"Advancements in minimally invasive treatment for lumbar disc herniation: insights into condoliase and chondroitin sulfate ABC endolyase".

This study examines the efficacy and safety of condoliase chemonucleolysis (CC) in treating lumbar disc herniation (LDH) and highlights emerging alternatives like chondroitin sulfate ABC endolyase. Research indicates that condoliase, an enzyme used to degrade glycosaminoglycans in the nucleus pulposus, provides effective and prompt relief of leg pain, with significant reductions observed within a day of treatment. Studies reveal that a lower pretreatment straight leg raising (SLR) angle may predict early symptom relief, and condoliase is generally effective at doses up to 1.25 U, balancing efficacy and safety. Despite promising results, concerns about long-term safety, including disc height reduction and imaging changes, persist. Additionally, chondroitin sulfate ABC endolyase shows potential as a safer and more effective alternative, though further research is needed to optimize treatment protocols and assess long-term outcomes. Future investigations should address current limitations, such as small sample sizes and short follow-up periods, to better understand the long-term benefits and risks of these treatments.

Advances in chondroitinase delivery for spinal cord repair.

Chondroitin sulfate proteoglycans (CSPGs) present a formidable barrier to regrowing axons following spinal cord injury. CSPGs are secreted in response to injury and their glycosaminoglycan (GAG) side chains present steric hindrance preventing the growth of axons through the lesion site. The enzyme chondroitinase has been proven effective at reducing the CSPG GAG chains, however, there are issues with direct administration of the enzyme specifically due to its limited timeframe of activity. In this perspective article, we discuss the evolution of chondroitinase-based therapy in spinal cord injury as well as up-to-date advances on this critical therapeutic. We describe the success and the limitations around use of the bacterial enzyme namely issues around thermostability. We then discuss current efforts to improve delivery of chondroitinase with a push towards gene therapy, namely through the use of lentiviral and adeno-associated viral vectors, including the temporal modulation of its expression and activity. As a chondroitinase therapy for spinal cord injury inches nearer to the clinic, the drive towards an optimised delivery platform is currently underway.

Chemonucleolysis with Chondroitin Sulfate ABC Endolyase for Treating Lumbar Disc Herniation: Exploration of Prognostic Factors for Good or Poor Clinical Outcomes.

Background and Objectives: Chondroitin sulfate ABC endolyase (condoliase) was launched as a new drug for chemonucleolysis in 2018. Few studies assessed its clinical outcomes, and many important factors remain unclear. This study aimed to clarify the preoperative conditions in which condoliase could be highly effective. Materials and Methods: Of 47 patients who received condoliase, 34 were enrolled in this study. The mean age of the patients was 33 years. The average duration since the onset of disease was 8.6 months. We evaluated patients' low back and leg pain using a numerical rating scale (NRS) score at two time points (before therapy and 3 months after therapy). We divided the patients into two groups (good group (G): NRS score improvement ≥ 50%, poor group (P): NRS score improvement < 50%). The parameters evaluated were age, disease duration, body mass index (BMI), and positive or negative straight leg raising test results. In addition, the loss of disc height and preoperative radiological findings were evaluated. Results: In terms of low back and leg pain, the G group included 9/34 (26.5%) and 21/34 (61.8%) patients, respectively. Patients' age (low back pain G/P, 21/36.5 years) was significantly lower in the G group for low back pain (p = 0.001). High-intensity change in the protruded nucleus pulposus (NP) and spinal canal occupancy by the NP ≥ 40% were significantly high in those with leg pain in the G groups (14/21, p = 0.04; and 13/21, p = 0.03, respectively). Conclusions: The efficacy of improvement in leg pain was significantly correlated with high-intensity change and size of the protruded NP. Condoliase was not significantly effective for low back pain but could have an effect on younger patients.

Therapeutic efficacy of microtube-embedded chondroitinase ABC in a canine clinical model of spinal cord injury.

