Beta-cell dependence to alpja-cell signals for proper insulin secretion in mouse pancreatic islets

The islets of Langerhans play a central role in detecting and regulating blood glucose levels. While insulin-producing beta-cells are well-characterized, much remains to be studied about the other cell types in pancreatic islets (alpha-, delta-, PPY-, and epsilon-cells). In this context, we have developed chimeric organoids that we use to understand the interactions between the different cell populations present in pancreatic islets. We previously developed an efficient approach to purify the major cell populations present in pancreatic islets (alpha, beta, and delta) using flow cytometry. We have now developed a technique to re-aggregate these sorted cell populations, enabling the production of clusters (pseudo-islets) in which we can modulate the proportion of each cell population on demand. We generated clusters devoid of delta cells or both alpha and delta cells and confirmed this depletion at the gene and protein levels. We then evaluated the function of these pseudo-islets by measuring glucose-stimulated insulin secretion. The absence of delta-cells did not affect insulin secretion. However, the insulin secretory capacity of pseudo-islets lacking both alpha- and delta-cells was significantly reduced. Transcriptomic analysis of these pseudo-islets did not reveal a loss of beta-cell identity as the cause of the observed functional impairment but highlighted potential new signaling pathways influenced by alpha- and delta-cells. This demonstrates the importance of interactions among different endocrine cell types within the islet for the function of pancreatic beta-cells. It represents a new and effective tool for identifying signaling pathways and compounds that directly or indirectly (via other endocrine cell types) modulate the identity and function of pancreatic endocrine cells. Overall design: RNAseq profiling of mouse pancreatic beta-cells from clusters cultured for 5 days with all other endocrine cells or culture alone

胰岛（islets of Langerhans）在血糖水平的检测与调控中发挥核心作用。尽管产胰岛素的β细胞已得到充分表征，但胰腺胰岛内的其他细胞类型（α、δ、PPY及ε细胞）仍有诸多科学问题有待探究。
在此研究背景下，我们构建了嵌合类器官（chimeric organoids），用于解析胰腺胰岛中不同细胞群之间的相互作用机制。此前，我们已建立一种基于流式细胞术（flow cytometry）的高效纯化方案，可分离得到胰腺胰岛中的主要细胞群（α、β及δ细胞）。
如今，我们开发了一项可重新聚集这些分选后细胞群的技术，能够按需精准调控每种细胞群的占比，从而构建人工细胞簇（伪胰岛，pseudo-islets）。我们成功构建了缺失δ细胞，或同时缺失α与δ细胞的细胞簇，并在基因和蛋白水平验证了该细胞剔除效果。
随后，我们通过检测葡萄糖刺激的胰岛素分泌（glucose-stimulated insulin secretion）评估了这些伪胰岛的功能。实验结果显示，单独缺失δ细胞并未对胰岛素分泌造成显著影响。然而，同时缺失α与δ细胞的伪胰岛，其胰岛素分泌能力出现了明显下降。
对这些伪胰岛的转录组学（transcriptomic）分析表明，β细胞特性的丧失并非本次观察到的功能损伤的诱因，而是凸显出受α和δ细胞调控的潜在全新信号通路。这一结果证实了胰岛内不同内分泌细胞类型间的相互作用对胰腺β细胞功能的重要性，同时也为直接或间接（通过其他内分泌细胞类型）调控胰腺内分泌细胞特性与功能的信号通路及化合物的筛选，提供了一种全新的有效研究工具。
实验整体设计：对分别与其他所有内分泌细胞共培养5天、或单独培养的细胞簇中的小鼠胰腺β细胞进行RNA测序（RNAseq）转录组分析。