Trans-neuronal transduction of spinal neurons following cortical injection and anterograde axonal transport of a bicistronic AAV1 vector.

Adeno-associated viral (AAV) vectors are one of the most promising gene delivery systems to the central nervous system. We now report, that AAV1 can be used to express transgenes trans-neuronally in neurons distant from the injection site. Specifically, intracortical injection of a bicistronic AAV1 vector trans-neuronally transduced spinal neurons as shown by fluorescence microscopy, the presence of AAV genome and AAV transcript in the contralateral spinal cord. Prior pyramidotomy abolished spinal transduction, confirming anterograde axonal transport of AAV1 in the corticospinal tract. These observations demonstrate the potential of bicistronic AAV1 for trans-neuronal expression of therapeutic transgenes in neurological disorders or reporter genes in connectivity studies.

Analytical validation of HER2DX genomic test for early-stage HER2-positive breast cancer.

BACKGROUND: HER2DX, a multianalyte genomic test, has been clinically validated to predict breast cancer recurrence risk (relapse risk score), the probability of achieving pathological complete response post-neoadjuvant therapy (pCR likelihood score), and individual ERBB2 messenger RNA (mRNA) expression levels in patients with early-stage human epidermal growth factor receptor 2 (HER2)-positive breast cancer. This study delves into the comprehensive analysis of HER2DX's analytical performance. MATERIALS AND METHODS: Precision and reproducibility of HER2DX risk, pCR, and ERBB2 mRNA scores were assessed within and between laboratories using formalin-fixed paraffin-embedded (FFPE) tumor tissues and purified RNA. Robustness was appraised by analyzing the impact of tumor cell content and protocol variations including different instruments, reagent lots, and different RNA extraction kits. Variability was evaluated across intratumor biopsies and genomic platforms [RNA sequencing (RNAseq) versus nCounter], and according to protocol variations. RESULTS: Precision analysis of 10 FFPE tumor samples yielded a maximal standard error of 0.94 across HER2DX scores (1-99 scale). High reproducibility of HER2DX scores across 29 FFPE tumors and 20 RNAs between laboratories was evident (correlation coefficients >0.98). The probability of identifying score differences >5 units was ≤5.2%. No significant variability emerged based on platform instruments, reagent lots, RNA extraction kits, or TagSet thaw/freeze cycles. Moreover, HER2DX displayed robustness at low tumor cell content (10%). Intratumor variability across 212 biopsies (106 tumors) was <4.0%. Concordance between HER2DX scores from 30 RNAs on RNAseq and nCounter platforms exceeded 90.0% (Cohen's κ coefficients >0.80). CONCLUSIONS: The HER2DX assay is highly reproducible and robust for the quantification of recurrence risk, pCR likelihood, and ERBB2 mRNA expression in early-stage HER2-positive breast cancer.

Efficient gene expression from integration-deficient lentiviral vectors in the spinal cord.

Gene transfer to spinal cord cells may be crucial for therapy in spinal muscular atrophy, amyotrophic lateral sclerosis and spinal cord injury. Lentiviral vectors are efficient for transduction of a variety of cells, but like all integrating vectors they pose a risk of insertional mutagenesis. Integration-deficient lentiviral vectors (IDLVs) remain episomal but retain the transduction efficiency of standard integrating lentiviral vectors, particularly when the episomes are not diluted out through repeated cell division. We have now applied IDLVs for transduction of spinal cord in vitro, in explants and in vivo. Our results demonstrate similar efficiency of eGFP expression from integrating lentiviral vectors and IDLVs in most cell types analyzed, including motor neurons, interneurons, dorsal root ganglia (DRG) neurons and astroglia. IDLV-mediated expression of pro-glial-cell-derived neurotrophic factor (Gdnf) rescues motor neuron cultures from death caused by removal of exogenous trophic support. IDLVs also mediate efficient RNA interference in DRG neuron cultures. After intraparenchymal injection in the rat and mouse cervical and lumbar regions in vivo, transduction is mainly neuronal, with both motor neurons and interneurons being efficiently targeted. These results suggest that IDLVs could be efficient and safer tools for spinal cord transduction in future therapeutic strategies.

Ocular Involvement in Transfusion Dependent Thalassemia Children.

