Long-Term Expansion of Pancreatic Islet Organoids from Resident Procr+ Progenitors

Self-organization of organoids from endoderm-derived cells

Organoids constitute biological systems which are used to model organ development, homeostasis, regeneration, and disease in vitro and hold promise for use in therapy. Reflecting in vivo development, organoids form from tissue cells or pluripotent stem cells. Cues provided from the media and individual cells promote self-organization of these uniform starting cells into a structure, with emergent differentiated cells, morphology, and often functionality that resemble the tissue of origin. Therefore, organoids provide a complement to two-dimensional in vitro culture and in vivo animal models of development, providing the experimental control and flexibility of in vitro methods with the three-dimensional context of in vivo models, with fewer ethical restraints than human or animal work. However, using organoids, we are only just beginning to understand on the cellular level how the external conditions and signaling between individual cells promote the emergence of cells and structures. In this review, we focus specifically on organoids derived from endodermal tissues: the starting conditions of the cells, signaling mechanisms, and external media that allow the emergence of higher order self-organization.

Islet-Resident Endocrine Progenitors: A New Hope for Beta Cell PROCReation?

The existence of an endocrine progenitor in the adult mouse pancreas has been controversial. Recently in Cell, Wang et al. (2020) use the cell-surface marker Procr to define a population of cells within the adult islet of Langerhans that is capable of generating all endocrine cells and is amenable to in vitro expansion.

Lineage tracing: technology tool for exploring the development, regeneration, and disease of the digestive system

Lineage tracing is the most widely used technique to track the migration, proliferation, and differentiation of specific cells in vivo. The currently available gene-targeting technologies have been developing for decades to study organogenesis, tissue injury repairing, and tumor progression by tracing the fates of individual cells. Recently, lineage tracing has expanded the platforms available for disease model establishment, drug screening, cell plasticity research, and personalized medicine development in a molecular and cellular biology perspective. Lineage tracing provides new views for exploring digestive organ development and regeneration and techniques for digestive disease causes and progression. This review focuses on the lineage tracing technology and its application in digestive diseases.

The Effect of Bariatric Surgery on Exocrine Pancreatic Function

INTRODUCTION

After bariatric surgery (BS), patients might suffer from nutrient maldigestion, malabsorption, and vitamin deficiencies. In this study, our aim was to assess pancreatic functions after BS using fecal elastase-1 assay (FE-1).

MATERIAL AND METHODS

Sixty patients (21M) undergoing BS and 20 (6M) healthy controls were included into the study. Stool samples were collected 1 year after surgery. Ten patients from one anastomosis gastric bypass (OAGB) and single anastomosis duodenal switch (SADS) groups with the lowest value of FE-1 and GIQLI scores were given pancreatic enzyme replacement therapy (PERT). After PERT, FE-1, excess weight loss (EWL), BMI, GIQLI scores, and vitamin D levels were measured.

RESULTS

Vitamin D levels were detected as 19.04 (9-46.5) pg/ml, 15.1 (8.4-23.6) pg/ml, 17.8 (5-30) pg/ml, and 21.79 (11-40.3) pg/ml after sleeve gastrectomy (SG), OAGB, SADS, and control groups, respectively (p = 0.04). GIQLI scores in the first year were found to have increased in all patients (p = 0.02). FE-1 levels were found as 642.35 (566.3-711.4) μg/g, 378.52 (183.5-561.1) μg/g, 458.88 (252.5-593, 5) μg/g, and 518.2 (351.6-691) μg/g for the SG, OAGB, SADS, and control groups, respectively. There was a strong inverse correlation between EWL and FE-1 levels at the end of the first year (Spearman's rho = - 0.688, p = 0.003). After having performed PERT for patients with the lowest FE-1 levels, the levels increased to 683.39 (615.5-720) μg/g in the OAGB and 691.5 (643.1-720) μg/g in the SADS groups (p = 0.011).

CONCLUSION

FE-1 measurements demonstrated that many patients suffer from malabsorption after OAGB or SADS, whereas functions remain normal after SG. PERT corrects pancreatic functions without affecting weight loss and also contributes to the normal serum level of vitamin D.

Applications of Organoids for Cancer Biology and Precision Medicine

Organoid technologies enable the creation of in vitro physiologic systems that model tissues of origin more accurately than classical culture approaches. Seminal characteristics, including three-dimensional structure and recapitulation of self-renewal, differentiation, and disease pathology, render organoids eminently suited as hybrids that combine the experimental tractability of traditional 2D cell lines with cellular attributes of in vivo model systems. Here, we describe recent advances in this rapidly evolving field and their applications in cancer biology, clinical translation and precision medicine.

Regeneration of the pancreas: proliferation and cellular conversion of surviving cells

The most common pancreas-related disorders are diabetes, pancreatitis and different types of pancreatic cancers. Diabetes is a chronic condition which results from insufficient functional β-cell mass, either as a result of an autoimmune destruction of insulin producing β-cells, or as their death or de-differentiation following years of hyperactivity to compensate for insulin resistance. Chronic pancreatitis leads to cell death and can develop into diabetes or pancreatic cancer. To stimulate regeneration in such pathologies, it is of high importance to evaluate the endogenous regeneration capacity of the pancreas, to understand the conditions needed to trigger it, and to investigate the cellular and molecular regenerative responses. This short review focuses on observations made in the last 2 years on the mechanisms enhancing pancreatic cell proliferation, notably new combinations of pharmacological agents, as well as those triggering cellular conversion.

Endometrial Organoids: A New Model for the Research of Endometrial-Related Diseases†

An ideal research model plays a vital role in studying the pathogenesis of a disease. At present, the most widely used endometrial disease models are cell lines and animal models. As a novel studying model, organoids have already been applied for the study of various diseases, such as disorders related to the liver, small intestine, colon, and pancreas, and have been extended to the endometrium. After a long period of exploration by predecessors, endometrial organoids (EOs) technology has gradually matured and maintained genetic and phenotypic stability after long-term expansion. Compared with cell lines and animal models, EOs have high stability and patient specificity. These not only effectively and veritably reflects the pathophysiology of a disease, but also can be used in preclinical drug screening, combined with patient derived xenografts (PDXs). Indeed, there are still many limitations for EOs. For example, the co-culture system of EOs with stromal cells, immune cell, or vascular cells is not mature, and endometrial cancer organoids have a lower success rate, which should be improved in the future. The investigators predict that EOs will play a significant role in the study of endometrium-related diseases.

A single-cell transcriptomic atlas of primate pancreatic islet aging

Aging-related degeneration of pancreatic islet cells contributes to impaired glucose tolerance and diabetes. Endocrine cells age heterogeneously, complicating the efforts to unravel the molecular drivers underlying endocrine aging. To overcome these obstacles, we undertook single-cell RNA sequencing of pancreatic islet cells obtained from young and aged non-diabetic cynomolgus monkeys. Despite sex differences and increased transcriptional variations, aged β-cells showed increased unfolded protein response (UPR) along with the accumulation of protein aggregates. We observed transcriptomic dysregulation of UPR components linked to canonical ATF6 and IRE1 signaling pathways, comprising adaptive UPR during pancreatic aging. Notably, we found aging-related β-cell-specific upregulation of HSP90B1, an endoplasmic reticulum-located chaperone, impeded high glucose-induced insulin secretion. Our work decodes aging-associated transcriptomic changes that underlie pancreatic islet functional decay at single-cell resolution and indicates that targeting UPR components may prevent loss of proteostasis, suggesting an avenue to delaying β-cell aging and preventing aging-related diabetes.