Laboratory in a Plastic Bag
Plasma Functionalizes Film Surface
Scientists worldwide are looking for ways to heal diseases using stem cells. These cells offer the potential to develop new types of therapies and drugs. Stem cell material also holds the key to researching diseases in a way that was not possible before. If researchers are to achieve meaningful and transferable results, there must be an increase in the cell material to be examined.
As part of the LabBag project, the Fraunhofer Institute for Biomedical Engineering IBMT, the Fraunhofer Institute for Surface Engineering and Thin Films IST, and the Fraunhofer Institute for Process Engineering and Packaging IVV have pooled their expertise to develop a miniature laboratory in the form of a plastic bag.
Inside this bag, human induced pluripotent stem cells – in other words, artificially produced stem cells which do not raise ethical questions – are able both to grow and to form 3D aggregates in a sterile environment. These cells can be used by the pharmaceutical industry as patient- or disease-specific test systems for drug development and research into active ingredients.
Induced pluripotent stem cells (iPS) are cells that have been artificially generated by reprogramming. They can be used in a laboratory to make almost any type of cell in the human body, which means they are pluripotent. As a result, these cells are highly relevant for the pharmaceutical industry, as companies can test patient-specific drug candidates directly on cells affected by a particular disease.
No More Manual Pipetting
Until now, stem cell aggregates have been generated by using pipette feeder robots (which are expensive to purchase and maintain) or by means of manual pipetting (which is labor- and time-intensive). Manual pipetting in petri dishes requires a lot of practice, and there is also the risk of contamination. The “laboratory in a bag” developed by Fraunhofer researchers aims to reduce the costs of labor and materials while also significantly increasing cell yield and process reliability. Simply by shaking the transparent bag, it takes just a few seconds to produce several hundred hanging droplets of nutrient solution, virtually automatically. The droplets function as mini-bioreactors in which cell aggregates are able to form.
First of all, the nutrient solution containing the stem cells is poured into the bag. The bag is rotated once and then returned to its initial position. During this process, the droplets remain suspended on round hydrophilic spots. The cells sink to the bottom of the droplets, where they bind together and fuse to form a defined 3D aggregate. “We have coated the polymer film of the bag with two different coatings,” explains Dr. Michael Thomas, project manager and scientist at Fraunhofer IST, whose team is responsible for the coating of the polymer film. “A hydrophobic, water-repellent base layer ensures that the nutrient solution containing proteins flows over the surface and doesn’t stick to it. However, the second layer consists of 150 hydrophilic round spots, each with a diameter of 5 millimeters. The solution gets ‘caught’ on these spots, thus creating the droplets.”
To functionalize the surface of the film in such a specific way, the Fraunhofer researchers make use of atmospheric pressure plasma processes. In this method, physical plasma is generated in a gas gap between two electrodes by applying alternating voltage. This plasma is then used to treat the surfaces of a wide variety of materials.
One of the outstanding feature of LabBag is that the resulting cell models can even be frozen in the bag. Unlike with manual pipetting, there is no longer any need to transfer material into a separate cryogenic vessel.
Table of content
- 1: Laboratory in a Plastic Bag
- 2: High-Quality 3D Cell Models Grow within 72 Hours