The collagen cell carrier

Silke Busch looks at how collagen products produced for the food market have transferred to cell biology and biomedical applications.

For 80 years collagen type I products have been produced for the food market in a standardised and large-scale industrial production process.

Then the idea arose to translate this huge knowledge into the development of a special collagen membrane for use in research and development in cell biology and/or regenerative medicine, respectively tissue engineering.

Collagen is the most common protein in mammalians and is an essential structural element of the extra-cellular matrix. That makes collagen per se in vitro and in vivo an ideal substrate for cell and tissue culture.

Complex cell structures

Thanks to its special characteristics, the collagen cell carrier (CCC) is an excellent support material for the establishment of complex cell and tissue structures (including organotypic cell culture models, like, for example, differentiated and stratified epithelial structures).

During the production process the collagen from bovine skin middle splits will be processed and ends up in a combination of an extraction and cleaning of the insoluble collagen fraction.

So the collagen type I products like the CCC are neither acidic solubilised nor enzymatic digested but rather contain fibrous collagen type I. Thus the collagen mass consists of highly concentrated collagen type I.

After intense R & D work on the collagen membrane itself (eg, membrane thickness, degree of cross-linking) and testing variations to optimise the composition of the collagen mass, first proof-of-principal studies with collagen films for cell cultivation were performed.

In these studies a lot of different adherent primary cell types were included, mesenchymal stem cells (MSC) too. Additionally, MSC can also be differentiated in all four lineages (chondrogenic, osteogenic, adipogenic and neurogenic) directly on the CCC.

This in vitro result together with all the analytical data shows that the knowledge transfer from production of collagen products for the food market to life science and biomedical applications is possible.

The detection line

A lot of new analyses, according to ASTM 2212-02 for CCC, were performed which shows that levels of contaminating DNA or RNA, foreign proteins, heavy metals or even endotoxins are all at or under the detection line, the collagen type I purity is 99 per cent in Mascot Score.

We have developed a new collagen type I membrane with very special characteristics:

* Ultrathin structure with preserved long collagen fibres;

* No chemical cross-linking;

* Non-porous but semi-permeable membrane allows the exchange of soluble factors through the membrane (air-lift organotypic cell cultures possible);

* Cells can grow on both sides of the membrane, which makes co-culture systems possible;

* High cell densities can be achieved without induction of apoptosis;

* Cells can grow multi-layered on top of the CCC;

* Cell seeded CCC can be embedded for histology; both in cryosections and also in paraffin;

* Fixation of cells followed by immunohistological or fluorescence staining can be performed directly on the CCC;

* High mechanical stability (eg, tensile strength);

* Very good elasticity and flexibility;

* High chemical resistance;

* Nearly no auto-fluorescence;

* Excellent biocompatibility in vitro and in vivo, with nearly no induction of inflammation;

* Biodegradable;

* Excellent handling during surgeries, the membrane can be sutured without tearing of joints;

* High thermo stability especially at low temperatures (e.g. can be frozen in liquid nitrogen);

* Long shelf-life if stored at room temperature in the dark (at least five years);

* Can be sterilised by γ-irradiation.

Therefore the CCC is predestined for use in cell biology, regenerative medicine and tissue engineering, either as membrane alone or as cell seeded patch.

Investments into orientating in vitro and in vivo trials using CCC for selected medical indications clearly demonstrated the applicability in the field of regenerative medicine.

The CCC was tested for different biomedical applications, eg, Hirschsprungs's disease, wound healing, myocardial repair, etc, in small and large animal model and also long-term models.

Process chain

We have established the whole process chain: starting from purchasing of raw material, followed by processing of the collagen and ending with producing the membranes. This enables us to develop tailor made collagen products for special applications or even to fulfil customer needs.

Additionally our team combines engineers and scientist (chemists, chemical engineers and cell biologist). In parallel we build up a network with co-operation partners that include clinicians which allows us to further develop collagen materials that fit perfectly for medical applications and the use in, eg, surgeries.

For more information at www.scientistlive.com/eurolab

Silke Busch is Manager Biomedicals & Cell Biology, Viscofan BioEngineering, a business unit of Naturin Viscofan GmbH, Weinheim, Germany. www.viscofan-bioengineering.com

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