Trafficking of superparamagnetic iron oxide particles (Combidex) from brain to lymph nodes in the rat

L. L. Muldoon, P. Varallyay, D. F. Kraemer, G. Kiwic, K. Pinkston, S. L. Walker-Rosenfeld, E. A. Neuwelt

Research output: Contribution to journalArticlepeer-review

37 Scopus citations


Central nervous system (CNS) drainage may occur via connections to the vasculature, but in animal models up to 50% occurs via perivascular, perineural and primitive lymphatic drainage to cervical lymph nodes. We evaluated efflux of particles from the brain to cervical lymph nodes in normal rats, using Combidex iron oxide-based magnetic resonance imaging (MRI) agent. After intracerebral, intraventricular, intracarotid or intravenous injection of Combidex in normal Long Evans rats, particle localization was assessed by MRI and histochemistry for iron and the dextran coat (n = 27). Intraventricular or intracerebral injection, but not intracarotid administration of Combidex (100 μg), resulted in MRI signal changes in the deep cervical lymph nodes around the carotid artery, and, less strongly, in the superficial cervical nodes. Within 2 h of Combidex administration, iron was histologically localized in cervical lymph nodes, with patched staining of capsule and peripheral sinus consistent with delivery via multiple afferent lymphatic vessels. Lymph node staining in groups receiving CNS Combidex was significantly different from controls (P < 0.0001) and was significantly localized in the deep vs. superficial cervical lymph nodes (P = 0.0003). The trafficking of the superparamagnetic iron particles from the CNS in the rat could be visualized by MRI and histology. Combidex provides a powerful tool to rapidly assess drainage of virus-sized particles from the CNS.

Original languageEnglish (US)
Pages (from-to)70-79
Number of pages10
JournalNeuropathology and Applied Neurobiology
Issue number1
StatePublished - Feb 2004


  • Animal model
  • Blood-brain barrier
  • Cerebrospinal fluid
  • Cervical lymphatics
  • Combidex
  • Lymph nodes
  • Magnetic resonance imaging

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Histology
  • Neurology
  • Clinical Neurology
  • Physiology (medical)


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