Research & Development
The concept of EP Medical is to combine flexible microdialysis system with our unique and longstanding knowledge of different applications of the system ex vivo.
This combination has proved to be attractive to the pharmaceutical industry and universities worldwide. By using our special expertise in well-defined areas we have been able to help conduct specific projects from protocol to report. In addition to our product line we have several protocols that can be used for studying effects of intradermal injections and atraumatic intra probe drug delivery on a range of small and large molecular biomarkers.
Microdialysis was introduced as a method for monitoring the concentrations of neurotransmitter in experimental animals (1). Microdialysis has since become an established method for sampling extracellular biomarkers in various tissues and species, including adipose tissue, skin, muscles, and other organs (2).
Linear microdialysis probes from EP Medical with small or large pore characteristics (low, high & ultra flux probes) can be used to detect small and large molecules respectively.
The sampling method using low flux probes have been extensively used to recover low molecular mediators like histamine, neuropeptides and prostaglandins (3; 4). More recently large molecules like the protease tryptase, cytokines, and growth factors have been sampled using high flux probes (5, 6). The intention has been to monitor the extracellular space for bioactive proteins and regulatory peptides as biomarkers of tissue homeostasis, inflammation, pathophysiology, pharmacological intervention and toxicological studies (7, 8).
Our low, high, and ultra high flux probes are presently used scientifically and commercially for ex vivo studies and exist in the following cut offs: 2 kDa, 20 kDa, 45 kDa, 300 kDa, 1000 kDa, & 3000 kDa.
A detailed description of the probes including a schematic drawing is given below
The prototype probes have been through comprehensive technical development and validation with respect to choice of materials. As shown in Fig.1 the microdialysis probe consists of several elements which are all of medical grade material. Further, the materials are resistant to ɣ-radiation. The probes consist of the following materials:
- Tubing: The tubing is the connection between the hollow microdialysis fiber and a syringe pump delivering perfusion fluid to the fiber. At the one end the inner lumen of the tubing is fixed (glued) to the microdialysis fiber. The other end is mounted to the syringe pump delivering a constant flow of perfusion fluid through the tubing to the microdialysis fiber.
Besides being of medical grade the tubing has:
- An inner diameter of 500 µm allowing the microdialysis fiber to be inserted and glued into polyethylene tubing and
- An outer diameter of 650 µm allowing insertion of the tubing into a medical syringe connector adapted to the syringe.
- Glue. We have identified medical grade glue that polymerize when exposed to UV-light and fulfills our criteria of fixing the fiber to the tubing.
- Microdialysis fiber. Several types of microdialysis fibers have been identified. These fibers are obtained from hemodialysis and plasmapheresis devices. The fibers have an outer diameter between 215 – 380 µm depending of the type of probe and an inner diameter between 175 – 330 µm depending on the type of probe.
- Guide wire. A guide wire is inserted into the microdialysis fiber to maintain the stiffness of the microdialysis fiber making it easy to handle and insert the probe into the skin. The guide wire is a dedicated stainless steel wire of medical grade with a diameter of 100 µm.
- Tube marker. For identification of our 6 different products, each product is marked with a coloured marker.