As with any structure, the scaffold holds the key in the successful building of tissue for tendon or cartilage repair.
According to Professor Zheng, the reason the scaffold is so important is that it is the matrix that determines the shape and function of an organ or tissue.
So in therapies using stem cells or progenitor cells to grow new tendon or cartilage that may be damaged in patients with tennis elbow or arthritis, for example, the ideal scaffold is the Holy Grail.
“You can not just whack these stem cells or progenitor cells in, you have to ensure they will do what you want them to do, which is maintain the function of the tissue or the organ,” he said.
One way of achieving this is to integrate the cells with a scaffold to stimulate regeneration. “Our aim is to manufacture a scaffold that can mimic the process of organogenesis,” Professor Zheng said.
And it happens that Professor Zheng serendipitously hit upon the latest scaffold for the regeneration of bone and the meniscus, or cartilage that provides protection to the knee joint.
He was walking along the beach three years ago at Margaret River after convening a biotherapeutics forum and, his mind still racing with medical images, he noticed a sea sponge that looked remarkably like trabecular or internal human bone.
“Normally I would see just a sea sponge that is smelly and put it to one side,” he says. “But suddenly what I saw was not a sea sponge but a piece of the human body. It was the result of the stimulation of the meeting.”
He then picked up another sponge, which reminded him of the structure of the meniscus.
Back in the laboratory, the sea sponge turned out to be an ideal scaffold because it is made of collagen, which is the substance of human bone.
“Now we are using the sea sponge scaffold because its structure very much mimics the tissue texture of the meniscus and bone tissue,” Professor Zheng said.
WA has the largest collection of sea sponges in the world. “And the good thing about sea sponges is we can farm them,”
Professor Zheng said. “We can control the production of sea sponges under a controlled environment so we can make it safe for use in humans.”
For a tendon scaffold, the team uses a collagen-based scaffold derived from pigs, chemically modified in the laboratory to reduce the cellular density, enhance the bio-compatibility and increase the mechanical strength of the tendon.
Visiting Raine fellow Dr Zhang Xiagling, from the Shanghai Jaiotong Medical School, worked with Professor Zheng for three months this year on the scaffold research.
The collaboration between the two medical schools will continue into the future.
-By Cathy Saunders