Neuroprotection of completely lacerated spinal cord of adult rats by homotopic and heterotopic transplantation

To evaluate the neuroprotective effect of transplants placed in the lesion zone after a complete spinal cord (SC) laceration, two independent series of experiments were carried out. In the first, allogeneic or xenogeneic fetal SC was transplanted into the gaps of the damaged lower thoracic SC of adult rats. In the transplanted rats the incidence of life-threatening complications was reduced, and the survival rate was increased compared with the control group (lesion, without implant). Histological examination showed less damage to the neighboring SC parenchyma in the transplanted rats. The measurement of this neuroprotective effect was made in a second series of experiments. Using the same model of SC injury, allogeneic fetal SC, autologous peripheral nerve and/or adipose tissue were implanted. Rats with implants of Gelfoam and damaged rats without implants were the controls. The implanted rats of all groups, including the Gelfoam group, showed a better survival rate than the nonimplanted rats. Significantly less damage to the neighboring SC parenchyma was measured in implanted rats with any of the live tissues tested compared with non-implanted rats, although no significant differences were observed between the Gelfoam group and the nonimplanted rats. Histological evidence of tissue implant survival was observed in all corresponding groups. It is concluded that the transplanted tissues tested here have a neuroprotective effect, possibly by acting as a buffer to neurotoxic substance(s) released by the stumps, and/or by exerting trophic effect(s) on the host.

Lipid peroxidation inhibition in spinal cord injury: cyclosporin-A vs methylprednisolone

To compare the effectiveness of cyclosporin-A (CsA) with methylprednisolone (MP) or a combination of both upon inhibition of lipid peroxidation (LP) after spinal cord (SC) injury, rats were treated with either CsA, MP, CSA+MP or vehicle starting 1 h after SC contusion at T9 level. LP was assessed 24h after injury by the lipid fluorescent product formation method. The survival rate was also evaluated in other series of rats by the Kaplan-Meier curves. Lipid peroxidation was similarly inhibited in rats treated with CsA, MP, or CSA+MP (p>0.05). Animals receiving MP (alone or combined with CsA) showed the poorest surviving rate. LP was inhibited by CsA to the same extent as by MP but without the lethal effect of the latter.

Cyclosporin-A inhibits lipid peroxidation after spinal cord injury in rats

Besides its immunosuppressive/anti-inflammatory activity, cyclosporin-A (CsA) may protect damaged tissues from lipid peroxidation (LP) by free radicals. To determine the effect of CsA on LP spinal cord (SC) injury, Wistar rats were treated with either vehicle or CsA (2.5 mg/kg per 12 h i.p.) 1, 2, 6 or 12 h after SC trauma by T8-T9 spinal cord contusion, analyzing LP 24 h after injury at the lesion site by the lipid fluorescent products formation method. CsA significantly diminished LP to levels below control values after contusion (P < 0.05). The greater inhibition was observed when CsA was given during the first 6 h after injury, furthermore, animals showed a significant clinical improvement. Results show that CsA may be beneficial to injured tissue by inhibiting the levels of LP.

Spontaneous long-term remyelination after traumatic spinal cord injury in rats

The capability of the central nervous system to remyelinate axons after a lesion has been well documented, even though it had been described as an abortive and incomplete process. At present there are no long-term morphometric studies to assess the spinal cord (S.C.) remyelinative capability. With the purpose to understand this phenomenon better, the S.C. of seven lesionless rats and the S.C. of 21 rats subjected to a severe weight-drop contusion injury were evaluated at 1, 2, 4, 6, and 12 months after injury. The axonal diameter and the myelination index (MI = axolemmal perimeter divided by myelinated fiber perimeter) were registered in the outer rim of the cord at T9 SC level using a transmission electron microscope and a digitizing computer system. The average myelinated fiber loss was 95.1%. One month after the SC, 64% of the surviving fibers were demyelinated while 12 months later, only 30% of the fibers had no myelin sheath. The MI in the control group was 0.72 +/- 0.07 (X +/- S.D.). In the experimental groups, the greatest demyelination was observed two months after the lesion (MI = 0.90 +/- 0.03), while the greatest myelination was observed 12 months after the injury (MI = 0.83 +/- 0.02). There was a statistical difference (p < 0.02) in MI between 2 and 12 months which means that remyelination had taken place. Remyelination was mainly achieved because of Schwann cells. The proportion of small fibers (diameter = 0.5 micron or less) considered as axon collaterals, increased from 18.45% at 1 month to 27.66% a year after the contusion. Results suggest that remyelination is not an abortive phenomenon but in fact a slow process occurring parallel to other tissue plastic phenomena, such as the emission of axon collaterals.

