89Zr]Oxinate4 for long-term in vivo cell tracking by positron emission tomography

Putthiporn Charoenphun,Philip J Blower,Levente K Meszaros,James R Ballinger,Trevor J Ferris,Ehsan Sharif-Paghaleh,Michael J Went,Gregory E D Mullen,Krisanat Chuamsaamarkkee

doi:10.1007/s00259-014-2945-x

Abstract

Purpose 111In (typically as [111In]oxinate3) is a gold standard radiolabel for cell tracking in humans by scintigraphy. A long half-life positron-emitting radiolabel to serve the same purpose using positron emission tomography (PET) has long been sought. We aimed to develop an 89Zr PET tracer for cell labelling and compare it with [111In]oxinate3 single photon emission computed tomography (SPECT).Methods[89Zr]Oxinate4 was synthesised and its uptake and efflux were measured in vitro in three cell lines and in human leukocytes. The in vivo biodistribution of eGFP-5T33 murine myeloma cells labelled using [89Zr]oxinate4 or [111In]oxinate3 was monitored for up to 14 days. 89Zr retention by living radiolabelled eGFP-positive cells in vivo was monitored by FACS sorting of liver, spleen and bone marrow cells followed by gamma counting.ResultsZr labelling was effective in all cell types with yields comparable with 111In labelling. Retention of 89Zr in cells in vitro after 24 h was significantly better (range 71 to >90 %) than 111In (43–52 %). eGFP-5T33 cells in vivo showed the same early biodistribution whether labelled with 111In or 89Zr (initial pulmonary accumulation followed by migration to liver, spleen and bone marrow), but later translocation of radioactivity to kidneys was much greater for 111In. In liver, spleen and bone marrow at least 92 % of 89Zr remained associated with eGFP-positive cells after 7 days in vivo.Conclusion[89Zr]Oxinate4 offers a potential solution to the emerging need for a long half-life PET tracer for cell tracking in vivo and deserves further evaluation of its effects on survival and behaviour of different cell types.Electronic supplementary materialThe online version of this article (doi:10.1007/s00259-014-2945-x) contains supplementary material, which is available to authorized users.

Highlights

Cell tracking by scintigraphy with radionuclides has been routine in nuclear medicine for 30 years [1] for tracking autologous leukocytes to detect sites of infection/ inflammation [2, 3]
To assess the effect of [89Zr]oxinate4 on viability of eGFP5T33 cells, samples of 1.2–1.4×106 cells were radiolabelled as described above, washed and incubated in 20 ml of RPMI1640 in T75 tissue culture flasks at 37 °C (5 % CO2)
Mice were culled by CO2 asphyxiation 2 (n=3) and 7 days (n=3) after inoculation with 107 enhanced green fluorescent protein (eGFP)-5T33 cells labelled with 1.5 MBq [89Zr]oxinate4

Summary

Introduction

Cell tracking by scintigraphy with radionuclides has been routine in nuclear medicine for 30 years [1] for tracking autologous leukocytes to detect sites of infection/ inflammation [2, 3]. Regenerative medicine and cell-based therapies are creating new roles for tracking stem cells and chimeric antigen receptor-expressing T-lymphocytes [14, 15]. The near-ubiquitous presence of glucose transporters allows labelling with [18F]fluorodeoxyglucose (FDG), but labelling efficiencies are highly variable, the radiolabel is prone to rapid efflux and the short half-life (110 min) of 18F allows only brief tracking [16,17,18]. A “PET analogue” of [111In]oxinate, capable of cell tracking over 7 days or more, would be highly desirable but is not yet available

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