Andrew Krueger

Introduction: Type 1 diabetes occurs when the body’s immune system attacks its own beta cells due to a variety of environmental and genetic causes that are yet to be fully understood^{1, 2}. The result is complete destruction of the beta cells and eventually complete insulin insufficiency and dependance on exogenous insulin to control blood glucose levels. In 2019 diabetes cost $760b/yr³ in direct medical expenses and can lead to a host of other medical problems including death via coma or diabetic ketoacidosis. Stem cells are being heavily researched as potential therapy for type 1 diabetics but there are still many difficulties in this line of research. Beta cells are proving difficult to produce with high fidelity and on top of that, are currently only culturable in expensive and specialized 3d culture medias⁴. This article will review a new beta cell differentiation method that used latrunculin A to control cytoskeletal polymerization, allowing less expensive and more reliable production of induced beta cells in 2d culture. Methods: Latrunculin A, an actin binding macrolide that prevents actin polymerization, was added after 5 rounds of the differentiation protocol with various growth factors. Control protocols were ran with all the same growth factors but without the addition of latrunculin A. The cells were tested with immunofluorescence for c-peptide and NKX6-1 as markers for insulin and beta cell maturity, respectively, as well as a variety of other unwanted endocrine cell line markers⁴. In a later study they also cultured beta cells with this method and implanted them into diabetic mice and measured glucose levels over 27 weeks⁵. Results: Cultures that had latrunculin A showed a significantly higher percentage of cells expressing NKX6-1 with c-peptide and a greatly reduced amount of off-target endocrine cell lines⁴. After implantation into mice, they blood glucose returned to under 200 mg/dl within a week (from 550) and held at 81 mg/dl from week 2 till 27⁵. Conclusion: This work highlights the importance of controlling stem cell cytoskeletal polymerization to produce high fidelity beta cells for transplantation. This allows for cheaper, more accessible, and large scale production of induced beta cells in the future. More work needs to be done to fine tune the differentiation protocol and increase beta cell functionality and maturity further.

1. Powers AC. Type 1 diabetes mellitus: much progress, many opportunities. Journal of Clinical Investigation. 2021;131(8)doi:10.1172/jci142242
2. Primavera M, Giannini C, Chiarelli F. Prediction and Prevention of Type 1 Diabetes. Front Endocrinol (Lausanne). 2020;11:248. doi:10.3389/fendo.2020.00248
3. Williams R, Karuranga S, Malanda B, et al. Global and regional estimates and projections of diabetes-related health expenditure: Results from the International Diabetes Federation Diabetes Atlas, 9th edition. Diabetes Res Clin Pract. Apr 2020;162:108072. doi:10.1016/j.diabres.2020.108072
4. Hogrebe NJ, Augsornworawat P, Maxwell KG, Velazco-Cruz L, Millman JR. Targeting the cytoskeleton to direct pancreatic differentiation of human pluripotent stem cells. Nat Biotechnol. Apr 2020;38(4):460-470. doi:10.1038/s41587-020-0430-6
5. Maxwell KG, Augsornworawat P, Velazco-Cruz L, et al. Gene-edited human stem cell-derived beta cells from a patient with monogenic diabetes reverse preexisting diabetes in mice. Sci Transl Med. Apr 22 2020;12(540)doi:10.1126/scitranslmed.aax9106