Shrinking speeds up tissue engineering

UCL (University College London) bioengineers have discovered an unexpected shortcut in tissue engineering.

The UCL team found that the usual method of growing tissue on a scaffold using cells can be vastly accelerated by simply removing the water present in the starting material.

The result is a tissue ready in minutes rather than days or weeks. It is hoped the process could eventually be incorporated into a tool kit for hospital theatres and reconstructive surgery.

Cell-seeded collagen gel typically takes weeks to develop into weak, early-stage tissues. In the UCL study, published today in Advanced Functional Materials online, the team sucked most of the water out of the structure in a procedure known as plastic compression rather than waiting for the cells to do their job.

The result - following huge-scale shrinkage by a factor of at least 100 - was a simple collagen-based tissue created in 35 minutes. The shrinkage - a new approach to microfabrication - also gave the tissue an average break strength of 0.6 MPa (megapascals) compared with tissues conventionally grown over 1 to 12 weeks of around 0.3 MPa. Given that collagen sheets are fragile - in the study they were around 30 micrometres thick - the team rolled them up like swiss rolls to produce 3D rods which were easier to handle and manipulate.

Tissue engineering typically involves placing cells on a polymer scaffold and allowing them to grow into the desired tissues, which can then be used for surgical implantation. The process can take days or weeks and is difficult to control, cells may also fail to develop into the target material and at best, produce a tissue of less than 1 MPa break strength compared with natural collagen which can be up to 100 MPa strong in a human tendon.

Collagen is a protein which acts as a structural support for skin, bone, tendon, ligament, cartilage, blood vessels and nerves and as such it makes up 25 per cent of the human body.

Professor Robert Brown, of the UCL Institute of Orthopaedics, says: "We stumbled across this discovery while trying to measure the compression properties of collagen gel. Our method offers a simple and controllable means of quickly engineering tissue structures. The next stage is to test whether this method could help repair injured tissues.

"The speed and control it offers means that our method could one day be used to produce implant tissue at the bedside or in the operating theatre. We have a proof of concept grant from UCL BioMedica to produce a semi-automatic device for implant production. Ultimately, the goal is to design a rapid, inexpensive, automatic process for creating strong tissues which could supply hospital surgical units with a tool kit of spare parts for reconstructive surgery."

Notes for Editors:

1. For more information or to set up an interview, please contact Judith H Moorel at the UCL Media Relations Office on +44 (0)20 7679 7678, Mobile +44 (0)7 733 307 596, Out of Hours: +44 (0)7917 271364 or e-mail Judith.moore@ucl.ac.uk

2. 'Ultrarapid engineering of biomimetic materials and tissues: fabrication of nano- and microstructures by plastic compression', by Robert Brown, Mike Wiseman, Cher-Bing Chuo, Umber Cheema and Showan Nazhat, is published in Advanced Functional Materials on 13/10/05 http://dx.doi.org/10.1002/adfm.200500042

3. The study was carried out by researchers from the UCL Institute of Orthopaedics and the UCL Eastman Dental Institute.

4. UCL BioMedica Plc is a wholly owned subsidiary of UCL that aims to generate income and create capital value for UCL through the commercial exploitation of the bioscience research base at UCL and its associated Institutes.