See Moon and Bradbury (doi:10.1093/brain/awy067) for a scientific commentary on this article.Many hundreds of thousands of people around the world are living with the long-term consequences of spinal cord injury and they need effective new therapies. Laboratory research in experimental animals has identified a large number of potentially translatable interventions but transition to the clinic is not straightforward. Further evidence of efficacy in more clinically-relevant lesions is required to gain sufficient confidence to commence human clinical trials. Of the many therapeutic candidates currently available, intraspinally applied chondroitinase ABC has particularly well documented efficacy in experimental animals. In this study we measured the effects of this intervention in a double-blinded randomized controlled trial in a cohort of dogs with naturally-occurring severe chronic spinal cord injuries that model the condition in humans. First, we collected baseline data on a series of outcomes: forelimb-hindlimb coordination (the prespecified primary outcome measure), skin sensitivity along the back, somatosensory evoked and transcranial magnetic motor evoked potentials and cystometry in 60 dogs with thoracolumbar lesions. Dogs were then randomized 1:1 to receive intraspinal injections of heat-stabilized, lipid microtube-embedded chondroitinase ABC or sham injections consisting of needle puncture of the skin. Outcome data were measured at 1, 3 and 6 months after intervention; skin sensitivity was also measured 24 h after injection (or sham). Forelimb-hindlimb coordination was affected by neither time nor chondroitinase treatment alone but there was a significant interaction between these variables such that coordination between forelimb and hindlimb stepping improved during the 6-month follow-up period in the chondroitinase-treated animals by a mean of 23%, but did not change in controls. Three dogs (10%) in the chondroitinase group also recovered the ability to ambulate without assistance. Sensitivity of the dorsal skin increased at 24 h after intervention in both groups but subsequently decreased to normal levels. Cystometry identified a non-significant improvement of bladder compliance at 1 month in the chondroitinase-injected dogs but this did not persist. There were no overall differences between groups in detection of sensory evoked potentials. Our results strongly support a beneficial effect of intraspinal injection of chondroitinase ABC on spinal cord function in this highly clinically-relevant model of chronic severe spinal cord injury. There was no evidence of long-term adverse effects associated with this intervention. We therefore conclude that this study provides strong evidence in support of initiation of clinical trials of chondroitinase ABC in humans with chronic spinal cord injury.

Enhancing Spinal Plasticity Amplifies the Benefits of Rehabilitative Training and Improves Recovery from Stroke.

The limited recovery that occurs following stroke happens almost entirely in the first weeks postinjury. Moreover, the efficacy of rehabilitative training is limited beyond this narrow time frame. Sprouting of spared corticospinal tract axons in the contralesional spinal cord makes a significant contribution to sensorimotor recovery, but this structural plasticity is also limited to the first few weeks after stroke. Here, we tested the hypothesis that inducing plasticity in the spinal cord during chronic stroke could improve recovery from persistent sensorimotor impairment. We potentiated spinal plasticity during chronic stroke, weeks after the initial ischemic injury, in male Sprague-Dawley rats via intraspinal injections of chondroitinase ABC. Our data show that chondroitinase injections into the contralesional gray matter of the cervical spinal cord administered 28 d after stroke induced significant sprouting of corticospinal axons originating in the peri-infarct cortex. Chondroitinase ABC injection during chronic stroke without additional training resulted in moderate improvements of sensorimotor deficits. Importantly, this therapy dramatically potentiated the efficacy of rehabilitative training delivered during chronic stroke in a skilled forelimb reaching task. These novel data suggest that spinal therapy during chronic stroke can amplify the benefits of delayed rehabilitative training with the potential to reduce permanent disability in stroke survivors.SIGNIFICANCE STATEMENT The brain and spinal cord undergo adaptive rewiring ("plasticity") following stroke. This plasticity allows for partial functional recovery from stroke induced sensorimotor impairments. However, the plasticity that underlies recovery occurs predominantly in the first weeks following stroke, and most stroke survivors are left with permanent disability even after rehabilitation. Using animal models, our data show that removal of plasticity-inhibiting signals in the spinal cord (via intraspinal injections of the enzyme chondroitinase ABC) augments rewiring of circuits connecting the brain to the spinal cord, even weeks after stroke. Moreover, this plasticity can be harnessed by rehabilitative training to significantly promote sensorimotor recovery. Thus, intraspinal therapy may augment rehabilitative training and improve recovery even in individuals living with chronic disability due to stroke.

