Simultaneous Administration of Statins and Pioglitazone Limits Tumor Growth in a Rat Model of Malignant Glioma

BACKGROUND/AIM

Statins are cholesterol reducers with considerable dose-dependent effect against glioma cells. The apoptotic effect could be increased by combining statins or by adding pioglitazone (PGZ). The last one is an anti-diabetic drug, an agonist of the peroxisome proliferator-activated receptor-gamma (PPARG). We used an animal model to test the effect of such combination in vivo and we investigated the changes on immunological processes.

MATERIALS AND METHODS

Thirty-three rats (F344/DuCrl) were anesthetized and glioblastoma (F98) cells were implanted stereotactically. Animals were randomized into four groups: i) control (N=9); ii) intraperitoneal injection of PGZ 10 mg/kg/day (N=8); iii) oral administration of atorvastatin (ATVS) 40 mg/kg and lovastatin (LVS) 50 mg/kg (N=8); iv) oral administration of ATVS 40 mg/kg, LVS 50 mg/kg and PGZ 5 mg/kg (N=8). Treatment was started at 3rd postoperative day and continued for 14 days. The animals were followed-up for 30 days after start of therapy. Survival time, tumor volume, proliferation rate, counts of peripheral and tumor infiltrating leukocytes were compared.

RESULTS

No difference of survival time or incidence of neurological deficits was observed. The combination of statins with PGZ led to a significant reduction in tumor volume by approximately 40% (p<0.05), statins combination was less effective and PGZ alone did not affect tumor volume. The groups treated with statins displayed significantly lower counts of peripheral CD3⁺, CD4⁺ and CD8⁺ T-cells and lower tumor associated CD68-positive cells (p<0.01, in respect to controls or PGZ alone). The proliferation rate was not statistically different. No relevant toxic effects were observed.

DISCUSSION

Statins and PGZ are well-tolerated in rats and produced a significant tumor reduction, while an impact on neurological deficits or survival improvement could not be demonstrated. The reduction of infiltrating macrophages by using statins and PGZ should be further studied.

Brain restoration as an emerging field in neurology and neuroscience

Restoration of brain function was long thought to be impossible. However, as the publications in the journal Restorative Neurology and Neuroscience (RNN) for more than 20 years attest, clinically useful improvement can be achieved after damage or diseases of the brain, the retina, and the peripheral nervous system. By reviewing both pre-clinical studies and clinical work, we explore what advancements can be made today and what to expect going forward. For example, in the last few years we have seen a clinical focus in the area of non-invasive brain stimulations and rehabilitation training trials. In basic animal research multi-modal approaches have been presented to restore brain function with a combination of different treatments. We think that this is an exciting time in the area of restoration of brain function with many new strategies aimed at helping recovering their impaired neurological functions.

Transcorneal electrical stimulation alters morphology and survival of retinal ganglion cells after optic nerve damage

Traumatic optic nerve injury leads to retrograde death of retinal ganglion cells (RGCs), but transcorneal electrical stimulation (TES) can increase the cell survival rate. To understand the mechanisms and to further define the TES-induced effects we monitored in living animals RGC morphology and survival after optic nerve crush (ONC) in real time by using in vivo confocal neuroimaging (ICON) of the retina. ONC was performed in rats and ICON was performed before crush and on post-lesion days 3, 7 and 15 which allowed us to repeatedly record RGC number and size. TES or sham-stimulation were performed immediately after the crush and on post-injury day 11. Three days after ONC we detected a higher percentage of surviving RGCs in the TES group as compared to sham-treated controls. However, the difference was below significance level on day 7 and disappeared completely by day 15. The death rate was more variable amongst the TES-treated rats than in the control group. Morphological analysis revealed that average cell size changed significantly in the control group but not in stimulated animals and the morphological alterations of surviving neurons were smaller in TES-treated compared to control cells. In conclusion, TES delays post-traumatic cell death significantly. Moreover, we found "responder animals" which also benefited in the long-term from the treatment. Our in vivo cellular imaging results provide evidence that TES reduces ONC-associated neuronal swelling and shrinkage especially in RGCs which survived long-term. Further studies are now needed to determine the differences of responders vs. non-responders.

