[Carrier combination of tissue engineered bone by sodium alginate and xenograft bone and bone formation in vivo]

To produce a new bone tissue engineered carrier through combination of xenograft bone (X) and sodium alginate (A) and to investigate the biological character of the cells in the carrier and the ability of bone-forming in vivo, so as to provide experimental evidence for a more effective carrier.

BMSCs were extracted from 2-week-old New Zealand rabbits and the BMSCs were induced by rhBMP-2 (1 x 10(-8)mol/L). The second generation of the induced BMSCs was combined with 1% (V/W) A by final concentration of 1 x 10(5)/mL. After 4-day culture, cells in gel were investigated by HE staining. The second generation of the induced BMSCs was divided into the DMEM gel group and the DMEM containing 1% A group. They were seeded into 48 well-cultivated cell clusters by final concentration of 1 x 10(5)/mL. Seven days later, the BMP-2 expressions of BMSCs in A and in commonly-cultivated cells were compared. The second generation of the induced BMSCs was mixed with 2% A DMEM at a final concentration of 1 x 10(10)/mL. Then it was compounded with the no antigen X under negative pressure. After 4 days, cells growth was observed under SEM. Twenty-four nude mice were randomly divided into 2 groups (n = 12). The compound of BMSCs-A-X (experimental group) and BMSCs-X (control group) with BMSCs whose final concentration was 1 x 10(10)/mL was implanted in muscles of nude mice. Bone formation of the compound was histologically evaluated by Image Analysis System 2 and 4 weeks after the operation, respectively.

Cells suspended in A and grew plump. Cell division and nuclear fission were found. Under the microscope, normal proliferation, many forming processes, larger nucleus, clear nucleolus and more nuclear fission could be seen. BMP-2 expression in the DMEM gel group was 44.10% +/- 3.02% and in the DMEM containing 1% A group was 42.40% +/- 4.83%. There was no statistically significant difference between the two groups (P > 0.05). A was compounded evenly in the micropore of X and cells suspended in A 3-dimensionally with matrix secretion. At 2 weeks after the implantation, according to Image Analysis System, the compound of BMSCs-A-X was 5.26% +/- 0.24% of the total area and the cartilage-like tissue was 7.31% +/- 0.32% in the experimental group; the compound of BMSCs-X was 2.16% +/- 0.22% of the total area and the cartilage-like tissue was 2.31% +/- 0.21% in the control group. There was statistically significant difference between the two groups (P < 0.05). At 4 weeks after the operation, the compound of BMSCs-A-X was 7.26% +/- 0.26% of the total area and the cartilage-like tissue was 9.31% +/- 0.31% in the experimental group; the compound of BMSCs-X was 2.26% +/- 0.28% of the total area and the cartilage-like tissue was 3.31% +/- 0.26% in the control group. There was statistically significant difference between the two groups (P < 0.05).

The new carrier compounding A and no antigen X conforms to the superstructural principle of tissue engineering, with maximum cells load. BMSCs behave well in the compound carrier with efficient bone formation in vivo.