Thalassemia is one of the most common haemoglobinopathies in the world. Transfusion dependent thalassemia patients need regular blood transfusion. Repeated blood transfusions lead to iron overloads which can affect various organs in the body including eyes. The present study aims to evaluate the ocular involvements in transfusion dependent thalassemia children and their relationship with duration of the disease and serum ferritin level. This cross-sectional observational study included 46 multi-transfused thalassemia children aged 3-18 years. Detailed ophthalmological examination including visual acuity, slit lamp bio microscopy, direct and indirect ophthalmoscopy was done. Statistical analysis was done using SPSS version (IBM) 23.0. Student's t-test and chi-square (χ²) test was done and p value of <0.05 was considered significant. Out of 46 thalassemia children male were 25(54.3%) and female were 21(45.7%). Mean age of the children was 8.94±5.04 years, mean duration of disease was 7.02±3.5 years and mean serum ferritin level 1543.68±914.43ng/dl. Ocular involvements were detected in 19(41.3%) children. Among them 8(17.39%) children had more than one ocular involvements. The ocular manifestations were decreased visual acuity in 17(36.95%), corneal dryness in 7(15.21%), lens opacity in 6(13.04%), optic disc atrophy in 7(15.21%), peripheral retinal pigmentation in 5(10.86%) and retinal vessels tortuosity in 3(6.52%) children. Higher serum ferritin level and increased duration of the disease were significantly (p<0.001) related with ocular involvement. Various ocular involvements were found in transfusion dependent thalassemia children. Therefore, transfusion dependent thalassemia children should be screened periodically for early detection and proper management of ocular changes.

Safe and effective delivery of high-power, short-duration radiofrequency ablation lesions with a flexible-tip ablation catheter.

Background: High-power, short-duration (HPSD) radiofrequency ablation (RFA) may reduce ablation time. Concerns that catheter-mounted thermocouples (TCs) can underestimate tissue temperature, resulting in elevated risk of steam pop formation, potentially limit widespread adoption of HPSD ablation. Objective: The purpose of this study was to compare the safety and efficacy of HPSD and low-power, long-duration (LPLD) RFA in the context of pulmonary vein isolation (PVI). Methods: An open-irrigated ablation catheter with a contact force sensor and a flexible-tip electrode containing a TC at its distal end (TactiFlexTM Ablation Catheter, Sensor EnabledTM, Abbott) was used to isolate the left pulmonary veins (PVs) in 12 canines with HPSD RFA (50 W for 10 seconds) and LPLD RFA (30 W for a maximum of 60 seconds). PVI was assessed at 30 minutes and 28 ± 3 days postablation. Computed tomographic scans were performed to assess PV stenosis after RFA. Lesions were evaluated with histopathology. Results: A total of 545 ablations were delivered: 252 with LPLD (0 steam pops) and 293 with HPSD RFA (2 steam pops) (P = .501). Ablation time required to achieve PVI was >3-fold shorter for HPSD than for LPLD RFA (P = .001). All 24 PVs were isolated 30 minutes after ablation, with 12/12 LPLD-ablated and 11/12 HPSD-ablated PVs still isolated at follow-up. Histopathology revealed transmural ablations for HPSD and LPLD RFA. No major adverse events occurred. Conclusion: An investigational ablation catheter effectively delivered RFA lesions. Ablation time required to achieve PVI with HPSD with this catheter was >3-fold shorter than with LPLD RFA.

Optimal conditions for high-power, short-duration radiofrequency ablation using a novel, flexible-tipped, force-sensing catheter.

Background: High-power, short-duration (HPSD) radiofrequency ablation (RFA) reduces procedure time; however, safety and efficacy thresholds vary with catheter design. Objective: The study sought to determine optimal HPSD ablation conditions with a novel flexible-tipped, contact force-sensing RFA catheter. Methods: RFA lesions were created in thigh muscle (16 swine) over a range of conditions (51-82 W, 2-40 g, 8-40 mL/min irrigation). An intracardiac study was performed (12 swine) to characterize steam pop thresholds. Lesions were created in a second intracardiac study (14 swine, n = 290 pulmonary vein isolation [PVI] lesions) with combinations of radiofrequency power, duration, and contact force. PVI was tested, animals were sacrificed, and lesions were measured. Results: The likelihood of coagulation formation in the thigh model was <20% when power was ≤79 W, when contact force was ≤40 g, when duration was ≤11 seconds, and when irrigation rates were 8 to 40 mL/min. The impact of contact force on lesion safety and efficacy was more pronounced using HPSD (60 W/8 seconds) compared with conventional ablation (30 W/45 seconds) (P = .038). During PVI, focal atrial lesions ranged in width from 4.2 to 12.5 mm and were transmural 80.8% of the time. PVI was achieved in 13 of 14 veins. Logistic regression identified that the optimal parameters for radiofrequency application were 60 to 70 W with a duration <8 seconds and <15 g contact force. Conclusions: Optimal HPSD lesions with this this flexible-tipped, force-sensing RFA catheter were created at 60 to 70 W for <8 seconds with <15 g contact force. Chronic studies are ongoing to assess radiofrequency parameter refinements and long-term lesion durability using these conditions.

