Monday, December 31, 2012

Live Cell Imaging

My friends at Essen Bioscience are taking live cell imaging to new heights. I previously posted their neurite outgrowth solutions (hippcampal neurons).
In this posting, I would like share highlights from the December 2012 issue of "Genetic and Biotechnology News": Essen BioScience’s IncuCyte ZOOM™(live cell imaging in your incubator) and CellPlayer™ reagents enable you to overcome the limitations of static cell based assays. The solutions enable the acquisition, analysis, and quantification of images from living cells that remain unperturbed by the detection method, allowing for repeated measures of cell biology over long periods of time, from days to weeks. This is true Live Content Imaging.

Example: Real-Time Cell Counting in Mixed Cultures.
Cell-based models composed of more than one cell type in the same culture are increasingly recognized as more biologically relevant than monocultures. For example, a recent cancer study illustrated that some stromal cell types confer resistance to tumor cells in coculture, proposing this as a possible mechanism
of tumor resistance in the clinic.
Integrated image processing algorithms provided an independent nuclear count of both cell types continuously in time. The combined attributes of this approach can be used to better elucidate the mechanism and timing of drug responses on cell proliferation in biologically relevant, mixed culture systems.

Capabilities extend to a wide range of other phenotypic assays, including cell death, angiogenesis, neurite dynamics, and cell migration and invasion.

These solutions are have the ability to save time and drive costs out of the drug discovery process. I will keep you posted.

Friday, December 28, 2012

Ischemic Conditioning Prevents Retinopathy

What is Ischemic Conditioning?
I must confess that I had little knowledge of Ischemic Conditioning and its therapeutic potential before accessing this publication by my friend +Laura A. Pasquini and her team at University of Buenos Aires (users of Neuromics' Neuronal-Glial Markers and Neurotrophins Antibodies.

In the conditioning or pre-conditioning process, blood supply to an organ or a tissue is impaired for a short time (usually less than five minutes) then restored so that blood flow is resumed, and the process repeated two or more times, the cells downstream of the tissue or organ are robustly protected from a final ischemic insult when the blood supply is cut off entirely and permanently.

Here the authors used pressure pulses to induce retinal ischemia. Their results suggest that early vision loss in diabetes could be abated by ischemic conditioning which preserved axonal function and structure: Diego C. Fernandez, Laura A. Pasquini, Damián Dorfman, Hernán J. Aldana Marcos, Ruth E. Rosenstein. Ischemic Conditioning Protects from Axoglial Alterations of the Optic Pathway Induced by Experimental Diabetes in Rats. Research Article | published 20 Dec 2012 | PLOS ONE.

They used our PDGFR-α and an O1 marker to compare conditioned, diabetic with unconditioned, diabetic and controls rats to determine protection on ONs of the eye.

Immature OL (O1+ cells) and OL precursor (PDGFR-α+ cells) were evaluated by immunostaining in transverse ON sections. In the diabetic ON from eyes that received a sham treatment, a significant increase in O1(+) and PDGFR-α (+) area was observed, with the presence of disorganized and hypertrophic cells. In the right panel, the area occupied by glial cells (measured as total optical density (OD)) is shown. Ischemic conditioning significantly prevented these alterations and a clear decrease in O1- and PDGFR-α-immunoreactivity, with cells aligned parallel to axon bundles were found. Data are mean ± SEM (n = 6 nerves/group).

Results suggest that early vision loss in diabetes could be abated by ischemic conditioning which preserved distal axonal function and structure before the neuronal soma loss. Moreover, the present results add new potentialities to the therapeutic effects of ischemic tolerance, which is axon protection. Thus, ischemic tolerance could have promise for application in other neurodegenerative axonal diseases. I will keep you updated on progress.

Sunday, December 16, 2012

P2X Receptor Markers-Pubs Update

2012 has been a record year for publications referencing use of our Purinergic Receptor Antibodies. These publications demonstrate use of these markers in a variety of assays and applications. Examples range from analysis of P2X2 expression in human bladder epithelial cells to showing P2X3 expressing nerve fiber boutons in rat horizontal spinal cord sections by immunofluorescence and much more.

Here's a summary of publications: F.C. Pradoa, D. Araldia, A.S. Vieiraa, M.C.G. Oliveira-Fusarob, C.H. Tambelia, C.A. Parada. Neuronal P2X3 receptor activation is essential to the hyperalgesia induced by prostaglandins and sympathomimetic amines released during inflammation. non-fat dry milk at room temperature, followed by incubation with P2X3 or PKCɛ rabbit polyclonal antibody (1:500; Neuromics) overnight at 4 °C, rinsed six times with TBST, and then incubated for 40 min in goat anti-rabbit IgG peroxidase conjugate...

