Dr Sergey Alexandrov, Soorya James and Niamh Duffy recently presented their work in STARSTEM at the MSI/SMS Joint Symposium in Galway.

The meeting ran from the 6th to the 8th of April 2022 in Galway, Ireland. The symposium was hosted by the National University of Ireland Galway (NUIG) and brought together around 200 researchers from around the world for discussions on microscopy themes such as advances in image analysis, instrumentation development, life and physical sciences, along with many other microscopy applications.

Sergey Alexandrov, Senior Research Fellow at TOMI NUIG gave a talk titled, “Label-free approaches for 2d and 3d visualization of sub-wavelength structures and imaging beyond the resolution limit of the imaging system“.

Soorya James, a PhD student with TOMI NUIG presented a poster titled, ” Bioconjugation of gold nanostars for active targeting and tracking of extracellular vesicles“. Soorya commented that “it was so nice to have an in-person conference after such a long time. There was an early research career discussion panel, which was quite informative and interesting.

Abstract: While mesenchymal stem cells (MSCs) remain at the forefront of regenerative medicine, recently significant focus has been placed on understanding the role of MSC-derived extracellular vesicles (EVs). Evidence suggests that the beneficial effects of MSCs may be realised by their released EVs, thus not requiring the administration of the cells. Enhancing the body of evidence supporting the clinical administration of EVs can be facilitated by exploring the therapeutic potential of EVs in preclinical studies. Nanoparticles are often employed for tracking stem cells via direct labelling, but this is not suitable for EVs due to their variability in size and their inability to engulf nanoparticles. To overcome this, gold nanostars were covalently conjugated with antibodies for facilitating active targeting and tracking of EVs in vivo. The complex structure and morphology of gold nanostars, with their sharp tips and long branches are what contribute to their localised surface plasmon resonance. The optical properties of these nanostars can be tuned by tweaking the length of the branches or the sharpness of the tips which facilitates imaging in the second near-infrared region. Flow cytometry and transmission electron microscopy show that the optical signature was preserved and bioconjugation of nanostars was stable for tracking EVs in vivo.

 

Niamh Duffy a PhD student with REMEDI NUIG gave a talk titled, “Investigation and Characterisation of NanoStar-Labeled Mesenchymal Stem Cells for in vivo Cell Tracking in Osteoarthritis using Optoacoustic Imaging“.

 

 

Abstract:

Introduction: Osteoarthritis (OA) is the most common degenerative joint disease and the leading cause of pain and disability worldwide. Bone marrow derived mesenchymal stem cells (MSCs) have been investigated for their potential to treat and prevent disease progression in OA. Clinical translation of MSCs has been hampered in part by an incomplete understanding about their mechanism of action in vivo. Molecular imaging can provide information about cell fate, engraftment or biodistribution following injection. Optoacoustic imaging (OAI) specifically multi-spectral optoacoustic tomography (MSOT) has excellent resolution and capabilities in functional imaging. Contrast agents such as gold nanoparticles can enhance the signal response in OAI and serve as a labeling device to allow tracking of cells. This project aims to investigate nanostar-labeled MSCs for in vivo cell imaging in OA using MSOT.

Methods: A novel nanostar was produced and characterised using spectrophotometry, nanosize assessment and transmission electron microscopy (TEM). The internalization efficiency by MSCs was investigated in vitro, and TEM was utilised to identify the optimal conditions for labeling. Following labeling, MSCs were characterised to ensure no phenotypic changes with respect to viability, tri-lineage differentiation, surface immunophenotype and potency had occurred. Nanostar-labeled MSCs were administered intra-articularly in a murine model of OA and tracked using MSOT for 7 days. Histological analysis was performed to assess biodistribution to other organs and potential pathology.

Results: Viability, tri-lineage differentiation capacity and surface immunophenotype were not altered post-labeling. Minor alterations with respect to gene expression following stimulation with IFN-g and TNF-a were observed. Biodistribution analysis using MSOT demonstrated that MSCs were still present within the joint 7 days post-transplantation. No overt pathology was found in the lungs, spleen, kidney, liver or heart. A therapeutic preclinical study has been performed using a murine model of OA and nanostar-labeled MSCs with analysis currently ongoing.