Tailoring the collagen film structural properties via direct laser crosslinking of star-shaped polylactide for robust scaffold formation.

Application of restructured collagen-based biomaterials is generally restricted by their poor mechanical properties, which ideally must be close to those of a tissue being repaired. Here, we present an approach to the formation of a robust biomaterial using laser-induced curing of a photosensitive star-shaped polylactide. The created collagen-based structures demonstrated an increase in the Young's modulus by more than an order of magnitude with introduction of reinforcing patterns (from 0.15 ±â€¯0.02 MPa for the untreated collagen to 51.2 ±â€¯5.6 MPa for the reinforced collagen). It was shown that the geometrical configuration of the created reinforcing pattern affected the scaffold's mechanical properties only in the case of a relatively high laser radiation power density, when the effect of accumulated thermomechanical stresses in the photocured regions was significant. Photo-crosslinking of polylactide did not compromise the scaffold's cytotoxicity and provided fluorescent regions in the collagen matrix, that create a potential for noninvasive monitoring of such materials' biodegradation kinetics in vivo.

Osteoinducing scaffolds with multi-layered biointerface.

This study was aimed to design and characterise hybrid tissue-engineered constructs composed of osteoinducing polylactide-based scaffolds with multi-layered cellular biointerface for bone tissue reconstruction. Three-dimensional scaffolds with improved hydrophilic and osteoinducing properties were produced using the surface-selective laser sintering (SSLS) method. The designed scaffold pattern had dimensions of 8 × 8 × 2.5 mm and ladder-like pores (∼700 µm in width). Hyaluronic acid-coated polylactide microparticles (∼100 µm in diameter) were used as building blocks and water was used as the photosensitizer for SSLS followed by photocross-linking with Irgacure 2959 photoinitiator. Resulting scaffolds provided successful adhesion and expansion of human bone marrow mesenchymal stromal cells from a single-cell suspension. Induced calcium deposition by the cells associated with osteogenic differentiation was detected in 7-21 days of culturing in basal medium. The values were up to 60% higher on scaffolds produced at a higher prototyping speed under the experimental conditions. Innovative approach to graft the scaffolds with multi-layered cell sheets was proposed aiming to facilitate host tissue-implant integration. The sheets of murine MS-5 stromal cell line exhibited contiguous morphology and high viability in a modelled construct. Thus, the SSLS method proved to be effective in designing osteoinducing scaffolds suitable for the delivery of cell sheets.