Corticospinal tract transduction: a comparison of seven adeno-associated viral vector serotypes and a non-integrating lentiviral vector.

The corticospinal tract (CST) is extensively used as a model system for assessing potential therapies to enhance neuronal regeneration and functional recovery following spinal cord injury (SCI). However, efficient transduction of the CST is challenging and remains to be optimised. Recombinant adeno-associated viral (AAV) vectors and integration-deficient lentiviral vectors are promising therapeutic delivery systems for gene therapy to the central nervous system (CNS). In the present study the cellular tropism and transduction efficiency of seven AAV vector serotypes (AAV1, 2, 3, 4, 5, 6, 8) and an integration-deficient lentiviral vector were assessed for their ability to transduce corticospinal neurons (CSNs) following intracortical injection. AAV1 was identified as the optimal serotype for transducing cortical and CSNs with green fluorescent protein (GFP) expression detectable in fibres projecting through the dorsal CST (dCST) of the cervical spinal cord. In contrast, AAV3 and AAV4 demonstrated a low efficacy for transducing CNS cells and AAV8 presented a potential tropism for oligodendrocytes. Furthermore, it was shown that neither AAV nor lentiviral vectors generate a significant microglial response. The identification of AAV1 as the optimal serotype for transducing CSNs should facilitate the design of future gene therapy strategies targeting the CST for the treatment of SCI.

A drug-induced hypotensive challenge to verify catheter-based radiofrequency renal denervation in an obese hypertensive swine model.

OBJECTIVE: Sham-controlled trials provided proof-of-principle for the blood pressure-lowering effect of catheter-based renal denervation (RDN). However, indicators for the immediate assessment of treatment success are lacking. This study sought to investigate the impact of RDN on renal renin arteriovenous difference (renal renin AV-Δ) following a hypotensive challenge (HC). METHODS: Twelve hypertensive Ossabaw swine underwent either combined surgical and chemical (n = 3) or catheter-based RDN (n = 9). A telemetry monitor was implanted to acquire hemodynamic data continuously. Before and after RDN, a sodium nitroprusside-induced HC was performed. Renal renin AV-Δ was calculated as the difference of plasma renin concentrations drawn from the renal artery and vein. RESULTS: In total, complete renal renin AV data were obtained in eight animals at baseline and six animals at baseline and 3 months of follow-up. Baseline renal renin AV-Δ correlated inversely with change in 24-h minimum systolic (- 0.764, p = 0.02), diastolic (r = - 0.679, p = 0.04), and mean (r = - 0.663, p = 0.05) blood pressure. In the animals with complete renin secretion data at baseline and follow-up, the HC increased renal renin AV-Δ at baseline, while this effect was attenuated following RDN (0.55 ± 0.34 pg/ml versus - 0.10 ± 0.16 pg/ml, p = 0.003). Renin urinary excretion remained unchanged throughout the study (baseline 0.286 ± 0.187 pg/ml versus termination 0.305 ± 0.072 pg/ml, p = 0.789). CONCLUSION: Renin secretion induced by HC was attenuated following RDN and may serve as an indicator for patient selection and guide successful RDN procedures.

Australia's national trends in the incidence of Type 1 diabetes in 0-14-year-olds, 2000-2006.

AIMS: To determine the national incidence of Type 1 diabetes in children aged 0-14 years and examine trends in incidence between 2000 and 2006 by age, sex and calendar year. METHODS: Case ascertainment was from the Australian National Diabetes Register, a prospective population-based incidence register established in 1999, with two sources of ascertainment: the National Diabetes Services Scheme and the Australasian Paediatric Endocrine Group's state-based registers. Denominator data were from the Australian Bureau of Statistics. RESULTS: There were 6350 new cases of Type 1 diabetes (3323 boys and 3027 girls). Case ascertainment was 97.1% complete using the capture-recapture method. The mean adjusted incidence rate for 2000-2006 was 21.6 per 100,000 person-years [95% confidence interval (CI) 21.0, 22.1], and increased from 19.8 in 2000 to 23.4 per 100,000 in 2006, an average increase of 2.8% (95% CI 1.5, 4.1) per year. Mean incidence for the 7-year period increased with age, and was significantly higher in boys aged 0-4 years and 10-14 years than in girls of the same age. CONCLUSIONS: The incidence of Type 1 diabetes among 0-14-year-olds in Australia is very high compared with available data from many other countries. The rate of increase observed globally in the last decade has continued well into this decade in Australia. The rising incidence cannot be explained by changes in genetic susceptibility; there is an urgent need to examine the environmental factors that have contributed to this increase. The findings of this study also have important implications for resource planning.

