometrical, physiological fluid flow conditions and cell-particle and cell-cell interactions. Hence, proper design of vascular-targeted drug carriers that efficiently deliver therapeutics to the targeted cells or tissue at effective concentrations must account for these complex conditions observed in vivo. In this study, we build upon our previous results with the goal of characterizing the effects of bifurcations and their corresponding angle on adhesion of functionalized particles and neutrophils to activated endothelium. Our hypothesis is that adhesion is significantly affected by the type of biochemical interactions between particles and vessel wall as well as the presence of bifurcations and their corresponding angle. Here, we investigate adhesion of functionalized particles (2 μm and 7 μm microparticles) to protein coated channels as well as adhesion of human neutrophils to human endothelial cells under various physiological flow conditions in microfluidic bifurcating channels comprising of different contained angles (30°, 60°, 90°, or 120°). Our findings indicate that both functionalized particle and neutrophil adhesion propensity increase with a larger bifurcation angle. Moreover, the difference in the adhesion patterns of neutrophils and rigid, similar sized (7 μm) particles is more apparent in the junction regions with a larger contained angle. By selecting the right particle size range, enhanced targeted binding of vascular drug carriers can be achieved along with a higher efficacy at optimal drug dosage. Hence, vascular drug particle design needs to be tailored to account for higher binding propensity at larger bifurcation angles.

A novel microfluidic assay reveals a key role for protein kinase C δ in regulating human neutrophil–endothelium interaction

A key step in neutrophil‐mediated tissue damage is the migration of activated neutrophils across the vascular endothelium. Previously, we identified protein kinase C δ as a critical regulator of neutrophil migration in sepsis but did not identify specific steps in migration. In this study, we used our novel biomimetic microfluidic assay to delineate systematically the mechanism by which protein kinase C δ regulates individual steps in human neutrophil–endothelial interaction during inflammation. The biomimetic microfluidic assay includes a network of vascular channels, produced from in vivo images connected to a tissue compartment through a porous barrier. HUVECs cultured in vascular channels formed a complete lumen under physiologic shear flow. HUVECs were pretreated with TNF‐α ± a protein kinase C δ inhibitor, and the tissue compartment was filled with a chemoattractant (fMLP or IL‐8). Under physiologic shear flow, the role of protein kinase C δ on spatial and temporal neutrophil adherence/migration was quantified. Protein kinase C δ inhibition significantly reduced neutrophil adhesion in response to fMLP and IL‐8 only under low shear rate and near bifurcations. Protein kinase C δ inhibition also decreased adherence to nonactivated HUVECs in response to fMLP or IL‐8. Protein kinase C δ inhibition reduced neutrophil migration into the tissue compartment in response to fMLP and to a lesser degree, to IL‐8. Antibody‐coated microparticles demonstrated that protein kinase C δ inhibition down‐regulated E‐selectin and ICAM‐1 but not VCAM‐1 expression. With the use of a physiologically relevant in vitro model system, we demonstrate that protein kinase C δ plays an important role in the regulation of neutrophil adherence/migration during inflammation and identifies key steps regulated by protein kinase C δ in neutrophil–endothelial interactions.

Targeted multidrug delivery system to overcome chemoresistance in breast cancer

Chemotherapy has been widely used in breast cancer patients to reduce tumor size. However, most anticancer agents cannot differentiate between cancerous and normal cells, resulting in severe systemic toxicity. In addition, acquired drug resistance during the chemotherapy treatment further decreases treatment efficacy. With the proper treatment strategy, nanodrug carriers, such as liposomes/immunoliposomes, may be able to reduce undesired side effects of chemotherapy, to overcome the acquired multidrug resistance, and to further improve the treatment efficacy. In this study, a novel combinational targeted drug delivery system was developed by encapsulating antiangiogenesis drug bevacizumab into liposomes and encapsulating chemotherapy drug doxorubicin (DOX) into immunoliposomes where the human epidermal growth factor receptor 2 (HER2) antibody was used as a targeting ligand. This novel combinational system was tested in vitro using a HER2 positive and multidrug resistant breast cancer cell line (BT-474/MDR), and in vivo using a xenograft mouse tumor model. In vitro cell culture experiments show that immunoliposome delivery led to a high cell nucleus accumulation of DOX, whereas free DOX was observed mostly near the cell membrane and in cytoplasm due to the action of P-gp. Combining liposomal bevacizumab with immunoliposomal DOX achieved the best tumor growth inhibition and the lowest toxicity. Tumor size decreased steadily within a 60-day observation period indicating a potential synergistic effect between DOX and bevacizumab through the targeted delivery. Our findings clearly indicate that tumor growth was significantly delayed in the combinational liposomal drug delivery group. This novel combinational therapy has great potential for the treatment of patients with HER2/MDR double positive breast cancer.

