AAN Meeting: Spinal cord injury Abstracts Apr 13-20, Denver, CO

[Wise Young]

Abstracts

[Wise Young]

[P01.035] Clinical Evaluation of Oral Fampridine-SR (Sustained-Release 4-Aminopyridine) in Patients with Chronic Motor-Incomplete Spinal Cord Injury
Daniel Lammertse, Virgina Graziani, Mitchell A. Katz, Andrew R. Blight, SCI-F201 Study GroupÂ*Englewood, CO; Philadelphia, PA; Hawthorne, NY
OBJECTIVE: Assess the safety and efficacy of multiple oral doses of fampridine-SR, a sustained-release formulation of fampridine (4-aminopyridine), in patients with chronic motor-incomplete spinal cord injury (SCI).
BACKGROUND: Fampridine-SR is a potassium channel blocking agent being investigated for its efficacy to improve neurologic function in patients with chronic SCI and multiple sclerosis.
DESIGN/METHODS: In this double-blind, parallel-group study, a total of 91 patients in 11 centers were randomized to receive fampridine-SR 25 mg bid, fampridine-SR 40 mg bid, or placebo for 8 weeks (2-week dose escalation, 4-week fixed dose, 2-week down-titration). Safety was evaluated from adverse event reports and standard clinical assessments. Efficacy assessments included measures of spasticity (Ashworth scale), bowel and bladder function, male sexual function, Clinical Global Impression, and Subject Global Impression (SGI). Statistical significance was established at P<.025 to adjust for multiple comparisons.
RESULTS: In total, 78% of patients completed the study. Proportionally, more patients dropped out from the 40 mg bid group. The most frequently reported adverse events for all treatment groups (30%) were hypertonia, generalized spasm, insomnia, dizziness, asthenia, pain, constipation, and headache. One patient in the 40-mg group with a history of traumatic brain injury experienced a seizure; study medication was stopped and no further seizures occurred. Two outcome measures were statistically significant in favor of fampridine-SR 25 mg bid: SGI (P = .02) and number of days with bowel movements (P = .02). Several other outcome measures favored fampridine-SR 25 mg bid (spasticity, number of bladder accidents per day, and male sexual function), but did not reach statistical significance.
CONCLUSIONS: Fampridine-SR 25 mg bid was well tolerated and showed statistically significant improvement on SGI and in bowel function. Further testing of fampridine-SR (25 mg bid) in larger clinical trials is ongoing.
Category - Neural Repair and Rehabilitation
SubCategory - Clinical: Spinal Cord Injury

[Wise Young]

Future of Spinal Cord Injury: Therapy Based on Neural Repair and Gait Retraining
Michael Selzer, MD, PhDÂ*
Seminar description:
Faculty will review progress toward restoring function following spinal cord injury. Faculty will discuss the use of stem cell and neuronal progenitor transplantation to replace lost neurons, encourage axon regeneration, and promote remyelination of demyelinated and regenerated axons. Faculty will review progress in restoring locomotor function in spinal cord-injured patients by enhancing the efficacy of the human spinal central pattern generator. Evidence suggests that partial body weight-supported treadmill training can strengthen the intrinsic locomotor circuitry and that this can be further augmented pharmacologically.
Upon completion:
Participants will be able to understand the status of efforts to repair the injured spinal cord and translate the restored anatomical connections of useful function in experimental animals and human patients.

[Wise Young]

[P06.059] Bereitschaft and Supplemental Motor Area Interaction in Movement Generation
Joseph B. Green, Peter A. St.Arnold, Leonid I. Rozhkov, Nancy GarrottÂ*Memphis, TN
OBJECTIVE: To better understand the relative roles of the Supplemental Motor Area (SMA) and the Bereitschaft Potential (BP) in the generation of passive and self-paced finger movements in normal controls and spinal cord injury patients.
BACKGROUND: The BP consists of movement related cortical potentials, peaking in the Motor Potential (MP). The MP may trigger a contralateral neuronal discharge into the pyramidal tract, activating the spinal cord. Voluntary movements require the activation of the SMA.
DESIGN/METHODS: The techniques of High-Resolution EEG and Dipole Source Analysis were applied to record and map the MP's and SMA activations in 11 normal subjects and 18 patients with spinal cord injury. Each subject performed self-paced movements of the middle finger (rapid flexion-extension every 5-10 seconds) and had the same finger moved in similar manner by an operator (passive movements). Patients with quadriplegia and hand/finger paralysis also made maximum effort to move their fingers or hands. All subjects were monitored by EMG to detect voluntary movement.
RESULTS: According to Deeke et. al., a negative cortical potential developed in the BP up to 1.5 seconds prior to self-initiated movement with maximum amplitude at the vertex and involving the SMA. We conducted a time sequence series of 25 images on one individual over the course of 100 ms, from -70 to 170 ms intervals confirming that the SMA is activated early and continues prior to and throughout the MP activation (Dipole Source Analysis by CURRY program). Upon onset of SMA activation there was an indication of electro-negativity at the initiation site pointing to where the MP would eventually occur.
Clinically: (1) The SMA was activated in every subject who was able to perform the self-paced movement. The activation involved the ventrocaudal SMA with few exceptions. (2) SMA location differed between the controls and paraplegics with respect to the Y-axis, i.e. from an anterior to a posterior location (p<0.0003). [3) Passive movements did not activate the SMA in either patients or controls. [4) Passive movements did initiate MP's despite lack of movements. [5) Self-paced MP's displayed a difference between all spinal cord patients and controls with respect to the Y-axis, i.e. from an anterior to a posterior location [p<0.0003).
CONCLUSIONS: Activity of the SMA and course of the BP were parallel in respect to voluntary movement. This included anterior-posterior relocation of motor potentials in spinal cord (paraplegic) patients and a similar anterior-posterior relocation of the SMA.
Supported By: Supported by the Office of Research and Development, Medical Research Service, and Rehabilitation R&D Service, Department of Veterans Affairs. Thanks are also due for the generous support of the Christopher Reeve Paralysis Foundation.
Category - Clinical Neurophysiology
SubCategory - Imaging

