Fabrication And Cell Responsive Behavior Of Macroporous PLLA/Gelatin Composite Scaffold

In clinical orthopedics, large-size bone injuries and defects caused by trauma, tumor and infection are one of troubling problems. Bone tissue engineering holds promise in providing an improved clinical therapy, to create an alternative solution to repair bone defects. Its typical method is seeding cells in the scaffold with a specific structural and functional to form cells/scaffold constructs. For a biomimetic scaffold, the model is the natural extracellular matrix (ECM). Scaffolds to provide a3D environment which can effectively promote the adhesion, proliferation and differentiation of cells are crucial to tissue engineering/regeneration. In this study, the PLLA scaffold with hierarchical pore structural was fabricated via two-step thermally induced phase separation (TIPS). To mimic both the physical architecture and chemical composite of natural bone ECM, gelatin fibers were introduced into the pores of PLLA scaffolds and formed3-D network structure via TIPS. Finally, human adipose tissue-derived stromal cells were harvested and seeded into PLLA/Gel scaffolds and cultured in vitro. The biocompatibility of the scaffold and the cell morphology, viability and osteogenic differentiation were investigated.In this work, the PLLA scaffolds with porous, hierarchical pore structural, highly interconnective3-D structure were fabricated via two-step thermally induced phase separation (TIPS). The surface morphology, porosity and compressive modulus of scaffolds were characterized by scanning electron microscopy (SEM), density analysis and compression test respectively. The results showed that PLLA scaffolds had high porosity (91.62%), a good compressive modulus (2.79±0.20MPa), nanometer fibers (diameter around186.39～354.30nm) and different grades of pore size which large pores with size up to225.90±34.15μm and the pore size of microporous from several nanometers to387.94±102.48nm. The bioactivity of the PLLA scaffold was demonstrated by the bone-like apatite deposition throughout the scaffold in a simulated body fluid (SBF). Preincorporation of nanosized hydroxyapatite eliminated the induction period and facilitated the apatite growth in the1.5×SBF. The scaffolds following mild hydrolysis by NaOH was modified by EDC/NHS. Gelatin was performed onto PLLA scaffold via TIPS aiming at enhancement cell-material interaction. In comparison with the PLLA scaffold, the PLLA/Gel scaffold had better biological performance and the mechanical properties because the gelatin fibers homogeneously distributed in each pore of PLLA scaffold and formed3D network structure. The protein adsorbability was upgraded from8.44±0.86mg/g to17.31±0.82mg/g. The water absorption of PLLA/Gel composite scaffolds was increased by5.6±0.42times. A large number of cells in the PLLA/Gel scaffolds were observed under confocal laser scanning microscopy (CLSM) after the viable cells were stained with PI/Calcein-AM. Cells show more spreading morphology. Von kossa staining showed that hADSCs within the composite scaffolds was induced into osteogenic phenotype after2weeks of culture. These features indicate that these PLLA/Gel scaffolds have potential application in tissue engineering, especially for bone regeneration.