Retinal regeneration a step closer
13 Apr 2011 by Evoluted New Media
Mouse stem cells can spontaneously form into the optic cup – the precursor of eyes – without any external signalling say researchers in Japan.
Mouse stem cells can spontaneously form into the optic cup – the precursor of eyes – without any external signalling say researchers in Japan.
The finding may have important implications for regenerative medicine for those suffering from retinal degenerative disorders.
Researchers added extracellular matrix proteins to serum-free culture of embryoid body-like aggregates (SFEBq) medium, and within seven days epithelially-organised retinal precursors at high efficiencies were observed.
On day eight, optic vesicle-like structures began to form, followed by bi-layered optic cup-like structures by day 10. The pigmented and neuronal character of the inner and outer layers of cells in these spontaneously-formed tissues was confirmed by gene expression – indicating that the optic cup development occurred in vitro and without any external signalling sources.
“What we’ve been able to do in this study is resolve a nearly century-old problem in embryology, by showing that retinal precursors have the inherent ability to give rise to the complex structure of the optic cup,” said Y. Sasai from the RIKEN Centre for Developmental Biology.
Multi-photo microscopy explored the mechanism behind the process of self assembly in 3D. Researchers found that after ES cell-derived retinal precursors differentiated into pigmented epithelial and neuronal layers, the tissue underwent a four-step morphological rearrangement as it formed the optic cup structure.
Three principle forces explain how the optic cup forms. First, regions of the epithelium must lose rigidity – myosin activity drops – allowing it to buckle inward, after which cells at the hinge points undergo apical constriction, giving them a wedge-like shape. Once these conditions are met, expansion of the tissue surface by cell division results in further involution of the cup.
“It’s exciting to think that we are now well on the way to becoming able to generate not only differentiated cell types, but organised tissues from ES and iPS cells, which may open new avenues towards applications in regenerative medicine,” Sasai said.
