Microcapsules with intrinsic barium radiopacity for immunoprotection and X-ray/CT imaging of pancreatic islet cells

Dian R. Arifin, Sameer Manek, Emma Call, Aravind Arepally, Jeff W.M. Bulte

Research output: Contribution to journalArticlepeer-review

40 Scopus citations


Microencapsulation is a commonly used technique for immunoprotection of engrafted therapeutic cells We investigated a library of capsule formulations to determine the most optimal formulation for pancreatic beta islet cell transplantation, using barium as the gelating ion and clinical-grade protamine sulfate (PS) as a new cationic capsule cross-linker Barium-gelated alginate/PS/alginate microcapsules (APSA, diameter = 444 ± 21 μm) proved to be mechanically stronger and supported a higher cell viability as compared to conventional alginate/poly- l-lysine/alginate (APLLA) capsules Human pancreatic islets encapsulated inside APSA capsules, gelated with 20 m m barium as optimal concentration, exhibited a sustained morphological integrity, viability, and functionality for at least 3-4 weeks in vitro, with secreted human C-peptide levels of 0.2-160 pg/ml/islet Unlike APLLA capsules that are gelled with calcium, barium-APSA capsules are intrinsically radiopaque and, when engrafted into mice, could be readily imaged in vivo with micro-computed tomography (CT) Without the need of adding contrast agents, these capsules offer a clinically applicable alternative for simultaneous immunoprotection and real-time, non-invasive X-ray/CT monitoring of engrafted cells during and after in vivo administration.

Original languageEnglish (US)
Pages (from-to)4681-4689
Number of pages9
Issue number18
StatePublished - Jun 2012


  • Barium
  • CT imaging
  • Diabetes
  • Islet cell
  • Microcapsule

ASJC Scopus subject areas

  • Biophysics
  • Bioengineering
  • Ceramics and Composites
  • Biomaterials
  • Mechanics of Materials


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