[Wise Young]

[S04.002] Alternative Sources of Neurons and Glia from Somatic Stem Cells
Yvan Y. Torrente, Marzia M. Belicchi, Federica F. Pisati, Francesca F. Ciceri, Stefano S. Pagano, Francesco F. Fortunato, Manuela M. Sironi, Maria Grazia M. G. D'Angelo, Sara S. Bonato, Eugenio E. Parati, Guglielmo G. Scarlato, Nereo N. BresolinÂ*Milan, Italy
OBJECTIVE: The benefices of the neural stem cell transplantation as a means of restoring CNS diseases or spinal cord injury are well-recognized. The use of human embryonic Neural Stem Cells raises ethical issue as well as practical problems: the behavior of an embryonic cell in an adult environment and the need for immunosuppression. One apparent advantage of using adult stem cells therefore is that they could be derived from and transplanted to the same patient, thereby avoiding potential tissue rejection. The identification of a source of readily accessible neural progenitors (NPs) that can be obtained without permanent damage from the individual requiring transplantation therapy could provide a great benefit.
BACKGROUND: Stem cell populations have been shown to be extremely versatile: they can generate differentiated cells specific to the tissue in which they reside and descendents which are of different germ layer origin. This raises the possibility of obtaining neuronal cells from new biological source of the same adult human subjects.
DESIGN/METHODS: A tissue culture system to facilitate enrichment of somatic-derived progenitor cells was used in muscle and bone marrow tissues from C57BL/10J mice. Individual cells isolated were plated in growth medium containing epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF). Self-maintenance was demonstrated by serial subcloning experiments where single primary spheres were dissociated and replated in a 96-well plates as 1 cell/well. Single-cell-derived primary spheres generates clonally derived secondary spheres capable of producing after their dissotiation tertiary spheres that could either be differentiated into neurons and glia.
RESULTS: In this study, we found that epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF) cooperated to induce the proliferation, self-renewal, and expansion of neural stem cell-like population isolated from several newborn and adult mouse tissues, such muscle and hematopoietic tissues. This population, in both primary culture and secondary expanded clones, formed spheres of undifferentiated cells that were induced to differentiate into neurons, astrocytes, and oligodendrocytes. Brain engraftment of the somatic-derived neural stem cells generated neuronal phenotypes.
CONCLUSIONS: The availability of human NPs from non-neuronal tissues and the possibility of autologous transplantation provide exciting perspectives for the treatment of CNS human diseases. Further tests are necessary to determine whether human NPs isolation from several somatic tissues may be applied similarly to their murine counterparts.
Category - Neural Repair and Rehabilitation
SubCategory - Basic Science: Cell Transplantation/Stem Cells

[Wise Young]

