Dana Blessington

Metabolism-enhanced tumor localization by fluorescence imaging: in vivo animal studies.

We present a high-sensitivity near-infrared optical imaging system for noninvasive cancer detection and localization based on molecularly labeled fluorescent contrast agents. This frequency-domain system utilizes the interferencelike pattern of diffuse photon density waves to achieve high detection sensitivity and localization accuracy for the fluorescent heterogeneity embedded inside the scattering media. A two-dimensional localization map is obtained through reflectance probe geometry and goniometric reconstruction. In vivo measurements with a tumor-bearing mouse model by use of the novel Cypate-mono-2-deoxy-glucose fluorescent contrast agent, which targets the enhanced tumor glycolysis, demonstrate the feasibility of detection of a 2-cm-deep subsurface tumor in the tissuelike medium, with a localization accuracy within 2-3 mm.

Tricarbocyanine cholesteryl laurates labeled LDL: new near infrared fluorescent probes (NIRFs) for monitoring tumors and gene therapy of familial hypercholesterolemia.

For monitoring low-density lipoprotein receptors (LDLr) in tumors and in livers of patients with familial hypercholesterolemia (FH) treated with gene therapy, a series of tricarbocyanine cholesteryl laurates were synthesized with the cholesteryl laurate moiety serving as the lipid-chelating anchor for low-density lipoprotein (LDL). One of these conjugates, TCL17, was successfully used to label LDL to give a new NIRF, TCL17-LDL. Ex vivo biological studies on an LDLr overexpressing tumor model, human hepatoblastoma G(2) (HepG(2)), confirmed that this NIRF were internalized selectively by the tumor and detected with high sensitivity by a low-temperature 3-D redox scanner.

Redox ratio of mitochondria as an indicator for the response of photodynamic therapy

The effect of photodynamic therapy (PDT) treatment on the metabolic state of tumor mitochondria is investigated by imaging of tumor redox status. PDT is performed using the photosensitizer pyropheophorbide-2-deoxyglucosamide (Pyro-2DG), which utilizes the glucose import pathway. It is found that Pyro-2DG-induced PDT resulting in a highly oxidized state of tumor mitochondria. This is determined from the redox ratio changes derived from the intrinsic oxidized flavoprotein (Fp) and reduced pyridine nucleotide (PN) [i.e., reduced nicotinamide adenine dinucleotide (NADH)] fluorescence signals observed using a cryoimager. Thus, the redox ratio is a sensitive indicator for providing reliable and informative measurements of PDT-induced tissue damage. In the PDT treated region of the tumor, highly oxidized flavoprotein and diminishing NADH fluorescence is detected, suggesting that flavoprotein and NADH are oxidized by singlet oxygen produced in the photosensitization process.

High-resolution three-dimensional scanning optical image system for intrinsic and extrinsic contrast agents in tissue

This article presents the theory and development of a three-dimensional (3D) imaging instrument capable of determining the biochemical properties of tissue by measuring the absorption or fluorescence of different intrinsic and extrinsic agents simultaneously. A bifurcated optical fiber bundle, serving to deliver the excitation light and collect the emission or reflection light, scans over the flat tissue surface retrieving optical signals in each pixel. Two-dimensional (2D) images of a series of subsequent sections are obtained after signal conversion and processing to yield a 3D image. Manipulation of the scanning step and diameter size of the fibers within the bundle, the spatial resolution of the instrument attains a maximum of 40 × 40 × 10 μm3. The wavelength range is extended from ultraviolet to the near infrared (NIR) through specialized optical design, typically employed for the NIR extrinsic contrast agents study. The instrument is most applicable in situations involving the measurement of fluores...

Near-infrared phase cancellation instrument for fast and accurate localization of fluorescent heterogeneity

Near-infrared (NIR) diffuse optical imaging has become a promising method for noninvasive in vivo detection of breast cancer with intrinsic chromophores. Recent developments in molecular specific targeting fluorescent contrast agents offer high tumor to normal tissue contrast, and are capable of selectively labeling various precancer/cancer signatures, thus enhancing both the sensitivity and specificity of cancer detection. To detect a subsurface tumor labeled by fluorescent contrast agents, we have developed a phase cancellation imaging system for fast localization of fluorescent object embedded several centimeters deep inside the turbid media. The instrument is a frequency domain (50 MHz) phase modulation system with dual out-of-phase sources. The excitation wavelength is 780 nm and the fluorescence photons are collected through an 830±10 nm band-pass filter. Localization of fluorescent objects inside the scattering media is accurate using a phase cancellation device. The localization error for a 5 mm d...

