Abstract
BackgroundBreast cancer is the first cause of cancer death among women and its incidence doubled in the last two decades. Several approaches for the treatment of these cancers have been developed. The axillary lymph node dissection (ALND) leads to numerous morbidity complications and is now advantageously replaced by the dissection and the biopsy of the sentinel lymph node. Although this approach has strong advantages, it has its own limitations which are manipulation of radioactive products and possible anaphylactic reactions to the dye. As recently proposed, these limitations could in principle be by-passed if semiconductor nanoparticles (quantum dots or QDs) were used as fluorescent contrast agents for the in vivo imaging of SLN. QDs are fluorescent nanoparticles with unique optical properties like strong resistance to photobleaching, size dependent emission wavelength, large molar extinction coefficient, and good quantum yield.MethodsCdSe/ZnS core/shell QDs emitting around 655 nm were used in our studies. 20 μL of 1 μM (20 pmol) QDs solution were injected subcutaneously in the anterior paw of healthy nude mice and the axillary lymph node (ALN) was identified visually after injection of a blue dye. In vivo fluorescence spectroscopy was performed on ALN before the mice were sacrificed at 5, 15, 30, 60 min and 24 h after QDs injection. ALN and all other organs were removed, cryosectioned and observed in fluorescence microscopy. The organs were then chemically made soluble to extract QDs. Plasmatic, urinary and fecal fluorescence levels were measured.ResultsQDs were detected in ALN as soon as 5 min and up to 24 h after the injection. The maximum amount of QDs in the ALN was detected 60 min after the injection and corresponds to 2.42% of the injected dose. Most of the injected QDs remained at the injection site. No QDs were detected in other tissues, plasma, urine and feces.ConclusionEffective and rapid (few minutes) detection of sentinel lymph node using fluorescent imaging of quantum dots was demonstrated. This work was done using very low doses of injected QDs and the detection was done using a minimally invasive method.
Highlights
Breast cancer is the first cause of cancer death among women and its incidence doubled in the last two decades
The filter set consisted of a 400–440 nm band pass excitation filter associated with a Chemical extraction of Quantum dots (QDs) in axillary lymph node Chemical extraction (Figure 1) of QDs in ALN revealed the presence of 40 ± 12 pmol/g tissue in the ALN already 5 min after injection with a maximum of 209 ± 75 pmol/ g at 60 min after injection
QDs: Quantum Dots; ALN: Axillary Lymph Node after the injection corresponds to 2.42% of the total injected dose
Summary
Breast cancer is the first cause of cancer death among women and its incidence doubled in the last two decades. The axillary lymph node dissection (ALND) leads to numerous morbidity complications and is advantageously replaced by the dissection and the biopsy of the sentinel lymph node This approach has strong advantages, it has its own limitations which are manipulation of radioactive products and possible anaphylactic reactions to the dye. Axillary lymph node dissection (ALND) is the standard surgical treatment in breast cancer patients It consists in whole lymphatic axillary chain removal with the aim to reveal presence of metastases by histology analyses. This procedure leads to numerous morbidity problems such as pain, lymphocel, restriction of arm motion, chronic lymphedema, paresthesia, and, as a consequence, deterioration of life quality For these reasons, an alternative treatment consisting in the sentinel lymph node (SLN) biopsy has been met with enthusiasm by clinicians. This is difficult, if not impossible, to accomplish and is applicable only in endoscopically accessible regions of the colon and stomach [7]
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