People affected by cystic fibrosis (CF) could potentially be treated with their own bone marrow cells, say US scientists. A team based at the University of Pittsburgh has shown that stem cells from bone marrow are able to grow into epithelial cells, , which line the airways of the lungs. The researchers also managed to deliver a working copy of the CF gene to the cells growing in the laboratory, paving the way for a new cell-based therapy for this inherited lung disease.
CF mainly affects the lungs, where thick mucus builds up causing repeated infections and breathing difficulties, and the pancreas, where blockages cause digestive problems. People with CF cannot control the levels of salt and water in their body cells properly, so their body fluids are thicker than usual. In 1989, researchers discovered that people with CF have no working version of the CFTR gene (cystic fibrosis transmembrane conductance regulator), which usually makes a protein that controls salt levels.
Since the discovery of the CFTR gene, many researchers have been trying to develop a gene therapy treatment for CF, based on delivering a working copy of the gene to the affected tissues. However, one of the challenges facing gene therapy researchers is getting enough of the replacement gene into the cells, and achieving a permanent effect. The new study, published in the Proceedings of the National Academy of Sciences, shows that it might be possible to overcome this problem by combining stem cell and gene therapy approaches.
Previous studies have suggested that bone marrow stem cells can grow into other types of body cell, as well as different types of blood cells. In the latest study, the researchers took stem cells from healthy individuals, and grew them together with mature epithelial cells in the laboratory for 14 days. After this time, the bone marrow cells took on the appearance and characteristics of the epithelial cells. Importantly, the team also showed that bone marrow stem cells taken from three CF patients could produce airway epithelial cells. They then transferred a working CFTR gene into these cells, using a virus. After the treatment, the cells were better at controlling their salt levels than untreated CF stem cells.
'Our results provide proof of principle that a cell-based therapy using marrow stromal cells is both a feasible and promising clinical approach', said lead author Jay K Kolls, adding that the team hope to perform 'a small clinical trial in the next two to three years'. Although Kolls stresses that much more work is needed, he is optimistic about the approach, since it uses a patient's own cells, and so would not trigger an immune system attack.
Meanwhile, a team based at Great Ormond Street Hospital in London has also published evidence that bone marrow stem cells can turn into lung cells. In a study published in the journal Thorax, a team lead by Adam Jaffe studied lung tissue from two male CF patients who received lung transplants from females. They found that the tissue contained cells with the male Y chromosome, which suggests that stem cells in the boys' blood travelled to the lungs and grew into new lung cells. 'It's extremely exciting. This really is a true phenomenon', said Jaffe.
Sources and References
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Adult stem cells from bone marrow stroma differentiate into airway epithelial cells: Potential therapy for cystic fibrosis
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Combined stem cell-gene therapy approach seen as potential treatment for cystic fibrosis
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Gene-tweaked Stem Cells Enlisted to Battle Cystic Fibrosis
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Stem cell lung therapy progress
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