Showing papers by "Savas Tasoglu published in 2013"

Flow induces epithelial-mesenchymal transition, cellular heterogeneity and biomarker modulation in 3D ovarian cancer nodules

Abstract: Seventy-five percent of patients with epithelial ovarian cancer present with advanced-stage disease that is extensively disseminated intraperitoneally and prognosticates the poorest outcomes. Primarily metastatic within the abdominal cavity, ovarian carcinomas initially spread to adjacent organs by direct extension and then disseminate via the transcoelomic route to distant sites. Natural fluidic streams of malignant ascites triggered by physiological factors, including gravity and negative subdiaphragmatic pressure, carry metastatic cells throughout the peritoneum. We investigated the role of fluidic forces as modulators of metastatic cancer biology in a customizable microfluidic platform using 3D ovarian cancer nodules. Changes in the morphological, genetic, and protein profiles of biomarkers associated with aggressive disease were evaluated in the 3D cultures grown under controlled and continuous laminar flow. A modulation of biomarker expression and tumor morphology consistent with increased epithelial–mesenchymal transition, a critical step in metastatic progression and an indicator of aggressive disease, is observed because of hydrodynamic forces. The increase in epithelial–mesenchymal transition is driven in part by a posttranslational up-regulation of epidermal growth factor receptor (EGFR) expression and activation, which is associated with the worst prognosis in ovarian cancer. A flow-induced, transcriptionally regulated decrease in E-cadherin protein expression and a simultaneous increase in vimentin is observed, indicating increased metastatic potential. These findings demonstrate that fluidic streams induce a motile and aggressive tumor phenotype. The microfluidic platform developed here potentially provides a flow-informed framework complementary to conventional mechanism-based therapeutic strategies, with broad applicability to other lethal malignancies.

Nanoplasmonic Quantitative Detection of Intact Viruses from Unprocessed Whole Blood

Abstract: Infectious diseases such as HIV and hepatitis B pose an omnipresent threat to global health. Reliable, fast, accurate, and sensitive platforms that can be deployed at the point-of-care (POC) in multiple settings, such as airports and offices, for detection of infectious pathogens are essential for the management of epidemics and possible biological attacks. To the best of our knowledge, no viral load technology adaptable to the POC settings exists today due to critical technical and biological challenges. Here, we present for the first time a broadly applicable technology for quantitative, nanoplasmonic-based intact virus detection at clinically relevant concentrations. The sensing platform is based on unique nanoplasmonic properties of nanoparticles utilizing immobilized antibodies to selectively capture rapidly evolving viral subtypes. We demonstrate the capture, detection, and quantification of multiple HIV subtypes (A, B, C, D, E, G, and subtype panel) with high repeatability, sensitivity, and specificity down to 98 ± 39 copies/mL (i.e., HIV subtype D) using spiked whole blood samples and clinical discarded HIV-infected patient whole blood samples validated by the gold standard, i.e., RT-qPCR. This platform technology offers an assay time of 1 h and 10 min (1 h for capture, 10 min for detection and data analysis). The presented platform is also able to capture intact viruses at high efficiency using immuno-surface chemistry approaches directly from whole blood samples without any sample preprocessing steps such as spin-down or sorting. Evidence is presented showing the system to be accurate, repeatable, and reliable. Additionally, the presented platform technology can be broadly adapted to detect other pathogens having reasonably well-described biomarkers by adapting the surface chemistry. Thus, this broadly applicable detection platform holds great promise to be implemented at POC settings, hospitals, and primary care settings.

Manipulating biological agents and cells in micro-scale volumes for applications in medicine

Abstract: Recent technological advances provide new tools to manipulate cells and biological agents in micro/nano-liter volumes. With precise control over small volumes, the cell microenvironment and other biological agents can be bioengineered; interactions between cells and external stimuli can be monitored; and the fundamental mechanisms such as cancer metastasis and stem cell differentiation can be elucidated. Technological advances based on the principles of electrical, magnetic, chemical, optical, acoustic, and mechanical forces lead to novel applications in point-of-care diagnostics, regenerative medicine, in vitro drug testing, cryopreservation, and cell isolation/purification. In this review, we first focus on the underlying mechanisms of emerging examples for cell manipulation in small volumes targeting applications such as tissue engineering. Then, we illustrate how these mechanisms impact the aforementioned biomedical applications, discuss the associated challenges, and provide perspectives for further development.

Exhaustion of Racing Sperm in Nature-Mimicking Microfluidic Channels During Sorting

Abstract: Fertilization is central to the survival and propagation of a species, however, the precise mechanisms that regulate the sperm's journey to the egg are not well understood. In nature, the sperm has to swim through the cervical mucus, akin to a microfluidic channel. Inspired by this, a simple, cost-effective microfluidic channel is designed on the same scale. The experimental results are supported by a computational model incorporating the exhaustion time of sperm.

Paramagnetic levitational assembly of hydrogels.

