CK19+ cell expansion in medium containing bFGF, EGF, HGF and KGF compared to control media.

<p>A) Growth curve based on the number of CK19+ cells enumerated at different time points in the presence of 20 ng/mL each of bFGF, EGF, HGF and KGF or control media (*p<0.05 for two-way comparisons with the 10% FBS condition). B) Phase contrast images of the cultures taken on day 6. N = 1 pancreas with 6 replicate cultures.</p

Phenotype of dispersed unsorted islet-depleted pancreatic cells cultured in serum-containing medium.

<p>On day 8, mixed cultures of CK19+ duct-like cells and vimentin+ fibroblast-like cells with very rare amylase+ cells are obtained. After a single passage, cultures consisted mainly of vimentin+ cells.</p

Fractions of cells obtained before and after sorting on day 1.

<p>Fractions of cells obtained before and after sorting on day 1.</p

Validation of a screening platform to identify CK19+ cell mitogens.

<p>A) Number of CK19+ cells at the end of the culture normalized to the number obtained in basal serum-free medium culture. B) Fraction of CK19+ cells that incorporated BrdU during the last day of culture, normalized to BrdU incorporation in basal medium culture. Unsorted cells were seeded on day 0 while CD90-depleted cells were sorted and seeded on day 1. The data were pooled from cultures ending on day 8 (N = 5 pancreata) or day 6 (N = 3 pancreata) and normalized for each pancreas prior to calculating averages and errors. The non-normalized results obtained at the end of the cultures in basal medium were as follows: the unsorted populations contained 0.05±0.02×10⁵ CK19+ cells/cm² of which 6±3% were BrdU+; the CD90-depleted populations contained 0.07±0.02×10⁵ CK19+ cells/cm² of which 1.0±0.6% were BrdU+. *p<0.05 compared to basal medium.</p

Evolution of cell populations after CD90 magnetic-activated cell sorting assessed by FACS.

<p>Evolution of cell populations after CD90 magnetic-activated cell sorting assessed by FACS.</p

Magnetic Resonance Imaging of Alginate Beads Containing Pancreatic Beta Cells and Paramagnetic Nanoparticles

Microencapsulation is being investigated as a means to avoid rejection of transplanted pancreatic islets. Monitoring bead distribution and stability in vivo is an important step toward improving microencapsulated islet transplantation strategies. Islet co-encapsulation with gadolinium-labeled mesoporous silica nanoparticles (Gd-MSNs) could allow bead visualization while immobilizing and limiting the potential internalization of the contrast agent. The porous nature of the MSNs could also be used to locally release anti-inflammatory, angiogenic, or anti-apoptotic factors. Mouse insulinoma 6 (MIN6) beta cells were co-encapsulated with Gd-MSNs in alginate beads produced by emulsification and internal gelation. Gd-MSN alginate beads appeared brighter in <i>T</i>₁-weighted imaging sequences (detection threshold of 0.016 mM Gd; relaxometric ratio <i>r</i>₂/<i>r</i>₁ = 1.45) than beads without Gd-MSNs. No leaching of Gd³⁺ from the hydrogels was detected over the course of 3 months. MIN6 cells co-encapsulated with Gd-MSNs were viable without significant differences in cell growth rate compared to encapsulated controls without Gd-MSNs. This study paves the way for microencapsulated islet tracking via MRI using co-encapsulated paramagnetic nanomaterials