Min Liu, PhD, MD, Yun-fei Xu, PhD, MD, Yuan Feng, PhD, MD, Fengqiang Yang, MD, Jun Luo, MD, Wei Zhai, PhD, MD, Jian-ping Che, MD, Guang-chun Wang, MD, Jun-hua Zheng, PhD. Epigallocatechin gallate attenuates interstitial cystitis in human bladder urothelium cells by modulating purinergic receptors. Journal of Surgical Research.
...P2X2 (Neuromics, Northfield, MN)...

Abeer W Saeed, Alfredo Ribeiro-da-Silva. Non-peptidergic primary afferents are presynaptic to neurokinin-1 receptor immunoreactive lamina I projection neurons in rat spinal cord. Molecular Pain 2012, 8:64 doi:10.1186/1744-8069-8-64Anna M.W. Taylora, Maria Osikowicza, Alfredo Ribeiro-da-Silva. Consequences of the ablation of nonpeptidergic afferents in an animal model of trigeminal neuropathic pain. PAIN. Volume 153, Issue 6, June 2012, Pages 1311–1319.
Confocal images at high power obtained from horizontal spinal cord sections. In a confocal optical section from lamina I adjacent to the white matter (A), note the relatively abundant P2X3-IR fibers with varicosities (boutons). CGRP-IR fibers and boutons were considerably more abundant in this lamina. In a confocal optical section from inner lamina II (B), note the very high density of P2X3-IR fibers and varicosities, higher than that of CGRP-IR fibers in lamina I. Note that most varicosities display either P2X3 or CGRP immunoreactivity, although some co-localization is observed (yellow). Scale bar (A, B) = 20 μm.
T. Cho, V. V. Chaban. Interaction Between P2X3 and Oestrogen Receptor (ER)α/ERβ in ATP-Mediated Calcium Signalling In Mice Sensory Neurones. Journal of Neuroendocrinology Volume 24, Issue 5, pages 789–797, May 2012...with polyclonal rabbit antibody against P2X3 receptor (dilution 1 : 1000; Neuromics)...

Anna M.W. Taylora, Maria Osikowicza, Alfredo Ribeiro-da-Silva. Consequences of the ablation of nonpeptidergic afferents in an animal model of trigeminal neuropathic pain. PAIN. Volume 153, Issue 6, June 2012, Pages 1311–1319. were then incubated for 48 hours at 4°C with a guinea pig polyclonal anti-P2X3 antibody (1:25,000; Neuromics, Edina, MN, USA), diluted in PBS-T. Following primary antibody incubation, sections were treated with a biotin-conjugated...

Ji Z-G , Ito S , Honjoh T , Ohta H , Ishizuka T , et al. 2012 Light-evoked Somatosensory Perception of Transgenic Rats That Express Channelrhodopsin-2 in Dorsal Root Ganglion Cells. PLoS ONE 7(3): e32699...guinea-pig anti-P2X3 (1:1,000, GP10108, Neuromics, Edina, MN, USA)...
Distribution of ChR2V in the dorsal part of the spinal cord. A–C. Immunohistochemical localization of ChR2V with the cell-type specific markers, NF200 (A), CGRP (B) or P2X3 (C). Scale bars indicate 40 µm. doi:10.1371/journal.pone.0032699.g003.

I will continue to post new publications and data in the coming year. Stay tuned. 

Monday, December 10, 2012

Pain Research and Gene Expression Analysis

There have been multiple publications referenced here on using Neuromics' i-Fect siRNA Delivery Kit to study the effect of silencing genes known to play a role in Pain Signaling. These include: DOR,The β3 subunit of the Na+,K+-ATPase, NTS1, NAV1.8, TRPV1 NOV, β-arrestin, TRPV1, CAV1.2 and ASIC.

I would like to highlight an exciting new study referencing how knocking down Kv9.1 Potassium Channel Subunit in vivo mediates neuropathic pain: Christoforos Tsantoulas, Lan Zhu, Yasin Shaifta, John Grist, Jeremy P. T. Ward, Ramin Raouf, Gregory J. Michael, and Stephen B. McMahon. Sensory Neuron Downregulation of the Kv9.1 Potassium Channel Subunit Mediates Neuropathic Pain following Nerve Injury. The Journal of Neuroscience, 28 November 2012, 32(48): 17502-17513; doi: 10.1523/​JNEUROSCI.3561-12.2012.

