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Posted at: Feb 11, 2018, 1:43 AM; last updated: Feb 11, 2018, 1:43 AM (IST)

Lab develops mini human eye in test tube

Lab develops mini human eye in test tube
The ‘eye’ resembles the developing eyes of an early-stage embryo.

Suresh Dharur in hyderabad

It is a breakthrough that holds promise to tackle blindness. Researchers at Hyderabad-based LV Prasad Eye Institute (LVPEI), the country's premier ophthalmic research centre and hospital, have successfully grown miniature eye-like organs, using stem cells in a test tube, that closely resemble the developing eyes of an early-stage embryo.

The miniature eyes were produced using induced pluripotent stem (iPS) cells. The iPS cells are produced by genetically manipulating human skin cells to produce embryonic-like stem cells that are capable of forming any cell types of the body.

Though it might take years to perfect the procedure to develop the complete eye through stem cells, the development holds a huge promise in a country that accounts for largest number of people suffering from blindness. Out of an estimated 37 million people across the globe who are blind, over 15 million are from India. What is worse, nearly 75% of these are cases of avoidable blindness. This is largely due to the acute shortage of optometrists and donated eyes for the treatment of corneal blindness. 

While India needs over 40,000 optometrists, it has only 8,000. While India needs 2.5 lakh donated eyes every year, the country's 109 eye banks manage to collect just about 25,000 eyes.

A research team led by Dr Indumathi Mariappan at the Sudhakar & Sreekanth Ravi Stem Cell Biology Laboratory at LVPEI has succeeded in developing complex 3D corneal organoids, which are miniature versions of a larger organ developed in a test tube. These organoids developed by the institute are capable of recapitulating steps of normal corneal development.

The eye field primordial (EFP) clusters that emerged from differentiating PSCs developed into whole eyeball-like, self-organized, three-dimensional miniature structures, the researchers said in a presentation at the International Congress of Cell Biology held at the Centre for Cellular and Molecular Biology (CCMB) in Hyderabad. 

“These organoids recapitulate the early developmental events in vitro and displayed similar anatomical features and marker expression profiles as that of adult tissues and offers an alternative tissue source for regenerating different tissues of the eye and eliminate the need for complicated cell enrichment procedures,” the researchers said.

“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, the lead author.

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. 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 scientist explained.

The corneal epithelial sheets that could 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 technology can also be utilised for treating critical eye injuries. For the last one-and-half decades, the institute has been conducting research on stem cells to develop human eye.

“Availability of such mini corneas at 10 weeks of maturation circumvents the need for complicated cell enrichment protocols and offers a simpler method of establishing enriched cultures of corneal epithelial cell sheets for basic research and for regenerative applications,” Dr Indumathi said in her presentation.

The iPS cells are produced by genetically manipulating human skin cells to produce embryonic-like stem cells that are capable of forming any cell types of the body. The corneal epithelial cell sheets grown with the help of these miniature eyes can help in restoration of vision in patients with damaged limbus region of the cornea. The limbus region of the cornea contains stem cells, and chemical or thermal damage to this region affects corneal regeneration and results in vision loss.

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