Abstract 14461: Versican Facilitates the Differentiation and Migration of Endothelial Progenitor Cells in Yolk Sac for Vasculogenesis
Background: During embryogenesis, endothelial progenitor cells (EPCs) of blood islands develop migratory phenotype and directed to form anterior choroid plexus, thus initiates vasculogenesis. One of the key factors is EPCs and extracellular matrix interaction. However, the architecture and the way extracellular matrix direct the migration of EPCs in yolk sac vasulogenesis is still obscure.
Methods and results: Medaka mutant, linear heart tube (lht) was established using ENU mutagenesis. Medaka lht mutant showed poorly characterized endocardial layer and cardiac cushion, absence of proper blood vascular system and terminated development at linear heart tube stage. Positional cloning and morpholino experiment confirmed mutation in a proteoglycan gene, versican, which is present in extracellular matrix. By sequencing analysis, we found point mutation at 3’ UTR of versican gene. This phenotype is very stable as we could obtain approximately 25% homozygous through heterozygous-heterozygous cross even after 20 generations. By In Situ Hybridization (ISH), versican was found to express in heart tube, blood island located between 6th and 11th somite at ventral side, and yolk sac after 60 hours post fertilization (hpf). However, by immunohistochemistry, chondroitin sulfate expression was decreased in lht homozygous compared to wild type (wt). Intracellular transmembrane protein, Tmem 100, is an embryonic endothelium enriched gene activated by BMP 9 and 10. By ISH, we observed Tmem 100 positive endothelial cells arrange along the cuvierian ducts and vitello-caudal vein, in yolk sac of wt at 60 hpf. However, in lht homozygous, such localization of Tmem 100 positive cells in blood vessels was absent along with poorly characterized blood vessels. Also, in vitro, versican enhances the differentiation of EPCs and increased endothelial cells migration by transwell migration assay.
Conclusion: Interaction of extracellular matrix with EPCs is very critical in blood island niche. Our results indicated that versican drives differentiation of EPCs and its migration during vasculogenesis.
- © 2013 by American Heart Association, Inc.