Glenn T. Gobbel, Douglas Kondziolka, Wendy Fellows-Mayle and Martin Uram
Cell transplantation has shown promise for the treatment of various neurological disorders, but the factors that influence cell survival and integration following transplantation are poorly understood. In fact, little is known regarding how simple but potentially critical variables, including the method of cellular preparation and administration, might affect transplant success. The goal of the present study was to determine the impact of time between tissue preparation and implantation on cellular viability. Time can vary with cell preparation, delivery to the operating room, and surgical technique. This study was also designed to evaluate the sensitivity of various methods of assessing implant viability.
Cell lines of neural progenitor cells and bone marrow stromal cells were generated from healthy adult mice. On the day of experimentation, the cells were collected, suspended in a balanced salt solution, and sequentially assessed for viability for up to 3.5 hours based on their appearance under phase-contrast microscopy, their ability to retain a fluorescent dye, and their attachment to a cultivation surface for 24 hours.
When viability was measured based on the ability of cells to retain a fluorescent dye, there was a decrease in viability of 10–15% each hour. Based on the ability of the cells to attach to a culture surface and grow for 24 hours, viability decreased more rapidly at approximately 20% per hour. In addition, only about one-third of the cells judged viable based on phase-contrast microscopy or acute dye retention were found to be viable based on plating, and only 10% of the cells initially judged as viable were still capable of survival after 3 hours in suspension.
The authors' results indicate that that there can be significant losses in viability between preparation and implantation and that more sophisticated methods of evaluation, such as the ability of cells to attach to a substrate and grow, may be required to detect decreases in viability. The time between preparation and implantation will be an important factor in clinical trial design.
Christopher M. Bonfield, Lesley M. Foley, Shinjini Kundu, Wendy Fellows-Mayle, T. Kevin Hitchens, Gustavo K. Rohde, Ramesh Grandhi and Mark P. Mooney
Craniosynostosis is a condition in which one or more of the calvarial sutures fuses prematurely. In addition to the cosmetic ramifications attributable to premature suture fusion, aberrations in neurophysiological parameters are seen, which may result in more significant damage. This work examines the microstructural integrity of white matter, using diffusion tensor imaging (DTI) in a homogeneous strain of rabbits with simple, familial coronal suture synostosis before and after surgical correction.
After diagnosis, rabbits were assigned to different groups: wild-type (WT), rabbits with early-onset complete fusion of the coronal suture (BC), and rabbits that had undergone surgical correction with suturectomy (BC-SU) at 10 days of age. Fixed rabbit heads were imaged at 12, 25, or 42 days of life using a 4.7-T, 40-cm bore Avance scanner with a 7.2-cm radiofrequency coil. For DTI, a 3D spin echo sequence was used with a diffusion gradient (b = 2000 sec/mm2) applied in 6 directions.
As age increased from 12 to 42 days, the DTI differences between WT and BC groups became more pronounced (p < 0.05, 1-way ANOVA), especially in the corpus callosum, cingulum, and fimbriae. Suturectomy resulted in rabbits with no significant differences compared with WT animals, as assessed by DTI of white matter tracts. Also, it was possible to predict to which group an animal belonged (WT, BC, and BC-SU) with high accuracy based on imaging data alone using a linear support vector machine classifier. The ability to predict to which group the animal belonged improved as the age of the animal increased (71% accurate at 12 days and 100% accurate at 42 days).
Craniosynostosis results in characteristic changes of major white matter tracts, with differences becoming more apparent as the age of the rabbits increases. Early suturectomy (at 10 days of life) appears to mitigate these differences.
Ezequiel Goldschmidt, Wendy Fellows-Mayle, Rachel Wolfe, Ajay Niranjan, John C. Flickinger, L. Dade Lunsford and Peter C. Gerszten
Stereotactic radiosurgery (SRS) has been used to treat trigeminal neuralgia by targeting the cisternal segment of the trigeminal nerve, which in turn triggers changes in the gasserian ganglion. In the lumbar spine, the dorsal root ganglion (DRG) is responsible for transmitting pain sensitivity and is involved in the pathogenesis of peripheral neuropathic pain. Therefore, radiosurgery to the DRG might improve chronic peripheral pain. This study evaluated the clinical and histological effects of high-dose radiosurgery to the DRG in a rodent model.
Eight Sprague-Dawley rats received either 40- or 80-Gy SRS to the fifth and sixth lumbar DRGs using the Leksell Gamma Knife Icon. Animals were euthanized 3 months after treatment, and the lumbar spine was dissected and taken for analysis. Simple histology was used to assess collagen deposition and inflammatory response. GFAP, Neu-N, substance P, and internexin were used as a measure of peripheral glial activation, neurogenesis, pain-specific neurotransmission, and neurotransmission in general, respectively. The integrity of the spinothalamic tract was assessed by means of the von Frey test.
The animals did not exhibit any signs of motor or sensory deficits during the experimentation period. Edema, fibrosis, and vascular sclerotic changes were present on the treated, but not the control, side. SRS reduced the expression of GFAP without affecting the expression of Neu-N, substance P, or internexin. The von Frey sensory perception elicited equivalent results for the control side and both radiosurgical doses.
SRS did not alter sensory or motor function but reduced the activation of satellite glial cells, a pathway for DRG-mediated pain perpetuation. Radiosurgery provoked changes equivalent to the effects of focal radiation on the trigeminal ganglion after SRS for trigeminal neuralgia, suggesting that radiosurgery could be successful in relieving radiculopathic pain.