Complement C5 regulates the expression of insulin-like growth factor binding proteins in chronic experimental allergic encephalomyelitis.

Complement activation plays a central role in autoimmune demyelination. To explore the possible effects of C5 on post-inflammatory tissue repair, we investigated the transcriptional profile induced by C5 in chronic experimental allergic encephalomyelitis (EAE) using oligonucleotide arrays. We used C5-deficient (C5-d) and C5-sufficient (C5-s) mice to compare the gene expression profile and we found that 390 genes were differentially regulated in C5-s mice as compared to C5-d mice during chronic EAE. Among them, a group of genes belonging to the family of insulin-like growth factor binding proteins (IGFBP) and transforming growth factor (TGF)-beta3 were found most significantly differentially regulated by C5. The dysregulation of these genes suggests that these proteins might be responsible for the gliosis and lack of remyelination seen in C5-d mice with chronic EAE.

Comparison of branch and distally focused main renal artery denervation using two different radio-frequency systems in a porcine model.

OBJECTIVES: Anatomic placement of lesions may impact efficacy of radio-frequency (RF) catheter renal denervation (RDN). However, it is unclear if it is necessary to perform treatments post bifurcation with systems that may provide deeper penetration to achieve successful RDN. METHODS: Sixteen domestic swine (n=16) were randomly assigned to 4 groups: 1) 8 lesions created in the branch arteries using the Spyral catheter (SP8); 2) 8 lesions created in the branch arteries plus 4 lesions created in the main artery using the SP catheter (SP12); 3) 8 lesions created in the main artery using the EnligHTN catheter with the distal position as close as possible to the bifurcation (EN8); and 4) 12 lesions created in the main artery using the EN catheter with the distal position as close as possible to the bifurcation (EN12). RESULTS: Each arm showed statistically significant changes in kidney norepinephrine (NE, ng/g) between treated kidneys vs. untreated contralateral control. There were no statistically significant differences in tissue NE% reductions across each arm based on catheter, anatomic location, & number of lesions (p=0.563): EN8 -74±34%, EN12 -95±3%, SP8 -76±16%, SP12 -82±17% (p=0.496). A total of 46 lesions were measured for lesion depth: EN main (3.3±2.8mm) vs. SP branch (2.0±1.0mm, p=0.039), SP main (2.9±1.6mm) vs. SP branch (p=0.052), and EN main vs. SP main (p=0.337). CONCLUSIONS: Distally-focused main renal artery treatment using the EN system appears to be equally efficacious in reducing tissue NE levels compared with SP treatment in the branches plus main renal arteries, advocating for device-specific procedure execution.

Complement activation in autoimmune demyelination: dual role in neuroinflammation and neuroprotection.

Multiple sclerosis and its animal model experimental allergic encephalomyelitis are inflammatory demyelinating diseases of the central nervous system mediated by activated lymphocytes, macrophages/microglia and the complement system. Complement activation and the C5b-9 terminal complex contribute to the pathogenesis of these diseases through its role to promote demyelination. C5b-9 was also shown to protect oligodendrocytes from apoptosis both in vitro and in vivo. Our findings indicate that activation of complement and C5b-9 assembly plays a pro-inflammatory role in the acute phase, but may also be neuroprotective.

Motor enrichment sustains hindlimb movement recovered after spinal cord injury and glial transplantation.

