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Brand-New Bones
August 29, 2012   
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Wojciech ¦więszkowski, a researcher with a postdoctoral degree from the Faculty of Materials Engineering at the Warsaw University of Technology, talks to Karolina Olszewska. ¦więszkowski manages a project that aims to develop bioimplants for cancer patients missing bone tissue.

Your bioimplants are designed to promote the regeneration of bone tissue damaged by tumors. For this purpose, you use a patient’s stem cells. Could you describe the project in greater detail?

Statistics speak for themselves. Every year, there are around 1,500 patients in Poland who need surgery for the reconstruction of their facial skeleton parts, in particular the jawbone, lost in the course of cancer treatment. At present, such reconstructions involve grafts of bone fragments taken from various parts of the patient’s body, for example the calf bone. However, these procedures are not fully effective because they may lead to serious complications, not to mention the damage to the site from which the bone tissue is harvested. There is a need to develop new treatment methods.

Dr. Janusz Jaworowski from the Oncology Center in Warsaw and I are working to develop an innovative treatment method using tissue engineering. We want to help patients regenerate their own tissue by giving them stem cells harvested from their fatty tissue and a synthetic material as a scaffold for tissue growth. The stem cells have the ability to form a new tissue in the environment created by the implant.

Can this method be used for reconstructing bones in other parts of the body apart from the face and the skull?
It can, though initially the method is dedicated to cancer patients with lesions in this area of the body. The engineering technologies we are developing provide the ability to reconstruct bone tissue not only in the facial region but also in the region of long bones, where substitutes are needed for damaged bone sections longer than several centimeters.

What is especially innovative about our method is that it makes it possible to create a tree-dimensional copy of the lost bone fragment. We are developing a PC control system that will enable the production of scaffolds tailored to the needs of specific patients.

Does this mean that the computer will do all that automatically?
The computer is not able to do anything without man. The physician has to work closely with the engineer to work out optimum solutions for specific patients. The engineer will be supporting the process of implantation. The use of computer navigation will make it possible to accurately position the implant in the place where the bone fragment is missing.

Will it be a typical implant—one that stays in the patient’s body for many years or even for the rest of their lives?

No, we use the term bioimplant because it combines biological material—human stem cells—with synthetic material. Our bioimplant will last only as long as it takes for the tissue to regenerate, that is for several months. Then the implant should “disappear” from the place where it has been inserted. We use advanced materials to ensure this. They have to be prone to hydrolysis, which means they have to degrade in the human body within a controlled time frame. Compared with methods already used internationally, it is one of the newest ones. But of course it is not the only method. This problem is so interesting and so potentially beneficial for patients that many research centers in the world are working to design scaffolds supporting the regeneration of bone tissue. Most of these materials are non-resorbable—they do not degrade in the patient’s body. It is true that they are slightly stronger than the materials we have proposed. But our materials, thanks to their composite structure, have strength comparable to that of porous metallic or ceramic materials.

What will happen if the patient’s body rejects the bioimplant?

We assume that our bioimplant will not be rejected because it is built of the most modern materials and the patient’s own cells. Additionally, to prevent this kind of problems, we have decided to work only with materials already approved for use in humans because these are not rejected. What is more, the materials are bioactive—they interact with tissues and cells. Some widely used absorbable surgical sutures, which do not need to be removed, are made of similar materials. Our idea is similar. The difference is that the process of making a three-dimensional structure with a predetermined porosity and appropriate mechanical properties is much more complex. Such a structure has to enable cell adhesion—our implant has to be “cell-friendly” enough for the cells to be able to adhere to the material. Then, they have to be able to contact each other on the material and at the same time retain the ability to divide and differentiate properly. We should remember that the cells we deliver to the site where bone is missing are stem cells, which can differentiate into diverse cell types. And our goal is for them to form bone tissue rather than cancerous tissue. This is why we need to select the right material to be able to fully control this process.

What are you going to do to ensure that the regenerated tissue is able to proliferate and strengthen?

An important element we deliver with our bioimplant are growth factors, usually proteins. They are produced by the human body and support tissue growth. However, they are only present in insufficient quantities in the area where the bone is missing. We have to deliver them together with the implant to support tissue regeneration. This is especially important in cancer patients because healing processes in such individuals are slower as a result of chemotherapy and radiotherapy.

At what stage in the treatment process will the bioimplant be used?

We would like it to be implanted immediately after the removal of the tumor so as to avoid additional reconstructive surgery. We are preparing for this. The goal is to immediately help every patient after cancer surgery, even those who have not been fully cured and have to undergo further treatments. The problem is that cancer treatment—radiotherapy and chemotherapy—will adversely affect the cells delivered with the implant. This is why, at least at this initial stage of research, we are trying to select patients for whom the cancer treatment process has already been completed.

