A breakthrough could speed recovery and limit disfigurement for patients who have suffered large soft tissue trauma – as occurs with serious injury or cancer surgery. By biomedically engineering a muscle flap that includes a patient's own blood vessels, the team created tissue that could be transferred to other parts of the body along with the patient's blood supply. Current techniques – including grafts and synthetic material – for reconstructing such trauma often fail because of lost blood supply.
Led by Professor Shulamit Levenberg, of the Department of Biomedical at the Technion-Israel Institute of Technology, the scientists fabricated the flap using a variety of added cells and connective tissues to strengthen it. They tested it by reconstructing deep abdominal wall tissue defects in mice.
Research results appear this week in the Online Early Edition of the Proceedings of the National Academy of Sciences (www.pnas.org).
Successful reconstruction of large, soft tissue defects has been a clinical challenge in the past. To improve outcomes, the researchers developed the muscle flap using a patient's own tissues, added important and advantageous cellular components to strengthen it, and engineered it in such a way as to vascularize to include the patient's own blood vessels so that the patient retained their own blood supply during the reconstruction process.
"We designed and evaluated an engineered muscle flap with robust vascularization," says Levenberg, whose research focuses on vascularization of engineered tissues. "Proper vascularization is essential for successfully integrating the flap within the host."
The study provides evidence that tissue-specific cells, such as myoblasts (cells that form muscles), endothelial cells (the thin layer of cells that lines the interior surface of blood vessels), and fibroblasts (the cells providing the structural framework for animal tissues), are necessary to more effectively integrate within the host tissue.
Within one week of being transferred into the test mice, the engineered muscle flaps were "viable, highly vascularized," and demonstrated "firm attachment to the surrounding tissues." The researchers also noted that the muscle flaps had the mechanical strength to support the "abdominal viscera," or organs in the abdominal region.
The researchers say the results will stimulate more research and lead to clinical studies with human patients. They also suggest there are far-reaching uses of the muscle flap as it can be transferred as a 'free flap' to reconstruct defects in other parts of the body. This could circumvent the need to harvest and transfer large amounts of tissue, avoiding many of the current complications.
The study was performed in collaboration with Dr. Yulia Shandalov (who was a doctoral student under Levenberg), and Dr. Dana Egozi, from the Rambam Health Care Campus. It is part of a research project funded by the European Research Council (ERC).