A method for the efficient iron-labeling of patient-derived xenograft cells and cellular imaging validation


  • Natasha N. Knier Western University
  • Veronica P. Dubois Western University
  • Yuanxin Chen
  • John A. Ronald Western University
  • Paula J. Foster Western University


bioluminescence imaging, breast cancer, cellular imaging, magnetic particle imaging patient-derived xenografts ?


There is momentum towards implementing patient-derived xenograft models (PDX) in cancer research to reflect the histopathology, tumor behavior, and metastatic properties observed in the original tumor. These models are more predictive of clinical outcomes and are superior to cell lines for preclinical drug evaluation and therapeutic strategies. To study PDX cells preclinically, we used both bioluminescence imaging (BLI) to evaluate cell viability and magnetic particle imaging (MPI), an emerging imaging technology to allow for detection and quantification of iron nanoparticles. The goal of this study was to develop the first successful iron labeling method of breast cancer cells derived from patient brain metastases and validate this method with imaging during tumor development. Luciferase expressing human breast cancer PDX cells (F2-7) were successfully labeled after incubation with micron-sized iron oxide particles (MPIO; 25 μg Fe/ml). NOD/SCID/ILIIrg−/− (n = 5) mice received injections of 1x106 iron-labeled F2-7 cells into the fourth mammary fat pad (MFP). BLI was performed longitudinally to day 49 and MPI was performed up to day 28. In vivo BLI revealed that signal increased over time with tumor development. MPI revealed decreasing signal in the tumor over time. Here, we demonstrate the first application of MPI to monitor the growth of a PDX MFP tumor. To accomplish this, we also demonstrate the first successful labeling of PDX cells with iron oxide particles. Imaging of PDX cells provides a powerful system to better develop personalized therapies targeting breast cancer brain metastasis.


DeSantis C, Ma J, Bryan L, Jemal A. Breast cancer statistics, 2013. CA Cancer J Clin. 2014 Jan-Feb;64(1):52–62. https://doi.org/10.3322/caac.21203 PMID:24114568

Kennecke H, Yerushalmi R, Woods R, Cheang MC, Voduc D, Speers CH, et al. Metastatic behavior of breast cancer subtypes. J Clin Oncol. 2010 Jul;28(20):3271–7. https://doi.org/10.1200/JCO.2009.25.9820 PMID:20498394

Shaffrey ME, Mut M, Asher AL, Burri SH, Chahlavi A, Chang SM, et al. Brain metastases. Curr Probl Surg. 2004 Aug;41(8):665–741. https://doi.org/10.1067/j.cpsurg.2004.06.001 PMID:15354117

Engel J, Eckel R, Aydemir U, Aydemir S, Kerr J, Schlesinger-Raab A, et al. Determinants and prognoses of locoregional and distant progression in breast cancer. Int J Radiat Oncol Biol Phys. 2003 Apr;55(5):1186–95. https://doi.org/10.1016/S0360-3016(02)04476-0 PMID:12654426

Barnholtz-Sloan JS, Sloan AE, Davis FG, Vigneau FD, Lai P, Sawaya RE. Incidence proportions of brain metastases in patients diagnosed (1973 to 2001) in the Metropolitan Detroit Cancer Surveillance System. J Clin Oncol. 2004 Jul;22(14):2865–72. https://doi.org/10.1200/JCO.2004.12.149 PMID:15254054

Hidalgo M, Amant F, Biankin AV, Budinská E, Byrne AT, Caldas C, et al. Patient-derived xenograft models: an emerging platform for translational cancer research. Cancer Discov. 2014 Sep;4(9):998–1013. https://doi.org/10.1158/2159-8290.CD-14-0001 PMID:25185190

Dobrolecki LE, Airhart SD, Alferez DG, Aparicio S, Behbod F, Bentires-Alj M, et al. Patient-derived xenograft (PDX) models in basic and translational breast cancer research. Cancer Metastasis Rev. 2016 Dec;35(4):547–73. https://doi.org/10.1007/s10555-016-9653-x PMID:28025748

