Global medical investigations have shown that cardio-vascular diseases cause 29% of all deaths that is 17 million people annually. Cardio-vascular diseases cause more deaths than car, crash, cancer, tuberculosis and AIDS combined. In Australia 40% of total deaths are from cardio-vascular diseases, and the annual budget for cardio-vascular treatment is about $8.8 billion. Internationally about 80% of lethal cardio-vascular diseases occur in developing countries with low income. In most cases
of cardio-vascular disease a life can be saved by an operation that replaces organs or parts.
One of the most common implants are heart implants or implants concerned with heart or vascular systems. An implantation of donor organs has many ethical problems and is limited by donor possibilities. Many patients die waiting for a donor organ to become
available. Therefore, artificial implants may be the preferable way to save lives.
Modern artificial implants work successfully in organisms for more then 20 years. The success of the medical implant industry and surgery practice is proved by a high number of operations. Research has shown that 73% of people who received artificial heart implants
survived after 9 years and 65% survived after 18 years, while only 48% of people who received the therapeutic treatment survived after 5 years. In the case of artificial aorta
implants 85% of people survive after 5 years, while only 10% of people who received the therapeutic treatment survived after 5 years. Further development of the biomaterial science and surgery techniques can increase this difference.
Full biocompatibility of the implant with the organism is the goal. However, an intrusion of any artificial material into an organism causes a reaction of the organism’s immune system. The immune reaction on the foreign body protects the organism against bacteria, viruses and injuries, and causes an isolation of the implant from the organism tissue that can break a functionality of the implant. In the worst case scenario the implant must be removed or
replaced. This involves a secondary operation that increases the risk of lethality significantly, especially for elderly people who mostly need the implants. Research has shown that 100% of all artificial implants cause an immune reaction, and 35% of them require a secondary operation. Therefore, the immune response of the organism on
the artificial implant is a problem and must be solved. The artificial implant with
absent or decreased immune response is necessary to save patients and to improve quality of life.
This research proves that the cross-linked non-soluble polyurethane can be synthesised so that it has adjustable mechanical properties comparable to soft tissue with low stiffness and
sufficient mechanical strength, and which also has low residuals, is non-toxic and stable in the organism. We have modified the polyurethane with Plasma Immersion Ion Implantation (PIII) and created the active carbonised layer. The modified polyurethane implant was characterised with different physical and chemical methods and it was shown, that:
- Modified polyurethane has thin carbonised surface layer consisting of condensed aromatic
structures like graphite or grapheme. The carbon atoms on the edge of this surface layer have unpaired electrons known as free radicals;
- These free radicals are responsible for the polyurethane implant’s high hydrophilicity and high chemical activity, which allows the organism’s protein to covalently attach to the implant surface forming total stable coverage.
The carbonised layer provides fast total endothelialisation of the implant surface like control TCP surface.
The polyurethane implants as disks were implanted subcutaneously in mice and the polyurethane graft replaced the abdominal aorta of a rat. The animal experiments and following histological investigations showed that the PIII treated implant causes significantly weaker immune response of the organism than the untreated implant.
This is evidenced by the thinner collagen capsule (p<0.001), lower number and activity of macrophages (p<0.001), specific distribution of macrophages near the implant surface, less cell proliferation activity (p<0.001), less pro-inflammatory factor activity (p<0.001). In some cases the capsule and macrophages activity was absent. The absence of the immune reaction on an artificial soft polyurethane implant with PIII treatment is possible.