[P01.032] Cell Proliferation in the CNS Following Transection of the Lamprey Spinal Cord
Ivonne Vidal Pizarro, Gary P. Swain, Scott A. Keeney, Michael E. SelzerÂ*Philadelphia, PA
OBJECTIVE: To determine the extent, cell type and location of cellular proliferation after transection of the lamprey spinal cord, in order to elucidate the contribution of cell proliferation to axonal regeneration.
BACKGROUND: Transected lamprey spinal axons regenerate selectively in their correct directions. The transection scar is relatively acellular and mitotic figures have not been described. We postulated that an absence of proliferation and migration of injured glial cells might maintain the glial architecture and enforce the observed longitudinal orientation of glial processes in the transection scar that guides regenerating axons. On the other hand, the reconstitution of the ependymal layer around an expanded central canal within the scar suggests that some proliferation and/or migration must occur.
DESIGN/METHODS: Larval lamprey spinal cords were transected in winter, when little mitosis occurs normally in CNS. Animals were allowed to recover 2-21 days, injected i.p. with BrdU, and 3 hours later, processed for immunohistochemistry. Untransected control animals were sacrificed 3 hours after BrdU injection. Particular attention was paid to the lesion site and adjacent spinal cord 0.5 mm rostral and caudal to the transection site, and to the rhombencephalon, where most of the axotomized spinal-projecting neurons reside. The nature of the cells undergoing mitosis was determined by double labeling with mAbs specific for lamprey neurofilaments and glial keratins.
RESULTS: Labeled cells were found in the CNS, skin, gills and other organs. In the CNS, BrdU-positive cells also stained positively for glial keratin, but not for neurofilament. In control animals, mitotic index (MI, % of cells BrdU+) was << 0.01% in the spinal cord and 0.01% in the rhombencephalon. After transection, mitosis at the lesion site was 800-2,200 times greater than in controls, with a peak MI of 22.20% occurring at 1 week. Proliferation in adjacent regions was 200-300 times greater than in controls, with a peak MI of 2.60% at 3 weeks. Proliferation was 6 times greater than baseline in the rhombencephalon, with a peak MI of 0.09% at 2 weeks. Most of the reactive proliferation in the spinal cord was seen in the ependyma, whereas in the rhombencephalon it was in the parenchyma.
CONCLUSIONS: Spinal cord injury results in glial and ependymal cell proliferation that is greatest in the injury zone but extends remotely, possibly along the path of axonal degeneration. Proliferation is seen predominantly in ependymal cells that reconstitute an enlarged central canal. Thus far there is no evidence for proliferation of neurons or neuronal progenitors, either in control animals or after spinal cord transection.
Supported By: NIH NRSA grant NS-11009 (to IVP) and RO1 NS-14837 and RO1 NS-25581.
Category - Neural Repair and Rehabilitation
SubCategory - Basic Science: Axon Regeneration/Guidance

[Wise Young]

[S04.001] Magnetic Resonance Microimaging and Diffusion Measurements of Individual Axons in the Transected Lamprey Spinal Cord
Masaya Takahashi, Alexander C. Wright, Guixin Zhang, David B. Hackney, Suzanne L. Wehrli, Felix W. Wehrli, Michael E. SelzerÂ*Philadelphia, PA
OBJECTIVE: To image individual axons in the living spinal cord of the sea lamprey and measure water diffusion across the axolemma as an indication of early degeneration.
BACKGROUND: The sea lamprey is a primitive vertebrate with large (20-50mm diameter) reticulospinal axons, many of which regenerate after spinal cord transection. We wish to develop methods to image the regenerating axons in the living animal and to detect subtle physiological changes that may precede Wallerian degeneration.
DESIGN/METHODS: Spinal cords of large larval sea lampreys were excized under anesthesia and placed in a 0.9mm ID capillary tube perfused with cold buffer. A custom-made RF coil (ID 2.5 mm) was used for diffusion imaging at 9.4 Tesla. Gradients were applied to measure the diffusion coefficients parallel (l-ADC) and transverse (t-ADC) to the long axis of the spinal cord. The spinal cords were then fixed and processed for histology.
RESULTS: Resolution by T1 weighted imaging of fixed tissue was 9mm, permitting visualization of many individual axons. Resolution in diffusion weighted imaging of fresh tissue was 19 mm but this still permitted discrimination of several large axons. In animals that had received a spinal hemisection, the lesioned side was differentiated easily from the intact side. In the large axons, intra-axonal diffusion coefficients of water were: t-ADC = 0.97 ± 0.11 cm2/sec; l-ADC = 0.98 ± 0.06 cm2/sec. In axon tracts with smaller axons, diffusion was anisotropic and t-ADCs were reduced. In different regions, t-ADC was inversely proportional to the axon density (i.e., axons/mm2). By contrast, l-ADCs were almost identical across regions. Thus, diffusion was isotropic when measured entirely within a single axon, and anisotropic when measured across multiple axons. After transection, l-ADC remained unchanged, while t-ADC across multiple axons increased, even before Wallerian degeneration was apparent histologically.
CONCLUSIONS: It is possible to image individual axons in the isolated lamprey spinal cord. Since whole lampreys are only 5 mm in diameter, we are approaching the ability to follow regeneration of individual axons in the living animal. The isotropy of diffusion within individual axons and anisotropy of diffusion across multiple axons is consistant with the notion that the cell membrane is the primary source of diffusion anisotropy in fiber tracts of the central nervous system. This may provide a means to follow degeneration and regeneration even in tracts of small axons after spinal cord injury.
Supported By: NIH grants R01 NS-4180, R01 NS25921, R01 NS14837 and R01 NS38537.
Category - Neural Repair and Rehabilitation
SubCategory - Basic Science: Axon Regeneration/Guidance