Contreras-Zárate MJ, Ormond DR, Gillen AE, Hanna C, Day NL, Serkova NJ, et al. Development of novel patient-derived xenografts from breast cancer brain metastases. Front Oncol. 2017 Nov;7:252. https://doi.org/10.3389/fonc.2017.00252 PMID:29164052

Prescher JA, Contag CH. Guided by the light: visualizing biomolecular processes in living animals with bioluminescence. Curr Opin Chem Biol. 2010 Feb;14(1):80–9. https://doi.org/10.1016/j.cbpa.2009.11.001 PMID:19962933

Parkins KM, Hamilton AM, Makela AV, Chen Y, Foster PJ, Ronald JA. A multimodality imaging model to track viable breast cancer cells from single arrest to metastasis in the mouse brain. Sci Rep. 2016 Oct;6(1):35889. https://doi.org/10.1038/srep35889 PMID:27767185

Heyn C, Ronald JA, Ramadan SS, Snir JA, Barry AM, MacKenzie LT, et al. In vivo MRI of cancer cell fate at the single-cell level in a mouse model of breast cancer metastasis to the brain. Magn Reson Med. 2006 Nov;56(5):1001–10. https://doi.org/10.1002/mrm.21029 PMID:17029229

Makela AV, Murrell DH, Parkins KM, Kara J, Gaudet JM, Foster PJ. Cellular imaging with MRI. Top Magn Reson Imaging. 2016 Oct;25(5):177–86. https://doi.org/10.1097/RMR.0000000000000101 PMID:27748707

Bulte JW. Superparamagnetic iron oxides as MPI tracers: A primer and review of early applications. Adv Drug Deliv Rev. 2019 Jan;138(138):293–301. https://doi.org/10.1016/j.addr.2018.12.007 PMID:30552918

Wu LC, Zhang Y, Steinberg G, Qu H, Huang S, Cheng M, et al. A Review of Magnetic Particle Imaging and Perspectives on Neuroimaging. AJNR Am J Neuroradiol. 2019 Feb;40(2):206–12. https://doi.org/10.3174/ajnr.A5896 PMID:30655254

Parkins KM, Melo KP, Chen Y, Ronald JA, Foster PJ. Visualizing tumour self-homing with magnetic particle imaging. Nanoscale. 2021 Mar;13(12):6016–23. https://doi.org/10.1039/D0NR07983A PMID:33683241

Nejadnik H, Pandit P, Lenkov O, Lahiji AP, Yerneni K, Daldrup-Link HE. Ferumoxytol Can Be Used for Quantitative Magnetic Particle Imaging of Transplanted Stem Cells. Mol Imaging Biol. 2019 Jun;21(3):465–72. https://doi.org/10.1007/s11307-018-1276-x PMID:30194566

Zheng B, von See MP, Yu E, Gunel B, Lu K, Vazin T, et al. Quantitative Magnetic Particle Imaging Monitors the Transplantation, Biodistribution, and Clearance of Stem Cells In Vivo. Theranostics. 2016 Jan;6(3):291–301. https://doi.org/10.7150/thno.13728 PMID:26909106

Bulte JW, Walczak P, Janowski M, Krishnan KM, Arami H, Halkola A, et al. Quantitative “Hot Spot” Imaging of Transplanted Stem Cells using Superparamagnetic Tracers and Magnetic Particle Imaging (MPI). Tomography. 2015 Dec;1(2):91–7. https://doi.org/10.18383/j.tom.2015.00172 PMID:26740972

Wang P, Goodwill PW, Pandit P, Gaudet J, Ross A, Wang J, et al. Magnetic particle imaging of islet transplantation in the liver and under the kidney capsule in mouse models. Quant Imaging Med Surg. 2018 Mar;8(2):114–22. https://doi.org/10.21037/qims.2018.02.06 PMID:29675353

