Dual-modal magnetic resonance and photoacoustic tracking of tendon stem cell labeled with PLGA/IO MPs

Abstract

Objective To detect the efficiency of the newly developed PLGA/IO MPs in tracking tendon stem cells (TSCs) by magnetic resonance (MR) and photoacoustic (PA) imaging. Methods Both PLAG/IO MPs and TSCs were prepared and acquired according to the previous study, and TSCs were incubated with PLGA/IO MPs for labeling.TSCs were collected for MR and PA imaging, prussian blue staining was performed, and the iron concentration of labeled TSCs was determined using inductively coupled plasma optical emission spectrometry (ICP-OES) at 3, 7, 14, 21 and 28 days after labeling respectively. The rotator cuff injury model was built on the right side of SD rats by surgery and the labeled TSCs were implanted instantly. Dual-modal MR/PA imaging was performed to observe the implanted labeled TSCs at day 3, 7, 14, 21 and 28 after implantation respectively. Results Along with the increase of labeling time, both MR and PA signal of labeled TSCs decreased gradually, and the amount of intracellular Fe loading was gradually decreased. At day 28, the difference of Fe concentration per cell between labeled TSCs and non-labeled TSCs was not significant (1.45 pg Fe/cell vs 1.17 pg Fe/cell, P>0.05). MR and PA imaging allowed a long-term tracking of labeled TSCs for 21 and 7 days respectively in the rat rotator cuff injury model. Conclusions PLGA/IO MPs are able to label TSCs for up to 21 days, and dual-modal MR/PA imaging could be used to track the labeled TSCs in the rat rotator cuff injury model. Key words: Tendon stem cells; Cell tracking; Magnetic resonance imaging; Photoacoustic imaging