Background Alzheimer’s disease (AD) is the most common form of age-related neurodegenerative diseases. Cerebral deposition of Aβ peptides, especially Aβ42, is considered the major neuropathological hallmark of AD and the putative cause of AD-related neurotoxicity. Aβ peptides are produced by sequential proteolytic processing of APP, with β-secretase (BACE) being the initiating enzyme. Therefore, BACE has been considered an attractive therapeutic target in AD research and several BACE inhibitors have been tested in clinical trials, but so far, all have had negative outcomes or even led to worsening of cognitive function. AD can be triggered by Aβ years before the first symptoms appear and one reason for the failures could be that the clinical trials were initiated too late in the disease process. Another possible explanation could be that BACE inhibition alters physiological APP processing in a manner that impairs synaptic function, causing cognitive deterioration. Methods The aim of this study was to investigate if partial BACE inhibition, mimicking the putative protective effect of the Icelandic mutation in the APP gene, could reduce Aβ generation without affecting synaptic transmission. To investigate this, we used an optical electrophysiology platform, in which effects of compounds on synaptic transmission in cultured neurons can be monitored. We employed this method on primary cortical rat neuronal cultures treated with three different BACE inhibitors (BACE inhibitor IV, LY2886721, and lanabecestat) and monitored Aβ secretion into the cell media. Results We found that all three BACE inhibitors tested decreased synaptic transmission at concentrations leading to significantly reduced Aβ secretion. However, low-dose BACE inhibition, resulting in less than a 50% decrease in Aβ secretion, did not affect synaptic transmission for any of the inhibitors tested. Conclusion Our results indicate that Aβ production can be reduced by up to 50%, a level of reduction of relevance to the protective effect of the Icelandic mutation, without causing synaptic dysfunction. We therefore suggest that future clinical trials aimed at prevention of Aβ build-up in the brain should aim for a moderate CNS exposure of BACE inhibitors to avoid side effects on synaptic function.

Diseases such as chronic pain with complex etiologies are unlikely to respond to single, target-specific therapeutics but rather require intervention at multiple points within a perturbed disease system. Such approaches are being enabled by the rise of computational methods to identify key points of intervention and by new screening techniques that focus on a relevant condition or phenotype, rather than a specific target. Here we apply an in silico network pharmacology approach to identify small-molecule compounds with the potential to selectively disrupt the structure of a chronic-pain specific disease network, which we validate using a novel phenotypic screen that recapitulates key aspects of neuronal and pain biology by measuring changes in neuronal excitability in native sensory neurons. The combination of network pharmacology with a phenotypic screen is a powerful approach; we show that hit rates increase from 26% to 42%. This represents a rational approach to the discovery of compounds with a poly-pharmacology based therapeutic value, which will be vital for the discovery of treatments for complex disease.

Manual patch clamp recordings offer direct insight into ion channel properties through the characterization of ion channel activity. Due to the high quality data it is considered the gold standard for ion channel research. Still, the limited throughput means that maximizing data from each cell, especially sensitive primary cells, is important.We have developed a patch clamp‐based assay for characterization fast‐acting ion channels, in this case exemplified by P2X, in primary dorsal root ganglion (DRG) neurons. This assay is based on the use of primary DRG neurons in culture as a cell model for chronic pain. These neurons retain their sensory functionality and remain responsive to thermal, mechanical and functional stimuli, and when supplemented with nerve growth factor (NGF) they can be used to mimic peripheral sensitization. The assay utilizes a microfluidic perfusion system, Dynaflow Resolve, to facilitate a stable recording situation and fast and programmable solution exchange. At the start of the experiment, compounds and buffer are loaded in the 16 wells of the Dynaflow Resolve chip. Micro‐channels connect each well to a recording chamber where the cells are added. To be able to provide fast solution exchange the DRG neuron is lifted using the patch pipette and positioned in front of the micro‐channel outlets. Then, the cell is scanned through the discrete flow zones formed outside the channels.A comparison between conventional bath perfusion and the automated Dynaflow Resolve system showed that both systems have similar capacity when it comes to obtaining successful high resistance seals. However, for collecting full 5‐8 point dose‐responses from single cells, the success rate for the Dynaflow Resolve superseded the conventional system. This enables a dramatically increased productivity when performing more complex pharmacological characterizations.

In cell‐based high throughput screening applications, the assumption is typically made that all molecules have equal and complete access to the target of interest. In the case of intracellular targets, this is most likely not the case, as the molecules in a diverse screening library will exhibit varying degrees of cell permeability, or even lack thereof. This is likely to result in in false negatives.Electroporation is the use of brief electric pulses to overcome the barrier of the cell membrane. By the application of external electric fields, transient and reversible breakdown of the membrane can be induced. This transient state can be used to load cells with a variety of different molecules. Initially developed for gene transfer, electroporation can be used for delivery of a variety of other molecules ranging from ions to drugs, dyes, tracers and antibodies. Electroporation has proven useful both in vitro, in vivo and in patients, where drug delivery to tumors has been performed.In this work, we have explored the use of a high throughput electroporation platform, Cellaxess Elektra, for unbiased delivery of small molecules into cells in a cell‐based assay. The molecules selected were fluorescent and were representative of those that can be found in a small molecule library. The cell permeability with and without electroporation was characterized by means of fluorescence microscopy, and in the selected collection of ~400 compounds, 20 exhibited low or no cell permeability which could be enhanced by means of electroporation. We believe that this could prove to be a valuable tool in identifying families of new leads previously undiscovered.