Fabrication and evaluation of multilayered tissue engineering scaffolds incorporated with mesenchymal stem cells

Abstract

Mesenchymal stem cells (MSCs) are now increasingly used in tissue engineering. For scaffold-based tissue engineering, incorporating MSCs in scaffolds while protecting them during manufacture is a challenge in fabricating cell-laden scaffolds. Further, synthetic polymer scaffolds need to be functionalized for achieving better biological performance. In this investigation, multilayered scaffolds were constructed, which consisted of a nanofibrous poly(lactic acid-co-glycolic acid) (PLGA) membrane as the base, a microfibrous gelatin mesh with an adhesive protein dopamine, and MSC-containing alginate hydrogel microspheres. PLGA membranes were fabricated by electrospinning, the gelatin networks were produced by thermally induced phase separation, and microcapsules with an alginate hydrogel shell and an aqueous liquid core containing living MSCs were made via coaxial electrospray. In this sandwich-like fibrous sponge composite (the multilayered 3D scaffolds), the fibrous PLGA membrane would provide adequate mechanical support for the whole system and fibrous gelatin would enhance cell growth and maturation after MSCs are released from hydrogel microspheres. Dopamine would functionalize the scaffold and also act to cross-link gelatin to avoid its dissolution in water. MSCs were encapsulated in the core of microspheres for protection during scaffold manufacture. The successful introduction of dopamine and gelatin on the surface of PLGA nanofibers was confirmed by Fourier transform infrared spectroscopy. Scanning microscopy was used to examine the effects of gelatin deposition on the surface morphology of PLGA membranes and also in vitro degradation kinetics. The hydrophilicity or hydrophobicity of the products were studied by measuring water contact angles. Before and after the cell release treatment, MSCs in microspheres were stained by live/dead viability assay. Furthermore, confocal laser scanning microscopy was used to study MSCs in scaffolds. The results of these studies showed that the multilayered scaffolds were biocompatible and biodegradable and could maintain MSC viability. These scaffolds with MSC delivery have the potential for tissue regeneration.