Gene Expression Profiling of Mouse Embryonic Stem Cell Progeny Differentiated by Lumelsky’s Protocol

β-cell neogenesis: A rising star to rescue diabetes mellitus

BACKGROUND

Diabetes Mellitus (DM), a chronic metabolic disease characterized by elevated blood glucose, is caused by various degrees of insulin resistance and dysfunctional insulin secretion, resulting in hyperglycemia. The loss and failure of functional β-cells are key mechanisms resulting in type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM).

AIM OF REVIEW

Elucidating the underlying mechanisms of β-cell failure, and exploring approaches for β-cell neogenesis to reverse β-cell dysfunction may provide novel strategies for DM therapy.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Emerging studies reveal that genetic susceptibility, endoplasmic reticulum (ER) stress, oxidative stress, islet inflammation, and protein modification linked to multiple signaling pathways contribute to DM pathogenesis. Over the past few years, replenishing functional β-cell by β-cell neogenesis to restore the number and function of pancreatic β-cells has remarkably exhibited a promising therapeutic approach for DM therapy. In this review, we provide a comprehensive overview of the underlying mechanisms of β-cell failure in DM, highlight the effective approaches for β-cell neogenesis, as well as discuss the current clinical and preclinical agents research advances of β-cell neogenesis. Insights into the challenges of translating β-cell neogenesis into clinical application for DM treatment are also offered.

Beyond islet transplantation in diabetes cell therapy: from embryonic stem cells to transdifferentiation of adult cells

Exogenous insulin is, at the moment, the therapy of choice of diabetes, but does not allow tight regulation of glucose leading to long-term complications. Recently, pancreatic islet transplantation to reconstitute insulin-producing β cells, has emerged as an alternative promising therapeutic approach. Unfortunately, the number of donor islets is too low compared with the high number of patients needing a transplantation leading to a search for renewable sources of high-quality β-cells. This review, summarizes more recent promising approaches to the generation of new β-cells from embryonic stem cells for transdifferentiation of adult cells, particularly a critical examination of the seminal work by Lumelsky et al.

Evaluating protocols for embryonic stem cell differentiation into insulin-secreting beta-cells using insulin II-GFP as a specific and noninvasive reporter

Stable and full differentiation of pluripotent stem cells into functional beta-cells offers the potential to treat type I diabetes with a theoretically inexhaustible source of replacement cells. In addition to the difficulties in directed differentiation, progress toward an optimized and reliable protocol has been hampered by the complication that cultured cells will concentrate insulin from the media, thus making it difficult to tell which, if any, cells are producing insulin. To address this, we utilized a novel murine embryonic stem cell (mESC) research model, in which the green fluorescent protein (GFP) has been inserted within the C-peptide of the mouse insulinII gene (InsulinII-GFP). Using this method, cells producing insulin are easily identified. We then compared four published protocols for differentiating mESCs into beta-cells to evaluate their relative efficiency by assaying intrinsic insulin production. Cells differentiated using each protocol were easily distinguished based on culture conditions and morphology. This comparison is strengthened because all testing is performed within the same laboratory by the same researchers, thereby removing interlaboratory variability in culture, cells, or analysis. Differentiated cells were analyzed and sorted based on GFP fluorescence as compared to wild type cells. Each differentiation protocol increased GFP fluorescence but only modestly. None of these protocols yielded more than 3% of cells capable of insulin biosynthesis indicating the relative inefficiency of all analyzed protocols. Therefore, improved beta-cells differentiation protocols are needed, and these insulin II GFP cells may prove to be an important tool to accelerate this process.

A comparison of protocols used to generate insulin-producing cell clusters from mouse embryonic stem cells

Embryonic stem cells (ESCs) have the capacity to generate a panoply of tissue types and may therefore provide an alternative source of tissue in regenerative medicine to treat potentially debilitating conditions like Type 1 diabetes mellitus. However, the ability of mouse ESCs to generate insulin-producing cell clusters (IPCCs) remains highly contentious. In an attempt to clarify this issue, three protocols for the ESC-based generation of IPCCs (referred to as Blyszczuk, Hori, and Lumelsky protocols) were modified and evaluated for their ability to express pancreatic islet genes and proteins and their capacity to function. Herein, we show that the Blyszczuk protocol reproducibly generated IPCCs with gene-expression characteristics that were qualitatively and quantitatively most reminiscent of those found in pancreatic islets. Furthermore, compared to the Hori and Lumelsky protocols, Blyszczuk-derived IPCCs exhibited superior expression of c-peptide, a by-product of de novo insulin synthesis. Functionally, Blyszczuk IPCCs, in contrast to Hori and Lumelsky IPCCs, were able to transiently restore normal blood glucose levels in diabetic mice (<1 week). Longer normoglycemic rescue (>2 weeks) was also achieved in a third of diabetic recipients receiving Blyszczuk IPCCs. Yet Blyszczuk IPCCs were less able to rescue experimental diabetes than isolated syngeneic pancreatic islet tissue. Therefore, depending on the mode of differentiation, ESCs can be driven to generate de novo IPCCs that possess limited functionality. Further modifications to differentiation protocols will be essential to improve the generation of functional IPCCs from mouse ESCs.