[A preliminary study for the effect of nano hydroxyapatite on human adipose-derived mesenchymal stem cells mixture 3D bio-printing].

Objective: To study the effect of nano hydroxyapatite on human adipose-derived mesenchymal stem cells(hASCs) mixture 3D bio-printing for cells' proliferation and osteogenesis.
Methods: P5 hASCs were used as seed cells, 10 g/L nano hydroxyapatite was added into the cell-sodium alginate-gelatin mixture (concentration: 20 g/L sodium alginate, 80 g/L gelatin; cell density: 1×10 ⁶ /mL), then the mixture was printed by 3D bio-printer as the experimental group. And the cell-sodium alginate-gelatin mixture without nano hydroxyapatite was printed as the control group. Respectively, both the experimental and control groups were detected by microscope, CCK-8, Western blot and PCR at certain time pointsafter being printed, whose cells' proliferation and osteogenic differentiation were analyzed.
Results: The microscopic observation and CCK-8 results showed that the cells of the experimental group and the control group both had a good proliferation 24 h and 7 d after being printed. The Western blot results showed that 14 d after printing, the expression of Runt-related transcription factor 2 (RUNX2) had no statistical difference between the experimental group and control group. The PCR results showed that 14 d after printing, the expression of osteogenesis-related genes (RUNX2, osterix, and osteocalcin) was significantly higher in the experimental group than in the control group.
Conclusion: Nano hydroxyapatite can increase osteogenic differentiation of the hASCs mixture after bio-printing, in which the cells still have a good proliferation.