Multimodality imaging in the assessment of bone marrow-derived mesenchymal stem cell therapy for doxorubicin-induced cardiomyopathy

Abstract

Due to their broad-spectrum effects and high antitumor efficacies, anthracycline-based chemotherapies are commonly prescribed in various solid and hematological malignancies. Doxorubicin (DOX) is one of the most highly used anthracyclines but has been shown to cause lethal cardiomyopathy in clinical practice. Studies have demonstrated that bone marrow-derived mesenchymal stem cells (BMSCs) have the ability to rescue DOX-induced cardiomyopathy (DIC). However, novel molecular imaging techniques are required to explore the biological behaviors, safety, eventual viability, and environmental interactions of transplanted stem cells during therapy. To investigate the biological behaviors of transplanted BMSCs, we applied bioluminescence imaging (BLI) and magnetic resonance imaging (MRI) techniques to trace firefly luciferase (Fluc) and ultrasmall superparamagnetic iron oxide (USPIO) double-labeled mouse BMSCs after injection into the heart apex in a chronic DIC mouse model. Then, we determined the optimal BMSC number for transplantation into the heart and optimized MRI parameters to evaluate transplanted BMSCs in vitro and in vivo. Our results showed that the BLI trace signal could last 7 days in the DIC mouse model, whereas the MRI signal lasted up to 3 days. However, MRI provided more detailed pathophysiological information on DIC than BLI, such as inflammation and fibrosis signs. The optimal in vivo cell number for BLI and MRI was determined to be 1×10⁶. In conclusion, BLI combined with multimodality MRI could be used to monitor the biological behavior of BMSCs transplanted into a chronic DIC mouse model in a visual and dynamic manner.

Keywords: Bone marrow-derived mesenchymal stem cells; bioluminescence imaging; doxorubicin-induced cardiomyopathy; magnetic resonance imaging; multimodality imaging.

Figure 1

A. Alizarin red staining indicating osteogenesis of Balb/c mouse-derived BMSCs. B. Balb/c BMSCs labeled with GFP-LUC. C. CCK-8 and Vivotrax assessment.

Figure 2

Chronic DOX-induced cardiomyopathy mouse model. A. H&E staining showed connective tissue formation around myocardial tissues and blood vessels and collagen fibers in the myocardial interstitium. B. PSR staining showed increased and thickened collagen fibers (red). C. Masson staining showed collagen fibers (blue). D and E. Cardiac ultrasound showed an enlarged left ventricular cavity and decreased ejection fraction. F. The EF value between CTRL group (healthy mouse) and DOX group (chronic DIC mouse) showed a significant difference.

Figure 3

Correlations between cell number and BLI intensity. A. Viability of BMSCs, BMSC-LUC, BMSC-USPIO, and BMSC/LUC-USPIO. B. Viability of H9C2 cells incubated with normal medium and BMSC medium. C. BLI signal in vitro. D. T2 value in vitro. E. T2* relaxome value in vitro.

Figure 4

BLI signal intensity in vivo. (A) Images of BLI signal intensity. (B) Quantification of the BLI signal intensity in (A).

Figure 5

Cardiac MRI of Balb/c mice in the BMCS-treated group (A and B). Short-axis images with the GRE cine sequence on day 1 after myocardial injection of BMSC/LUC-USPIO. The signal of the anterior wall (white arrows) of the left ventricle was significantly decreased. Uneven delayed enhancement of the left ventricular septum can be observed on the right image. USPIO particle distribution (blue) in BMSCs in the myocardium of the chronic DIC mouse model (C).