Abstract: Figure 1 . (A) Schematic of hydrogel fabrication process. Hydrogel units were fabricated by photolithography. 20 μ L of gel precursor solution was Tissues and organs are composed of repeating functional units. [ 1–3,48 ] Among these repeating basic cellular structures are the hexagonal lobule in liver, the nephron in kidney, and the islets in pankreas. [ 4–6 ] Tissue engineering aims to mimic the native 3D tissue architecture. [ 7 , 47 ] Engineered tissue constructs have broad applications in regenerative medicine [ 8–10 ] and physiological systems for pharmaceutical research. [ 11 ] In vivo , cells are surrounded by extracellular matrix (ECM), and exist in well-defi ned spatial organization with neighboring cells. Tissue functionality depends on these components, their interactions and relative spatial locations. [ 12–14 ] A high level of control over 3D tissue architecture has applications in identifying structure–function relationships in order to resolve underlying mechanisms and to model biological phenomena and diseases in vitro. Scaffolding and existing top-down approaches offer limited control over recapitulating 3D architecture and complex features of native tissues. [ 15 , 16 ] On the other hand, bottom-up methods aim to generate complex tissue structures by assembling building blocks, such as cell encapsulating microscale hydrogels. [ 4 , 17–22 ]

Bioprinting: Functional droplet networks.

Abstract: Tissue-mimicking printed networks of droplets separated by lipid bilayers that can be functionalized with membrane proteins are able to spontaneously fold and transmit electrical currents along predefined paths.

Manipulating Biological Agents and Cells in Micro-Scale Volumes for Applications in Medicine

Abstract: Recent technological advances provide new tools to manipulate cells and biological agents in micro/nano-liter volumes. With precise control over small volumes, the cell microenvironment and other biological agents can be bioengineered; interactions between cells and external stimuli can be monitored; and the fundamental mechanisms such as cancer metastasis and stem cell differentiation can be elucidated. Technological advances based on the principles of electrical, magnetic, chemical, optical, acoustic, and mechanical forces lead to novel applications in point-of-care diagnostics, regenerative medicine, in vitro drug testing, cryopreservation, and cell isolation/purification. In this review, we first focus on the underlying mechanisms of emerging examples for cell manipulation in small volumes targeting applications such as tissue engineering. Then, we illustrate how these mechanisms impact the aforementioned biomedical applications, discuss the associated challenges, and provide perspectives for further development.

Transient swelling, spreading, and drug delivery by a dissolved anti-HIV microbicide-bearing film.

Abstract: There is a widespread agreement that more effective drug delivery vehicles with more alternatives, as well as better active pharmaceutical ingredients (APIs), must be developed to improve the efficacy of microbicide products. For instance, in tropical regions, films are more appropriate than gels due to better stability of drugs at extremes of moisture and temperature. Here, we apply fundamental fluid mechanical and physicochemical transport theory to help better understand how successful microbicide API delivery depends upon properties of a film and the human reproductive tract environment. Several critical components of successful drug delivery are addressed. Among these are: elastohydrodynamic flow of a dissolved non-Newtonian film; mass transfer due to inhomogeneous dilution of the film by vaginal fluid contacting it along a moving boundary (the locally deforming vaginal epithelial surface); and drug absorption by the epithelium. Local rheological properties of the film are dependent on local volume fraction of the vaginal fluid. We evaluated this experimentally, delineating the way that constitutive parameters of a shear-thinning dissolved film are modified by dilution. To develop the mathematical model, we integrate the Reynolds lubrication equation with a mass conservation equation to model diluting fluid movement across the moving vaginal epithelial surface and into the film. This is a complex physicochemical phenomenon that is not well understood. We explore time- and space-varying boundary flux model based upon osmotic gradients. Results show that the model produces fluxes that are comparable to experimental data. Further experimental characterization of the vaginal wall is required for a more precise set of parameters and a more sophisticated theoretical treatment of epithelium.

In Vitro Three-Dimensional Cancer Culture Models

Abstract: The efficacy of chemotherapy drug candidates is conventionally investigated using 2D cancer cell cultures and in vivo animal models. It is crucial to determine signaling pathways, controlling cell proliferation, metabolism, differentiation, and apoptosis functions, which are not optimal to investigate in the monolayer 2D cell culture models. Further, accurate investigation of tumor growth and therapeutic drug efficacy in murine models is challenging because of technical constraints of in vivo imaging and requires euthanizing the animals. Therefore, alternative in vitro cancer models are needed to facilitate the transition of new chemotherapeutic drug candidates from bench to clinical trials. Recent technological advances in microfabrication and bioengineering have provided tools to develop in vitro 3D cancer models that mimic natural tissue microenvironment. This chapter highlights recent developments in in vitro 3D cancer models and their applications for studying the efficacy of the chemotherapeutic drug candidates. We discuss the methods and technologies to develop 3D cancer models including embedded and overlay cell culture, suspension culture, bioprinting, hanging drop, microgravity bioreactor, and magnetic levitation. We also discuss the extracellular matrix components and synthetic scaffolds used in vitro 3D cancer models.