INTEC   05402
INSTITUTO DE DESARROLLO TECNOLOGICO PARA LA INDUSTRIA QUIMICA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Simultaneous, dual modal and quantitative tracking of two distinct cell populations
Autor/es:
F. BONETTO; M. SRINIVAS; A. HEERSCHAP; C. G. FIGDOR; I. J. M. DE VRIES
Lugar:
Aguas de Lindoia, Sao Paulo, Brasil
Reunión:
Encuentro; XXXV Encontro Nacional de Fisica da Materia Condensada; 2012
Institución organizadora:
Sociedade Brasileira de Fisica
Resumen:
Introduction:
The surge of interest in cellular therapeutics demands a technique for the localization and quanti¯cation of these
cells after transfer to the subject. However, imaging using typical iron-based contrast agents results in dark
spots in images, which can obscure anatomic detail, and quanti¯cation is di±cult. Hence, \hot-spot" imaging
is coming to the fore, primarily using 19F labels. 19F MRI allows direct quanti¯cation of label content, and
therefore cell numbers, from the image data. Here we exploit the technique further to show the simultaneous
tracking of two distinct dendritic cell populations using di®erent 19F labels. The labels we use here consist of
polymer-encapsulated per°uorocarbons (PFCs). Here we image both labeled cell populations simultaneously
using a sequence with a su±ciently broad receiving bandwidth. We also show that the technique is quantitative
for both compounds over a large range of concentrations. The particles are synthesized using components
approved for clinical use, where possible.
Methods:
Primary human DCs were cultured, as per standard protocols for DC vaccination trials. Cells were incubated
with the 19F label, washed and studied further. Nanoparticles were formulated with PFC, in this example we
used per°uoro-15-crown-ether (PFCE) and per°uorooctane (PFO). MRI was done on a 7T horizontal scanner,
using a modi¯ed gradient echo sequence. False color 19F turbo spin-echo images (TR/TE=200/2.82ms, 20o
°ip angle, 1.88x0.94x2mm voxels, 512 averages, 27min) are overlaid on corresponding grayscale 1H images
(TR/TE=1500/14ms, 0.12x0.6x2mm voxels, 8 averages).
Results and Discussion:
The addition of °uorescent dyes allows °uorescent imaging. The imaging sequence allows for simultaneous
acquisition of both signals. Note that this is not chemical shift imaging, but a gradient echo sequence. Thus,
the imaging time is much reduced. The image shows the 19F image obtained, and the post-processing that
can be carried out to correct for the frequency shift. This is calculated using the known frequency of the
compounds and the transmitter, and the bandwidth per pixel. Furthermore, we found that the received signal
is quantitative for both frequencies, over a large range of concentrations. Finally we found that there was no
e®ect on the primary human DC populations labeled, in terms of maturation, ability to active lymphocytes
and migration. Thus, using this technique it will be possible to measure the migration of two cell populations
quantitatively.