175. the development of contrast agents for immune cell trafficking

Department: NanoEngineering
Faculty Advisor(s): Jesse V. Jokerst

Primary Student
Name: Jeanne Elizabeth Lemaster
Email: jlemaste@ucsd.edu
Phone: 614-657-2222
Grad Year: 2019

Recent evidence continues to implicate the immune system in cancer and suggests an intricate role for macrophages in cancer patients. These cells permeate the tumor stroma and act as tumor-associated macrophages (TAMs). TAMs are part of an inflammatory response used by carcinoma cells to form a supportive stroma. These TAMs may increase angiogenesis, tumor cell invasion, and metastasis throughout the host. Improved imaging of these TAMs is needed and can help explain the biology of the tumor stroma and metastasis. Here, we propose a multimodal contrast agent using acoustic and MRI to image these TAMs. The outcome is real-time knowledge of the tumor stroma to visualize differences in TAM concentrations across metastases while defining tumor borders and determining treatment response. This PLGA-based iron oxide nanoparticle (diameter = 180 nm) was labeled with DiR as a trimodal contrast agent. The PLGA coating facilitated ultrasound signal, the DiR enhanced the photoacoustic signal, and the iron oxide generated the MRI signal. As a model of TAMs, human mesenchymal stem cells were labeled with varying concentrations of PLGA-based nanobubbles from 0 ? 0.48 mg/mL and showed a linear response in ultrasound (US) and photoacoustic (PA) intensity based on concentration with R2 values equal to 0.97 and 0.96 respectively. We then imaged different concentrations of these cells in vivo. Future work will label macrophages both ex vivo and in situ to better understand their trafficking patterns in the tumor

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