domingo, 25 de octubre de 2009

Curar a los ciegos

Los avances de la biotecnología es otro de los temas que nos ocupará a lo largo del año. La lista de enfermedades de origen genético es interminable y algunas de ellas podrían encontrar en la manipulación de ciertos genes una terapia efectiva. Conseguir que los ciegos vean podría ser una realidad en el futuro.

Gene Therapy Helps Blind Children See

By Jocelyn Kaiser
ScienceNOW Daily News
24 October 2009

A single injection of DNA into the eyes of four children born with a blindness-causing disease has given them enough vision to walk without help. The study, published today, confirms that if patients with this disease are given gene therapy early in life, the results can be dramatic.

Several clinical trials in the United States and Europe have been using gene therapy to treat a disease called Leber's congenital amaurosis (LCA), which affects about 3000 people in the United States. Those born with LCA start losing their sight at birth and are completely blind by age 40. Children born with one form, LCA2, have defects in a gene called RPE65 that helps the retina's light-sensing cells make rhodopsin, a pigment needed to absorb light. Without rhodopsin, the photoreceptor cells gradually die.

Two years ago, the Penn team began a small safety study of the therapy in humans with collaborators at the Children's Hospital of Philadelphia. They injected each patient's worse eye with a modified virus carrying the RPE65 gene. Early results from this trial and a similar study in the United Kingdom published in April 2008 showed that four of six young adults with LCA2 who received the treatment could later sense more light and perform better in an obstacle course.

But the Penn researchers knew from their studies in animals that children should improve even more because they have more intact retinal tissue than adults do. Today in an online paper in The Lancet, their team and collaborators in Europe report full study results for three of the adults they treated earlier and nine more patients, including four children ages 8 to 11. The children gained more light sensitivity than the adults did--their light sensitivity increased as much as four orders of magnitude, versus one--and they made far fewer mistakes in an obstacle course.

The LCA2 trials are a rare success for the field of gene therapy, which has also cured children with the immune disorder known as bubble boy disease. And they should pave the way for treating more vision disorders. "It's an incredible launching pad to be able to target other diseases," says Penn gene therapy researcher Jean Bennett, who led the study.

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