Polymer tendons
Artificial tendons restored the functions of rat paws
Russian scientists from the Federal State Budgetary Institution "National Medical Research Center of Transplantology and Artificial Organs named after Academician V.I. Shumakov" demonstrated the work of an artificial Achilles tendon based on polymer materials. The corresponding article was published in the Journal of Biomedical Materials Research (Olkhov et al., Composite tendon implant based on nanofibrillar polyhydroxybutyrate and polyamide filaments).
The authors used a five percent solution of poly(3-hydroxybutyrate) in chloroform – the polymer was previously obtained by microbiological synthesis in a German laboratory and delivered to Russia – for electrostatic winding of threads. The final product of the winding, in fact, was an artificial Achilles tendon. Four polyamide fibers served as the frame on which the threads were wound.
The tendons were then implanted into ten rats whose own tendons had previously been damaged. One of the rat's legs received an implanted artificial tendon, while the other did not (control case).
As a result of the experiment, it turned out that the rats were able to restore the functions of the leg with an artificial tendon within a short time, while the leg without an implant did not restore its functions. The cells of the connective tissue of rats penetrated into the gaps between the micro- and nanofilaments of the tendon, using them as a framework. The mechanical tensile strength for the artificial tendon was 16 newtons, while for the natural tendon of rats of this line, it is usually no higher than 12 newtons.
The researchers also conducted experiments with human fibroblasts – connective tissue cells, allowing them to "grow" an artificial tendon in the laboratory. The cells successfully grew on such material, and the proportion of dead cells did not exceed three percent.
It should be noted that experiments with human fibroblasts are not entirely informative. The human immune system is known to cause aseptic inflammation around implants, even if they are quite safe for the body. It is clear that one "reaction" of fibroblasts, in isolation from the immune system, is not enough to understand whether a new tendon will cause an immune response or not. However, experiments on rats are quite encouraging: such a tendon did not cause an immune response in them.
Given the high strength of the artificial Achilles tendon tested by scientists and the non-toxicity of its components, it looks very promising. At the moment, the replacement of damaged tendons is one of the most difficult problems in the field of implants in general.
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