Evidence for in vivo macrophage mediated tumor uptake of paramagnetic/fluorescent liposomes

Daniela Delli Castelli, Enzo Terreno, Claudia Cabella, Linda Chaabane, Stefania Lanzardo, Lorenzo Tei, Massimo Visigalli, Silvio Aime

Research output: Contribution to journalArticlepeer-review


Dysprosium (Dy)-loaded liposomes act as excellent T2- susceptibility agents at high magnetic field strength. The R2- enhancement increases with the size of the liposomes and the concentration of entrapped paramagnetic metal complexes. Neuro-2a tumor cells are readily labeled when Dy-loaded liposomes, suitably functionalized with glutamine residues (Gln), are added to the culture medium as glutamine receptors are highly expressed in such proliferating tumor cells. By using fluorescent liposomes doped with fluorescent dyes (either incorporated in the membrane or included in the inner cavity), confocal microscopy experiments showed that targeted liposomes are taken up much more avidly than non-targeted vesicles. In vivo studies showed that glutamine-functionalized and nonfunctionalized liposomes accumulate in the tumor region to a similar extent. Confocal images of the excised tumor showed extensive co-localization of liposomes and macrophages in both cases. It is suggested that the loss of tumor specificity, shown by Gln-functionalized liposomes in vivo, has to be associated with the efficient removal of liposomes operated by the RES (reticulo endoplasmatic system) or tumor associated macrophages.

Original languageEnglish
Pages (from-to)1084-1092
Number of pages9
JournalNMR in Biomedicine
Issue number10
Publication statusPublished - 2009


  • Lanthanides
  • Liposomes
  • Macrophages
  • MRI
  • Tumor

ASJC Scopus subject areas

  • Molecular Medicine
  • Spectroscopy
  • Radiology Nuclear Medicine and imaging


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