Healthcare and Medicine Reference
In-Depth Information
12
Radionuclid e Cell-Labeling Methods
Rong Zhou and Hui Qiao
CONTENTS
12.1 Introduction ................................................................................................ 217
12.2 Direct Labeling of Stem Cells with Radionuclides ............................... 218
12.3 Tracking Stem Cells by Reporter Genes Detected by
Radionuclide Imaging............................................................................... 221
12.4 Limitations of Reporter Gene Approach ................................................ 227
12.5 Conclusion .................................................................................................. 227
References............................................................................................................. 228
12.1 Introduction
Positron emission tomography (PET) and single-photon emission tomogra-
phy (SPECT) detect radionuclides and their interactions with biochemical
processes in living subjects. These radionuclide imaging modalities are rou-
tinely used in the clinic for a variety of diagnostic purposes. Due to their
exquisite subnanomolar (10 −11 to 10 −10 M) sensitivity, PET and SPECT are able
to measure biological processes at very low concentrations. The mass of radi-
onuclides can be injected in tracer quantities and generally does not affect
the biological system of the host.
Technological developments of both PET and SPECT have led to the imple-
mentation of specialized systems for small-animal imaging, with much
higher spatial resolution (<2 mm) [1-11]. Such systems, often referred to as
µPET and µSPECT, have dramatically advanced the in vivo imaging in small-
animal models and facilitated clinical translation of diagnostic or therapeu-
tic strategies developed in these models.
The high sensitivity of radionuclide imaging makes it suitable for noninva-
sive tracking of stem cells. In this chapter, methods available to detect stem
cells by radionuclide imaging are discussed. In general, they can be divided
into two categories: (a) the direct labeling method and (b) the reporter gene
approach [12]. The former involves loading radionuclides into stem cells, which
are imaged for short-term (hours or days) tracking of cell distribution. The
latter involves transfecting stem cells with a reporter gene whose expression
is imaged and associated with cell survival or proliferation over a relatively
 
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