Highlights: Here, we report that the potassium channel subunit Kv9.1 is expressed in myelinated sensory neurons, but is absent from small unmyelinated neurons. Kv9.1 expression was strongly and rapidly downregulated following axotomy, with a time course that matches the development of spontaneous activity and pain hypersensitivity in animal models. Interestingly, siRNA-mediated knock-down of Kv9.1 in naive rats led to neuropathic pain behaviors. Diminished Kv9.1 function also augmented myelinated sensory neuron excitability, manifested as spontaneous firing, hyper-responsiveness to stimulation, and persistent after-discharge. Intracellular recordings from ex vivo dorsal root ganglion preparations revealed that Kv9.1 knock-down was linked to lowered firing thresholds and increased firing rates under physiologically relevant conditions of extracellular potassium accumulation during prolonged activity. Similar neurophysiological changes were detected in animals subjected to traumatic nerve injury and provide an explanation for neuropathic pain symptoms, including poorly understood conditions such as hyperpathia and paresthesias. In summary, our results demonstrate that Kv9.1 dysfunction leads to spontaneous and evoked neuronal hyperexcitability in myelinated fibers, coupled with development of neuropathic pain behaviors.

n vivo RNA interference: Anesthetized rats were subjected to a thoracic laminectomy and a silastic tube was inserted subdurally to lie just rostral to L3 DRG and externalized to deliver bolus injections (one injection per day for 4 consecutive days). Animals were allowed to recover for 5 d before treatment commenced. On the day of injection, siRNA was mixed with i-Fect (Neuromics) to a final concentration of 0.2 μg μl−1, according to published protocols (Luo et al., 2005). For each treatment, 10–20 μl of Kv9.1 siRNA or scrambled control mixture was injected, followed by a 10 μl saline flush. Twenty-four hours after the fourth injection animals were killed and L5 DRGs fresh dissected for qRT-PCR analysis. A separate set of animals were PFA perfused and DRGs retrieved for IHC. Passenger strand sequences for Kv9.1 and scrambled control siRNAs were cuuggaaucuguaggauca and gaggcctaatcgatatgtt, respectively (Dharmacon; “in vivo processing” option).
Intrathecal Kv9.1 siRNA treatment induces pain behaviors in naive rats. A, qRT-PCR quantification of Kv9.1 mRNA in rat PASMC cultures transfected with one of three Kv9.1 siRNA sequences or control siRNA (control, n = 6; siRNA, n = 3 per group; *p < 0.05 vs control, one-way ANOVA with Tukey's). B, qRT-PCR showing Kv9.1 in vivo knock-down in L5 DRG, 4 d after intrathecal delivery of siRNA #1 compared with vehicle or matched scrambled control (vehicle, n = 4; scrambled, n = 5; Kv9.1, n = 7; *p < 0.05, t test). C, IHC for Kv9.1 in scrambled- and siRNA-treated DRG to determine protein knockdown. Graphs illustrate quantification of number of positive myelinated neurons and mean Kv9.1 signal intensity (scrambled, n = 4; siRNA, n = 6; **p < 0.01, ***p < 0.001, t test). D, Kv9.1 siRNA infusion inflicts a reduction in mechanical pain withdrawal thresholds (Kv9.1, n = 7; control, n = 6; *p < 0.05, **p < 0.01, ***p < 0.001 vs scrambled control or baseline, two-way repeated measurements ANOVA with Tukey's). E, There was no change in heat pain thresholds after siRNA treatment. Vertical arrows on x-axis denote siRNA injections. All data represent mean ± SEM.
Kv9.1 knock-down triggers ectopic activity and a form of peripheral wind-up in response to stimulation. A, Schematic illustrating the positions of stimulating and recording electrodes. B, Example recordings from centrally disconnected L4/L5 strands demonstrating SA in Kv9.1 siRNA-treated or nerve-injured rats, but not in control (scrambled siRNA) animals. C, Frequency-dependent SEA (denoted by double arrowheads) in Kv9.1 siRNA-treated (middle) and injured (right), but not control (left) animals. This activity is not locked in time and can be seen in between stimulation events (vertical arrows on top of 5 Hz stimulation traces, only first 5 shown). Also note the prolonged after-discharge (AD) observed in siRNA-treated and injured animals. D, Percentage of units showing SA and SEA in control (n = 269), Kv9.1 siRNA-treated (n = 369) and injured (n = 176) animals (*p < 0.05, **p < 0.01, ***p < 0.001 vs control, χ2 test). E, Firing rate of SEA units at different stimulation frequencies (mean ± SEM; control, n = 4; siRNA, n = 22; injured, n = 17; *p < 0.05 vs control, two-way ANOVA with Tukey's). F, Quantification of AD rate per SEA unit (mean ± SEM; *p < 0.05 vs control, Mann–Whitney test).

Results propose that Kv9.1 downregulation after nerve injury may be the molecular switch controlling myelinated sensory neuron hyperexcitability. Intriguingly, a recent wide-genome association screen in humans identified a Kv9.1 polymorphism associated with susceptibility to develop chronic neuropathic pain after back surgery or leg amputation (Costigan et al., 2010), suggesting that the mechanisms described in our studies will be of direct clinical relevance to human pain. Future efforts to elucidate the precise pathways involved, combined with approaches aiming to compensate loss of Kv9.1 function, may create novel therapeutic opportunities for neuropathic pain management.