Low-intensity pulsed ultrasound increases cellular uptake of superparamagnetic iron oxide nanomaterial: results from human osteosarcoma cell line U2OS.
OBJECTIVE
To determine whether low-intensity pulsed ultrasound (LIPUS) is able to facilitate the uptake of a superparamagnetic iron oxide (SPIO) nanomaterial by cells that do not express high endocytosis capacity.


METHODS
The human osteosarcoma cell line U2OS and a silica-coated SPIO functionalized peripherally with amines groups (overall diameter 8 nm) were used in this study. Adherent U2OS cells were labeled with SPIO by incubating with culture media containing the SPIO at 4.5 microg[Fe]/mL. LIPUS with the same parameters as those used in clinical application to accelerate bone fracture healing (1.5 MHz, duty cycle 1:4, spatial-average temporal-average intensity 30 mW/cm(2)) was applied to the cells at the beginning of the labeling process for 0, 0.5, 1, or 3 hours. The total incubation time with SPIO was 12 hours. SPIO labeling efficiency was evaluated with Prussian blue staining and a blueness measurement method, and magnetic resonance imaging (MRI) of cell pellets via measuring areas of SPIO-induced signal void.


RESULTS
Both Prussian blue staining and in vitro MRI demonstrated that LIPUS application increased the SPIO nanomaterial labeling efficiency for U2OS cells in an exposure-duration-dependent manner.


CONCLUSIONS
This study is a "proof of concept" that LIPUS can facilitate the cellular take-up of SPIO nanomaterial.
Department of Diagnostic Radiology and Organ Imaging, Prince of Wales Hospital, Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR, China. yixiang_wang@cuhk.edu.hk
Yi-Xiang J
YX
Wang
Ken Cham-Fai
KC
Leung
Wing-Hoi
WH
Cheung
Hao-Hao
HH
Wang
Lin
L
Shi
De-Feng
DF
Wang
Ling
L
Qin
Anil T
AT
Ahuja
D045744:Cell Line, Tumor; D003287:Contrast Media / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004705:Endocytosis; D005290:Ferric Compounds / Q000737:chemistry*; D005295:Ferrocyanides / Q000494:pharmacology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D049329:Nanostructures / Q000737:chemistry; D036103:Nanotechnology / Q000379:methods; D014465:Ultrasonics; D014463:Ultrasonography / Q000379:methods*
D003287:Contrast Media; D005290:Ferric Compounds; D005295:Ferrocyanides; C000499:ferric oxide; C000170:ferric ferrocyanide