posted on 2020-06-12, 12:07authored byYonghong Yang, Claudia Fryer, Jack Sharkey, Aidan Thomas, Ulrike Wais, Alexander W. Jackson, Bettina Wilm, Patricia Murray, Haifei Zhang
Noninvasive bioimaging
techniques are critical for assessing the biodistribution of cellular
therapies longitudinally. Among them, photoacoustic imaging (PAI)
can generate high-resolution images with a tissue penetration depth
of ∼4 cm. However, it is essential and still highly challenging
to develop stable and efficient near-infrared (NIR) probes with low
toxicity for PAI. We report here the preparation and use of perylene
diimide derivative (PDI) with NIR absorbance (around 700 nm) as nanoprobes
for tracking mesenchymal stromal cells (MSCs) in mice. Employing an
in-house synthesized star hyperbranched polymer as a stabilizer is
the key to the formation of stable PDI nanoparticles with low toxicity
and high uptake by the MSCs. The PDI nanoparticles remain within the
MSCs as demonstrated by in vitro and in vivo assessments. The PDI-labeled
MSCs injected subcutaneously on the flanks of the mice are clearly
visualized with PAI up to 11 days postadministration. Furthermore,
bioluminescence imaging of PDI-labeled luciferase-expressing MSCs
confirms that the administered cells remain viable for the duration
of the experiment. These PDI nanoprobes thus have good potential for
tracking administered cells in vivo using PAI.