In this study, we prepared hydrogel scaffolds for tissue engineering by computer-assisted extrusion three-dimensional (3D) printing with photocured (λ = 445 nm) hyaluronic acid glycidyl methacrylate (HAGM). The developed product was compared with the polylactic-co-glycolic acid (PLGA) scaffolds generated by means of the original antisolvent 3D printing methodology. The cytotoxicity and cytocompatibility of the scaffolds were analyzed in vitro by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide tests, flow cytometry, and scanning electron microscopy. Anti-inflammatory and proangiogenic properties of the scaffolds were evaluated in the dorsal skinfold chamber mouse model by means of intravital fluorescence microscopy, histology, and immunohistochemistry throughout an observation period of 14 days. In vitro, none of the scaffolds revealed cytotoxicity on days 1, 2, and 5 after seeding with umbilical cord-derived multipotent stromal cells, and the primary cell adhesion to the surface of HAGM scaffolds was low. In vivo, implanted HAGM scaffolds showed enhanced vascularization and host tissue ingrowth, and the inflammatory response to them was less pronounced compared with PLGA scaffolds. The results indicate excellent biocompatibility and vascularization capacity of the developed 3D printed HAGM scaffolds and position them as strong candidates for advanced tissue engineering applications.

The detection of double bonds in polymers exploited as scaffold materials, e.g. hyaluronic acid (HA) derivatives, is crucial for their further applications. The quantity variations of unsaturated units significantly affect the photoinduced crosslinking degree responsible for the mechanical properties of scaffolds. We demonstrate a simple, selective and rapid quantitative method that enables the detection of double bond moieties in polymers. The approach is based on a reaction with potassium permanganate which is spectrophotometrically confirmed. The effect of glycidyl methacrylate concentration and various reaction catalysts introduced at the stage of HA modification, as well as the change of double bond concentration over time, has been investigated using the proposed method. In addition, the developed quantitative method can be utilized for rapid and efficient detection of unreacted double bonds after photopolymerization as a tool for monitoring conversion over time.

3D printing became a widely used technique for tissue engineering applications. This additive technology enables easy fabrication of very complicated structures. However, selection and preparation of initial compositions for 3D printing satisfying high biocompatibility and processability requirements still remains challenging. One of the most promising materials for mimicking of the living tissues are hydrogels possessing properties close to native tissues. In this work, the printability of hydrogels based on hyaluronic acid and poly(ethylene glycol) derivatives dissolved in phosphate buffer saline in presence of flavin mononucleotide as an endogenous photosensitizer has been studied. To produce a hydrogel pattern, the extrusion of photocurable composition has been combined with its simultaneous photoinduced crosslinking under laser irradiation at 450 nm. Cytotoxicity of fabricated films and 3D scaffolds has been tested in vitro using human fibroblasts BJ-5ta.Key words: extrusion; 3D printing; photocurable hydrogel; hyaluronic acid. Hоw to cite: Savelyev A.G., Sochilina A.V., Akasov R.A., Mironov A.V., Semchishen V.A., Generalova A.N., Khaydukov E.V., Popov V.K. Extrusion-based 3D printing of photocurable hydrogels in presence of flavin mononucleotide for tissue engineering. Sovremennye tehnologii v medicine 2018; 10(1): 88, https://doi