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Abstract: To date, few treatment strategies applying cellular transplantation to the chronically injured spinal cord have yielded significant functional improvement in animal experiments. Here we report that significant improvement of locomotor function was achieved in rats with chronic spinal cord injury (SCI) by the application of combination treatments with tail nerve electrical stimulation (TANES), which can activate the central pattern generator, inducing active weight-supported stepping. Contusion injury (25mm) to spinal cord T10 was produced by using the NYU impactor device in female, adult Long–Evans rats. Rats in 2 of 4 groups with SCI received basic treatments (scar ablation followed by transplantation of lamina propria of olfactory mucosa and cultured olfactory ensheathing cells into the lesion cavity) 6weeks after SCI. Rats both with and without basic treatments were subjected to TANES one week after secondary surgery or 7weeks after SCI. Sixteen weeks after secondary surgery or 22weeks after SCI rats in two groups receiving TANES significantly improved their functional recovery compared with those without TANES, when evaluated with BBB open field rating scale (p <0.01). Among them, however, rats with basic treatments performed better than those without basic treatments. TANES may contribute to the activity-dependent plasticity below the injury level, which is critical for functional recovery. Additionally, TANES may promote axonal regeneration, including those from supraspinal level. Since TANES demonstrated considerable potential for achieving improvement of functional recovery in rat model, it would suggest a new strategy for chronic SCI. [Copyright &y& Elsevier]

Abstract: We have successfully removed an existing glial scar in chronically contused rat spinal cord using a rose Bengal-based phototoxic method. The purpose of this study is to examine if scar ablation benefits the anatomical recovery by cell/tissue transplantation, and thus provides a more permissive physical and biochemical environment for axonal growth, which may lead to functional recovery. Immediately after scar ablation, we transplanted lamina propria (LP) of the olfactory mucosa alone or in combination with cultured olfactory ensheathing cells (OEC) into the lesion cavity 6weeks after contusion injury (NYU impactor device, 25mm height setting) at spinal cord segment T10 of adult female Long–Evans rats. Sixteen weeks after scar ablation and transplantation, we found that the initial repaired tissue significantly expanded, companied by remarkable reduction or disappearance of the lesion cavity and integration of repaired tissue with the spared tissue, thus resulting in histological repair of damaged cord tissue at the injury epicenter. Glial scar reformation was effectively prevented after ablation due to the tissue repair. In addition, at the injury epicenter P0 (myelin glycoprotein P-zero)-positive myelination formed by Schwann cells, which are known to myelinate regenerating and demyelinated axons, were significantly increased in number compared with the control animals. However, when evaluated with BBB open-field scale a significant improvement of locomotor function was not observed in this study; the possible reasons were discussed. [Copyright &y& Elsevier]

Abstract: Intrathecal infusion has been widely used to directly deliver drugs or neurotrophins to a lesion site following spinal cord injury. Evidence shows that intrathecal infusion is efficient for 7 days but is markedly reduced after 14 days, due to time dependent occlusion. In addition, extensive fibrotic scarring is commonly observed with intrathecal infusion. These anomalies need to be clearly elucidated in histology. In the present study, all adult Long-Evans rats received a 25mm contusion injury on spinal cord T10 produced using the NYU impactor device. Immediately after injury, catheter tubing with an outer diameter of 0.38mm was inserted through a small dural opening at L3 into the subdural space with the tubing tip positioned near the injury site. The tubing was connected to an Alzet mini pump, which was filled with saline solution and was placed subcutaneously. Injured rats without tubing served as control. Rats were behaviorally tested for 6 weeks using the BBB locomotor rating scale and histologically assessed for tissue scarring. Six weeks later, we found that the intrathecal tubing caused extensive scarring and inflammation, related to neutrophils, macrophages and plasma cells. The tubing''s tip was occluded by scar tissue and inflammatory cells. The scar tissue surrounding the tubing consists of 20–70 layers of fibroblasts and densely compacted collagen fibers, seriously compressing and damaging the cord tissue. BBB scores of rats with intrathecal tubing were significantly lower than control rats (p <0.01) from 2 weeks after injury, implying serious impairment of functional recovery caused by the scarring. [Copyright &y& Elsevier]

