Plastic Bags May Replace Petri Dishes

Sealed plastic bags can be modified at atmospheric pressure so that human cells can adhere to and reproduce on their walls.

Physicians are increasingly using live cells in their treatments as in blood transfusions and bone marrow transplants, as well as in stem cell therapies and following severe burns.

Scientists at the Fraunhofer Institute for Surface Engineering and Thin Films (Braunschweig, Germany) collaborating with other institutions cultivated the cells in sealed, sterile plastic bags, where the inner surface of the bags has to be modified so that they provide cells with good conditions for survival. The new bags facilitate the sterile handling of cell cultures.

When using the new technology with its sealed bag system, the cells migrate directly into the bag via an injection needle or connected tube systems without coming into contact with their surroundings. The sterile interior of the bags contains nutrient medium and germ-free air or a suitable gas, which been added beforehand. Even during the cultivation period, the containers do not have to be opened, and at the end, the cells can be removed again by injection needle.

If the bags are provided with a three-dimensional structure, cells could attach themselves to it and create artificial skin, nerves, cartilage, or bone, which could be used prosthetically in the patient. In collaboration with the University of Tübingen (Germany) local scientists plan to isolate certain stem cells from tissue samples and investigate on which of the new plastic surfaces they could develop into bone or cartilage.

Kristina Lachmann, PhD, a scientific assistant at the Fraunhofer Institute, explained, "We fill the bags with a specific gas mixture, and apply an electrical voltage. Inside them, for a brief period, plasma is created, i.e., a luminescent, ionized gas, which chemically alters the plastic surface." During this process, the bag remains sterile as plasmas also have a disinfecting action. The advantage of the process is that it operates at atmospheric pressure and is therefore cost-effective, fast, and flexible.

Related Links:
Fraunhofer Institute for Surface Engineering and Thin Films
University of Tübingen