In vivo visualisation of nanoparticle entry into central nervous system tissue

Because the potential neurotoxicity of nanoparticles is a significant issue, characterisation of nanoparticle entry into the brain is essential. Here, we describe an in vivo confocal neuroimaging method (ICON) of visualising the entry of fluorescent particles into the parenchyma of the central nervous system (CNS) in live animals using the retina as a model. Rats received intravenous injections of fluorescence-labelled polybutyl cyanoacrylate nanoparticles that had been synthesised by a standard miniemulsion polymerisation process. We performed live recording with ICON from before and up to 9 days after particle injection and took photomicrographs of the retina. In addition, selective retrograde labelling of the retinal ganglion cells was achieved by stereotaxic injection of a fluorescent dye into the superior colliculus. Using ICON, we observed vascular kinetics of nanoparticles (wash-in within seconds), their passage to the retina parenchyma (within minutes) and their distribution (mainly cellular) under in vivo conditions. For the detection of cell loss--which is important for the evaluation of toxic effects--in another experiment, we semi-quantitatively analysed the selectively labelled retinal neurons. Our results suggest that the dye per se does not lead to neuronal death. With ICON, it is possible to study nanoparticle kinetics in the retina as a model of the blood-brain barrier. Imaging data can be acquired within seconds after the injection, and the long-term fate of cellular uptake can be followed for many days to study the cellular/extracellular distribution of the nanoparticles. ICON is thus an effective and meaningful tool to investigate nanoparticle/CNS interactions.

Recovery of axonal transport after partial optic nerve damage is associated with secondary retinal ganglion cell death in vivo

PURPOSE

Traumatic injury of the optic nerve leads to retrograde cell death of retinal ganglion cells (RGCs) but usually a certain percentage of neurons survive. It has been suggested that recovery of axonal transport is beneficial for survival. The present study was therefore performed to provide a synopsis of the temporal pattern of axonal transport decline/recovery and the viability of RGCs after optic nerve crush (ONC).

METHODS

Fluorescent dyes were injected into the superior colliculus to retrogradely label RGCs. Axonal transport kinetics into the RGCs was visualized with in vivo confocal neuroimaging (ICON) in uninjured rats and in rats which had mild or moderate ONC. Red fluorescent beads were injected on day 2 post-ONC and green beads on day 7.

RESULTS

At 2 to 4 days post-ONC significant axonal transport was detected, but within 1 week the transport of the fluorescent beads was decreased. Interestingly, during post-ONC week 3 the axon transport slowly recovered. However, despite this recovery, retrograde cell death rate continued and was even increased in a "second wave" of cell death in those neurons that displayed axon transport recovery.

CONCLUSIONS

After damage many surviving RGCs lose their axon transport, but after approximately 3 weeks, this transport recovers again, a sign of intrinsic axon repair. Contrary to the prediction, axon transport recovery is not associated with better cell survival but rather with a second wave of cell death. Thus, the accelerated cell death associated with recovery of axon transport suggests the existence of a late retrograde cell death signal.

Special issues in brain plasticity, repair and rehabilitation: 20 years of a publishing strategy

The journal Restorative Neurology and Neuroscience (RNN) is focused on the emerging field of brain plasticity, repair and rehabilitation, including original and review papers both in basic research (in vitro studies, animal experiments) and in the clinical domain, including brain imaging studies. The publication of special issues on vital topics, summarizing the work of leading experts in the field of restoration and plasticity has become a major strategy of RNN and has attracted worldwide attention. Special issues are typically organized by specialized guest-editors familiar with the respective science field. Special issues cover a particular sub-discipline and often contain laboratory review papers. The first special issue appeared in 1990, and until today RNN has published a total of 25 special issues on a variety of basic science and clinical matters. In this way, RNN promotes the dissemination of information in the field of neuroplasticity, repair and rehabilitation, providing the reader with up-to-date information prepared by leading experts in the field.

