Researchers use stem cells to regenerate lenses in infants

Researchers in the United States and China have shown for the first time that endogenous stem cells can regenerate functional lenses in infants after removal of congenital cataracts, as reported online March 9, 2016 in the journal Nature.

Results showed that this approach regenerated lenses with superior visual function in all 12 infants with congenital cataracts who received the new surgery. It also resulted in many fewer surgical complications than the current standard—lens extraction and artificial intraocular lens (IOL) implantation.

“An ultimate goal of stem cell research is to turn on the regenerative potential of one’s own stem cells for tissue and organ repair and disease therapy,” said co-lead author of the study Kang Zhang, MD, PhD, Professor of Ophthalmology and Chief of Ophthalmic Genetics at the University of California San Diego’s Shiley Eye Institute, in San Diego, CA.

For this investigation, Dr. Zhang and colleagues developed a minimally-invasive capsulorhexis method that considerably reduced the size of the incision and relocated the capsulorhexis opening from the central visual axis to the periphery. These changes improved transparency of the visual axis, preserved the integrity of the capsular bag and, most importantly, retained lens epithelial cells (LECs) after removal of the cataract.

Dr. Zhang and colleagues first tested the minimally invasive method in rabbits and monkeys before conducting a small clinical trial in infants. They found the new surgical technique allowed pre-existing LECs to regenerate into functional lenses. In the infant trial, regenerated transparent biconvex lens structures had formed by 3 months post-surgery. By 8 months post-surgery, the average central thickness of the regenerated lenses had increased significantly, comparable to a native lens.

When researchers tested the accommodative ability of the infants’ regenerated lenses, they found the mean accommodative response had increased to 2.5 diopters at 8 months—a significant difference compared to the 0.10-diopter increase in 25 aphakic infants used as controls. Also, the latter control group experienced a higher incidence of post-surgery inflammation, early-onset ocular hypertension, and increased lens clouding.

“The success of this work represents a new approach in how new human tissue or organs can be regenerated and human disease can be treated, and may have a broad impact on regenerative therapies by harnessing the regenerative power of our own body,” Dr. Zhang said.

Building on the success of this investigation, the researchers are now setting their sights on treatment of age-related cataracts. “However, there are important differences between pediatric and adult cataracts,” the authors wrote. “Hard cataracts in adults may require phacoemulsification, which could damage LECs. In addition, tissue consistency and capsular thickness/elasticity may pose other challenges for adult lens regeneration. Furthermore, differences between the regenerative capacities of pediatric and adult lenses may suggest a prolonged period of regeneration in adults.”

Despite these challenges, the researchers are optimistic about the potential for this technique. “We believe that our new approach will result in a paradigm shift in cataract surgery and may offer patients a safer and better treatment option in the future,” Dr. Zhang said.