Superelastic bones

Created "paint" for printing artificial bones

Alexander Ershov, N+1

Scientists from Northwestern University have developed a new type of plastic for 3D printers that can be used to print elastic artificial bones. It does not cause an immune response, fills with cells on its own and ossifies naturally. The description of the new material is published in the journal Science (Jakus et al., Hyperelastic “bone”: A highly versatile, growth factor–free, osteoregenerative, scalable, and surgically friendly biomaterial).

The material for artificial bone is based on two substances: the mineral hydroxyapatite, which is also present in real bones, providing their rigidity, and polyester polycaprolactone – a biocompatible polymer already widely used in medicine. The polymer part is only ten percent of the new material by weight, but this is enough to ensure its high elasticity. "Artificial bones" based on the material can be stretched without destroying the structure by 30-60 percent of the length.

In addition to elasticity, the material has a high porosity – micro-voids account for up to half of the volume of "artificial bone". This allows the cells to penetrate into the internal structure of the material and populate it, thus carrying out regeneration. At the same time, blood vessels appear in artificial bones and real bone tissue begins to grow. Over time, polycaprolactone is destroyed to capronic acid, water and carbon dioxide, and only the mineral part and the patient's own cell remain inside the implant.

The scientists tested the new material on mice and rats. In the latter, with the help of implants based on a new material, doctors tried to cure a spinal fracture, which as a result was even more effective than with the help of donor grafts (pieces of real bone that are used as an implant). A separate test of the material was also done on macaques, which were implanted with an artificial bone from a new material instead of one of the skull fragments. According to the authors of the article, there was no inflammation or any other undesirable response from the immune system in any case. Blood vessels penetrated the implants well and populated them with living cells.

Such artificial materials, which are implanted in place of the damaged organ and then populated with the patient's own cells, are called scaffolds, i.e. skeletons. Usually, special dew factors are present in the composition of scaffolds, which should stimulate cell growth. Sometimes stem cells are added to the scaffold – this technology is being investigated, but is not yet used in the clinic. In this case, the authors of the material managed to achieve good healing even without the use of growth factors such as BMP (Bone Morphogenetic Protein, bone morphogenetic protein – VM) and stem cells.

In the field of bone prosthetics, the main disadvantages of artificial scaffolds are excessive fragility and an increased risk of inflammation. An alternative approach involves the use of the patient's own bone tissue obtained from another organ, but this technology is also not without serious drawbacks. It requires a complex operation, which takes a lot of time, but does not always guarantee the result. Obtaining artificial bones using 3D printing is not only much easier, but also incomparably faster - the creation of an implant, according to the authors of the article, takes only about 5 hours.

At the moment, it is impossible to talk about the complete safety of the technology, since it has been tested only on animals, besides, the observation time does not exceed several weeks yet. However, all components of the system have already been used in medicine and have not yet caused serious complications.

Portal "Eternal youth" http://vechnayamolodost.ru  30.09.2016