Detection and imaging of the reconstituted pyropheophorbide-cholesterol oleate labeled low-density lipoprotein in the HepG2 tumor

We utilized the nude mouse model bearing the human hepatoblastoma G2 (HepG2) tumor and B-16 Murine Melanoma tumor to study the delivery and detection of the reconstituted Pyropheophorbide Cholesterol Oleate (r-pyroCE) molecular beacon. The delivery vehicle, low-density lipoprotein (LDL), labeled with the porphyrin derivative, was employed in response of the overexpression of LDL receptors in the HepG2 tumor. The B-16 melanoma tumor was also observed in this study for its overexpression of the LDL receptors. The tumors were imaged using the 3D low temperature scanner to produce images throughout several sliced sections of each tumor. The fluorescence signal of the pyropheophorbide was detected at 720nm when excited at 670nm in the tumor tissue. The uniform distribution of the signal in the HepG2 tumor shows extravasation of the beacon from the blood vessels. The B-16 tumor did not exhibit strong fluorescent signals and successful delivery as the HepG2 tumor outside the blood vessels and into the tumor tissue.

Novel Fluorochromes for Functional Imaging of Cancer

In spite of no molecular beacon has been used in a significant trial with human breast cancer patients, biopsy specimens open the opportunity to image intrinsic and extrinsic signals of animal and human cancers.

Imaging of tumor hypermetabolism with near-infrared fluorescence contrast agents

We have developed a high sensitivity near-infrared (NIR) optical imaging system for non-invasive cancer detection through molecular labeled fluorescent contrast agents. Near-infrared (NIR) imaging can probe tissue deeply thus possess the potential for non-invasively detection of breast or lymph node cancer. Recent developments in molecular beacons can selectively label various pre-cancer/cancer signatures and provide high tumor to background contrast. To increase the sensitivity in detecting fluorescent photons and the accuracy of localization, phase cancellation (in- and anti-phase) device is employed. This frequency-domain system utilizes the interference-like pattern of diffuse photon density wave to achieve high detection sensitivity and localization accuracy for the fluorescent heterogeneity embedded inside the scattering media. The opto-electronic system consists of the laser sources, fiber optics, interference filter to select the fluorescent photons and the high sensitivity photon detector (photomultiplier tube). The source-detector pair scans the tissue surface in multiple directions and the two-dimensional localization image can be obtained using goniometric reconstruction. In vivo measurements with tumor-bearing mouse model using the novel Cypate-mono-2-deoxy-glucose (Cypate-2-D-Glucosamide) fluorescent contrast agent, which targets the enhanced tumor glycolysis, demonstrated the feasibility on detection of 2 cm deep subsurface tumor in the tissue-like medium, with a localization accuracy within 2 ~ 3 mm. This instrument has the potential for tumor diagnosis and imaging, and the accuracy of the localization suggests that this system could help to guide the clinical fine-needle biopsy. This portable device would be complementary to X-ray mammogram and provide add-on information on early diagnosis and localization of early breast tumor.

Fluorescent imaging the characteristic of Pyro-2DG uptake in the normal tissue using the Cryo-Imager

In the previous study, we have proved that Pyro-2DG could be trapped and accumulated in the tumor. The fluorescent signal of Pyro-2DG has high correlation with the redox ratio. To further study the extrinsic probe Pyro-2DG, the characteristic of Pyro-2DG uptake by the liver tissue of rats and the distribution of Pyro-2DG in various tissues were detected using the Cryo-Imager. The result indicated that Pyro-2DG uptake by the liver resulted in the metabolic state shift towards an increased concentration of oxidized electron carriers and it completely recovered after 24hrs. Pyro-2DG with infusion injection could avoid the oxidized damage of the normal tissue induced by Pyro-2DG uptake. The distribution of Pyro-2DG in various normal tissues indicated that Pyro-2DG could be as a tumor special near infrared ray (NIR) probe besides the hepatic tumor and lymph system tumor.

Determination of subsurface tumor localization in animal models with near-infrared (NIR) fluorescence imaging

We have developed a novel imaging system for determining the localization of tumors labeled by fluorescent contrast agents and embedded several centimeters inside the highly scattered medium. This frequency-domain system utilizes the phased cancellation configuration with a goniometric probe. The instrumentation performance on the phantom test can detect 3 mm diameter sphere filled with 1 nM fluorescent dye, Indocyanine Green (ICG), and 3 cm deep inside the scattering medium with similar optical properties as human breast tissue within a 1 mm localization confidence. Mouse tumor model immersed in appropriate scattering/absorbing medium is used for animal test. Intra-tumor injection of ICG demonstrates the localization of the tumor (5 mm in diameter) submerged 3 cm deep inside the highly scattered medium with 2 mm position error. Results with NIR804-D-Glucosamide on the AR42J tumor bearing nude mouse are also presented with 3 mm localization error. The accuracy of the localization suggest that this system would be helpful to guide the clinical fine-needle biopsy for early breast cancer detection.