Optical imaging of the peri-tumoral inflammatory response in breast cancer.
OBJECTIVE
Peri-tumoral inflammation is a common tumor response that plays a central role in tumor invasion and metastasis, and inflammatory cell recruitment is essential to this process. The purpose of this study was to determine whether injected fluorescently-labeled monocytes accumulate within murine breast tumors and are visible with optical imaging.


METHODS
Murine monocytes were labeled with the fluorescent dye DiD and subsequently injected intravenously into 6 transgenic MMTV-PymT tumor-bearing mice and 6 FVB/n control mice without tumors. Optical imaging (OI) was performed before and after cell injection. Ratios of post-injection to pre-injection fluorescent signal intensity of the tumors (MMTV-PymT mice) and mammary tissue (FVB/n controls) were calculated and statistically compared.


RESULTS
MMTV-PymT breast tumors had an average post/pre signal intensity ratio of 1.8+/- 0.2 (range 1.1-2.7). Control mammary tissue had an average post/pre signal intensity ratio of 1.1 +/- 0.1 (range, 0.4 to 1.4). The p-value for the difference between the ratios was less than 0.05. Confocal fluorescence microscopy confirmed the presence of DiD-labeled cells within the breast tumors.


CONCLUSIONS
Murine monocytes accumulate at the site of breast cancer development in this transgenic model, providing evidence that peri-tumoral inflammatory cell recruitment can be evaluated non-invasively using optical imaging.
Sista
Akhilesh K
AK
Department of Radiology and Biomedical Engineering, University of California, San Francisco, USA. asista@gmail.com
Knebel
Robert J
RJ
Tavri
Sidhartha
S
Johansson
Magnus
M
DeNardo
David G
DG
Boddington
Sophie E
SE
Kishore
Sirish A
SA
Ansari
Celina
C
Reinhart
Verena
V
Coakley
Fergus V
FV
Coussens
Lisa M
LM
Daldrup-Link
Heike E
HE
D000818:Animals; D001943:Breast Neoplasms / Q000276:immunology / Q000473:pathology*; D005260:Female; D005456:Fluorescent Dyes / Q000378:metabolism; D006801:Humans; D007249:Inflammation / Q000473:pathology*; D008325:Mammary Neoplasms, Experimental / Q000276:immunology / Q000473:pathology*; D008324:Mammary Tumor Virus, Mouse / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D018613:Microscopy, Confocal / Q000379:methods; D008856:Microscopy, Fluorescence / Q000379:methods*; D009000:Monocytes / Q000166:cytology / Q000378:metabolism
D005456:Fluorescent Dyes