INSERM U833, Collège de France, Paris, France.
PLoS One. 2012;7(1):e29438. doi: 10.1371/journal.pone.0029438. Epub 2012 Jan 17.
AIMS/HYPOTHESIS: Islet vascularization, by controlling beta-cell mass expansion in response to increased insulin demand, is implicated in the progression to glucose intolerance and type 2 diabetes. We investigated how hyperglycaemia impairs expansion and differentiation of the growing pancreas. We have grafted xenogenic (avian) embryonic pancreas in severe combined immuno-deficient (SCID) mouse and analyzed endocrine and endothelial development in hyperglycaemic compared to normoglycaemic conditions.
14 dpi chicken pancreases were grafted under the kidney capsule of normoglycaemic or hyperglycaemic, streptozotocin-induced, SCID mice and analyzed two weeks later. Vascularization was analyzed both quantitatively and qualitatively using either in situ hybridization with both mouse- and chick-specific RNA probes for VEGFR2 or immunohistochemistry with an antibody to nestin, a marker of endothelial cells that is specific for murine cells. To inhibit angiopoietin 2 (Ang2), SCID mice were treated with 4 mg/kg IP L1-10 twice/week.
In normoglycaemic condition, chicken-derived endocrine and exocrine cells developed well and intragraft vessels were lined with mouse endothelial cells. When pancreases were grafted in hyperglycaemic mice, growth and differentiation of the graft were altered and we observed endothelial discontinuities, large blood-filled spaces. Vessel density was decreased. These major vascular anomalies were associated with strong over-expression of chick-Ang2. To explore the possibility that Ang2 over-expression could be a key step in vascular disorganization induced by hyperglycaemia, we treated mice with L1-10, an Ang-2 specific inhibitor. Inhibition of Ang2 improved vascularization and beta-cell density.
This work highlighted an important role of Ang2 in pancreatic vascular defects induced by hyperglycaemia.
目的/假设：胰岛血管生成通过控制β细胞质量的扩张来响应增加的胰岛素需求，与葡萄糖耐量受损和 2 型糖尿病的进展有关。我们研究了高血糖如何损害正在生长的胰腺的扩张和分化。我们已经将异种（禽类）胚胎胰腺移植到严重联合免疫缺陷（SCID）小鼠中，并分析了高血糖与正常血糖条件下的内分泌和内皮发育。
在正常血糖或高血糖、链脲佐菌素诱导的 SCID 小鼠的肾包膜下移植 14 天鸡胰腺，并在两周后进行分析。使用针对 VEGFR2 的鼠和鸡特异性 RNA 探针的原位杂交或针对 nestin 的免疫组织化学，分别从定量和定性两方面分析血管生成。nestin 是内皮细胞的标志物，特异性针对鼠细胞。为了抑制血管生成素 2（Ang2），SCID 小鼠每周两次腹腔注射 4mg/kg IP L1-10。
在正常血糖条件下，鸡源性内分泌和外分泌细胞发育良好，移植内的血管由鼠内皮细胞排列。当胰腺移植到高血糖小鼠中时，移植物的生长和分化发生改变，我们观察到内皮连续性中断，出现大的充满血液的空间。血管密度降低。这些主要的血管异常与鸡 Ang2 的强烈过表达有关。为了探讨 Ang2 过表达是否可能是高血糖引起的血管紊乱的关键步骤，我们用 L1-10 治疗小鼠，L1-10 是一种 Ang2 特异性抑制剂。Ang2 的抑制改善了血管生成和β细胞密度。
这项工作强调了 Ang2 在高血糖诱导的胰腺血管缺陷中的重要作用。
