The breakthrough work achieved by
the partners in this project puts Europe well ahead of the USA in
the very competitive area of medical diagnostics. MEBIOCE is a medical
breakthrough that has already attracted great interest.
Diagnostic techniques for identifying pathogens or cancerous cells
need to be very sensitive if they are to identify low levels of contamination
or the very early stages of illness. This project has developed a
system to identify abnormal cells at concentrations down to a hundredth
of those that can be detected by conventional tests.
The three-stage process, which involves tiny magnetic beads, new separation
membranes and a computerised image recognition system, brings together
two SMEs and a series of university research centres. It should result
in a commercial product within the next year.
An illness spotted early usually means
quicker, more effective and less costly treatment. As a result,
it is not surprising that the subject of new diagnostic tests has
become one of the hottest topics in medical research. At the moment,
though, there is a trade-off between the sensitivity of a test and
the precision of its results. The ideal test would yield quantitative
information and yet would be extremely sensitive.
MEBIOCE offers just such a combination. Using powerful new techniques
to isolate and count mammalian cells and bacteria, it can measure
their concentrations at extraordinarily low levels - down to a hundredth
of those possible with current tests. Amongst other things this
will mean earlier diagnosis of cancer and less risk of bacterial
contamination in food. The project partners estimate that the potential
market for their technology could be worth about 21 billion ECU.
MEBIOCE has brought together two SMEs, each with complementary experience
in detecting specific types of cells at very low concentrations.
Several universities have also contributed to designing and testing
the new system, which will be on sale soon. The project's results
have already caused considerable interest.
The need to do better
MEBIOCE relies on the fact that many diseases and disease-causing
organisms can be identified by the cells they leave behind. The
bloodstream of someone suffering from a bacterial infection contains
cells of the organism itself, whilst in the case of a cancer patient
the tell-tale markers are damaged versions of the patient's own
cells. Either way, locating these abnormal cells is an important
first step towards identifying the illness.
Early in the course of an illness the number of abnormal cells can
be very small, so the detection system must be sensitive. An existing
technique, DNA analysis using the polymerase chain reaction, is
sensitive but time consuming, gives little information about the
number of abnormal cells present and doesn't preserve the cell when
visual confirmation is essential in medical diagnosis. Another technique,
flow cytometry, yields quantitative information but is not very
There is a similar compromise in the methods used to detect bacterial
contamination of food and water. Traditional cultures are quantitative
and allow the cells to be examined further using other techniques,
but they take several days to do. Newer indirect methods based on
the presence of the chemical ATP are much quicker, but are not quantitative
or specific, often lack sensitivity and damage the cells so that
they cannot be examined further. There is clearly room for improvement.
The project began in 1994 with two main partners. The French partner
BIOCOM, which coordinated the project, contributed its expertise
in cell separation and image recognition systems. The Norwegian
company Dynal is one of the specialists, using magnetic beads for
An attractive approach
The MEBIOCE system uses a three-stage approach, first capturing
cells with immuno-magnetic beads and collecting them in a flow separator,
then concentrating them using special membrane filters, and finally,
using computer-based image-recognition technology to pick out and
characterise those that are of interest.
Dynal is an SME founded in 1986 to develop magnetic bead technology,
otherwise known as immunomagnetic separation. The company makes
its magnetic beads from polymers mixed with tiny grains of iron
oxide. These are then covered with a smooth layer of polymer to
which proteins and other biological molecules can stick. A further
layer, this time of antibodies, increases the system's precision
by attracting only particular types of cell.
The beads stand the best chance of coming into contact with very
rare cells if they are very tiny and used in large quantities, thus
providing the maximum surface area to mix with the sample. The smaller
the beads, however, the more difficult they are to separate in the
next stage of the process, so a compromise is needed. The best size
of beads has proved to be just under three micrometres in diameter.
After mixing the beads with the sample of blood or other material
to be tested, the next task is to separate them so that they can
be analysed. In theory this is simple - just apply a powerful magnet
and the beads will move towards it - but previous methods have been
slow and labour-intensive. BIOCOM has developed the first automated
magnetic separation system (CELF), based on a long spiral tube through
which the sample flows continuously. When a nearby electromagnet
is switched on, the beads stick to the walls of the tube. When the
magnet is switched off the beads can be flushed out of the tube
and on to the next stage of the process.
The cells are then concentrated and the beads removed using advanced
filters developed at the Catholic University of Louvain. The filters
are made from microporous polymers. As well as separating they can
also serve as culture media for mammalian cells, helping to reduce
the need for animal experiments.
Improving the image
The final step is image analysis to identify and count the harmful
cells. BIOCOM, which employs about 20 people, has been working in
this area since 1986 and is an European leader, having installed
more than 400 image analysis systems. Each uses a microscope attached
to a video camera to view the sample. A computer then analyses the
shapes, colours and contrasts in the video image, decides which
represent cells of different kinds, and counts them.
The MEBIOCE system, however, is different. Instead of a microscope
it uses an approach borrowed from astronomy, where researchers use
long photographic exposures to reveal distant stars. BIOCOM's device
(ASTERIAS) uses a highly sensitive video camera and long exposures
to build up a picture of an entire sample at once. This, says the
company, is simpler and quicker than assembling several hundred
separate images obtained through the limited field of view of a
BIOCOM has developed two image analysers using this principle: one
for research laboratories and another targeted at rapid analyses
in hospitals and industry. Both have the ability to work at different
wavelengths, so samples can be examined with both visible light
and, for instance, ultra-violet fluorescence. The multiple-wavelength
approach is an important aid to characterising cells accurately.
Ahead of the USA
Another project partner, the University of Nantes, and four other
French universities - Marseilles, Nice, Compiègne and Lyons
- are now testing the system. Full evaluation for medical diagnostics
may take a further two or three years, but in the meantime the partners
plan to market a system for measuring microbiological contamination.
Promising markets are the analysis of food and drinking water, and
control of sterility in the pharmaceutical industry.
Once the system has proven itself in the medical field, detecting
micrometastases - potential nuclei for new cancers - and making
non-invasive genetic antenatal diagnosis are two of its most likely
applications. The magnetic beads could even potentially be used
to remove harmful cells as well as to detect them; blood given by
donors, for example, could be cleansed of undesirable cells before
being used for transfusions. The total demand for the new tests
is estimated to be 60 million tests a year.
The work has already generated a lot of interest, and the partners
believe that they are ahead of the USA in this highly competitive
field. Such an innovative project, they say, would not have been
possible without both the contacts and the money provided by BRITE-EURAM.