Conformal coating

Aaron A. Stock, Alice A. Tomei

Research output: Chapter in Book/Report/Conference proceedingChapter


Encapsulation of islets of Langerhans is a promising strategy to enable immunosuppression-free islet transplantation to cure autoimmune diabetes. Traditional encapsulation platforms based on the electrostatic droplet generation of hydrogel-based microcapsules have demonstrated safety of islet encapsulation but have not yielded clinical success yet despite over 30 years of research. Failure of microencapsulated islet grafts is likely due to the large barrier to diffusion presented by the ~ 1 mm in diameter capsules, there resulting sizeable graft volumes, and the instability of commonly employed hydrogel platforms. A new conformal coating technology was developed to address these limitations of conventional microencapsulation. Conformal coating is the encapsulation of islets in a thin (few tens of microns) layer of hydrogel, where the coating thickness is not a function of islet diameter. So, islets of 50-500 µm diameter are coated with hydrogels of constant thickness of few tens of microns. Conformal coatings are achieved by flow focusing and subsequent jet breakup of the islet/pregel polymer slurry, as defined by the Plateau-Rayleigh instability. The conformal coating technology facilitates a vast reduction in graft volumes, which in turn permits transplantation of encapsulated islets in confined and well-vascularized sites such as the omentum. Further, hydrogels used in conformal coating employ covalent cross-linking methods which result in biostable and bioinert hydrogel coatings. Conformal coating has been shown to be applicable to differently sourced islets, including human islets and to protect transplanted allogeneic islets from immune recognition resulting in long-term diabetes reversal in an immunocompetent mouse model.

Original languageEnglish (US)
Title of host publicationTransplantation, Bioengineering, and Regeneration of the Endocrine Pancreas
Subtitle of host publicationVolume 2
Number of pages16
ISBN (Electronic)9780128148310
ISBN (Print)9780128148327
StatePublished - Jan 1 2019
Externally publishedYes


  • Diabetes
  • Encapsulation
  • Glucose-stimulated insulin secretion
  • Human islets
  • Hydrogel
  • Immunoisolation
  • Mice
  • Polyethylene glycol

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)


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