PURPOSE: This study investigated whether enrichment improves hindlimb movement following complete spinal cord transection and transplantation of olfactory ensheathing glia (OEG), with or without a Schwann cell (SC) bridge. METHODS: Motor activity was encouraged through provision of motor enrichment housing (MEH); a multi-level cage containing ramps, textured surfaces and rewards. Hindlimb joint movement was assessed weekly for 22 weeks starting one week post-surgery, comparing rats housed in MEH to those in basic housing (BH). Transganglionic tracer was injected into the crushed right sciatic nerve three days prior to sacrifice, allowing sensory axons in the dorsal columns to be visualized by immunolabeling. Serotonergic axons and glial cells expressing low affinity nerve growth factor receptor were identified by immunolabeling. RESULTS: All rats, having received transplants, recovered some hindlimb movement. Rats housed in BH progressively lost recovered hindlimb function whereas recovered hindlimb movements were sustained in most rats in MEH. In rats transplanted with SCs and OEG, effects of MEH were first significant 14 weeks after injury. In rats transplanted with OEG, a trend was seen from 14 weeks after injury, but this did not reach significance. In all rats, traced sensory axons died back from sites of transplantation and did not regenerate rostrally. Further, in no rat were serotonergic axons observed regenerating into, around or beyond transplants. CONCLUSIONS: Transection and transplantation of SC/OEG or OEG induced recovery of hindlimb function. This recovered hindlimb movement was sustained in rats housed in MEH but was progressively lost in rats housed in BH. Because benefits of MEH were not observed until 14 weeks after injury, long-term assessment of behavior is recommended. BH conditions are not conducive to maintenance of recovered hindlimb function, and MEH should be used in studies of recovery of function following spinal cord injury.

Catheter-based radio-frequency renal nerve denervation lowers blood pressure in obese hypertensive swine model.

OBJECTIVES: Radio-frequency renal denervation (RDN) therapy is under investigation for the treatment of uncontrolled hypertension. Data in hypertensive, drug-naïve large animal models using RDN is limited. METHODS: A cohort of Ossabaw swine (N = 9) was implanted with telemetry monitors, enrolled on a high calorie-feed regimen and randomly assigned to RDN. Blood pressure (BP) data were separated and analyzed according to the following epoch definitions: 24-h (h), most-active-h, light-h, and dark-h. RESULTS: The mean weight increased by 45% from 86.5 ±â€Š2.5 kg at telemetry implant (day 87) to 125.2 ±â€Š4.5 kg at time of RDN therapy (day 227). Hypertension developed in all swine (24-h BP: 169.5/128.3 ±â€Š5.8/5.1 mmHg pre-RDN). RDN resulted in significant reductions in noradrenaline kidney tissue concentration by 63%. Significant BP reductions were documented at 45 days post-RDN in all defined interday epochs, except for the dark-h period. The most pronounced SBP/DBP reduction was 12.4/11.2 mmHg (P < 0.05), observed during the most-active-h period. Animals continued to gain weight after the RDN procedure to the end of the study at 90 days (125.2 ±â€Š4.5-138.5 ±â€Š6.6 kg, P < 0.001). At 90 days post-RDN, the mean 24-h BP returned near pre-RDN baseline values. Given the strong relationship of BP to weight (R = 0.87, P < 0.001), group mean SBP/DBP was normalized by weight resulting in significant and continued reductions at both 45 and 90 days post-RDN across all intradaily epochs. CONCLUSION: Catheter-based RDN, using a multielectrode system, resulted in a significant reduction in 24-h BP in this drug-naïve, hypertensive animal model.

Schwann cells for spinal cord repair.

The complex nature of spinal cord injury appears to demand a multifactorial repair strategy. One of the components that will likely be included is an implant that will fill the area of lost nervous tissue and provide a growth substrate for injured axons. Here we will discuss the role of Schwann cells (SCs) in cell-based, surgical repair strategies of the injured adult spinal cord. We will review key studies that showed that intraspinal SC grafts limit injury-induced tissue loss and promote axonal regeneration and myelination, and that this response can be improved by adding neurotrophic factors or anti-inflammatory agents. These results will be compared with several other approaches to the repair of the spinal cord. A general concern with repair strategies is the limited functional recovery, which is in large part due to the failure of axons to grow across the scar tissue at the distal graft-spinal cord interface. Consequently, new synaptic connections with spinal neurons involved in motor function are not formed. We will highlight repair approaches that did result in growth across the scar and discuss the necessity for more studies involving larger, clinically relevant types of injuries, addressing this specific issue. Finally, this review will reflect on the prospect of SCs for repair strategies in the clinic.

Dose-dependent effects of tamoxifen on long bones in growing rats: influence of ovarian status.

