3D printing is a modern technology for manufacturing three-dimensional physical objects layer-by-layer from a digital model and is considered the latest technology in reconstructive medicine, including the creation of scaffolds and implants for repairing damaged tissues and organs. The development of additive technologies is associated with the individual patient treatment. The success of the development of 3D printing technologies is largely due to the search for functional materials that ensure the creation of highly functional implants and structures with the required characteristics. An important position among degradable polymers is occupied by polyhydroxyalkanoates. In this work, using the P(3HB-co-3HV) copolymer, the processes of manufacturing 3D scaffolds and their characterization were investigated. The process included preliminary production of filaments by extrusion and subsequent 3D printing of scaffolds using FDM technology. The complete technological chain included a series of sequential and interrelated stages: 1) obtaining and isolating samples of polymer material from bacterial biomass; 2) receiving granulate from the melt; 3) extrusion preparation of filaments from the melt; and 4) FDM printing and scaffolds production. The biological compatibility and ability of 3D scaffolds to support cell proliferation on the surface and in the cells between the filaments was studied in vitro in a culture of mouse fibroblasts NIH 3T3. In vivo 3D scaffolds were studied on a segmental osteotomy model in an animal experiment. The experimental protocol was approved by the Local Ethics Committee of the Siberian Federal University. 3D scaffolds of a cellular cylindrical shape were obtained from 12 perpendicularly located successive layers formed by cylindrical filaments with an interconnected porosity of 65%. Light and fluorescence microscopy images of cultured cells on 3D scaffolds showed that the cells formed a monolayer over the entire surface, migrated, and gradually radially closed the space between the filaments. X-ray studies performed 150 days after surgery and implantation of 3D scaffolds, showed that the model defect was completely closed: the place of the defect in the area of material implantation is replaced by mature bone lamellar tissue of a normal histological structure without the phenomena of osteomyelitis. The developed and studied 3D implants nevertheless ensured the formation of full and mature bone tissue and complete restoration of the defect. The results of the experiment and the initial assessment of the osteoplastic properties of 3D scaffolds made of P(3HB-co-3HV), allow us to conclude that the resulting scaffolds are promising for reconstructive osteogenesis.

Conflicts of interest:
The authors declare that they have no conflict of interest in the publication of this article. The authors have no conflicts of interest to report in this work. Abstract was not submitted elsewhere and was first published here.

Funding:
The study was funded by State Assignment of the Ministry of Science and Higher Education of the Russian Federation (project No. 0287-2021-0025).