Assessment of the suitability of chitosan/polybutylene succinate scaffolds seeded with mouse mesenchymal progenitor cells for a cartilage tissue engineering approach

In this work, scaffolds derived from a new biomaterial originated from the combination of a natural material and a synthetic material were tested for assessing their suitability for cartilage tissue engineering applications. In order to obtain a better outcome result in terms of scaffolds' overall properties, different blends of natural and synthetic materials were created. Chitosan and polybutylene succinate (C-PBS) 50/50 (wt%) were melt blended using a twin-screw extruder and processed into 5 × 5 × 5 mm scaffolds by compression moulding with salt leaching. Micro-computed tomography analysis calculated an average of 66.29% porosity and 92.78% interconnectivity degree for the presented scaffolds. The salt particles used ranged in size between 63 and 125 μm, retrieving an average pore size of 251.28 μm. Regarding the mechanical properties, the compressive modulus was of 1.73 ± 0.4 MPa (E_sec 1%). Cytotoxicity evaluation revealed that the leachables released by the developed porous structures were not harmful to the cells and hence were noncytotoxic. Direct contact assays were carried out using a mouse bone marrow-derived mesenchymal progenitor cell line (BMC9). Cells were seeded at a density of 5 × 10⁵ cells/scaffold and allowed to grow for periods up to 3 weeks under chondrogenic differentiating conditions. Scanning electron microscopy analysis revealed that the cells were able to proliferate and colonize the scaffold structure, and MTS test demonstrated cell viability during the time of the experiment. Finally, Western blot performed for collagen type II, a natural cartilage extracellular matrix component, showed that this protein was being expressed by the end of 3 weeks, which seems to indicate that the BMC9 cells were being differentiated toward the chondrogenic pathway. These results indicate the adequacy of these newly developed C-PBS scaffolds for supporting cell growth and differentiation toward the chondrogenic pathway, suggesting that they should be considered for further studies in the cartilage tissue engineering field.