Stem cell study eyes world-first treatment

More than 250 Kiwis require a corneal transplant each year. Photo / RF123

Efforts to tackle a major eye problem that can lead to blindness could be boosted by a world-first Kiwi study into newly discovered and potentially game-changing adult stem cells.

The new project, led by Dr Jie Zhang of Auckland University's Department of Ophthalmology, could also ease the increasing demand for New Zealand donor corneas.

Disease, damage or loss of the innermost layer of the cornea, called the corneal endothelium, can result in blindness.

Each year, more than 250 Kiwis, from the young to the elderly, require a corneal transplant because of disorders where the cornea becomes cloudy, scarred or infected.

Visual impairment or blindness due to corneal disease is currently treated by transplanting a viable cornea from a recently deceased person.

Unfortunately, a lack of supply of donor tissue is limiting the number of patients who can be treated, at a time when factors such as increased life expectancy and an ageing population is driving up demand.

Zhang's new study, supported by a $300,000 Marsden Fund grant, aims to address this problem by boosting the number of patients who can be treated from a single donor.

Her team will investigate a particular type of adult stem cell, recently discovered in a specific area of the cornea called the transition zone, that could be able to regenerate the corneal endothelium.

"This group of stem cells haven't previously been studied that much, as they're just newly discovered," she said.

Disease, damage or loss of the innermost layer of the cornea, called the corneal endothelium, can result in blindness. Photo / 123RF

"So first, we will try to determine whether they're truly stem cells, and whether they can proliferate, generating many cells from just one cell, and whether they can differentiate into corneal endothelial cells to repair or replace diseased or lost tissue."

Zhang said the area had long been a challenging area to study, mainly because corneal endothelia cells were difficult to grow in culture.

Dr Jie Zhang. Photo / University of Auckland

"But this transition zone containing the stem cells is new and not many people have cultured it before, so we don't really know what we'll discover."

If the study proved successful, each donor cornea could be a source for several transplants.

Meanwhile, another Marsden Fund-supported project will investigate a potential new approach to strengthening bones.

Scientists understand that repetitive stress on bone leads to increased strength and higher bone density, whereas disuse can cause them to thin - an effect much like that in our muscles.

This suggests the existence of a "bone bio-sensor" that registers mechanical stress and activates an appropriate response.

Professor Stephen Robertson, of Otago University's Dunedin School of Medicine, and Dr Sujay Ithychanda from the US-based Lerner Research Institute, have discovered mutations in two different human genes that result in excessive bone density, or hyperostosis, where bones are denser and stronger than normal.

Their project will investigate whether the proteins encoded by these genes represent the long-sought sensor of mechanical stress in bone-forming cells.

Professor Stephen Robertson of Otago University's Dunedin School of Medicine. Photo / Supplied

Finding out how our bones sense mechanical stress - and how this leads to increased bone density and strength - could lead to new therapies being developed for treating bone loss in osteoporosis or during immobilisation of fractures.

This project will also study how our bones sense environmental signals.

How our skeleton interacts with gravity may even shed light on ways to combat the effects of weightlessness on bones during space travel.