Researchers at the University of Glasgow’s Colleges of Science and Engineering and Medical, Veterinary and Life Sciences in Scotland are working to harness the power of stem cells to improve orthopedic implant surgery. In coordination with surgeons at Glasgow’s Southern General Hospital, they are developing a new type of implant that may be considerably stronger and more long-lasting than currently available products.

Fig. 1 – Researchers at the University of Glasgow’s James Watt Nanofabric ation Centre.
Implants currently are made from materials such as polyethylene, stainless steel, titanium, or ceramic, and have a limited life - span due to loosening, requiring replacement after 15 or 20 years of use. In hip replacement surgery, the head of the femur is removed and replaced with an implant that is held in place by a rod fixed within the marrow along the length of the bone. Bone marrow is a rich source of mesenchymal stem cells, which have the potential to differentiate into other types of cells such as skin, muscle, or bone.

When traditional implants are fixed into bone marrow, the marrow’s stem cells do not receive messages from the body to differentiate into bone cells, which would create an effective bond between the implant and the bone. Instead, they differentiate into soft tissue which, combined with the natural loss of bone density that occurs as people age, can weaken the bond between the implant and the body.

The team of scientists say that they have found a reliable method to encourage bone cell growth around a new type of implant made of an implantable polymer known as PEEK-OPTIMA®, which is commonly used in spinal procedures.

Dr. Matthew Dalby, of the University’s Institute of Molecular, Cell, and Systems Biology, explained: “Last year, we developed a plastic surface that allowed a level of control over stem cell differentiation that was previously impossible. The surface, created at the University’s James Watt Nanofabrication Centre, is covered in tiny pits 120 nanometers across. When stem cells are placed onto the surface, they grow and spread across the pits in a way that ensures they differentiate into therapeutically useful cells.”

By covering the PEEK implant with this surface, the scientists say that they can ensure that the stem cells differentiate into bone cells. This will help the implant site repair itself more effectively and prolong the life of the implant as well as the well-being of the patient, who may not need to have implant replacement surgery.

“PEEK products can be made using an injection-molding technique. Although our nanopatterned surface is complex, the process of production is similar to that which makes Blu-Ray discs, which means that future mass-production of the implant is a very real possibility,” Dalby explained.