Chondroitinase ABC for neurological recovery after acute brain injury: systematic review and meta-analyses of preclinical studies.

OBJECTIVES: Damage to critical brain regions causes deficits in important neurological functions. Chondroitinase ABC (ChABC) has been shown to promote neuroplasticity and may ameliorate neurological deficits caused by disease or trauma. This systematic review identifies and evaluates preclinical studies of ChABC as a treatment for acute brain injury. METHODS: Four databases were searched for studies relating to ChABC and brain or brain injuries. Controlled studies in mammals with acute brain injuries treated with ChABC were included in meta-analyses of neurobehavioural outcomes. Means and standard deviations from the fifth day of treatment were extracted, and normalised mean differences were calculated. RESULTS: Of 775 identified records, 16 studies administered ChABC after acute brain injury, of which 9 reported neurobehavioural outcomes. The estimated treatment effect on neurological recovery over the duration of included studies was 49.4% (CI: 30.3-68.4% with Hartung-Knapp-Sidik-Jonkman adjustment, p = 0.0002). The mechanisms of action may involve decreasing astroglial scar formation, promoting neuronal sprouting, and selective synaptic strengthening of sprouting neurites and activated neural pathways. CONCLUSIONS: The summary of published evidence suggests that ChABC treatment is effective in improving neurological outcomes in preclinical models of acute brain injury. However, more studies are needed for better assessment of the specific translational potential of ChABC. ABBREVIATIONS: AVM - Arteriovenous Malformation; ChABC - Chondroitinase ABC; CI - Confidence Interval; CSPG - Chondroitin Sulphate Proteoglycans; HKSJ - Hartung-Knapp-Sidik-Jonkman; MCA - Middle Cerebral Artery; NMD - Normalised Mean Difference; NSPC - Neural Stem/Progenitor Cells; PI - Prediction Interval; SD - Standard Deviation; SMD - Standardised Mean Difference; TBI - Traumatic Brain Injury.

Expressing Constitutively Active Rheb in Adult Neurons after a Complete Spinal Cord Injury Enhances Axonal Regeneration beyond a Chondroitinase-Treated Glial Scar.

After a spinal cord injury (SCI), CNS axons fail to regenerate, resulting in permanent deficits. This is due to: (1) the presence of inhibitory molecules, e.g., chondroitin sulfate proteoglycans (CSPG), in the glial scar at the lesion; and (2) the diminished growth capacity of adult neurons. We sought to determine whether expressing a constitutively active form of the GTPase Rheb (caRheb) in adult neurons after a complete SCI in rats improves intrinsic growth potential to result in axon regeneration out of a growth-supportive peripheral nerve grafted (PNG) into the SCI cavity. We also hypothesized that treating the glial scar with chondroitinase ABC (ChABC), which digests CSPG, would further allow caRheb-transduced neurons to extend axons across the distal graft interface. We found that targeting this pathway at a clinically relevant post-SCI time point improves both sprouting and regeneration of axons. CaRheb increased the number of axons, but not the number of neurons, that projected into the PNG, indicative of augmented sprouting. We also saw that caRheb enhanced sprouting far rostral to the injury. CaRheb not only increased growth rostral and into the graft, it also resulted in significantly more regrowth of axons across a ChABC-treated scar into caudal spinal cord. CaRheb(+) neurons had higher levels of growth-associated-43, suggestive of a newly identified mechanism for mTOR-mediated enhancement of regeneration. Thus, we demonstrate for the first time that simultaneously addressing intrinsic and scar-associated, extrinsic impediments to regeneration results in significant regrowth beyond an extremely challenging, complete SCI site. SIGNIFICANCE STATEMENT: After spinal cord injury (SCI), CNS axons fail to regenerate, resulting in permanent deficits. This is due to the diminished growth capacity of adult neurons and the presence of inhibitory molecules in the scar at the lesion. We sought to simultaneously counter both of these obstacles to achieve more robust regeneration after complete SCI. We transduced neurons postinjury to express a constitutively active Rheb to enhance their intrinsic growth potential, transplanted a growth supporting peripheral nerve graft into the lesion cavity, and enzymatically modulated the inhibitory glial scar distal to the graft. We demonstrate, for the first time, that simultaneously addressing neuron-related, intrinsic deficits in axon regrowth and extrinsic, scar-associated impediments to regeneration results in significant regeneration after SCI.

