A soft spot for stem cells helps cornea healing

New research developed by scientists which reveals a potential revolutionary way to treat eye injuries and prevent blindness by softening the tissue hosting the stem cells.

It has been discovered that a simple application of collagenase, a tissue softening enzyme prevents the loss of corneal stem cells following an injury and could prevent patients from losing their sight. This shows that keeping corneal stem cells in a soft environment is fundamental for their reproduction, self-renewal and ability to heal the damaged tissue. It offers hope to almost 500,000 people a year who lose their sight due to chemical burns including acid attacks. 

Scientists were able to determine that the corneal stem cell niche, the area of tissue in the cornea where stem cells live is a much softer environment than the rest of the tissue and stiffening the niche causes stem cells to mature and lose their self-renewing and wound healing properties. "This study demonstrates a new way to treat injuries by changing the stiffness of the natural environment. This approach provides a valuable tool to analyse live cells within the cornea, as well as to further explore new therapies for restoring or even improving their function."

Like skin, the cornea is covered by a multi-layered epithelium forming a barrier to physical harm and invading microorganisms. Unlike skin, when an injury occurs at the corneal epithelium is repaired by stem cells clustered in the periphery, first by quickly dividing in huge numbers and then by migrating towards the damaged site as matured epithelial cells in order to heal the wound. 

Using live corneal tissues as a model system, the team recreated the effects of chemical burns. After treating the wounded, stiffened areas of the cornea using small doses of collagenase, a tissue-softening enzyme to restore the stem cell niche, it once again became malleable and able to support stem cells and promotes healing. The topical application of collagenase is safe and effective in restoring the normal stiffness of the cornea and helps tissue regeneration by preventing the differentiation and loss of adult stem cells after such injuries.

The scientists believe the same technique could be applied to help alleviate the lack of corneas available for transplantation by the almost 5 million people suffering from total blindness due to corneal scarring caused by burns, disease, lacerations or abrasion.