NMR imaging of biocapsules for monitoring the performance of cell and tissue implants

The development of microtechnologies for the analysis of groups of cells is stimulating new approaches in the design of diagnostic or therapeutic treatments in medicine. Micropackaging of cells provides a means of directly regulating the biocompatibility and biological responsiveness of tissue implants (e.g. pancreatic islet cells for the treatment of diabetes). These devices must function independently within the body where they both protect the implant and support the normal physiological function of the entrapped cells. We are developing NMR tools that assess the cell environment within the microcapsule, which is non-invasive, and can provide direct chemical or physical information on cell function. In this paper we describe a new design for an biocapsule (silicone, 5 mm×6 mm×1.5 mm) that is integrated with a 2 mm planar RF spiral surface-coil tuned and matched to operate at 500 MHz. We conclude that NMR techniques (spectroscopy and microimaging) are able to analyze the physical and physiological statuses of the pancreatic insulinoma βTC3 cells in a collagen gel that are loaded in a capsule, under implant conditions. This technology has the potential to be applied in vivo for periodic assessment of cell performance utilizing mutually-coupled NMR coils, which eliminate the need for direct electrical connections