**5. Conclusions**

Biphasic, but monolithic scaffolds exclusively from marine collagens are stable under cell culture conditions for up to three weeks without any delamination of the phases. We have tried to simultaneously differentiate hMSC into osteogenic and chondrogenic lineage spatially separated in the bone and cartilage layer of the marine scaffolds. However, the different chemical nature and mineralization of the layers, as well as different seeding densities, and the application of alginate hydrogel to embed the cells into the jellyfish collagen layer of the scaffold were not sufficient to trigger the differentiation of hMSC adequately into the respective direction. We therefore propose a sequential seeding of the biphasic scaffolds and pre-differentiation of the cells into both osteogenic and chondrogenic lineage to obtain functional osteochondral constructs.

**Acknowledgments:** We are grateful to the German Research Foundation (DFG) for funding the present study (BE 5139/1-1) and acknowledge Sophie Brüggemeier for excellent technical assistance. Thanks to Diana Jünger for preparing histological sections.

**Author Contributions:** A.B. performed the cell culture experiments, analyzed the data, and wrote the manuscript. B.P. prepared the monophasic mineralized salmon collagen scaffolds, developed the method for the preparation of the biphasic marine scaffolds, prepared all biphasic scaffolds, and did the SEM investigation. M.G. developed the original method of formation of biphasic but monolithic collagen scaffolds and was engaged in writing the manuscript.

**Conflicts of Interest:** The authors declare no conflict of interest. The founding sponsors had no role in the design of the study; in the collection, analyzes, or interpretation of data; in the writing of the manuscript, and in the decision to publish the results.
