Skin equivalent culture helps progress animal-free testing
The use of animals for toxicological studies of pharmaceuticals and cosmetics has been a contentious point of debate for decades. As a result, the development of in vitro alternatives has been an ongoing objective for many researchers. The creation of a tissue scaffold that behaves in the same way as human skin is far from simple, due to the requirement of yielding reliable and reproducible results. In addition, the ability to scale up operations, achieve a high-throughput and quick turnaround, whilst maintaining integrity is also a factor to consider.
How Cole-Parmer products were utilised
Sriram et al. (2018) recognised weaknesses in traditional culture systems and developed a microfluidic organ-on-chip, combining a fibrin-based dermal matrix and thermoplastic-based chip, upon which a skin equivalent was constructed. The authors set-up a dermal equivalent culture and generated full-thickness skin equivalents. Each organ-on-chip unit was fed culture media or receiver solution via a low-speed, 12-channel, digital Ismatec® IPC-N peristaltic pump using 2-stop PharMed® tubing. The pre-filtered culture media was held in a reservoir prior to delivery to the organ-on-chip where it was utilised in culturing. Once this phase was concluded the upper compartment of the unit was filled with air via 2-stop Tygon® tubing whilst the lower compartment continued to receive perfusate.
The Ismatec® IPC-N is ideal for this use as it offers the ability to pump accurately at flow rates as low as 0.4 µL/min while offering very low pulsation. At the heart of the IPC-N pump are eight stainless steel rollers driven individually by a planetary drive system. Each roller is directly driven by the sun wheel, preventing axial push-pull friction on the tubing, resulting in increased service-life of the tubing, lower pulsation, and high flow rate / dispense volume repeatability. These features make this pump an ideal component of toxicological in-vitro studies and perfusion protocols such as those undertaken by Sriram et al (2018). Additionally, the tubing used in this research is also well-suited to the application, with PharMed® traditionally being used for tissue and cell work due to its nontoxic and nonhemolytic properties, whilst Tygon® is ideal when low gas permeability is a requirement.
Summary of research findings
Through their investigations, Sriram et al. determined that a dermal matrix combined with the organ-on-chip system performs well as a skin equivalent, due to its ability to reproduce the function of human skin. The fluidically controlled development of the ‘skin’ was shown to allow morphogenesis and differentiation of dermal cells, whilst the use of the organ-on-chip system is ideal for directly testing integrity and permeability. What’s more, the use of this novel culturing system is scalable, with the potential for high throughput through the automation of culturing and testing. All in all, these findings lead to progress towards animal free testing.
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Author: Dr J J Lock, EMEA Cole-Parmer