"Collagen scaffolds are well known for their regenerative potential. However, the relatively poor mechanical properties represent a problem (scaffold deformation, partial collapse of internal open pore structure) for the translation into a clinical setting. In this study, we present a novel approach: A Mechano-Hybrid-Scaffold (MHS) that combines a collagen-based biomaterial with highly aligned channel-like pores with a 3D printed poly(ε-caprolactone) (PCL) support structure , overcoming contradictory requirements for mechanical stiffness and scaffold architecture.
The previously described orientated collagen scaffold  was combined with a 3D printed PCL macro-porous support structure  that preserves the internal architecture of the collagen scaffold. Internal architecture characterization (scanning electron microscopy imaging) and mechanical characterization (monoaxial compression test) were performed. Crosslinking and degradability were assessed by determination of the denaturation temperature of the collagen (Td).
MHS were successfully produced with stiffness of 9.56 MPa (stiff) and 0.01 MPa (soft) for the supporting structure, respectively. MHS characteristics, e.g. Td (79.8 ± 0.1 °C) and pore size (78.1 ± 18.1 µm), remain the same as the ones of collagen reference scaffolds without a PCL supporting structure. Scanning electron microscopy images show full integration of the support structure inside the collagen structure and no alteration of the scaffold inner architecture.
With this approach, mechanical characteristics can be tuned independently at the micro-scale (cell-level) and the macro-scale (tissue-level). The MHS opens the door for new applications of collagen scaffolds in rigid tissue regeneration by solving the paradox of providing soft cell environment and high structural stability in implantable materials.
 Patent pending: DE102016007931.2; PCT/DE2017/000183; US 16/313,937
 Petersen et al. (2018), Nat. Commun. 9:4430.
 Tortorici et al. (2021), Mat. Science & Engineering C 123 (2021) 111986
The authors acknowledge financial support by the German Federal Ministry of Education and Research (BMBF) via grants no. 13XP5048A-D)."