Perilesional treatment with chondroitinase ABC and motor training promote functional recovery after stroke in rats.

Ischemic stroke insults may lead to chronic functional limitations that adversely affect patient movements. Partial motor recovery is thought to be sustained by neuronal plasticity, particularly in areas close to the lesion site. It is still unknown if treatments acting exclusively on cortical plasticity of perilesional areas could result in behavioral amelioration. We tested whether enhancing plasticity in the ipsilesional cortex using local injections of chondroitinase ABC (ChABC) could promote recovery of skilled motor function in a focal cortical ischemia of forelimb motor cortex in rats. Using the skilled reaching test, we found that acute and delayed ChABC treatment induced recovery of impaired motor skills in treated rats. vGLUT1, vGLUT2, and vGAT staining indicated that functional recovery after acute ChABC treatment was associated with local plastic modification of the excitatory cortical circuitry positive for VGLUT2. ChABC effects on vGLUT2 staining were present only in rats undergoing behavioral training. Thus, the combination of treatments targeting the CSPG component of the extracellular matrix in perilesional areas and rehabilitation could be sufficient to enhance functional recovery from a focal stroke.

Cortical PKC inhibition promotes axonal regeneration of the corticospinal tract and forelimb functional recovery after cervical dorsal spinal hemisection in adult rats.

Our previous study shows that conventional protein kinases C (cPKCs) are key signaling mediators that are activated by extracellular inhibitory molecules. Inhibition of cPKC by intrathecal infusion of a cPKC inhibitor, GÖ6976, into the site of dorsal hemisection (DH) induces regeneration of lesioned dorsal column sensory, but not corticospinal tract (CST), axons. Here, we investigated whether a direct cortical delivery of GÖ6976 into the soma of corticospinal neurons promotes regeneration of CST and the recovery of forelimb function in rats with cervical spinal cord injuries. We report that cortical delivery of GÖ6976 reduced injury-induced activation of conventional PKCα and PKCß1 in CST neurons, promoted regeneration of CST axons through and beyond a cervical DH at C4, formed new synapses on target neurons caudal to the injury, and enhanced forelimb functional recovery in adult rats. When combined with lenti-Chondroitinase ABC treatment, cortical administration of GÖ6976 promoted even greater CST axonal regeneration and recovery of forelimb function. Thus, this study has demonstrated a novel strategy that can promote anatomical regeneration of damaged CST axons and partial recovery of forelimb function. Importantly, such an effect is critically dependent on the efficient blockage of injury-induced PKC activation in the soma of layer V CST neurons.

Intracerebral chondroitinase ABC and heparan sulfate proteoglycan glypican improve outcome from chronic stroke in rats.

