A radical gene therapy for cystic fibrosis, delivered to the foetus while it is still in the womb, is a step closer following the successful transference of transgenes to the lungs of five monkeys.
In the study, rhesus macaque foetuses received the genes via the amniotic fluid after a simple injection.
The results show the feasibility of this approach to gene therapy for lung conditions such as cystic fibrosis in humans, as well as unexpectedly revealing the technique as a possible way to target metabolic illnesses.
Craig Cohen, of Louisiana State University, New Orleans, Janet Larson, of the Alton Ochsner Medical Foundation, and colleagues reported their success in Molecular Therapy .
"We hope this will ultimately make cystic fibrosis a treatable disease," Cohen said.
The foetuses swallowed and breathed in the transgene mixture from the amniotic fluid after it was injected into their protective sac within the womb. The genes were then incorporated into the DNA of cells that came into contact with them.
This result had previously been demonstrated in rodents and appeared to be better tolerated by both mother and foetus than other in utero gene therapy techniques.
The transgenes were not incorporated into the foetuses' germline cells and did not provoke the inflammatory response that plagues similar gene transfer attempts after birth.
Thirty days after the treatment, the scientists found the transgenes were being expressed in the monkey foetuses' lungs without adverse effects. They also discovered that large amounts of the marker proteins created by the transgenes were found in the kidney, having travelled from the lungs through the blood stream.
The team had not anticipated this effect, but believes it may open up a new opportunity to tackle metabolic conditions by inserting appropriate transgenes into the lungs.
Nevertheless, the main target for the researchers is cystic fibrosis, utilising the technique to implant a gene that produces the protein CFTR.
Cystic fibrosis affects one in 2,500 children in the United Kingdom, with half dying before their 30th birthday. It is triggered by the lack of the normal CFTR-producing gene, which causes lung cells to malfunction and prompts respiratory infections and other complications.
Larson and Cohen's method of gene therapy relies on the assumption that cystic fibrosis is an illness linked to the faulty development of the foetus. This claim is disputed by many researchers.
In another experiment, the scientists inserted the CFTR gene into developing monkey foetuses. This resulted in their lungs developing faster than normal, adding weight to Cohen's argument.