The cell culture bag before (top) and during (bottom) coating. Image: Fraunhofer |
Physicians
are increasingly using live cells in their treatments: in blood
transfusions and bone marrow transplants, as well as in stem cell
therapies and following severe burns. Cells taken from the patients
themselves are ideal for replacing burned skin, eliminating immune
deficiencies, repairing degenerated cartilage or to treat injured bones
as they are not rejected by the immune system. These cells have to be
kept, cultivated, reproduced or even modified in a patient-specific
manner.
The
problem, however, lies in the shelf life of the cell solutions used. As
they can easily become infected by germs, they can only be stored for a
few days in the containers conventionally used today.
The
joint project InnoSurf aims to remedy this problem: scientists from
five research institutions, along with partners in the industry have
developed innovative plastic surfaces and measuring methods for
efficiently producing human cells for diagnostic and therapeutic
applications. The work was coordinated by the Helmholz Centre for
Infection Research (HZI) in Braunschweig, Germany.
The
idea is to cultivate the cells in sealed, sterile plastic bags. The
inner surface of the bags has to be modified so that they provide cells
with good conditions for survival. A team led by Dr. Michael Thomas at
the Fraunhofer Institute for Surface Engineering and Thin Films IST in
Braunschweig, Germany, has now developed a plasma technology process for
use at atmospheric pressure.
“We
fill the bags with a specific gas mixture and apply an electrical
voltage” explains scientific assistant Dr. Kristina Lachmann. “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” emphasizes group
leader Dr. Michael Thomas who specializes in the use of such atmospheric
pressure plasmas to modify surfaces.
The
new bags facilitate the sterile handling of cell cultures. Previously,
researchers and clinicians had to use open Petri dishes, bottles or
bioreactors. As these systems need to be opened, at least for filling,
contamination can easily occur. By contrast, 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.
The
researchers also maybe intend to use the disposable systems for growing
artificial organs. 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. So far their cultivation has mainly failed because the stem
cells have been reluctant to attach themselves to spatial structures.
The plasma process developed at the IST could solve this problem.
In
collaboration with the University of Tübingen, Braunschweig City
Hospital plans to isolate certain stem cells from tissue samples and
investigate on which of the new plastic surfaces they could develop into
bone or cartilage, for example. For this development by the group led
by Dr. Michael Thomas, the IST was awarded “Selected Location 2011” as
part of the “Land of Ideas” initiative. The prize will be awarded at the
IST in Braunschweig on December 8, 2011.
