Photoacoustic imaging of mesenchymal stem cells in living mice via silica-coated gold nanorods

Abstract

Improved imaging modalities are critically needed for optimizing stem cell therapy. Techniques with real-time content to guide and quantitate cell implantation are especially important in applications such as musculoskeletal regenerative medicine. Here, we report the use of silicacoated gold nanorods as a contrast agent for photoacoustic imaging and quantitation of mesenchymal stem cells in rodent muscle tissue. The silica coating increased the uptake of gold into the cell more than 5-fold, yet no toxicity or proliferation changes were observed in cells loaded with this contrast agent. Pluripotency of the cells was retained, and secretome analysis indicated that only IL-6 was disregulated more than 2-fold from a pool of 26 cytokines. The low background of the technique allowed imaging of down to 100 000 cells in vivo. The spatial resolution is 340 μm, and the temporal resolution is 0.2 s, which is at least an order of magnitude below existing cell imaging approaches. This approach has significant advantages over traditional cell imaging techniques like positron emission tomography and magnetic resonance imaging including real time monitoring of stem cell therapy.

Organic–inorganic nanohybrids for fluorescence, photoacoustic and Raman bioimaging

“…The silica-coated gold nanorods were also employed as contrast agents for the quantitation of mesenchymal stem cells (MSCs) in rodent muscle tissue through PAI. It was evident from the results that the silica coating enhances the uptake of gold into the cells without hindering the cell proliferation, indicating the retention of therapeutic benefit of the MSCs [64]. The tunable size and shape-dependent plasmonic properties [65,66] of gold nanosystems endow these nanomaterials the ability to absorb and scatter light from visible to NIR region, making them suitable for deep tissue PAI.…”

What is new in nanoparticle‐based photoacoustic imaging?

“…44 Third, silica can increase cellular uptake of gold into cells, which is useful for photoacoustic imaging of stem cell therapy. 45 Other recent alternatives include noncytotoxic PNIPAAmMA. This allows covalent attachment of targeting molecules like antibodies or magnetic nanoparticles and may also be used to improve target and anticancer therapies.…”

Effectiveness of Functionalized Nanosystems for Multimodal Molecular Sensing and Imaging in Medicine

“…All the prepared samples were imaged employing an experimental set-up already adopted in previous papers [13], [14], customized to our sample geometric features (Fig. 1).…”

“…Manuscript The safe and cost-effective clinical employment of multimodal molecular imaging led to the development of novel nanoparticle contrast agents (NPCAs), detectable by multiple non-invasive and non-ionizing techniques capable of effective extravasations to directly target cancer cells (pore size of tumor endothelium is typically in the range 380-780 nm) [10]- [12]. Efficacy in extravasation and targeting will also be needed for optimizing nanoparticle (NP)-based stem cell therapy, whose potential is currently being explored [13]. Multimodal NPs, reporting signals through more than one method (e.g., fluorescence and magnetic resonance imaging-MRI), are useful when the two modalities have complementary spatial resolution, sensitivity, or depth penetration [14].…”