Murine glomerular transcriptome links endothelial cell-specific molecule-1 deficiency with susceptibility to diabetic nephropathy

Diabetic nephropathy (DN) is the leading cause of kidney disease; however, there are no early biomarkers and no cure. Thus, there is a large unmet need to predict which individuals will develop nephropathy and to understand the molecular mechanisms that govern this susceptibility. We compared the glomerular transcriptome from mice with distinct susceptibilities to DN at four weeks after induction of diabetes, but before histologic injury, and identified differential regulation of genes that modulate inflammation. From these genes, we identified endothelial cell specific molecule-1 (Esm-1), as a glomerular-enriched determinant of resistance to DN. Glomerular Esm-1 mRNA and protein were lower in DN-susceptible, DBA/2, compared to DN-resistant, C57BL/6, mice. We demonstrated higher Esm-1 secretion from primary glomerular cultures of diabetic mice, and high glucose was sufficient to increase Esm-1 mRNA and protein secretion in both strains of mice. However, induction was significantly attenuated in DN-susceptible mice. Urine Esm-1 was also significantly higher only in DN-resistant mice. Moreover, using intravital microscopy and a biomimetic microfluidic assay, we showed that Esm-1 inhibited rolling and transmigration in a dose-dependent manner. For the first time we have uncovered glomerular-derived Esm-1 as a potential non-invasive biomarker of DN. Esm-1 inversely correlates with disease susceptibility and inhibits leukocyte infiltration, a critical factor in protecting the kidney from DN.

PKCδ inhibition as a novel medical countermeasure for radiation-induced vascular damage

In the event of a radiologic catastrophe, endothelial cell and neutrophil dysfunction play important roles in tissue injury. Clinically available therapeutics for radiation‐induced vascular injury are largely supportive. PKCδ was identified as a critical regulator of the inflammatory response, and its inhibition was shown to protect critical organs during sepsis. We used a novel biomimetic microfluidic assay (bMFA) to interrogate the role of PKCδ in radiation‐induced neutrophil‐endothelial cell interaction and endothelial cell function. HUVECs formed a complete lumen in bMFA and were treated with 0.5, 2, or 5 Gy ionizing radiation (IR). At 24 h post‐IR, the cells were treated with a PKCδ inhibitor for an additional 24 h. Under physiologic shear flow, the role of PKCδ on endothelium function and neutrophil adherence/migration was determined. PKCδ inhibition dramatically attenuated IR‐induced endothelium permeability increase and significantly decreased neutrophil migration across IR‐treated endothelial cells. Moreover, neutrophil adhesion to irradiated endothelial cells was significantly decreased after PKCδ inhibition in a flow‐dependent manner. PKCδ inhibition downregulated IR‐induced P‐selectin, intercellular adhesion molecule 1, and VCAM‐1 but not E‐selectin overexpression. PKCδ is an important regulator of neutrophil‐endothelial cell interaction post‐IR, and its inhibition can serve as a potential radiation medical countermeasure.—Soroush, F., Tang, Y., Zaidi, H. M., Sheffield, J. B., Kilpatrick, L. E., Kiani, M. F. PKCδ inhibition as a novel medical countermeasure for radiation‐induced vascular damage. FASEB J. 32, 6436–6444 (2018). www.fasebj.org

Abstract 3382: A physiological model of the tumor microenvironment for screening drug delivery systems

Tumor drug delivery is a complex phenomenon affected by several elements in addition to drug or delivery vehicle9s physico-chemical properties. Tumor microvasculature has many unique features including unusual transport characteristics, high interstitial pressure, and enhanced permeability and retention (EPR) effect. Current in vitro models of tumor drug delivery are oversimplified and, as a result, show poor correlation with in vivo performance. The objective of this study is to develop and characterize a synthetic 3D solid tumor - endothelium model in a novel microfluidic platform that mimics the tumor microenvironment observed in vivo. The novel synthetic tumor model consists of a vascular network of tumor derived endothelial cells forming a complete lumen in communication with 3D solid tumors. Primary human breast tumor associated endothelial cells (HBTAECs) were co-cultured under physiological fluid flow conditions with 3D tumor cells from metastastic (MDA-MB-231) or non-metastatic (MCF-7) origins to study the effect of metastatic potential on the integrity of the adjacent endothelial cell lining. Extravasation of fluorescently labeled liposomes across the endothelium to the tumors was measured following HBTAECs treatment with normal media, tumor conditioned media (TCM), or TNF-α. Tight junction formation was characterized using ZO-1 immunostaining. MDA-MB-231 cells quickly invaded into the vascular network from their primary culture location whereas MCF-7 cells rarely grew beyond the boundary of tumor origin. Permeability of liposomes across the endothelium was significantly higher with TCM treatment compared to both control and TNF-α treated cells (P We have successfully established an in vitro 3D tumor - endothelial cell co-culture model in a novel microfluidic platform that closely mimics the tumor microenvironment in vivo. This system reproduces the tumor permeability and retention (EPR) effect on a chip. This realistic in vitro model can have great potential in applications such as cell-cell/cell-drug carrier interaction studies, drug delivery carrier screening, and drug efficacy testing. Citation Format: Yuan Tang, Fariborz Soroush, Sudhir Deosarkar, Bin Wang, Balabhaskar Prabhakarpandian, Mohammad Kiani. A physiological model of the tumor microenvironment for screening drug delivery systems. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3382.