December 1, 2003.
By Dwayne Hunter,
A polymer scaffold has been used to grow corneal and nerve cells that could help treat corneal diseases that lead to blindness.
The tissue engineering strategy used by May Griffith of the University of Ottawa Eye Institute in Ontario and colleagues could alleviate problems of organ failure and donor organ shortages for transplantation.
Corneal diseases are a major cause of vision loss, second only to cataracts and affecting 10 million people worldwide.
The cornea is the main optical element in the eye. It refracts light onto the retina for vision and provides a tough protective barrier for delicate internal eye tissues.
The cornea is one of the most highly innervated tissues in the body. Nerve activity is responsible for maintaining overall corneal health.
Nerve loss and dysfunction can cause "dry eye," a condition that can involve decreased corneal sensitivity and corneal epithelial erosions.
When sensitivity is lost, the cornea becomes vulnerable to irreparable injury, ulceration, loss of vision and, in severe cases, blindness.
Few good treatments
Currently, the only widely accepted treatment for corneal blindness is transplantation with human donor tissue.
A major problem with this approach, however, is that the worldwide demand for transplantation corneas exceeds the supply, and this situation is expected to worsen as populations age.
An alternative for patients suffering from corneal disease is replacement of the damaged cornea with an artificial substitute.
Successful corneal replacement by synthetics, however, has not been achieved and existing prostheses neither integrate seamlessly into host tissue nor promote restoration of nerve control.
In search of a successful treatment, Griffith and colleagues turned to tissue engineering.
The researchers designed a matrix composed of collagen and a synthetic N-isopropylacrylamide-based polymer.
The matrix has the same optical clarity, curvature and biomechanical properties as a human cornea.
In vitro studies demonstrated that the matrix could support corneal and nerve cell growth.
When the researchers transplanted it into pigs with damaged corneas, nerve regeneration occurred within three weeks.
In contrast, pigs receiving traditional donor transplantations exhibited no nerve regeneration during the same time period.
Researchers can now control the strength and optical clarity of biosynthetic composites to the point that tissue engineering corneal replacements may address future world shortages of donor corneas.
In addition, such corneal implants could be the solution to potential problems resulting from the lack of nerve regeneration after eye surgery.
Biosynthetic matrices could also address the challenging problem of nerve regeneration in other organs and tissues.
This study is published in the Proceedings of the National Academy of Sciences (read abstract).
Copyright © 2002-2003 Betterhumans
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