Surface activation with oxygen plasma promotes osteogenesis with enhanced extracellular matrix formation in three‐dimensional microporous scaffolds

Abstract

Various types of synthetic polyesters have been developed as biomaterials for tissue engineering. These materials commonly possess biodegradability, biocompatibility, and formability, which are preferable properties for bone regeneration. The major challenge of using synthetic polyesters is the result of low cell affinity due to their hydrophobic nature, which hinders efficient cell seeding and active cell dynamics. To improve wettability, plasma treatment is widely used in industry. Here, we performed surface activation with oxygen plasma to hydrophobic copolymers, poly(l‐lactide‐co‐trimethylene carbonate), which were shaped in 2D films and 3D microporous scaffolds, and then we evaluated the resulting surface properties and the cellular responses of rat bone marrow stem cells (rBMSC) to the material. Using scanning electron microscopy and Fourier‐transform infrared spectroscopy, we demonstrated that short‐term plasma treatment increased nanotopographical surface roughness and wettability with minimal change in surface chemistry. On treated surfaces, initial cell adhesion and elongation were significantly promoted, and seeding efficiency was improved. In an osteoinductive environment, rBMSC on plasma‐treated scaffolds exhibited accelerated osteogenic differentiation with osteogenic markers including RUNX2, osterix, bone sialoprotein, and osteocalcin upregulated, and a greater amount of collagen matrix and mineral deposition were found. This study shows the utility of plasma surface activation for polymeric scaffolds in bone tissue engineering.

Induction of osteogenic differentiation of bone marrow stromal cells on 3D polyester-based scaffolds solely by subphysiological fluidic stimulation in a laminar flow bioreactor

“… 67 In rBMSC, the consequence of the robust mRNA expression of RUNX2 may be either cytoskeletal expression/diffusion or nuclear localisation. 29 In the present study, the quantification and line investigation confirmed that the mRNA upregulation of RUNX2 by fluid flow was accompanied by a degree of nuclear localisation. Similarly, collagen formation, ALP activity and mineral deposition were found to be enhanced in the dynamic culture groups.…”

“… 68 Nevertheless, the induction of osteogenesis, particularly in terms of collagen formation and mineral deposition, by fluid flow is apparently not as robust as that achieved by the osteogenic supplements as previously tested in a study of osteogenic differentiation of rBMSC on LTMC scaffolds. 29 This could be attributable to the characteristics of each component of the common osteogenic supplement (i.e. dexamethasone, β-glycerophosphate and ascorbic acid).…”

“…The scaffolds were placed in 48 well plates and sterilised using 70% ethanol and ultraviolet exposure for 2 h. The characterisation of LTCM scaffolds was described previously. 29 …”

“…Porous properties were parameterised using data previously obtained by microCT analysis of the scaffold, including porosity 91.708% and permeability 5.80216e-09 m 2 . 29 From the inlet to the outlet, a fully developed flow was applied at a flow rate of either 0.8 ml/min (FL-L) or 1.6 ml/min (FL-H). Non-slip wall condition was applied to the boundary condition of the fluid paths (i.e.…”

“…The scaffolds were placed in 48 well plates and sterilised using 70% ethanol and ultraviolet exposure for 2 h. The characterisation of LTCM scaffolds was described previously. 29 Before cell seeding, the scaffolds were prewetted with α-MEM for 24 h, and 250,000 cells were then seeded per scaffold and incubated at 37°C in 5% CO 2 humidified atmosphere for 72 h, before being transferred into the bioreactor.…”