Publishing in the field of brain plasticity, repair and rehabilitation: The 20th Anniversary issue of Restorative Neurology and Neuroscience

The journal Restorative Neurology and Neuroscience (RNN) now celebrates its 20th anniversary. Since 1989 RNN has published scientific findings in the emerging fields of brain plasticity, repair and rehabilitation via original scientific publications and review papers in basic research (animal experiments, in vitro studies) and clinical science. During the last decade RNN had a steady progress in reference value and scientific impact, reaching an ISI-impact factor of 1.978 (2008) and has published a total of 717 papers. The journal's success can be explained by different factors: (1) neuroplasticity, regeneration, recovery and rehabilitation have developed to main stream subjects with a worldwide increase in the number of publications and their citation rate, (2) RNN has published numerous special issues which summarize the work of leading experts in specialized sub-fields, (3) a dedicated, highly qualified editorial board (4) the quality of papers submitted to RNN has increased over time. RNN has now become a visible and leading source of original scientific information in the space of brain plasticity, rehabilitation and repair.

Two faces of calcium activation after optic nerve trauma: life or death of retinal ganglion cells in vivo depends on calcium dynamics

Calcium elevations after neurotrauma are not only implicated in cell death but may contribute to adaptive plasticity. We now wished to resolve this contradiction by following calcium dynamics after optic nerve crush in vivo. Adult rats received no injury (n = 5), unilateral mild (n = 10) or moderate optic nerve crush (n = 10) (ONC), or axotomy (n = 5). Before surgery, retinal ganglion cells (RGCs) were retrogradely labelled with Oregon Green BAPTA-dextran, a fluorescent calcium marker. Calcium-related fluorescence intensity (FI) was repeatedly measured in individual RGCs in vivo using the in vivo confocal neuroimaging (ICON) method. Four different RGC types were found. Normal RGCs without FI change were found in sham rats and also in both ONC groups. RGCs with mild damage were seen only after mild ONC, showing an initial calcium depression of 26% at day 4 followed by a 169% increase 15 days after ONC. RGCs with moderate damage were found only after moderate ONC and showed calcium hypoactivation followed by a slower return toward baseline and a delayed calcium increase of 72% above baseline. Sixty to sixty-five per cent of the RGCs in both ONC groups and all RGCs in the axotomy group died within 6 days following a fast and massive calcium increase of 316% with a concomitant 156% soma size increase. In conclusion rapid calcium elevation leads to cell death, while an initial calcium depression followed by a delayed and moderate calcium hyperactivation is associated with cell survival. We propose that immediate, massive calcium activation is maladaptive whereas delayed and moderate hyperactivation of surviving cells is adaptive. Implications for pharmacotherapy are discussed.

Publishing in the field of brain plasticity, repair and rehabilitation: an emerging neuroscience niche journal

The journal Restorative Neurology and Neuroscience (RNN) is now published in its 25th volume since its inception in 1989. RNN focuses on the emerging field of brain plasticity, repair and rehabilitation, including original and review papers both in basic research (animal experiments, in vitro studies) and in the clinical domain, including brain imaging studies. During the last decade RNN has experienced a steady progress in its reference value and scientific impact. The ISI-impact factor has risen from 1.117 (1997) to 2.862 (2006). This places the journal at the 81st rank among all 200 neuroscience journals, i.e. 60% of all neuroscience journals have a lower impact factor. When compared to other journals in the field of rehabilitation, RNN ranks number 1. Causes for this positive development are, among others: (1) the field of neuroplasticity, regeneration, recovery and rehabilitation is an emerging field in medicine and therefore the number of publications and their citation rate overall increases, (2) the special issues strategy, (3) a top level editorial board, and (4) the quality of papers submitted to RNN continuously improves as RNN is gaining increasing acceptance in the scientific community. Thus, in the space of neuroscience in general, and rehabilitation in particular, RNN has become a visible, high impact journal and a leading source of original scientific information pertaining to brain plasticity , rehabilitation and repair. RNN is likely to gain more momentum as the field matures further.