Week 4: Many ways to measure

Despite the fact that the midpoint checkpoint has now arrived for my immersion program and I will soon be winding down for a trip home to Ithaca, the arrangements for my culminating research project have only accelerated this week, to my excitement. Most likely, my project will evaluate methods of quantifying and assessing lymphatic function to diagnose lymphedema. Obesity is a well-documented risk factor for lymphedema and has been associated with decreased macromolecule clearance, impaired trafficking of antigen presenting cells and abnormal lymph node architecture. Thus, dramatic changes in lymphatic fluid and immune cell transport can be utilized as a diagnostic tool for observing lymphedema resulting from obesity. A potential goal would then be to discern which test for lymphatic function provides the best specificity and sensitivity for observing significant differences in lymphedema versus control. 

Dr. Mehrara introduced to me five methods for assessing lymphatic function: collecting vessel pumping, lymphatic leakiness, initial lymphatic vessel density, macromolecule clearance, and dendritic cell (DC) trafficking. As inflammatory conditions worsen in the affected lymphatics, the collecting lymphatic vessels downstream pump less frequently and with less force, which can be verified with image processing of NIR ICG imaging I mentioned in the previous blog post. Inflammatory damage in lymphedema also leads to lymphatic backflow, allowing collected lymph fluid to leak into interstitial space, and this can be seen both with NIR ICG and other dye injections. One of the hallmarks of lymphedema is lack of efficient lymphangiogenesis, and thus a lower density and area of lymphatic vessels. The impaired lymphatic uptake of interstitial fluid in lymphedema can also be measured by the degree of macromolecule clearance, often technetium-99m (99mTc) used as a radionuclide agent for medical imaging, or DC clearance. Of these techniques, lymphatic pumping measurement is the easiest to record in human patients, and thus might be the most feasible for observing in my clinical experience. 

While I performed extensive literature searching for the background of my project, I assisted in isolating protein from LECs treated with varying concentrations of VEGFC, treating them with a lysis buffer containing inhibitors for proteases and phosphatases, as the proteins of interest where phosphorylated forms of intracellular pathway components. So now I have experience with isolating both nucleic acids and proteins from LECs for downstream analysis. For my surgical shadowing experience of the week, I had the honor of accompanying my friends again to Dr. Spector's muscle flap tissue reconstruction surgery for a patient that had undergone cervical spine discectomy. By the time we arrived to the operating room, the patient's spine was already exposed in a wound and had been treated for the underlying neurological issue. Dr. Spector's expertise in plastic surgery was thus need to reconstruct this considerable wound with muscle from other parts of the body. It seemed that a team of many different experts are needed for even a single surgery.