Hohenstein Researchers Make Progress On Biotolerance Of Textile Implants

BOENNIGHEIM, Germany — May 5, 2010 — The capacity of a textile implant to be tolerated by the
body – known as biotolerance – plays an important role in regenerative medicine. Nevertheless, the
body does not always tolerate textile implants. Even modern implants made of resorbable
biopolymers, such as polylactic acid, break down in the body after a certain period of time and
decompose into individual acidic components. They can then cause considerable problems around the
implantation site ranging from inflammations to rejection. That is why biotolerability is a
decisive factor in the rapid generation of blood vessels at the implantation site (known as
angiogenesis). New capillaries ensure that acidic decomposition products resulting from the
breakdown of bioresorbable textile implants can be quickly transported away from the area. At the
same time, the new blood supply guarantees that cells involved in building up tissue receive
sufficient nutrients and the implant is integrated into the tissue rather than being encapsulated
as a foreign body. 

The Institute for Hygiene and Biotechnology (IHB) at Hohenstein has long been doing research
on how formation of vascular tissue can be stimulated specifically on textile implants. Only
recently, a research team made up of doctors and human biologists led by Prof. Dr. Dirk Hoefer
showed that specially modified textile fibres are also suited for functioning as a matrix for adult
human stem cells on the basis of which new, healthy tissue can be developed. 

Now the scientists at Hohenstein have successfully carried out a ground-breaking experiment
with respect to the tolerability of implants using an animal-free substitute method known as the
chorioallantoic membrane assay. Textiles that had been colonised with stem cells were applied onto
a chicken egg membrane with a dense network of blood vessels. The dense network of blood vessels of
the CAM and its lack of immune competence create optimal conditions for investigation of a
functional circulatory system. The scientists aim was to have the implant itself release the growth
factors required to stimulate the formation of new blood vessels. The stem cells were to assume
this function. The researchers first coated the fibres of the textile implants with specific
adhesion molecules, then colonised them with adult human stem cells that are known to release
growth factors for new blood vessels. In order to follow precisely the fate of the stem cells,
before they were introduced to the implant, the “all-rounders” were geneticallymodified so that
they produced a red, fluorescent pigment that allowed the integration of the stem cells in the
surrounding tissue to be visually monitored.

In several test series conducted in this way, the researchers observed directed
vascularisation within the textile implant microscopically and macroscopically. New blood vessels
grew within the implant and formed a functional capillary network. If the textiles were colonised
with connective tissue cells that did not release growth factors, vascularisation did not occur.The
Institute for Hygiene and Biotechnology’s new results may be used in future approaches in
regenerative medicine. Implants colonised with a patient’s stem cells could serve as biologic
textile implants (e.g. hernia mesh implants) that can be integrated into the patient’s body more
quickly and without rejection in order to regenerate damaged tissues.  The system applied at
Hohenstein also makes it possible to gain insights into many other aspects of circulation in
textile implants and routinely optimise these implants for medical use. This is an important
milestone in the further development of textile regenerative medicine. The researchers at
Hohenstein intend to publish their results in a specialist scientific journal.

Posted on May 18, 2010

Press Release Courtesy of the Hohenstein Institute