Introduction: Current treatments for type 1 diabetes are limited to exogenous insulin therapies which are both onerous and imprecise; or allogeneic islet transplantation, with islets sourced from deceased donors. Although often efficacious, implementation of allogeneic islet transplantation as a therapy is hampered by the scarcity of the source (donors) and by inconsistencies in composition of the donor derived islet preparations. This latter issue is further confounded by the lack of time-efficient techniques to characterize the quality and composition of islets prior to transplantation.
Release criteria of islet material destined for transplant involves assessment of purity and potency; however, current methodology yields inaccurate results and does not assess the proportion of specific cell types present within each preparation. We hypothesise that a standardised flow cytometric assay could be used to circumvent this problem, enabling the properties of transplant material to be correlated with therapeutic outcomes
Methods: We have used single-cell RNA sequencing data to identify a cohort of novel markers that display expression profiles specific for individual endocrine cell types within human islets. We further characterized the proteomic expression of these cell surface markers and tested their ability to isolate live endocrine cell populations by FACS.
Results: We identified a suite of novel cell surface markers specific for endocrine populations of the human pancreas. We show that these markers can be used to quantify the abundance of specific endocrine subsets in human pancreatic material. These markers were also shown to enable isolation of live target cell populations from human pancreatic material by FACS. Finally, we show how these cell surface markers can be combined to produce a scorecard that can serve as a benchmark for assessing islet composition and quality. 
Conclusion: We have identified a suite of novel cell surface markers that enable characterization of human pancreatic endocrine cell types. These markers can be combined to create a scorecard that will provide facile means to correlate transplant outcomes with the characteristics of transplanted material. In future scenarios, where stem cell-derived beta-cell replacement therapies reach clinical application, this scorecard could be equally applied, providing a unifying set of standards that spans all sources of transplantable material.