Magnetoliposomes (MLs) were synthesized and tested for longitudinal monitoring of transplanted pancreatic islets using magnetic resonance imaging (MRI) in rat models. The rat insulinoma cell line INS-1E and isolated pancreatic islets from outbred and inbred rats were used to optimize labeling conditions in vitro. Strong MRI contrast was generated by islets exposed to 50 µg Fe/ml for 24 hours without any increased cell death, loss of function or other signs of toxicity. In vivo experiments showed that pancreatic islets (50-1000 units) labeled with MLs were detectable for up to 6 weeks post-transplantation in the kidney subcapsular space. Islets were also monitored for two weeks following transplantation through the portal vein of the liver. Hereby, islets labeled with MLs and transplanted under the left kidney capsule were able to correct hyperglycemia and had stable MRI signals until nephrectomy. Interestingly, in vivo MRI of streptozotocin induced diabetic rats transplanted with allogeneic islets demonstrated loss of MRI contrast between 7-16 days, indicative of loss of islet structure. MLs used in this study were not only beneficial for monitoring the location of transplanted islets in vivo with high sensitivity but also reported on islet integrity and hereby indirectly on islet function and rejection.

• MeSH
• experimentální diabetes mellitus chemicky indukované   metabolismus   patologie   MeSH
• hyperglykemie metabolismus   patologie   MeSH
• inzulin metabolismus   MeSH
• játra metabolismus   patologie   MeSH
• kontrastní látky metabolismus   MeSH
• krysa rodu Rattus MeSH
• kultivované buňky MeSH
• Langerhansovy ostrůvky metabolismus   patologie   MeSH
• longitudinální studie MeSH
• magnetická rezonanční tomografie metody   MeSH
• magnetické nanočástice aplikace a dávkování   MeSH
• potkani inbrední LEW MeSH
• potkani Wistar MeSH
• streptozocin farmakologie   MeSH
• transplantace Langerhansových ostrůvků metody   MeSH
• vena portae metabolismus   patologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• inzulin MeSH
• kontrastní látky MeSH
• magnetické nanočástice MeSH
• streptozocin MeSH

BACKGROUND: In vitro labelling of cells and small cell structures is a necessary step before in vivo monitoring of grafts. We modified and optimised a procedure for pancreatic islet labelling using bimodal positively charged poly(lactic-co-glycolic acid) nanoparticles with encapsulated perfluoro crown ethers and indocyanine green dye via microporation and compared the method with passive endocytosis. RESULTS: Pancreatic islets were microporated using two pulses at various voltages. We tested a standard procedure (poration in the presence of nanoparticles) and a modified protocol (pre-microporation in a buffer only, and subsequent islet incubation with nanoparticles on ice for 10 min). We compared islet labelling by microporation with labelling by endocytosis, i.e. pancreatic islets were incubated for 24 h in a medium with suspended nanoparticles. In order to verify the efficiency of the labelling procedures, we used 19F magnetic resonance imaging, optical fluorescence imaging and confocal microscopy. The experiment confirmed that microporation, albeit fast and effective, is invasive and may cause substantial harm to islets. To achieve sufficient poration and to minimise the reduction of viability, the electric field should be set at 20 kV/m (two pulses, 20 ms each). Poration in the presence of nanoparticles was found to be unsuitable for the nanoparticles used. The water suspension of nanoparticles (which served as a surfactant) was slightly foamy and microbubbles in the suspension were responsible for sparks causing the destruction of islets during poration. However, pre-microporation (poration of islets in a buffer only) followed by 10-min incubation with nanoparticles was safer. CONCLUSIONS: For labelling of pancreatic islets using poly(lactic-co-glycolic acid) nanoparticles, the modified microporation procedure with low voltage was found to be safer than the standard microporation procedure. The modified procedure was fast, however, efficiency was lower compared to endocytosis.

• Klíčová slova
• 19F magnetic resonance imaging, Bimodal nanoparticles, Cell labelling, Confocal microscopy, Endocytosis, Fluorescence imaging, Microporation, Pancreatic islets,
• Publikační typ
• časopisecké články MeSH