Physical and chemical constraints imposed by the periinfarct glial scar may contribute to the limited clinical improvement often observed after ischemic brain injury. To investigate the role of some of these mediators in outcome from cerebral ischemia, we treated rats with the growth-inhibitory chondroitin sulfate proteoglycan neurocan, the growth-stimulating heparan sulfate proteoglycan glypican, or the chondroitin sulfate proteoglycan-degrading enzyme chondroitinase ABC. Neurocan, glypican, or chondroitinase ABC was infused directly into the infarct cavity for 7 d, beginning 7 d after middle cerebral artery occlusion. Glypican and chondroitinase ABC reduced glial fibrillary acidic protein immunoreactivity and increased microtubule-associated protein-2 immunoreactivity in the periinfarct region, and glypican- and chondroitinase ABC-treated rats showed behavioral improvement compared with neurocan- or saline-treated rats. Glypican and chondroitinase ABC also increased neurite extension in cortical neuron cultures. Glypican increased fibroblast growth factor-2 expression and chondroitinase ABC increased brain-derived neurotrophic factor expression in these cultures, whereas no such effects were seen following neurocan treatment. Thus, treatment with glypican or enzymatic disruption of neurocan with chondroitinase ABC improves gross anatomical, histological, and functional outcome in the chronic phase of experimental stroke in rats. Changes in growth factor expression and neuritogenesis may help to mediate these effects.

Combination treatment with anti-Nogo-A and chondroitinase ABC is more effective than single treatments at enhancing functional recovery after spinal cord injury.

Anti-Nogo-A antibody and chondroitinase ABC (ChABC) enzyme are two promising treatments that promote functional recovery after spinal cord injury (SCI). Treatment with them has encouraged axon regeneration, sprouting and functional recovery in a variety of spinal cord and central nervous system injury models. The two compounds work, in part, through different mechanisms, so it is possible that their effects will be additive. In this study, we used a rat cervical partial SCI model to explore the effectiveness of a combination of anti-Nogo-A, ChABC, and rehabilitation. We found that spontaneous recovery of forelimb functions reflects the extent of the lesion on the ipsilateral side. We applied a combination treatment with acutely applied anti-Nogo-A antibody followed by delayed ChABC treatment starting at 3 weeks after injury, and rehabilitation starting at 4 weeks, to accommodate the requirement that anti-Nogo-A be applied acutely, and that rehabilitation be given after the cessation of anti-Nogo-A treatment. We found that single treatment with either anti-Nogo-A or ChABC, combined with rehabilitation, produced functional recovery of similar magnitude. The combination treatment, however, was more effective. Both single treatments produced increases in sprouting and axon regeneration, but the combination treatment produced greater increases. Anti-Nogo-A stimulated growth of a greater number of axons with a diameter of > 3 µm, whereas ChABC treatment stimulated increased growth of finer axons with varicosities. These results point to different functions of Nogo-A and chondroitin sulfate proteoglycans in axonal regeneration. The combination of anti-Nogo-A, ChABC and rehabilitation shows promise for enhancing functional recovery after SCI.

Chondroitinase ABC reduces time to muscle reinnervation and improves functional recovery after sciatic nerve transection in rats.

Application of chondroitinase ABC (ChABC) to injured peripheral nerves improves axon regeneration, but it is not known whether functional recovery is also improved. Recordings of EMG activity [soleus (Sol) M response and H reflexes] evoked by nerve stimulation and of Sol and tibialis anterior (TA) EMG activity and hindlimb and foot kinematics during slope walking were made to determine whether ChABC treatment of the sciatic nerve at the time of transection improves functional recovery. Recovery of evoked EMG responses began as multiple small responses with a wide range of latencies that eventually coalesced into one or two more distinctive and consistent responses (the putative M response and the putative H reflex) in both groups. Both the initial evoked responses and the time course of their maturation returned sooner in the ChABC group than in the untreated (UT) group. The reinnervated Sol and TA were coactivated during treadmill locomotion during downslope, level, and upslope walking throughout the study period in both UT and ChABC-treated rats. By 10 wk after nerve transection and repair, locomotor activity in Sol, but not TA, had returned to its pretransection pattern. There was an increased reliance on central control of Sol activation across slopes for both groups as interpreted from elevated prestance Sol EMG activity that was no longer modulated with slope. Limb length and orientation during locomotion were similar to those observed prior to nerve injury during upslope walking only in the ChABC-treated rats. Thus treatment of cut nerves with ChABC leads to improvements in functional recovery.

