Gracie Vargas, Ph.D.
Associate Professor

Gracie Vargas, Ph.D.

Education

Bachelor of Arts, Gustavus Adolphus College, 1994 (Physics)
Master of Science, The University of Texas at Austin, 1997 (Biomedical Engineering)
Doctor of Philosophy, The University of Texas at Austin, 2001 (Biomedical Engineering)
Post-Doctoral Training, University of Texas at Austin, 2001-2002

About the Lab

The primary focus of our laboratory is the investigation and application of emerging optical techniques for monitoring of disease processes or injury. The fundamental basis of our work lies in the fact that optical signals arising from tissue are altered during disease progression, as the source of these signals originates in tissue microstructure and biochemical makeup. Our interests lies in optical signals that may be inherent to the tissue (autofluorescence, scattering, absorption) or arise from cellular/molecular contrast agents which give specificity to the signal source.

Research Projects

Nonlinear Optical Microscopy for staging of Epithelial Neoplasms. The goal of this NIH-funded project is the development and evaluation of a noninvasive imaging approach using multiphoton microscopy (MPM) and second harmonic generation microscopy (SHGM) for optical staging of epithelial precancerous lesions and early neoplasms. Optical alterations are known to occur with neoplastic tranformation. However, while a number of previous optical methods have been associated with high sensitivity to neoplastic change, they generally lacked specificity in detection and staging. Thus this project aims to develop a method with high sensitivity and specificity. In brief project involves the a) the spatiotemporal study of epithelial neoplastic transformation in vivo in an animal model for oral cancer in order to better understand alterations in endogenous optical signals revealed by MPM-SHGM and to identify significant image-based parameters which may serve as markers of neoplastic progression, b) the development and refinement of a noninvasive staging methodology by MPM-SHGM which may assist in guiding surgical resection and in surveillance of patients at risk for recurrence, and c) evaluation of the combination of exogenous contrast agents with MPM-SHGM to reveal molecular-specific signal alterations indicative of neoplastic potential.

Optical property control for enhanced optical monitoring and sensing. The focus of this NSF-funded project is the use of chemical agents for reversibly altering the scattering properties of normally turbid tissue to enhance light propagation. Light penetration in tissue is inherently limited to relatively superficial depths. A temporal window for enhanced light penetration can address limitations in the areas of laser therapeutics, optical diagnostics, and in vivo molecular sensing as in bioluminescence imaging. In collaborative efforts the method is being investigated clinically for laser therapeutics and for enhanced nanoparticle sensing in small animal cancer models.

Optical microscopy for assessing epithelial injury due to topical microbicides. This collaborative project is based on noninvasive optical assessment of cervicovaginal epithelial injury resulting from topical microbicides. Our role on the project is to develop a quantitative endoscopic confocal imaging-based approach that can be used to assess the degree of injury induced by microbicides and correlate the results to susceptibility to infection by HSV-2. In a related project, we are investigating noninvasive optical microscopy for mapping sites of epithelial disrupton with sites of HSV2-GFP fluorescence to better understand transmission mechanisms of HSV2. (UTMB collaborators: Massoud Motamedi, Nigel Bourne, Kathy Vincent, Susan Rosenthal)

Nonlinear optical microscopy for the study of vascular inflammation. This research being pursued along a number of collaborative tracks aims at using MPM and SHG for revealing pathological changes in vascular inflammation. Example projects which have/are being pursued include:

Extracellular matrix remodeling in dissecting aortic aneurysm (Collaborator: Paul Boor, UTMB)

Extracellular Matrix remodeling in vascular inflammation and aortic aneurysm. (Collaborators: Allan Brasier, Adrian Recinos)

Imaging of nanaparticle targeted biomarkers toward study of thrombosis in Antiphospholipid Syndrome (APS) (Collaborator: Silvia Pierangeli, UTMB)

Primary Optical Technologies incorporated into our research:

Multiphoton Microscopy (MPM, two-photon microscopy)

Second Harmonic Generation Microscopy (SHGM)

Confocal Reflectance Microscopy for tissue imaging

Confocal Microendoscopy

Fiber-based multiphoton microscopy

Fluorescence Lifetime Microscopy (FLIM)

Optical coherence tomography

Select Publications

Vargas G., Barton JK, Welch AJ, Use of hyperosmotic chemical agent to improve the laser treatment of cutaneous vascular lesions, Journal of Biomedical Optics, 2008; 13(2):021114.

    Gong B., Sun J., Vargas G, Xu Y,Chang Q, Srivastava D,Boor PJ, Nonlinear Imaging Study of Extracellular Matrix in Chemical-induced, Developmental Dissecting Aortic Aneurysm: Evidence for Defective Collagen Type III, Birth Defects Research Part A: Clinical and Molecular Teratology, 2008; 82(1); 16-24.

    Liu Y, Wang S, Krouse J, Kotov NA, Eghtedari M, Vargas G, Motamedi M, Rapid aqueous photo-polymerization route to polymer and polymer-composite hydrogel 3D inverted colloidal crystal scaffolds, J Biomaterials Res:A, 2007 Mar. 2.

    Youn JI, Vargas G, Wong BF, Milner TE, Depth-resolved phase retardation measurements for laser-assisted non-ablative cartilage reshaping, Physics in Medicine & Biology, 2005; 50:1937-1950.

    Sun J, Shilagard T, Bell B, Motamedi M, Vargas G, In vivo multimodal nonlinear optical imaging of mucosal tissue, Optics Express, 2004; 12(11):2478-86; http://www.opticsexpress.org/abstract.cfm?URI=OPEX-12-11-2478.

    Kotov NA, Liu Y, Wang S, Cumming C, Eghtedari M, Vargas G, Motamedi M, Nichols J, Cortiella J, Inverted colloidal crystals as three-dimensional cell scaffolds, Langmuir, 2004; 20(19):7887-7892.

    Vargas G, Readinger A, Dozier SS, Welch AJ, Morphological changes associated with increased visualization of subdermal blood vessels by tissue optical clearing measured using Doppler optical coherence tomography, Photochemistry & Photobiology, 2003; 77(5): 541-549.

    Choi B, Kim J, Milner TE, Vargas G, Aguilar G, Rylander CG, Nelson JS, Use of optical coherence tomography to monitor biological tissue freezing during cryosurgery, Journal of Biomedical Optics, 2004; 9(2):282-6.

    Telekov S, Vargas G, Nelson JS, Milner TE, Coherent thermal wave imaging of subsurface chromophores in biological materials, Physics in Medicine & Biology, 2002; 47:657-671.

    Vargas G, Chan KF, Thomsen SL, Welch AJ, “The use of osmotically active agents to alter the optical properties of tissue: effects on the fluorescence signal detected through skin, Lasers in Surgery and Medicine, 2001; 29:213-220.

    Chan KF, Choi B, Vargas G, Hammer DX, Sorg B, Pfefer JT, Teichman JMH, Welch AJ, and Jansen ED, “Free electron laser ablation of urinary calculi: an experimental study, IEEE Journal on Selected Topics in Quantum Electronics, 2001; 7(6):1022-1033.

    Barton JK, Vargas G, Pfefer TJ, Welch AJ, "Laser fluence for permanent damage of cutaneous blood vessels", Photochemistry & Photobiology, 70(6): 916-920, 1999.

    Vargas G, Chan EK, Barton JK, Rylander III HG, Welch, "Use of an agent to reduce scattering in skin, Lasers in Surgery and Medicine, 24(2): 133-141, 1999.