Scripps Research Institute scientists have offered new hope for parents whose children suffer from the rare genetic disorder 'cystinosis' by showing through an experiment on mice that stem cell transplantation can successfully correct the defect.
"After meeting the children who suffer from this disease, like an 18-year-old who has already had three kidney transplants, and the families who are desperately searching for help, our team is committed to moving toward a cure for cystinosis, a lysosomal storage disorder. This study is an important step toward that goal," said principal investigator Stephanie Cherqui.
In the study, the researchers used bone marrow stem cell transplantation to address symptoms of cystinosis in a mouse model.
The procedure virtually halted the cystine accumulation responsible for the disease, and the cascade of cell death that follows.
Cystine is a by-product of the break down of cellular components the body no longer needs in the cell's "housekeeping" organelles, called lysosomes.
Normally, cystine is shunted out of cells, but in cystinosis a gene defect of the lysosomal cystine transporter causes it to build up, forming crystals that are especially damaging to the kidneys and eyes.
Cystinosis is a rare but devastating disease affecting children as young as six months, who begin to suffer renal dysfunction, which grows progressively worse with time. Other symptoms include diabetes, muscular disease, neurological dysfunction, and retinopathy.
The only available drug to treat cystinosis, cysteamine, while slowing the progression of kidney degradation, does not prevent it, and end-stage kidney failure is inevitable.
In the new study, the researchers found that transplanted bone marrow stem cells carrying the normal lysosomal cystine transporter gene abundantly engrafted into every tissue of the experimental mice.
This led to an average drop in cystine levels of about 80 percent in every organ.
Not only it prevented kidney dysfunction, there was less deposition of cystine crystals in the cornea, less bone demineralization, and an improvement in motor function.
"The results really surprised and encouraged us. Because the defect is present in every cell of the body, we did not expect a bone marrow stem cell transplant to be so widespread and effective," says Cherqui.
Cherqui said that adult bone marrow stem cell therapy is particularly well suited as a potential treatment for cystinosis because these cells target all types of tissues.
In addition, stem cells reside in the bone marrow for the duration of a patient's life, becoming active as needed, a particular benefit for a progressive disease like cystinosis.
The study has been published in the journal Blood.