David Mooney, a bioengineer at the Harvard School of Engineering and Applied Sciences, studies how mammalian cells respond to signals from their environment. The professor of cell and tissue engineering uses this knowledge to develop new types of biomaterials. As an Einstein Visiting Fellow at the Berlin-Brandenburg School for Regenerative Therapies, he has made important contributions to biotechnology, immunology and the treatment of musculoskeletal disorders.
»Can biomaterials replace medical implants?«
Historically, we have tended to intervene in the human body in a very gross way. We typically treat the whole body, even though the problem may only exist in one particular tissue. With bioengineering, we are able to target flawed tissue or organs much more precisely. Right now we are developing procedures that use biomaterials, basically plastics, to transport stem cells to where they are needed to repair defective tissue. In the area of bone regeneration, we are exploring the capacity of biomaterials to “recruit” existing stem cells or, in other words, adhere to the cells and draw them to the regeneration site. We can decide when, where, and for how long we want these interventions to happen. Bioengineering will ultimately give us far better control in terms of time and space.
Our material is designed to be biodegradable; it should only be in the body as long as necessary for regeneration. Because the material orchestrates the behaviour of cells in this process, it has to communicate. This can be achieved chemically with biomaterials that release drugs or molecules which adhere to cells and change their function. Or we can change physical properties – such as stiffness – that affect cell responses in the body.
I absolutely believe that medicine will move away from treating symptoms and using materials as crude replacements. Instead, our approach will be to regenerate tissue in the body. It is going to be a tremendous revolution, but it will take some time.
When I first got involved in this area of research, I was very excited about the possibility of using cells to regenerate and grow tissue and organs. Then, in one of my first animal studies, I discovered that the vast majority of the cells that I had transplanted were dying. This experience eventually led to the idea that instead of pursuing transplants, we might be better off “training” cells that were already in the body. Although it was a disappointment, it actually led me down a very important path. Another disappointment came during our initial trials for therapeutic cancer vaccines when we discovered that we were actually making the tumours grow faster. What we learned, however, was that we could have an impact. In other words, if we can make something worse, we can probably also make it better. The worst outcome is zero change.
Over time I have realized that having some effect, any effect, is good. It means we can start to take control.