Skin graft technology hailed as 'breakthrough'

The technology could offer new hope for burns and wound victims and could be one of the first cell-based therapies to be approved under a new European regulation.

According to UK firm Intercytex, they have developed the "first artificial living skin graft to demonstrate full, consistent wound integration and persistence".

The use of skin grafts taken from a different part of the patient's own body is currently regarded as the optimal way to close wounds and burns, however, their use is avoided wherever possible because skin grafting is a painful and traumatic process that creates an additional wound.

Various synthetic forms of skin have been developed, with variable success in long-term healing.

The product, ICX-SKN "contrasts with all other living skin graft alternatives which biodegrade in situ after a matter of weeks," the firm said.

ICX-SKN is made up of human dermal fibroblasts (a skin cell precursor) in a matrix of collagen, produced by the cells themselves.

To create the matrix, Intercytex takes a product made by Baxter called Tisseel, which is a combination of fibrinogen and thrombin (extracted from human blood) and mixes it with living human fibroblasts taken from neonatal skin - discarded foreskins in fact.

This liquid formulation is then poured into a dish, where the thrombin reacts with the fibrinogen to make fibrin, and after 15 minutes forms a gel.

This gel is then left to incubate for six weeks and the living fibroblasts that are trapped within the gel slowly break down the fibrin.

At the same time they systhesise the collagenous matrix.

"It is a physical structure, but it is changing slowly," Dr Paul Kemp, Intercytex' founder and chief scientific officer told BioPharma-Reporter.com.

At the end of the incubation period, the resulting matrix sheet (which is about 1mm thick) is removed from the dish, packaged and stored ready for use.

Intercytex' scientists said they believe that the combination of living human fibroblasts in a human fibroblast-produced matrix "underpins the integration and acceptance of ICX-SKN by the host skin."

In the Phase I trial, conducted in London by a third party organisation, a full-thickness skin sample (1.5cm x 1cm) was excised from the upper arm of six volunteers and replaced with ICX-SKN.

After 28 days both visual and histological analysis showed that in all volunteers the grafts were rapidly vascularised and overgrown with the hosts' own cells, resulting in a fully integrated skin graft that had closed and healed the wound site, the firm said.

Results of the trial were published yesterday in the July issue of Regenerative Medicine.

Phase II efficacy trials in larger wounds with a view to generating data that would enable progress to pivotal trials are now planned for the end of the year.

The results of these tests will obviously give a better indication as to whether this new therapy is actually better than other synthetic products on the market, because it is more difficult to heal real burns and wounds in patients than it is to heal small, surgically-created wound in healthy volunteers.

Kemp said he was unsure whether they will be carried out in Europe or the US - the company is looking to eventually commercialise the product in both markets.

The picture is hazy on the issue of its regulatory pathway though.

At the moment, the product is being treated in Europe as a regular medicine, although the European Medicines Agency (EMEA) is due to release a new guideline covering the regulation of cell- or gene-based therapies (advanced therapeutic medicinal products: ATMP) by the end of the year.

After this point, the product will follow the new regulatory pathway.

"We don't know yet exactly what this new regulation will involve, however, I think it will be pretty similar to the process for regular medicines with a few slight changes," said Kemp.

This is because cell- or gene-based therapies have specific nuances, such as they can't be terminally sterilised because they contain living cells, he said.

In the US, Kemp said he was unsure whether it would be classed as a biologic or a device because the firm has not yet asked the Food and Drug Administration (FDA) and there is no pathway that deals specifically with cell- or gene-based therapies.

The market for such products is fairly new, and although it has so far been limited by an inability to create tissues in the laboratory that are recognised as natural and can be fully integrated into the body, it is beginning to show promise.

A recent US Department of Health and Social Services (DHSS) report states that the worldwide market for regenerative medicine is conservatively estimated to be $500bn (€371bn) by 2010.