Unfortunately, cartilage cells do not always do what you expect them to do. Cells that you grow in a dish, as usual, often start to produce the wrong type of collagen, says de Venlose. “As a result, those implants are often unsuccessful, especially in older patients.” Instead, at Orthopedic Biomechanics, they have succeeded in producing three-dimensional pieces of tissue in stirrers containing chunks of support material. She then implanted these so-called organoids, with a diameter of approximately 0.25 millimeters, in the cartilage plugs.
The cartilage cells used by Kleuskens came from the removed knees of patients. So cartilage from an affected joint of mostly older people. The question was whether this is the right source material to grow vital cartilage tissue from. “I therefore compared the culture results with results with cartilage cells from younger, healthy people from UMC Utrecht. I have not found any difference with patient tissue, which therefore seems perfectly suitable to work with. Moreover, that is material that is sufficiently available and that otherwise nothing would be done.”
Massage
To create as realistic a situation as possible, she also devised a way to expose the plugs with fresh implants to serious forces. Together with the LifeTec Group BV company, which emerged from the faculty, the PhD student developed a kind of training device that subjects the plugs to a massage by means of a set of pistons with smoothly polished heads (see the main photo). “So we use this device to imitate a walking person.” For a month, because that’s how long it takes for cartilage cells to form a collagen matrix in a new environment.
According to Kleuskens, the training device – together with the developed breeding techniques – is a good method for testing all kinds of things in the lab before laboratory animals come into view. “This way of working can accelerate the development of implants and limit the number of laboratory animals.” And there is still plenty to explore in this complex field of research. She prefers to look for a job in the corporate world, but she hopes that successors will be found for her at Orthopedic Biomechanics. “I have made an extensive manual, so I think that a student should also be able to work with it.”