This article by Lauren Tappan
A team of Indian scientists led by Dr. Indumathi Mariappan was able to grow complex eye-like organs in the lab by allowing the cells to organise themselves in three dimensions. The miniature eye closely resembles the developing eyes of an early-stage embryo. The eye-like structure consists of miniature forms of retina, cornea and eyelid. The results were published in the journalDevelopment.
“It took about four–six weeks for the eye-like structure to form from iPS cells. We then removed the cornea-like structure for further study,” says Dr. Mariappan from the Centre for Ocular Regeneration at the LV Prasad Eye Institute and the corresponding author of the paper.
The cornea has three layers — epithelium (outer layer), stroma (middle layer) and endothelium (inner layer). “All the three layers of the cornea were observed, indicating that the mini-cornea had developed correctly,” she says. “The cornea initially forms as a simple bubble-like structure which is very delicate to handle. It later matures to form a thick cornea-like structure over a period of 10-15 weeks.”
The corneal epithelial sheets that would be used for treating the damaged eyes were then grown in the lab using small pieces of the mini-cornea containing the epithelium and a portion of the stroma. The stem cells present in the tissue pieces proliferated and gave rise to a uniform sheet of epithelium of about 2.5 cm by 2.5 cm size.
The team is currently focusing on testing the usefulness of the corneal cells grown from iPS cells in restoring vision in animal models (rats). “We will soon be starting the animal experiments,” she says. Trials on human subjects will be considered if the animal experiments turn out to be safe and effective in restoring vision.
In parallel, the researchers are also working on producing mini-retinal tissue and actively exploring iPS cell-derived retinal tissues for treating several retinal diseases such as age-related macular degeneration (AMD), retinitis pigmentosa and certain forms of congenital blindness seen in children and young adults.
Already, retinal cells grown using human embryonic stem cells and iPS cells are being tested in clincal trials in a few countries to treat retinal diseases.