Establishment, characterization and long-term culture of human endocrine pancreas-derived microvascular endothelial cells

Background: In vitro primary cultures of microvascular endothelial cells from endocrine pancreas are difficult to obtain, but can be a very helpful tool for studies of islet biology, transplantation and regenerative medicine.

Methods: We applied a protocol recently described for the isolation and culture of brain microvascular endothelial cells (EC) on human pancreatic islets. EC obtained were characterized in terms of morphological (light and transmission electron microscopy), phenotypical (by immunofluorescence and flow cytometry) and functional (cord formation assay and protein secretion by multiplex bead-based assay) characteristics.

Results: EC were obtained from 25% of islet preparations processed. Two primary endothelial cell lines showed high proliferative potential and were deeply characterized: they presented endothelial cell morphology and expressed CD31, CD49a, CD49e, CD34, von Willebrand Factor (vWF), Vascular Endothelial CAdherin (VE-CAD), Tyrosine Kinase with Ig and EGF Homology Domains-2 (TIE2), Vascular Endothelial Growth Factor Receptor 1 (VEGFR1), Ulex lectin and the endothelium endocrine-specific marker nephrin. Besides, they were able to form cordons in vitro and secreted factors involved in the process of angiogenesis such as Vascular Endothelial Growth Factor (VEGF), Monocyte Chemotactic Protein 1 (MCP-1), interleukin (IL)-8 and Melanoma Growth Stimulatory Activity Alpha (GROα). These cell lines were termed Human Islet Microvascular Endothelial Cells (HIMEC).

Discussion: This study establishes a simple and effective strategy for isolation and long-term culture of EC derived from human pancreatic islet. HIMEC in culture preserve phenotype and functional properties and are, therefore, a useful tool for future experiments of in vitro pancreas modelling, co-transplantation with pancreatic islets, re-vascularization of scaffold or matrix for regenerative medicine purposes.