Stem cells promise new disease treatments

US scientists have managed to grow human retina cells in the laboratory, using stem cell taken from early embryos. The team, based at biotech firm Advanced Cell Technology (ACT), hope that their achievement will lead to new treatments for some forms of age-related vision loss. Meanwhile, an Israeli team has shown that human embryonic stem cells (ES cell) can act as 'biological pacemakers' when injected into failing pig hearts.  

Many cases of age-related blindness are caused by the loss of cells called retinal pigment epithelial (RPE) cells, which play a crucial role in making sure that the light-sensitive cells work efficiently. The new research, published in the Journal of Cloning and Stem Cells, is the first time that these cells have been derived from human ES cells. 'We believe these new retinal cells could be used to treat blindness and may, in fact, be one of the very first applications of embryonic stem cell technology', said Robert Lanza, ACT's scientific director.

Lanza said that the first cell-based therapies for macular degeneration, a major cause of blindness in people over 60, could be available 'in one to two years'. He also criticised President Bush's ES cell policy, which limits federally-funded researchers to working on ES cell lines created on or before 9 August 2001. The retina cells were derived from newer batches of cell lines, created using private funds, which are not contaminated with animal viruses and could safely be transferred into people. 'The question is how many other important scientific or medical breakthroughs have not occurred because of the current stem cell policy', he said, adding 'this is what we've been trying to tell the president for years'.

In the second study, scientists at the Technion-Israel Institute of Technology used human embryo stem cells to grow heart muscle cells in the laboratory. They then injected these cells into the hearts of 13 pigs with unusually slow heartbeats, and found that in 11 of the animals the cells produced their own heart rhythm. The researchers, who published their results in the journal Nature Biotechnology, said that the same technique could potentially be used to make a 'biological pacemaker' to treat human patients with heart conditions. Tim Bowker, of the British Heart Foundation, called the results 'interesting', but cautioned that the technique is a long way from clinical applications in humans.