Is this kind of therapy suitable for every patient, for example children whose bones grow fast or elderly people who often suffer from osteoporosis?

We hope that our technology will be helpful for many patients. An implant for a child has to be designed in a different way than an implant for a person with osteoporosis. The child’s body has higher regeneration capabilities. In the case of young patients, it will not be necessary perhaps to deliver growth factors, or only small quantities of them will have to be delivered. In contrast, the formation of new tissue in elderly patients will certainly be much slower and they will need a modified treatment. This explains the need for constant cooperation between the physician and engineer—it will be necessary to design patient-specific implant architectures and adjust the amount of cells and growth factors needed by individual patients.

As regards children, the ability of the bioimplant to “disappear” is a vital thing. Children grow. If we use a non-resorbable implant it would quickly lose its usefulness. In the case of children, a biodegradable scaffold is the only sensible choice because it is important to enable the growth and remodeling of the bone tissue.

The project is interdisciplinary. Who are the individual partners making up the research consortium?

There are several partners in the research consortium—two universities of technology and two medical institutes. A team of around 20 researchers from the Warsaw University of Technology is tasked with building the scaffolds. Researchers from the Wrocław University of Technology are responsible for programming the navigation system for bioimplant insertion and for making titanium scaffolds. The former project is led by Prof. Romuald Będziński, the latter by Prof. Edward Chlebus.

Apart from resorbable scaffolds, we are also developing titanium scaffolds because, in some patients, damage to bone tissue is so substantial that even the areas adjoining the site where the bone is missing are weakened. As a result, it is impossible to anchor the implant. Meanwhile, the implant has to bear loads properly throughout the period of tissue regeneration—patients have to be able to eat while the bone tissue is healing. To ensure this, we need titanium reinforcements—temporary implants for fixing the biodegradable implant in place.

A team led by Prof. Małgorzata Lewandowska-Szumieł of the Warsaw Medical University is responsible for selecting and seeding cells to form bone tissue. They seed the cells in the sponge-resembling porous structure that we make and are now preparing to check the effectiveness of the seeding method on mice.

The Oncology Center in Warsaw is responsible for the medical side of the project, while our task is to help doctors develop this treatment method. The team led by doctor Janusz Jaworowski is tasked with selecting suitable patients and making computer images of missing facial bone fragments so that we can then develop standard implants and test them. Designing and testing the course of the implant surgery is very important for patients. Our computer system and surgical navigation are already used to perform surgery.

Another team from the Oncology Center, led by Prof. Zygmunt Pojda, is working on a method to isolate stem cells from fatty tissue and seed bioimplants with them. This is also a big change compared with the methods currently in use. We do not want to cause additional pain to the patient by harvesting the stem cells using the conventional method—from the wing of the ilium. Instead, we want to harvest them from abdominal fatty tissue. Then, the millions of cells obtained in this way will be used to seed our implants.

When will the results of your work benefit patients?

No plans for the first surgery have been made yet. At present, we are analyzing data from a group of patients. At the same time, we are trying to create a database with data on the geometry and size of lost bone fragments and bioimplant fixing methods. To an extent, this helps us prepare for the first implantation. The project is due to be completed when the treatment method is ready for initial clinical trials. We hope that after 2013 our technology will be so developed that obtaining permission for clinical trials will be just a formality. Of course, we do not rule out performing such surgical procedures earlier in an exceptional situation if we get permission from the Ethics Committee. We are aware that there are many patients waiting for such treatment.

Who will be producing the materials needed for implantation and providing specialist services after the project ends?

We are research centers. Our role is to develop technologies, or even prototypes that may be used at the stage of initial trials. But for the method to be used on a larger scale the results of the project have to be put to commercial use. Several companies interested in our research results, including Polish firms, have already approached us.

Will every patient with bone cancer be able to afford treatment using the bioimplant method?

The costs of cell treatments are reimbursed in some countries, but, as far as I know, Poland is not among these countries for the time being. Among the treatments developed in the world are cell transplants for patients with leukemia, and this method works. But in our case it is a whole fragment of bone tissue that has to be reconstructed. At present, cell transplants that enable the regeneration of cartilage are already performed in Poland, but there is no reimbursement. Such a procedure, involving small areas of damaged cartilage, costs around zl.20,000. I am afraid that in the case of our method the unit cost will be much higher because the bone loss involved is significant. However, if we look at the whole treatment process, its cost may actually be reduced because there will be no need to perform additional costly surgery. This is why a special therapeutic program should be developed.

The project has received substantial funding from the European Union’s Innovative Economy Operational Program...

Yes, indeed. The National Center for Research and Development (NCBiR), which disburses grants under this program, has awarded us over zl.27 million, or 85 percent of the total cost of the Bioimplant project. I have to stress that our treatment method, based on tissue engineering, requires more than four years of work. We are going to continue with this research.
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