Configuration of electrofusion-derived human insulin-secreting cell line as pseudoislets enhances functionality and therapeutic utility

    1. Peter R Flatt
    1. School of Biomedical Sciences, SAAD Centre for Pharmacy and Diabetes, University of Ulster, Cromore Road, Coleraine, Northern Ireland BT52 1SA, UK
      1MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
      2Institute for Science and Technology in Medicine, Keele University, Keele, UK
      3Department of Microbiology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Selangor 43400 Serdang, Malaysia
    1. (Correspondence should be addressed to P R Flatt; Email: pr.flatt{at}


    Formation of pseudoislets from rodent cell lines has provided a particularly useful model to study homotypic islet cell interactions and insulin secretion. This study aimed to extend this research to generate and characterize, for the first time, functional human pseudoislets comprising the recently described electrofusion-derived insulin-secreting 1.1B4 human β-cell line. Structural pseudoislets formed readily over 3–7 days in culture using ultra-low-attachment plastic, attaining a static size of 100–200 μm in diameter, corresponding to ∼6000 β cells. This was achieved by decreases in cell proliferation and integrity as assessed by BrdU ELISA, 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide, and lactate dehydrogenase assays. Insulin content was comparable between monolayers and pseudoislets. However, pseudoislet formation enhanced insulin secretion by 1.7- to 12.5-fold in response to acute stimulation with glucose, amino acids, incretin hormones, or drugs compared with equivalent cell monolayers. Western blot and RT-PCR showed expression of key genes involved in cell communication and the stimulus-secretion pathway. Expression of E-Cadherin and connexin 36 and 43 was greatly enhanced in pseudoislets with no appreciable connexin 43 protein expression in monolayers. Comparable levels of insulin, glucokinase, and GLUT1 were found in both cell populations. The improved secretory function of human 1.1B4 cell pseudoislets over monolayers results from improved cellular interactions mediated through gap junction communication. Pseudoislets comprising engineered electrofusion-derived human β cells provide an attractive model for islet research and drug testing as well as offering novel therapeutic application through transplantation.

    • Received in final form 25 May 2012
    • Accepted 6 June 2012
    • Made available online as an Accepted Preprint 8 June 2012
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