**5. Conclusions**

The literature analysis shows that the GSCM material has been very poorly studied, and no application in tissue engineering has been discussed so far. The results of our studies on the GSCM composition, structure, mechanical characteristics, cytotoxicity, and biodegradability testify that the GSCM of *D. gigas* is characterized by a high tensile strength and elasticity, along with a peculiar basketweave collagen structure and biocompatibility that allows the assumption that this material may be applicable in a number of tissue engineering fields (e.g., wound care materials, scaffolds for restoration of the musculoskeletal system, repair of hernias and the prolapse of pelvic organs, dental membranes, and other applications requiring good mechanical properties and slow degradation of the implanted material).

Upon the comparison with other squid species (in particular, *B.magister)*, one may conclude that the GSCM structure is represented by a typical reinforcing mesh consisting of collagen structures and providing the high strength and Young's modulus. However, since the Giant squid *D. gigas* has a large size of the mantle and, respectively, a large lateral size of the GSCM, this material is more advantageous from the processing viewpoint.

**Supplementary Materials:** The following are available online at https://www.mdpi.com/1660 -3397/19/12/679/s1, Table S1: Band positions for the GSCM, collagen Type I and II; Figure S1: Morphological and optical characteristics of the implanted intact GSCM; Figure S2: Morphological and optical characteristics of the implanted GSCM after the scCO2-treatment.

**Author Contributions:** Conceptualization, P.T. and S.K.; methodology, S.K., A.F. and E.I.; validation, P.T. and S.K.; formal analysis, A.M., E.G., P.B., V.E. and E.I.; investigation, A.F., N.A., I.N., A.M., E.G., Y.E., P.B., V.E. and A.K.; resources, A.F., N.A., I.N., A.M., E.G., Y.E., P.B., V.E., A.K., S.K., E.I., A.S., E.Z. and P.T.; data curation, A.F., S.K., E.I., A.S., E.Z. and P.T.; writing—original draft preparation, A.F., N.A., I.N., A.M., E.G., Y.E., P.B., V.E., A.K., S.K. and A.S.; writing—review and editing, A.F., A.S., S.K., E.I., E.Z. and P.T.; visualization, A.F., N.A., I.N., V.E., A.K. and A.S.; supervision, P.T.; project administration, P.T.; funding acquisition, P.T. All authors have read and agreed to the published version of the manuscript.

**Funding:** The study was financially supported by the Russian Science Foundation (18-15-00401).

**Data Availability Statement:** All the data supporting the conclusions of this article are included in this article.

**Acknowledgments:** The study was carried out using the unique scientific facility Transgenebank. The authors thank Anton Murashko (Moscow State University, Faculty of Physics) for drawing the graphical abstract. The authors are thankful to Anastasia Shpichka for her kind assistance with the cell experiments.

**Conflicts of Interest:** The authors declare no conflict of interest.