Chondroitinase ABC promotes compensatory sprouting of the intact corticospinal tract and recovery of forelimb function following unilateral pyramidotomy in adult mice.

Chondroitin sulphate proteoglycans (CSPGs) are extracellular matrix molecules whose inhibitory activity is attenuated by the enzyme chondroitinase ABC (ChABC). Here we assess whether CSPG degradation can promote compensatory sprouting of the intact corticospinal tract (CST) following unilateral injury and restore function to the denervated forelimb. Adult C57BL/6 mice underwent unilateral pyramidotomy and treatment with either ChABC or a vehicle control. Significant impairments in forepaw symmetry were observed following pyramidotomy, with injured mice preferentially using their intact paw during spontaneous vertical exploration of a cylinder. No recovery on this task was observed in vehicle-treated mice. However, ChABC-treated mice showed a marked recovery of function, with forelimb symmetry fully restored by 5 weeks post-injury. Functional recovery was associated with robust sprouting of the uninjured CST, with numerous axons observed crossing the midline in the brainstem and spinal cord and terminating in denervated grey matter. CST fibres in the denervated side of the spinal cord following ChABC treatment were closely associated with the synaptic marker vGlut1. Immunohistochemical assessment of chondroitin-4-sulphate revealed that CSPGs were heavily digested around lamina X, alongside midline crossing axons and in grey matter regions where sprouting axons and reduced peri-neuronal net staining was observed. Thus, we demonstrate that CSPG degradation promotes midline crossing and reinnervation of denervated target regions by intact CST axons and leads to restored function in the denervated forepaw. Enhancing compensatory sprouting using ChABC provides a route to restore function that could be applied to disorders such as spinal cord injury and stroke.

A Localized Materials-Based Strategy to Non-Virally Deliver Chondroitinase ABC mRNA Improves Hindlimb Function in a Rat Spinal Cord Injury Model.

Spinal cord injury often results in devastating consequences for those afflicted, with very few therapeutic options. A central element of spinal cord injuries is astrogliosis, which forms a glial scar that inhibits neuronal regeneration post-injury. Chondroitinase ABC (ChABC) is an enzyme capable of degrading chondroitin sulfate proteoglycan (CSPG), the predominant extracellular matrix component of the glial scar. However, poor protein stability remains a challenge in its therapeutic use. Messenger RNA (mRNA) delivery is an emerging gene therapy technology for in vivo production of difficult-to-produce therapeutic proteins. Here, mineral-coated microparticles as an efficient, non-viral mRNA delivery vehicles to produce exogenous ChABC in situ within a spinal cord lesion are used. ChABC production reduces the deposition of CSPGs in an in vitro model of astrogliosis, and direct injection of these microparticles within a glial scar forces local overexpression of ChABC and improves recovery of motor function seven weeks post-injury.

Self-assembling peptide hydrogels for the stabilization and sustained release of active Chondroitinase ABC in vitro and in spinal cord injuries.

Activated microglia/macrophages infiltration, astrocyte migration, and increased production of inhibitory chondroitin sulfate proteoglycans (CSPGs) are standard harmful events taking place after the spinal cord injuries (SCI). The gliotic scar, viz. the outcome of chronic SCI, constitutes a long-lasting physical and chemical barrier to axonal regrowth. In the past two decades, various research groups targeted the hostile host microenvironments of the gliotic scar at the injury site. To this purpose, biomaterial scaffolds demonstrate to provide a promising potential for nervous cell restoration. We here focused our efforts on two self-assembling peptides (SAPs), featuring different self-assembled nanostructures, and on different methods of drug loading to exploit the neuroregenerative potential of Chondroitinase ABC (ChABC), a thermolabile pro-plastic agent attenuating the inhibitory action of CSPGs. Enzymatic activity of ChABC (usually lasting less than 72 hours in vitro) released from SAPs was remarkably detected up to 42 days in vitro. ChABC was continuously released in vitro from a few days to 42 days as well. Also, injections of ChABC loaded SAP hydrogels favored host neural regeneration and behavioral recovery in chronic SCI in rats. Hence, SAP hydrogels showed great promise for the delivery of Chondroitinase ABC in future therapies targeting chronic SCI.