Histochemical evidence of the increased expression of nicotinamide adenine dinucleotide phosphate-dependent diaphorase in neurons of the myenteric plexus after acute spinal cord injury in adult rats

The expression of nitric oxide synthase in neurons of the gastrointestinal tract (GIT) after experimental spinal cord injury (SCI) was assessed in adult rats contused at T8. One day and 10 weeks after injury, specimens along the GIT were studied for NADPH-diaphorase histochemistry. A significant increase in the number of positive cell bodies and fibers in the myenteric plexus were observed 1 day after SCI, as compared to specimens from control and chronically injured rats, with the exception of the colon, which showed unchanged or decreased number of positive neurons in the acute and chronic stages, respectively. Positive neurons in the submucous plexus remained unchanged, excepting an increase in the colon after acute SCI, and a decrease in the duodenum in chronically injured rats. The altered nitric oxide neurotransmission in the GIT may be relevant to its reduced motility after SCI.

Magnetic resonance imaging of the normal and chronically injured adult rat spinal cord in vivo

We assessed the capacity of MRI to show and characterise the spinal cord (SC) in vivo in normal and chronically injured adult rats. In the chronically injured animals the SC was studied by MRI and histological examination. MRI was performed at 1.5 T, using gradient-echo and spin-echo (SE) sequences, the latter with and without gadolinium-DTPA (Gd-DTPA). Several positions were tried for good alignment and to diminish interference by respiratory movements. Images of the SC were obtained in sagittal, coronal, and axial planes. Normal SC was observed as a continuous intensity in both sequences, although contrast resolution was better using SE; it was not possible to differentiate the grey and white matter. Low signal was seen in the damaged area in chronically injured rats, which corresponded to cysts, trabeculae, mononuclear infiltrate, and fibroglial wall on histological examination. Gd-DTPA failed to enhance the SC in normal or chronically injured rats. It did, however, cause enhancement of the lesion after acute SC injury.

Development of post-traumatic cysts in the spinal cord of rats-subjected to severe spinal cord contusion

To study the development of post-traumatic spinal cord (SC) cysts, and their fine anatomic characteristics, rats were subjected to severe SC contusion. Specimens were analyzed from day 1 to 1 year post-injury. Using conventional light, and transmission and scanning electron microscopy, three stages were typified, namely: necrosis, repair, and stability. The final cell composition and thickness of the cyst walls were not uniform. Astrocytes, fibroblasts, ependymal cells, and collagen fibers were the main constituents. Chronic inflammatory cells were also observed. The neuropathologic characterization of posttraumatic SC cysts could be useful in planning strategies for SC reconstruction at different times post-injury.

[The first homotopic fetal homograft of the striatum in the treatment of Huntington's disease]

Fetal brain grafting has been used successfully in the restoration of striatal function in rat and non human primate models of Huntington's disease (HD). This is a report of the first clinical trial of this procedure applied to a 37 year old Mexican female with moderate to severe HD of 9 years evolution. The two striata from a 13 week-old human fetus were homotopically transplanted to 4 cavities in the ventricular wall of the right caudate nucleus. The months after surgery, her neurologic and neuropsychologic evaluations revealed the stabilization of many of her signs and most neuropsychologic parameters, a moderate improvement of her choreic movements, predominantly in the face, of her ability to define and express ideas in oral and written form, and of her articulatory agility, as well as of some activities of her daily life and social behavior. There was a slight deterioration of her gait and posture. Her saccadic system and optokinetic nystagmus, and her visuospatial and visuoperceptual functions were deteriorated.

Fetal homotransplants (ventral mesencephalon and adrenal tissue) to the striatum of parkinsonian subjects

Fetal ventral mesencephalon and fetal adrenal tissue grafted to the caudate nucleus of four and three parkinsonian patients, respectively, have been shown to be an alternative treatment for the amelioration of the signs of the disease. The ventral mesencephalon patients had a significant amelioration of rigidity, bradykinesia, postural imbalance, gait disturbance, and facial expression. Three of these four patients have returned to work. The fatal adrenal group only showed amelioration of rigidity and bradykinesia. Though these patients are now able to perform their basic daily living activities, and one of them has renewed her household tasks, the other two have not yet been able to return to work. The differences observed between the ventral mesencephalon- and the fetal adrenal-transplanted patients may be related to the heterogeneity of their disease and/or the type of graft implanted. However encouraging our results may be, this experimental procedure obviously requires further studies, and should not be practiced outside of highly qualified clinical research centers.