Abstract: Walking or stepping has been considered the result from the activation of the central pattern generator (CPG). In most patients with spinal cord injury (SCI) the CPG is undamaged. To date, there are no noninvasive approaches for activating the CPG. Recently we developed a noninvasive technique, tail nerve electrical stimulation (TANES), which can induce positive hind limb movement of SCI rats. The purpose of this study is to introduce the novel technique and examine the effect of TANES on CPG activation. A 25mm contusion injury was produced at spinal cord T10 of female, adult Long-Evans rats by using the NYU impactor device. Rats received TANES (∼40mA at 4kHz) 7 weeks after injury. During TANES all injured rats demonstrated active body weight-supported stepping of hind limbs with left–right alternation and occasional front–hind coordination, resulting in significant, temporary increase in BBB scores (p <0.01). However, there is no response to TANES from rats with L2 transection, consistent with other reports that the CPG may be located at L1–2. S1 transection negatively implies the key role of TANES in CPG activation. The TANES not only renders paralyzed rats with a technique-induced ability to walk via activating CPG, but also is likely to be used for locomotor training. It has more beneficial effects for physical training over other training paradigms including treadmill training and invasive functional electrical stimulation. Therefore the TANES may have considerable potential for achieving improvement of functional recovery in animal models and a similar method may be suggested for human study. [Copyright &y& Elsevier]

Abstract: Statins elicit numerous favorable effects on central nervous system (CNS) injury, including inhibition of the rhoA/ROCK pathway. In the present study, we show that statins decrease acute astrocyte activation in CNS injury, and decrease chondroitin sulfate proteoglycan (CSPG) levels in astrocyte cultures as well as CNS injury. CSPG levels decreased by up to 45% in simvastatin-treated astrocyte cultures compared to control cultures. In simvastatin-treated animals, CSPG levels declined by 60% 8 days after brain stab injury, and by 62–64% 4 weeks after spinal cord injury (SCI). Glial fibrillary acid protein (GFAP) levels decreased in brain stab at 8 days after surgery/intervention, suggesting that statins produce a decrease in astrocyte activation. Attenuation of astrocyte activation may contribute to the decline in CSPG levels. However, there are likely other contributing factors, since GFAP levels were not a contributing factor in the decline of CSPG levels in astrocyte cultures. Robust locomotor improvements were not observed with any treatment. The numerous beneficial effects of statins on CNS injury render them an attractive candidate in the treatment of CNS injury. [Copyright &y& Elsevier]

Abstract: Extensive dendritic beading of MAP2 (microtubule-associated protein 2) immunoreactivity has previously been observed in the contused rat spinal cord. However, we have also observed dendritic beading in occasional uninjured animals. The purpose of this study was to examine the possibility that perfusion conditions contributed to the dendritic beading. Under deep anesthesia, uninjured rats (adult female Long-Evans, 200–225g) were transcardially perfused with 0.9% saline solution followed by 4% paraformaldehyde at cold (4°C) or warm (20°C) temperature, and at a low (20ml/min) or high (50ml/min) flow rate. Dendrites were visualized by MAP2 immunoreactivity. The results demonstrate that perfusion with cold solutions at a high flow rate induces pronounced dendritic beading, and when perfused at a low flow rate, results in moderate dendritic beading. Warm perfusates did not induce dendritic beading when administered at a low flow rate, but occasional beading was observed with a high flow rate. Western blots revealed spectrin breakdown, but not MAP2 loss, in rats perfused with cold saline solution at a high flow rate, conditions that also resulted in dendritic beading. These findings demonstrate that dendritic morphology is sensitive to both temperature and flow rate of the perfusate. Warm fixative and a low perfusion flow rate minimized the perfusion-induced dendritic beading. [Copyright &y& Elsevier]

Abstract Schwann cells (SCs) have been shown to be a key element in promoting axonal regeneration after being grafted into the central nervous system (CNS). In the present study, SC-supported axonal regrowth was tested in an adult rat spinal cord implantation model. This model is characterized by a right spinal cord hemisection at the eighth thoracic segment, implantation of a SC-containing mini-channel and restoration of cerebrospinal fluid circulation by suturing the dura. We demonstrate that a tissue cable containing grafted SCs formed an effective bridge between the two stumps of the hemicord 1 month after transplantation. Approximately 10 000 myelinated and unmyelinated axons (1 : 9) per cable were found at its midpoint. In addition to propriospinal axons and axons of peripheral nervous system (PNS) origin, axons from as many as 19 brainstem regions also grew into the graft without additional treatments. Most significantly, some regenerating axons in the SC grafts were able to penetrate through the distal graft–host interface to re-enter the host environment, as demonstrated by anterograde axonal labelling. These axons coursed toward, and then entered the grey matter where terminal bouton-like structures were observed. In channels containing no SCs, limited axonal growth was seen within the graft and no axons penetrated the distal interface. These findings further support the notion that SCs are strong promotors of axonal regeneration and that the mini-channel model may be appropriate for further investigation of axonal re-entry, synaptic reconnection and functional recovery following spinal cord injury. [ABSTRACT FROM AUTHOR]