Combining peripheral nerve grafts and chondroitinase promotes functional axonal regeneration in the chronically injured spinal cord.

Because there currently is no treatment for spinal cord injury, most patients are living with long-standing injuries. Therefore, strategies aimed at promoting restoration of function to the chronically injured spinal cord have high therapeutic value. For successful regeneration, long-injured axons must overcome their poor intrinsic growth potential as well as the inhibitory environment of the glial scar established around the lesion site. Acutely injured axons that regenerate into growth-permissive peripheral nerve grafts (PNGs) reenter host tissue to mediate functional recovery if the distal graft-host interface is treated with chondroitinase ABC (ChABC) to cleave inhibitory chondroitin sulfate proteoglycans in the scar matrix. To determine whether a similar strategy is effective for a chronic injury, we combined grafting of a peripheral nerve into a highly relevant, chronic, cervical contusion site with ChABC treatment of the glial scar and glial cell line-derived neurotrophic factor (GDNF) stimulation of long-injured axons. We tested this combination in two grafting paradigms: (1) a peripheral nerve that was grafted to span a chronic injury site or (2) a PNG that bridged a chronic contusion site with a second, more distal injury site. Unlike GDNF-PBS treatment, GDNF-ChABC treatment facilitated axons to exit the PNG into host tissue and promoted some functional recovery. Electrical stimulation of axons in the peripheral nerve bridge induced c-Fos expression in host neurons, indicative of synaptic contact by regenerating fibers. Thus, our data demonstrate, for the first time, that administering ChABC to a distal graft interface allows for functional axonal regeneration by chronically injured neurons.

Partial functional recovery after complete spinal cord transection by combined chondroitinase and clenbuterol treatment.

Spinal cord injury not only disrupts axonal tracts but also causes gliotic, fibrotic, and Schwannotic scarring with resulting deposition of chondroitin sulfate proteoglycans (CSPGs) which prevent axonal reconnection and recovery of locomotor function. Here, we determined whether recovery of locomotor function could be promoted after complete transection, by degrading CSPGs enzymatically within the injury site with chondroitinase ABC (chABC) together with treatment with the beta(2)-adrenoceptor agonist, clenbuterol, a neuroprotective agent which can promote regrowth of lower motoneurons. Partial recovery of locomotor function was observed 8-12 weeks postinjury only after combined chABC and clenbuterol treatment. The recovery of locomotor function coincided with the presence of axons caudal to the injury site arising from neurons of the reticular, vestibular, and red nuclei also only with combined chABC and clenbuterol treatment. Axons myelinated by Schwann cells were most prominent in the transection site in the combined treatment group. Clenbuterol treatment activated cAMP response element binding protein within retrogradely traced neurons which has been associated with axonal regrowth. ChABC treatment decreased scarring due to both CSPG and collagen deposition as well as the gap between intact regions of the spinal cord. ChABC also increased numbers of phagocytic cells which remove myelin debris as well as populations of astrocytes thereby aiding blood-spinal cord barrier reformation. Together the results suggest that chABC and clenbuterol can act synergistically to promote recovery of locomotor function.

The effect of chondroitinase ABC and photobiomodulation therapy on neuropathic pain after spinal cord injury in adult male rats.

