Studies of the brain include a wide spectrum of subjects, from single cells, to tissues, to cellular networks. Accordingly, neuroscience research involves many layers of complexity, both in terms of experimentation and instrumentation. Neuroscience electrophysiology makes use of elaborate recording equipment and cellular preparations, often interfaced with cell and tissue imaging techniques. Model animals serve as experimental platforms to characterize and monitor system-level activity stemming from the action of cells and tissues.
These research applications typically require the controlled delivery of precise volumes of solution for analysis. Whether the focus is single cell electrophysiology, live cell imaging, or whole animal studies, the precision and performance of the perfusion system has a direct impact on the experimental outcome. In turn, many perfusion systems rely upon high performance syringe pumps to provide the volumes, flow rates, and versatile features to drive the best chances of success.
In vivo techniques such as microdialysis are very common methods for brain function monitoring. Precision syringe pumps and microdialysis probes can deliver small, accurate doses of chemicals or drugs to distinct regions of the brain, providing feedback, not only on the effects of chemical delivery, but on the metabolic function of select tissues or brain regions.
Ex vivo neuroscience studies, in contrast, focus on the intimate function of single cells or tissues outside the body, removing external variables and permitting detailed focus on cellular activities. Electrophysiological recording allows the measurement of electrical activity among excitable cells, such as the propagation of action potentials in neurons or the contractile activity of cardiac myocytes. Membrane electrical conductance, arising through the action of voltage-dependent ion channels and depolarization activity, can be measured using the appropriate electrophysiological techniques and equipment.
Electrophysiology rigs typically include a chamber that houses cells or tissues and built-in components such as perfusion ports, heating elements, electrode mounts, and other features. The configuration of the perfusion system depends on the nature of the cell type, the recording method, and the experimental format. Built-for-purpose perfusion valves are sometimes used to allow rapid switching between solutions and the administration of small volumes for compound delivery, concentration dependent dosing, and other functions.
Ex vivo electrophysiology is an enabling technology where the recording chambers, perfusion systems, and other elements can be custom built and configured to suit specific applications or experimental parameters. High performance syringe pumps can play a major role in this respect. Volume requirements can range from sub microliter to milliliter, dependent on the experimental step. Syringe switching is often necessary, typically when multiple solutions and volumes are used. Push-pull syringe operation is essential in many time-dependent delivery and washout experiments. The ability to program all of these functions into automated perfusion protocols, which may require complex multi-step methods, enhances both the accuracy and precision of investigations. Syringe pumps that can deliver these performance capabilities expand both the range of cell types that can be studied and the scope of investigations that can be explored.
Ex vivo cell imaging experiments involve a number of specialized elements matched with microscopy components and techniques. Live cell imaging chambers may include glass bottom Petri dishes, multi-well chambers mounted on microscope slides, heating stages with a variety of interchangeable perfusion adapters, and other features. Perfusion devices may include precision syringe pumps for custom applications to provide the accuracy, temperature control, precision, and reproducibility needed to support cell viability and high-resolution imaging.
The application of microfluidic technologies to neuroscience applications has gained significant appeal recently due to the capability to control the cellular microenvironment, both spatially and temporally. Although a great resource, live cells require specified cell culture conditions with regard to temperature and pH controlled incubation making them incompatible with typical electrophysiology and live cell microscopy experiments. As a result, the majority of live cell experiments in the past have relied on ‘snapshots’ of cells captured at various signalling and metabolic stages. These results have been challenged by the lack of reproducibility due to the number of variables between experiments. Moreover, studies of cell signalling, response to stimuli, and recovery to normal function have been limited temporally using traditional approaches.
In this regard, much work has been done to design the ideal cell culture environment that is both free from the burdens of cell incubators and compatible with high resolution electrophysiology and cell imaging platforms. High performance programmable syringe pumps are proving to be valuable tools with which to emulate the right cell conditions and to support advanced live cell experiments – and in essence to help drive innovation in the fields of neuroscience, cellular physiology, toxicology, and other areas.
Whole animal model systems allow ex vivo experiments to be extended to the organism level. Cells and tissues are no longer examined in isolation. Rather, the effects of compounds, drugs, and other variables are measured at the systems level in order to understand the broader implications. For animal injections, syringe pumps that are versatile both in performance and adaptability, such as the ability to mount to stereotaxic devices, offer distinct advantages.
Beyond typical microdialysis techniques which involve continuous perfusion, many whole animal studies require changes in flow rates, volumes, and solution types. For these applications, syringe pumps that offer a wide range of flow rates with microstepping functionality provide the versatility required for a range of infusion stages. Interchangeable syringe barrels and the use of multi-syringe racks extend the volumes and types of solutions which can be used in a given set of experiments. Programmable functions permit the reproducibility needed for multi-animal replicate experiments, in essence stratifying the statistical significance of data. All of these features serve to illuminate results while minimizing artifacts – important considerations in the complex background of whole animal studies.
Ex vivo electrophysiology and imaging experiments have made use of both built-for-purpose valve switching perfusion devices and high-performance syringe pumps. The accuracy, precision, and automatable features of high quality syringe pumps can add significant value to custom applications. Furthermore, advanced incubator-free cell culture methods making use of these syringe pumps can contribute insight into spatial and temporal aspects of cell processes. In the larger context, the use of precision syringe pumps in whole animal studies can add merit to the physiological basis of ex vivo results.
This article was written by LabX and published in conjunction with Chemyx.