Preparation, characterization and in vitro analysis of novel structured nanofibrous scaffolds for bone tissue engineering.

In a previous study, a three-dimensional nanofibrous spiral scaffold for bone tissue engineering was developed, which showed enhanced human osteoblast cell attachment, proliferation and differentiation compared with traditional cylinder scaffolds, owing to the incorporation of spiral structures and nanofiber. However, the application of these scaffolds to bone tissue engineering was limited by their weak mechanical strength. This limitation triggered the design for novel structured scaffolds with reinforced physical characteristics. In this study, spiral polycaprolactone (PCL) nanofibrous scaffolds were inserted into poly(lactide-co-glycolide) (PLGA) microsphere sintered tubular scaffolds to form integrated scaffolds to provide mechanical properties and bioactivity appropriate for bone tissue engineering. Four experiment groups were designed: PLGA cylinder scaffold; PLGA tubular scaffold; PLGA tubular scaffold with PCL spiral structured inner core; PLGA tubular scaffold with PCL nanofiber containing spiral structured inner core. The morphology, porosity and mechanical properties of the scaffolds were characterized. Furthermore, human osteoblastic cells were seeded on these scaffolds, and the cell attachment, proliferation, differentiation and mineralized matrix deposition on the scaffolds were evaluated. The integrated scaffolds had Young's modulus 250-300 MPa, and compressive strength 8-11 MPa under uniaxial compression. With the addition of an inner highly porous insert to the tubular shell, human osteoblast cells seeded on the integrated scaffolds showed slightly higher cell proliferation, 20-25% more alkaline phosphatase expression and twofold higher calcium deposition than those on the cylinder and tubular scaffolds. Furthermore, compared with sintered PLGA cylinder scaffolds, the integrated scaffolds allowed better cellular infiltration Therefore, this design demonstrates great potential for integrated scaffolds in bone tissue engineering applications.