Lymphatic vascular response to acute inflammation.

During acute inflammation, functioning lymphatics are believed to reduce edema and to provide a transiting route for immune cells, but the extent at which the dermal lymphatic remodeling impacts lymphatic transport or the factors regulating these changes remains unclear. Herein we quantify the increase in lymphatic endothelial cells (LECs) and examine the expression of pro-angiogenenic and lymphangiogenic factors during acute cutaneous hypersensitivity (CHS). We found that LECs actively proliferate during CHS but that this proliferation does not affect the lymphatic vessel density. Instead, lymphatic remodeling is accompanied by lymphatic vessel leakiness and lower ejection of lymph fluid, which is observed only in the proximal lymphatic vessel draining the inflamed area. LECs and the immune cells release growth factors and cytokines during inflammation, which impact the lymphatic microenvironment and function. We identified that FGF-2, PLGF-2, HGF, EGF, and KC/CXCL17 are differentially expressed within tissues during acute CHS, but both VEGF-C and VEGF-D levels do not significantly change. Our results indicate that VEGF-C and VEGF-D are not the only players and other factors may be responsible for the LECs proliferation and altered lymphatic function in acute CHS.

Quantifying multimodal contrast agent biological activity using near-infrared flow cytometry.

Prior to imaging agent use in preclinical studies and clinical diagnostics, biological activity must be validated. The Lindmo assay has been used conventionally to quantify radiolabeled antibody (Ab) immunoreactivity, although published findings suggest it does not provide consistently accurate results. We developed and tested a near-infrared (NIR) flow cytometry (FC) method for quantifying biological activity of a dual-labeled Ab for use as a multimodal contrast agent in small animal and human positron emission tomography and NIR fluorescence imaging. Antibody specific for epithelial cell adhesion molecule was conjugated to DOTA-NHS-ester, labeled with IRDye 800CW and further labeled with (64)Cu or nonradioactive Cu prior to reacting with human prostate cancer cells for testing by the Lindmo or FC method, respectively. Immunoreactivity of the dual-labeled agent was found to be 76.4 ± 15.7% by the Lindmo assay. When tested with and without Cu labeling using NIR FC, the biological activity was found to be 73.1 ± 7.7 and 79.4 ± 8.1%, respectively. No significant differences were found between these activity levels (p > 0.05), supporting NIR FC as an alternative method for measuring immunoreactivity and demonstrating that Cu labeling does not significantly affect the agent's ability to bind to its target. Biological activity was significantly reduced when the NIR dye-to-protein ratio was increased 3- to 4-fold in agent preparations when tested by FC and the Lindmo assay. In summary, NIR FC is an alternative with similar specificity and sensitivity, and greater reproducibility relative to the Lindmo assay for quantifying biological activity of NIR fluorophore-labeled, multimodal imaging agents.

Imaging prostate cancer lymph node metastases with a multimodality contrast agent.

BACKGROUND: Methods to detect lymph node (LN) metastases in prostate cancer (PCa) are limited. Pelvic LN dissection is commonly performed during prostatectomy, but often followed by morbid complications. More refined methods for detecting LN invasion are needed. METHODS: We developed a dual-labeled targeting agent having a near-infrared (NIR) fluorophore for intraoperative guidance, and a conventional radiotracer for detection of LN metastasis. Nu/Nu mice were orthotopically implanted with DsRed-expressing human PCa (PC3) cells. Antibody (Ab) specific for epithelial cell adhesion molecule was conjugated to DOTA, IRDye 800CW, and radiolabeled with (64) Cu. Dual-labeled Ab was administered intravenously at 10-12 weeks post-implantation, and positron emission tomography/computed tomography (PET/CT) and fluorescence imaging were performed within 18-24 hr. RESULTS: Metastasis to lumbar LNs was detected by DsRed fluorescence imaging, as well as pathology, in 75% of mice having pathology-confirmed primary prostate tumors. These metastases were also detected by NIR fluorescence imaging. In some cases, metastases to sciatic, medial, renal, and axillary nodes were also detected. For all LNs examined, no significant differences were found between the percentages of metastases detected by NIR imaging (63%) and µPET/CT (64%) (P = 0.93), or between those detected by DsRed imaging (25%) and pathological examination (19%) (P = 0.12). CONCLUSION: This study demonstrates that a multimodality contrast agent is useful for early detection of metastatic disease, and has applications for intraoperative PCa treatment. Further agent optimization is necessary to enhance specificity, and provide validation for prostate and other LN metastasizing epithelial cancers.