In many organs, the processes of vascularisation and innervation are frequently interdependent. In the pancreas, islet endocrine cells secrete vascular endocrine growth factor (VEGF) to direct vascularisation, but little is known about how islet innervation is regulated. On , Marcela Brissova, Alvin Powers and colleagues analyse the role of VEGF, and the vasculature, in controlling nerve fibre growth in the developing mouse pancreas. They find that, although neural crest-derived nerves surround the islets during embryonic development, they do not penetrate them until postnatal stages. This late step of islet innervation is dependent on VEGF, but indirectly - via its effects on the vasculature. Axon guidance molecules and extracellular matrix factors expressed by endothelial cells, and growth factors produced by endocrine cells are likely involved in promoting innervation; the authors propose that the islet vessels may act as a scaffold for nerve fibre growth. Such insights into how islet formation, vascularisation and innervation are coordinated are key for developing strategies to produce functional islets for therapeutic purposes.
