RESUMO
Objective To investigate the effect of silk fibroin (SF) on degradation and biocompatibility of poly (L-lactic acid-co-e-caprolactone) (P[LLA-CL]) in vivo. Methods The scaffolds of P(LLA-CL) (w/w=1:1) blended with 25% of SF (SF/P[LLA-CL]) and P(LLA-CL) were prepared by electrospinning. Both kinds of scaffolds were subcutaneously implanted in 45 6-month-old rats for up to 6 months to evaluate their degradation and biocompatibility characteristics. Results Pathological sections showed P(LLA-CL) scaffold become swollen and began to separate into different layers after 3 months, and then become broken after 6 months; while SF/P (LLA-CL) scaffold largely maintained its structure after 6 months. Immunohistochemical staining showed a large number of macrophages on the surface and in P(LLA-CL) scaffolds 1 month after implantation, and they could still be found 3 months after implantation, accompanied by foreign body giant cells; while no obvious macrophages or foreign body giant cells were found in SF/P(LLA-CL) scaffolds at different time points. Examination of inflammatory gene expression showed that TNF-α and IL-10 expression in P(LLA-CL) scaffolds was significantly higher than that in SF/P(LLA-CL) scaffolds 1 week after implantation (P<0. 05), the same was also true for TNF-α, IL-1β and IL-10 expression 1 month after implantation (P<0. 05), for TNF-α and IL-10 expression 2 months after implantation (P<0. 05), for TGF-β expression 3 months after implantation (P<0. 05%, and for IL-1β and TGF-β expression 6 months after implantation (P<0. 05%). Conclusion SF incorporation can delay degradation, reduce inflammation, and improve the biocompatibility of P(LLA-CL) scaffolds, which may provide reference for scaffold design in tissue engineering.
RESUMO
Objective To develop a new type of combined bone grafts mainly including nanometer hydroxyapatite (n-HA) and α-calcium sulphate hemihydrate (α-CSH), and investigate its setting property and compressive strength. Methods The setting time and compressive strength of nHA/α-CSH combined bone grafts with different liquid-to-solid (L/S) ratio or calcium sulphate dehydrate (CSD) amount were measured and observed by the X-ray diffraction (XRD) and the scanning electron microscope (SEM). Results The setting time of combined bone grafts was increased along with the increase of L/S ratio or nHA amount, and reduced with the increase of CSD amount. The setting time of the compound with 20% of nHA, 80% of α-CSH was (169±36) min, while that of the compound with 5% of nHA, 20% of CSD, 75% of α-CSH was (6±1.1) min. The compressive strength of combined bone grafts reduced along with the increase of nHA amount. The average compressive strength of pure α-CSH was (12.3±2.4) MPa, while that of the compound with 20% of nHA, 80% of CSH was (4.8±0.6) MPa. The XRD results showed that no other materials were produced except that α-CSH was transformed to CSD during the setting process. The SEM results indicated that nHA was filled in the crystal structure of the CSD, presenting two-phase structure. Conclusions The setting time and compressive strength of nHA/α-CSH combined bone grafts can be adjusted by the different proportion of nHA, CSD amount and L/S ratio, which provides an appropriate condition for clinical application.