Rivera-Rodriguez A, Hoang-Minh LB, Chiu-Lam A, Sarna N, Marrero-Morales L, Mitchell DA, et al. Tracking adoptive T cell immunotherapy using magnetic particle imaging. Nanotheranostics. 2021 Apr;5(4):431–44. https://doi.org/10.7150/ntno.55165 PMID:33972919

Makela AV, Gaudet JM, Schott MA, Sehl OC, Contag CH, Foster PJ. Magnetic Particle Imaging of Macrophages Associated with Cancer: Filling the Voids Left by Iron-Based Magnetic Resonance Imaging. Mol Imaging Biol. 2020 Aug;22(4):958–68. https://doi.org/10.1007/s11307-020-01473-0 PMID:31933022

Gaudet J, Mansfield J, Goodwill P. Imaging Cancer Immunology: Tracking Immune Cells in vivo with Magnetic Particle Imaging. J Immunol. 2019 May 1;202(1 Supplement):130.7-130.7.

Arbab AS, Yocum GT, Kalish H, Jordan EK, Anderson SA, Khakoo AY, et al. Efficient magnetic cell labeling with protamine sulfate complexed to ferumoxides for cellular MRI. Blood. 2004 Aug;104(4):1217–23. https://doi.org/10.1182/blood-2004-02-0655 PMID:15100158

Ni J, Ramkissoon SH, Xie S, Goel S, Stover DG, Guo H, et al. Combination inhibition of PI3K and mTORC1 yields durable remissions in mice bearing orthotopic patient-derived xenografts of HER2-positive breast cancer brain metastases. Nat Med. 2016 Jul;22(7):723–6. https://doi.org/10.1038/nm.4120 PMID:27270588

Sharma S, Wu SY, Jimenez H, Xing F, Zhu D, Liu Y, et al. Ca2+ and CACNA1H mediate targeted suppression of breast cancer brain metastasis by AM RF EMF. EBioMedicine. 2019 Jun;44:194–208. https://doi.org/10.1016/j.ebiom.2019.05.038 PMID:31129098

Oshi M, Okano M, Maiti A, Rashid OM, Saito K, Kono K, et al. Novel Breast Cancer Brain Metastasis Patient-Derived Orthotopic Xenograft Model for Preclinical Studies. Cancers (Basel). 2020 Feb;12(2):444. https://doi.org/10.3390/cancers12020444 PMID:32074948

Turner TH, Alzubi MA, Sohal SS, Olex AL, Dozmorov MG, Harrell JC. Characterizing the efficacy of cancer therapeutics in patient-derived xenograft models of metastatic breast cancer. Breast Cancer Res Treat. 2018 Jul;170(2):221–34. https://doi.org/10.1007/s10549-018-4748-4 PMID:29532339

Liu Z, Wang Y, Kabraji S, Xie S, Pan P, Liu Z, et al. Improving orthotopic mouse models of patient-derived breast cancer brain metastases by a modified intracarotid injection method. Sci Rep. 2019 Jan;9(1):622. https://doi.org/10.1038/s41598-018-36874-3 PMID:30679540

Yu EY, Bishop M, Zheng B, Ferguson RM, Khandhar AP, Kemp SJ, et al. Magnetic Particle Imaging: A Novel in Vivo Imaging Platform for Cancer Detection. Nano Lett. 2017 Mar;17(3):1648–54. https://doi.org/10.1021/acs.nanolett.6b04865 PMID:28206771

Knier NN, Hamilton AM, Foster PJ. Comparing the fate of brain metastatic breast cancer cells in different immune compromised mice with cellular magnetic resonance imaging. Clin Exp Metastasis. 2020 Aug;37(4):465–75. https://doi.org/10.1007/s10585-020-10044-0 PMID:32533389





How to Cite

Knier NN, Dubois VP, Chen Y, Ronald JA, Foster PJ. A method for the efficient iron-labeling of patient-derived xenograft cells and cellular imaging validation. J Biol Methods [Internet]. 2021Sep.2 [cited 2021Dec.4];8(3):e154. Available from: https://jbmethods.org/jbm/article/view/356