The application of stem cell implantation for the treatment of Parkinson’s disease has ebbed and flowed from successes to disappointments. F-18 DOPA PET imaging has played a consistently important role, however, in both initial diagnosis and treatment monitoring.
The application of stem cell implantation for the treatment of Parkinson's disease has ebbed and flowed from successes to disappointments. F-18 DOPA PET imaging has played a consistently important role, however, in both initial diagnosis and treatment monitoring.
Dr. Anders Björklund, section chief at the Wallenberg Neuroscience Center at Lund University in Sweden, explained the recent history of stem cell therapies for Parkinson's during the opening session of the Society for Molecular Imaging Wednesday in Cologne, Germany.
Many techniques that employ fetal stem cells are circumscribed in the U.S. because of the Bush administration's moratorium on research involving aborted fetuses. U.S. researchers traveled here to learn what Europeans are contributing to the field.
Some were disappointed with Björklund's emphasis on therapy. But during the question and answer period, it became clear that molecular imaging could play a role crucial to the disease's diagnosis and treatment.
Björklund noted early in his lecture that half of the dopamine-producing neurons in a Parkinson's disease patient's brain are dead before the first physical symptoms appear. Therapy could be less challenging and potentially more successful if it could be initiated earlier, he said. And better imaging could create opportunities for therapy.
After diagnosis, some dopamine-producing cells may survive in a dysfunction state, according to Björklund. Imaging techniques capable of identifying those cells would create opportunities to develop therapies that block further disease advancement.
Björklund described how F-18 DOPA imaging is used for disease phenotyping and the serial measurement of dopamine production after the introduction of recombinant stem cells. He was asked to identify the most important biochemical markers to improve the imaging.
The Holy Grail for Parkinson's imaging is the ability to see the cells themselves, Björklund said. Therapists would love to see a stable indicator of cell status and growth. He pointed to attempts in Germany and elsewhere to use MRI to monitor cell growth. He expects genomic markers to be identified that can reveal the evolution of embryonic stem cells, for example, through steps leading to their development into dopamine-producing neurons that will effectively treat Parkinson's disease.
"With such tools, we will be more efficient in monitoring the dynamics of stem cells," Björklund said.
Gene expression imaging would also help, he said. It would enable physicians to see the transformation of one cell type to another and to monitor cell phenotype.