RESUMO
Scaffolds providing a 3D environment which can effectively promote the adhesion, proliferation and differentiation of cells are crucial to tissue regeneration. In this study, the poly-l-lactic acid (PLLA) scaffold with hierarchical pore structural was fabricated via two-step thermally induced phase separation (TIPS). To mimic both physical architecture and chemical composite of natural bone extracellular matrix (ECM), gelatin fibers were introduced into the pores of PLLA scaffolds and formed 3D network structure via TIPS. Human adipose tissue-derived stem cells (ADSCs) were harvested and seeded into PLLA/gel hybrid scaffolds and cultured in vitro for biocompatibility assay. 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 hybrid scaffolds had high porosity (91.62%), a good compressive modulus (2.79 ± 0.20 MPa), nanometer fibers (diameter around 186.39~354.30 nm) and different grades of pore size from 7.41 ± 2.64 nm to 387.94 ± 102.48 nm. The scaffolds with mild hydrolysis by NaOH were modified by 1-ethyl-3-(3-dimethyl ami-nopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS). Gelatin was performed onto PLLA scaffold via TIPS aiming at enhancement cell-material interaction. In comparison with 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 formed 3D network structure.
RESUMO
The in vitro dynamic fabrications of tissue-engineered bones were performed to assess the advantages of human adipose-derived stem cells (hADSCs) combined with acellular cancellous bone scaffold coming from fresh pig femur in a spinner flask compared with traditional static culture. In this study, the bio-derived cancellous bone was regarded as a biomimetic scaffold, and its surface appearance was observed under scanning electron microscopy (SEM). Moreover, its modulus of elasticity and chemical composition were measured with universal testing machine (UTM) and infrared detector, respectively. hADSCs were inoculated into cancellous bone scaffold at a density of 1 × 10(6) cells/mL and cultured in spinner flask and T-flask with osteogenic medium (OM) for 2 weeks, respectively. Following to this, the osteogenic differentiation was qualitatively and quantitatively detected with alkaline phosphatase (ALP) kits, and the cell growth and viability were assayed using Live/Dead staining; cell adhesion and extracellular matrix secretion were observed under a SEM. The average pore size of cancellous bone scaffold was 284.5 ± 83.62 µm, the elasticity modulus was 41.27 ± 15.63 MPa, and it also showed excellent biocompatibility. The hADSCs with multidifferentiation potentials were well proliferated, could grow to 90 % fusion within 5 days, and were therefore suitable to use as seed cells in the construction of tissue-engineered bones. After 2 weeks of fabrication, cells were well-distributed on scaffolds, and these scaffolds still remained intact. Compared to static environment, the ALP expression, cell distribution, and extracellular matrix secretion on cancellous bones in spinner flask were much better. It confirmed that three-dimensional dynamic culture in spinner flask promoted ADSC osteogenic differentiation, proliferation, and matrix secretion significantly to make for the fabrication of engineered bone substitutes.