Effectiveness of bioengineered islet cell sheets for the treatment of diabetes mellitus

Background The present study aimed to evaluate whether bioengineered mouse islet cell sheets can be used for the treatment of diabetes mellitus. Methods Isolated mouse pancreatic islets were dispersed, and cells were plated on temperature-responsive culture plates coated with iMatrix-551. On day 3 of culture, the sheets were detached from the plates and used for further analysis or transplantation. The following parameters were assessed: (1) morphology, (2) expression of β-cell–specific transcription factors and other islet-related proteins, (3) methylation level of the pancreatic duodenal homeobox-1 ( Pdx-1 ) promoter, as determined by bisulfite sequencing, and (4) levels of serum glucose after transplantation of one or two islet cell sheets into the abdominal cavity of streptozotocin-induced diabetic severe combined immunodeficiency mice. Results From each mouse, we recovered approximately 233.3 ± 12.5 islets and 1.4 ± 0.1 × 10 5 cells after dispersion. We estimate that approximately 68.2% of the cells were lost during dispersion. The viability of recovered single cells was 91.3 ± 0.9%. The engineered islet cell sheets were stable, but the messenger RNA levels of various β-cell-specific transcription factors were significantly lower than those of primary islets, whereas Pdx-1 promoter methylation and the expression of NeuroD, Pdx-1, and glucagon proteins were similar between sheets and islets. Moreover, transplantation of islet cell sheets did not revert serum hyperglycemia in any of the recipient mice. Conclusions Engineering effective islet cell sheets require further research efforts, as the currently produced sheets remain functionally inferior compared with primary islets.