Old bones will still serve: scientists have developed a method for manufacturing implants based on natural bone

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The installation of such a foreign body as an implant is a great stress for the body, and that is why scientists pay great attention to ensuring quick survival and the longest possible life of the product. Success depends on the properties of the source material itself, as well as on the structural features of the implant, production methods, etc. You can use metal, ceramics, various polymers, as well as combinations thereof. Ideally, the less the body “feels” the foreignness of the implant, the faster it takes root, the freer the patient’s cells feel, the lower the risk of rejection. Guided by these principles, the scientists of NUST “MISiS” together with colleagues from the Scientific Research Center named after N.N. Blokhin and the Technical University of Dortmund have developed a unique technology for the manufacture of polymer implants, where a real bone serves as the “negative” for casting the product.

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One of the most popular materials for the production of bone implants is ultra high molecular weight polyethylene (UHMWPE). Scientists of NUST “MISiS” have been engaged in the development of biomimetic (repeating the real structure of bone implants) scaffolds (structures that become implants after implantation) for several years. Particular attention is paid to simulating the porosity of the bone core, so that after the implant is installed, the patient’s bone tissue cells can divide and “sprout” into the implant. Previously, the team achieved this architecture of samples by 3D-modeling and printing the “negative” of the bone, followed by filling the mold with polymer.

A new development of scientists is a biomimetic scaffold from UHMWPE, the structure of which is copied from the structure of a real mammalian bone. Initially, experiments were carried out with fragments of cow bones. The bone marrow was removed using hydrogen peroxide, then the bone was filled with polyethersulfone to form a “negative” internal structure. Then, the resulting “negative” was washed with hydrochloric acid, filled with UHMWPE powder, and thermal pressing occurred. Finally, the sample was immersed in N-methylpyrrolidone — it completely dissolved the polyethersulfone “negative”, leaving only the porous UHMWPE, which has a structure that mimics the original bone structure.

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“A characteristic feature of the spongy part of the bone is anisotropy – elongated pores along the length of the bone, ellipsoidal in the section. It is impossible to completely repeat this on a 3D printer because of the high viscosity of the UHMWPE melt, ”says Inna Bulygina, an employee of the Center for Composite Materials of NUST“ MISiS ”and the main author of the development. – When we used as a “negative” bone with lengths of the major and minor pore axes ~ 770 μm and 470 μm, respectively, we obtained polymer pores with axis lengths of ~ 700 μm and 500 μm. That is, the shape of the pores turned out to be ellipsoidal at the cut, as close to natural as possible. ”

Scientists from the Technical University of Dortmund assessed the topography of the sample, and thanks to specialists from the NMIC named after N.N. Blokhin were tested in vitro.

The experiments performed on incubation of the implant with multipotent mesenchymal stromal cells proved their 75% proliferation after 48 hours.
Next, scientists plan to test various combinations of materials for the manufacture of implants with a spongy core and hard shell. According to the researchers, the most promising niche for the potential implementation of the development is veterinary medicine.

The technology has already been patented, an article on the development published in the journal Polymer Degradation and Stability.


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