Tamoxifen is a nonsteroidal antiestrogen which has been reported by various investigators to have estrogen agonist and antagonist effects on rat bone. These different interpretations may be due to differences in the ovarian status, estrogen levels, and/or tamoxifen levels of the rats. To address this issue, a dose response was determined for the effects of tamoxifen on bone histomorphometry in intact female and ovariectomized (OVX) rats. The results were compared with those obtained after treatment of OVX rats with estrogen alone or a combination of estrogen and tamoxifen. OVX resulted in increases in growth rate (weight gain) and periosteal bone formation rate and decreases in uterine weight and cancellous bone fractional volume (BV/TV). Treatment of OVX rats with estrogen resulted in dose-dependent decreases in growth rate and periosteal bone formation rate as well as dose-dependent increases in uterine weight and BV/TV. Similarly, tamoxifen treatment resulted in dose-dependent decreases in overall growth rate and periosteal bone formation rate in both OVX and intact rats. Tamoxifen treatment prevented the decrease in BV/TV after OVX, although the highest dose of tamoxifen resulted in a small decrease in BV/TV in intact female rats. In contrast to estrogen, tamoxifen treatment prevented the increase in uterine weight in intact female rats as well as the decrease in uterine weight in OVX rats. Tamoxifen treatment did not alter the effects of 17 beta-estradiol on the periosteal bone formation rate in OVX rats, but reduced the increase in BV/TV to values similar to those in intact rats. These results are consistent with tamoxifen behaving as a partial estrogen agonist on rat bone.

Sublytic terminal complement attack induces c-fos transcriptional activation in myotubes.

Sublytic C5b-9 alters the molecular phenotype of myotubes by inhibiting muscle-specific gene expression. Here, we showed that C5b-9 induced c-fos mRNA and transcription. Using c-fos promoter-CAT constructs and electrophoretic mobility shift assay (EMSA), the minimal c-fos promoter activity was shown to increase within 30-min exposure to serum C5b-9, which also induced the binding of serum response factor (SRF), along with ternary complex factor (TCF) Elk1 and Sap1a to the serum response element. C5b-9 activated ERK1, which in turn activated Elk1 in myotubes. We propose that c-fos gene transcription associated with myotube dedifferentiation is induced by C5b-9 through ERK1-mediated assembly of serum response factor-ternary complex.

Inhibiting cell proliferation during formation of the glial scar: effects on axon regeneration in the CNS.

Following a CNS lesion many glial cell types proliferate and/or migrate to the lesion site, forming the glial scar. The majority of these cells express chondroitin sulphate proteoglycans (CS-PGs), previously shown to inhibit axonal growth. In this study, in an attempt to diminish glial scar formation and improve axonal regeneration, proliferating cells were eliminated from the lesion site. Adult rats received a continuous infusion of 2% cytosine-D-arabinofuranoside (araC) or saline for 7 days over the lesion site, immediately following a unilateral transection of the right medial forebrain bundle. Additional groups of rats that received subdural infusions prior to the lesion, and lesioned rats which received no infusion, were also compared in the analyses. Animals were killed at 4, 7, 12 or 18 days post-lesion (dpl) and immunohistochemistry was used to determine the effects of these treatments on tyrosine hydroxylase (TH)-lesioned axons, and on the injury response of glial cells. Almost complete elimination of NG2 oligodendrocyte progenitor cells from the lesion site was seen up to 7 dpl in araC-infused animals; reduced numbers of reactive CD11b microglia were also seen but no effects were seen on the injury response of GFAP astrocytes. Significantly more TH axons were seen distal to the lesion in araC-treated brains, but these numbers dwindled by 18 dpl.

Relationship between sprouting axons, proteoglycans and glial cells following unilateral nigrostriatal axotomy in the adult rat.

Proteoglycans may modulate axon growth in the intact and injured adult mammalian CNS. Here we investigate the distribution and time course of deposition of a range of proteoglycans between 4 and 14 days following unilateral axotomy of the nigrostriatal tract in anaesthetised adult rats. Immunolabelling using a variety of antibodies was used to examine the response of heparan sulphate proteoglycans, chondroitin sulphate proteoglycans and keratan sulphate proteoglycans. We observed that many proteoglycans became abundant between 1 and 2 weeks post-axotomy. Heparan sulphate proteoglycans were predominantly found within the lesion core (populated by blood vessels, amoeboid macrophages and meningeal fibroblasts) whereas chondroitin sulphate proteoglycans and keratan sulphate proteoglycans were predominantly found in the lesion surround (populated by reactive astrocytes, activated microglia and adult precursor cells). Immunolabelling indicated that cut dopaminergic nigral axons sprouted prolifically within the lesion core but rarely grew into the lesion surround. We conclude that sprouting of cut dopaminergic nigral axons may be supported by heparan sulphate proteoglycans but restricted by chondroitin sulphate proteoglycans and keratan sulphate proteoglycans.