Stem Cell Selection
The research group chose to use muscle stem cells, Dr. Halum said, because they could obtain therapeutic quantities with just a small muscle biopsy and for their ease of transduction. Researchers used ciliary neurotrophic factor (CNTF) after finding that 90 percent of cells survived in a muscle stem cell survival assay, compared to 50 percent in a saline group. The researchers then developed a lentivirus to encode the CNTF, finding they could do so with 92 percent efficiency, Dr. Halum said. In a pilot study, they established that vincristine could be used next to stem cells with no adverse effects on the stem cells’ reinnervation effects.
Finally, rat models were divided into five groups, with six in each group: a saline control group; a group with enhanced green fluorescent protein (EGFP)-expressing stem cells injected into the thyroarytenoid (TA) muscle and saline into the posterior cricoarytenoid (PCA) muscle; CNTF-expressing stem cells into the TA and saline into the PCA; EGFP-expressing stem cells into the TA and vincristine into the PCA; and CNTF-expressing stem cells into the TA and vincristine into the PCA.
On videolaryngoscopy after two months, researchers saw only some weak adduction in one CNTF animal. But, on laryngeal electromyography, they saw heightened recruitment scores in the TA muscles in the groups that had received CNTF. And they saw reduced scores in the PCA muscles in those who had received vincristine, as they had hoped.