Oral Presentation The Annual Scientific Meeting of the Endocrine Society of Australia and the Society for Reproductive Biology 2013

Non-invasive tracking of encapsulated insulin producing cells labelled with iron nanoparticles by Magnetic Resonance Imaging (MRI) (#202)

Vijayaganapathy Vaithilingam 1 , Mandy Yim 2 , Jayne Foster 2 , Timothy Stait-Gardner 3 , Bernard E Tuch 1 2 4
  1. Commonwealth Scientific and Industrial Research Organisation , North Ryde, NSW, Australia
  2. Diabetes Transplant Unit, Prince of Wales Hospital, Randwick, NSW, Australia
  3. Nanoscale Organisation and Dynamics Group, University of Western Sydney, Penrith, NSW, Australia
  4. Centre for Reproduction and Development, Monash Institute of Medical Research, Clayton, Victoria, Australia

Microencapsulating pancreatic islets is a strategy being explored as a treatment for type 1 diabetes which may overcome the immune-mediated rejection of the graft without toxic immunosuppression. Allo- and xeno- transplantation studies with microencapsulated islets have shown considerable promise but long term graft survival was limited and varied considerably. Microencapsulated cells are often injected free-floating into the peritoneal cavity, so the position of the grafts remains elusive after transplantation. The aim of this study was to assess magnetic resonance imaging (MRI) as a non-invasive means to track microencapsulated insulin-producing cells following transplantation.
Murine insulin-producing cells (MIN6) and human islets were labelled with fluorescent superparamagnetic iron oxide (SPIO) nanoparticles and encapsulated within barium alginate microcapsules. Viability and insulin secretion of encapsulated SPIO-labelled MIN6 and human islets were assessed. In vitro imaging of encapsulated SPIO-labelled cells was carried out using a clinical grade 3 T MRI. Encapsulated SPIO-labelled MIN6 were transplanted into the peritoneal cavity of immunocompetent (C57BL/6) mice and tracked non-invasively using both 3 T and 11.7 T MRI.
Fluorescent imaging demonstrated the uptake of SPIO nanoparticles by both MIN6 and human islets with no evident changes in cell morphology. SPIO-labelling affected neither the viability of encapsulated MIN6 and islets over 7 days in culture, nor their capacity to secrete insulin in response to glucose. Normalization of blood glucose levels was achieved when encapsulated SPIO-labelled MIN6 were transplanted into the peritoneal cavity of diabetic C57BL/6 mice. In vitro imaging demonstrated that clusters as well as single capsules of encapsulated SPIO-labelled MIN6 and islets could be visualised using the 3 T MRI (Figure 1). In vivo encapsulated SPIO-labelled MIN6 cells could be visualised within the peritoneal cavity as discrete hypointensities using the high power 11.7 T but not the clinical grade 3 T MRI (Figure 2).

1011-Figure%201.jpg1010-Figure%202.jpg