INTRODUCTION: . The goal of the study was to test the effects of photobiomodulation therapy (PBMT) and intra-spinal injection of chondroitinase ABC (chABC) both alone and combined on pain induced by spinal cord injury (SCI) in rats. MATERIAL AND METHODS: SCI was induced by compression using an aneurysm clip. PBMT used a 660 nm laser starting at 30 minutes after SCI and then daily for 2 week, and at the end of 1-week ChABC was injected into the spinal cord. Allodynia (mechanical and cold), hyperalgesia (mechanical and thermal) and functional recovery were measured. Molecular levels of IL6, BDNF, GDNF and Gad65 were evaluated. RESULTS: . Both ChABC, PBMT and the combination reduced allodynia and thermal hyperalgesia and improved functional recovery, but did not reduce mechanical hyperalgesia. Pain-related factors (BDNF and IL6) were decreased and anti-nociceptive factors (Gad65 and GDNF) were increased. CONCLUSION: . Treatment of SCI by PBM is a non-invasive technique, and could be improved by ChABC injection to reduce neuropathic pain and improve movement.

The yellow fluorescent protein (YFP-H) mouse reveals neuroprotection as a novel mechanism underlying chondroitinase ABC-mediated repair after spinal cord injury.

Chondroitinase ABC (ChABC) represents a promising therapeutic strategy for the treatment of spinal cord injury due to its potent effects on restoring function to spinal-injured adult mammals. However, there is limited mechanistic insight as to the underlying effects of ChABC treatment, where the effects are mediated, and which signaling pathways are involved in ChABC-mediated repair. Here we use a transgenic (YFP-H) mouse to demonstrate that cortical layer V projection neurons undergo severe atrophy 4 weeks after thoracic dorsal column injury and that ChABC is neuroprotective for these neurons after ICV infusion. ChABC also prevented cell atrophy after localized delivery to the spinal cord, suggesting a possible retrograde neuroprotective effect mediated at the injury site. Furthermore, neuroprotection of corticospinal cell somata coincided with increased axonal sprouting in the spinal cord. In addition, Western blot analysis of a number of kinases important in survival and growth signaling revealed a significant increase in phosphorylated ERK1 at the spinal injury site after in vivo ChABC treatment, indicating that activated ERK may play a role in downstream repair processes after ChABC treatment. Total forms of PKC and AKT were also elevated, indicating that modification of the glial scar by ChABC promotes long-lasting signaling changes at the lesion site. Thus, using the YFP-H mouse as a novel tool to study degenerative changes and repair after spinal cord injury we demonstrate, for the first time, that ChABC treatment regulates multiple signaling cascades at the injury site and exerts protective effects on axotomized corticospinal projection neurons.

Chondroitinase ABC and acute electrical stimulation are beneficial for muscle reinnervation after sciatic nerve transection in rats.

PURPOSE: Nerve regeneration and functional recovery are often incomplete after peripheral nerve damage. The aim of this study was to determine if chondroitinase ABC injection at the lesion site, 1 hour of electrical stimulation and the combination of these treatments at the time of repair could be effective in promoting muscle reinnervation. METHODS: The right sciatic nerve was completely sectioned in 32 female Sprague-Dawley rats. End-to-end microsuture repair was undertaken and fibrin glue was added. Five groups were studied: 1) suture (S) + fibrin glue (F) only; 2) S + F + chondroitinase ABC; 3) S + F + electrical stimulation; 4) S + F + chondroitinase ABC + electrical stimulation; 5) uninjured nerve. RESULTS: Post recovery kinematics showed larger excursion of the hip-ankle-toe angle during walking in groups 2, 3 and 4 than in group 1 (p < 0.05). In vivo electromyographic activity and maximal muscle force were similar between groups 2, 3, 4 and 5, with higher values in all of them compared to group 1 (p < 0.05). Also, the distal stump of the sciatic nerve was excised, and cross-sectioning revealed that the number of axons were similar in all groups. CONCLUSIONS: 150 days after nerve transection, recovery was incomplete with S and F only. Chondroitinase ABC injection at the lesion site and/or 1 hour of electrical stimulation of the proximal nerve stump were beneficial in promoting nerve regeneration and functional muscle reinnervation.