The novel procedure was tested in a small clinical trial using endogenous lens epithelial stem cells from the patients and resulted in regenerated lenses with superior visual function
In a collaborative effort, researchers from the University of California, San Diego School of Medicine, Shiley Eye Institute (both CA, USA) and colleagues from various Universities in China, have developed a new regenerative medicine approach to remove congenital cataracts in infants which induces endogenous stem cells to regrow functional lenses. The study was recently published in Nature.
Congenital cataracts are characterized by lens clouding that occurs at birth or shortly thereafter and are a significant cause of blindness in children. Current treatment is limited by the age of the patient and related complications. Most pediatric patients require corrective eyewear after cataract surgery.
The treatment, which has been previously tested in animals and in a small human clinical trial, produced much fewer surgical complications than the current standard-of-care. The surgery resulted in regenerated lenses with superior visual function in all 12 of the pediatric cataract patients.
“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,” commented Kang Zhang chief of Ophthalmic Genetics at UC San Diego School of Medicine.
In the new study, Zhang and colleagues relied upon the regenerative potential of endogenous stem cells in the retina. Unlike other stem cell approaches that involve producing stem cells in vitro and introducing them back into the patient and comes with potential difficulties such as pathogen transmission and immune rejection, endogenous stem cells are already naturally in place at the site of the injury or problem. In human eyes, lens epithelial stem cells (LECs) generate replacement cells throughout a person’s lifespan, though production declines with age.
Current cataract surgeries largely remove LECs within the lens; the lingering cells generate disorganized regrowth in infants and results in no useful vision. After confirming the regenerative potential of LECs in animal models, the researchers developed a novel minimally invasive surgery method that preserves the integrity of the lens capsule (a membrane that helps give the lens its required shape to function) and a way to stimulate LECs to grow and generate a new lens.
The human trial involved 12 infants under the age of 2 treated with the new method and 25 infants receiving current standard surgical care. The control group experienced a higher incidence of post-surgery inflammation, early-onset ocular hypertension and increased lens clouding. The 12 infants who underwent the new procedure experienced fewer complications and faster healing and, after three months the scientists reported a clear regenerated biconvex lens in all of the patients’ eyes.
“The success of this work represents a new approach in how new human tissue or organ 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,” explained Zhang.
The research team is now looking to expand their work to treating age-related cataracts. Age-related cataracts are the leading cause of blindness in the world. More than 20 million Americans suffer from cataracts and, despite technical advances, a large portion of patients undergoing surgery are left with suboptimal vision post-surgery and are dependent upon corrective eyewear. “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.”
Lin H, Ouyang H, Zhu J et al. Lens regeneration using endogenous stem cells with gain of visual function.Nature, doi:10.1038/nature17181 (2016) (Online before print); http://ucsdnews.ucsd.edu/pressrelease/stem_cells_regenerate_human_lens_after_cataract_surgery_restoring_vision?elqTrackId=0d6ba13e4e864dcc890a257cba132721&elq=952f28f8a15243a4911c3f0b8056a5d7&elqaid=14960&elqat=1&elqCampaignId=6