New generation of biological scaffolds

Professor Fisher and his colleague Professor Eileen Ingham have been working on ways of producing biological scaffolds, derived from natural human or animal tissues such as vascular patches, meniscus (knee cartilage), and tendons that will not be rejected by a patient's immune system and can be repaired and renewed like normal tissue.

The technique developed by the Leeds group removes the cells from natural tissues to leave a biological scaffold which can be regenerated by the patient's own cells. Scaffolds derived from human donor tissue are being developed by the NHS Blood & Transplant Tissue Services, while scaffolds developed from animal tissues are being developed and commercialised by Tissue Regenix Group PLC.

Professor Fisher said: "If you take a natural tissue and strip off all of the donor's cells you're left with a biological scaffold made mostly of a protein called collagen, which is compatible with the patient receiving the scaffold. That scaffold is good from an engineering perspective because it's strong, flexible and retains the properties of the natural tissue. It also has the appropriate shape and size, and from a biological perspective is good because a patient's cells can bind to it and repopulate it easily."

Because a patient's own cells can populate the new biological scaffolds, they are accepted by the immune system and can be repaired like normal tissue.. There is a significant advantage from this technique because of the longevity of the transplant compared to other previously developed techniques. Chemically treated and strengthened prosthetic heart valves from pigs, for example, have been in used in human transplants for more than a decade, but the chemical process which stops them from being rejected by the patient's immune system also leaves them lifeless and inert. Because they cannot be repaired like living tissues, these prosthetic valves are degraded over time and need to be replaced frequently.

Professor Fisher continued: "These new biological scaffolds will provide off-the- shelf tissues for surgeons for repairing blood vessels after surgery for blocked arteries, for repairing meniscus after sporting injuries and cartilage tears, for repairing torn ligaments or tendons and for heart valve repair or replacement.

This research is being developed in conjunction with the NHS Blood & Transplant Tissue Services and with Tissue Regenix Group PLC, a company set up by researchers to bring new biological scaffolds to market. Funding for the research in this area also came via the Engineering and Physical Sciences Research Council (EPSRC), the Biotechnology and Biological Sciences Research Council (BBSRC), the Children's Heart Surgery Fund, the Department of Health and the Wellcome Trust.