Biodegradable matrices containing magnetic nanoparticles (MNP) are promising for tissue engineering. Recently an osteoinductive effect of inorganic matrices with entrapped MNP was demonstrated even without an external magnetic field. Moreover, an increase in the proliferation of osteoblasts at cultivation on fibrous matrices containing MNP in a magnetic field was also reported [1, 2]. Natural polysaccharide chitosan (Chit) is widely used for matrix preparation due to its antibacterial and bioadhesive activities. To improve mechanical properties of the matrices, we have proposed silk protein fibroin (Fb), which was added to Chit-based hydrogel. This study was aimed at evaluation of biocompatibility of the macroporous Chit/Fb hydrogels with entrapped magnetite (Fe3O4) nanoparticles using an in vitro model for further development of magnetically sensitive matrices for tissue engineering. Macroporous matrices, namely Chit/Fb hydrogels containing MNP (5 and 10 wt. %) were prepared by lyophilization of a mixture of chitosan and fibroin solutions 1:1 (w/w) and by cross-linking the obtained samples with genipin. Chitosan cross-linked hydrogel with MNP (but without fibroin) was used as a control. The cytotoxicity of the obtained hydrogels was evaluated using an extraction test. The extracts were obtained after previous incubation of the hydrogel samples in DMEM (10% FBS) for 24 hours. Mouse fibroblasts (L929) were used as model cells. To study an ability of the hydrogels to support cell adhesion, growth and proliferation, L929 cells were cultured in the hydrogel matrices in DMEM (10% FBS) at CO2-incubator (5% CO2, 37oC) for 7 days. Cell growth was assessed qualitatively using confocal laser microscopy, while quantitative evaluation of cell viability was carried out by MTT-assay. In the extraction tests, all hydrogel matrices were shown to be non-cytotoxic. It was also found by confocal microscopy that all hydrogel samples supported well both adhesion and spreading of L929 mouse fibroblasts. All hydrogels samples provided rather good cell growth and proliferation, which was confirmed by MTT-assay. Thus, macroporous chitosan/fibroin hydrogels containing MNP could be proposed for further development of magnetically controlled matrices for tissue engineering.

Acknowledgement:
The study was funded by the Russian Science Foundation (grant № 22-13-00261).

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 published here firstly.