Performance of two bone substitutes of novel cotton-like ß-TCP/PDLGA and granular ß-TCP on bone regeneration in the femoral bone defect of the Beagle dogs.

This study aimed to clarify whether novel cotton-like composite made of ß-tricalcium phosphate (ß-TCP) and poly(Dl-lactide-co-glycolide) (PDLGA) has a different effect on in vivo bone regeneration after bone defect than that of granular ß-TCP. Five male Beagle dogs served as subjects. Cortical and medullary bone defect as non-through holes were made at the diaphysis of the bilateral femurs. One side was implanted with ß-TCP/PDLGA (ß-TCP/PDLGA group) and the other side was implanted with granular ß-TCP (ß-TCP group). At 4 weeks after implantation, we found no significant differences in the percentages of newly formed bone area and fibrous tissue area in the bone defect between the two groups. The ß-TCP/PDLGA group showed more uniform filling on the surface and earlier disappearance of the material in the medullary region, and there were fewer inflammatory cells and osteoclasts in the bone defect in the ß-TCP/PDLGA group. In conclusion, ß-TCP/PDLGA performs better at filling the bone defect uniformly and disappears earlier at the cortical and medullary regions while causing less inflammation and bone resorption. Although bone formation activity of the ß-TCP/PDLGA group in the cortical region was lower, the newly formed bone volume in bone defect of the ß-TCP/PDLGA group was equal to that of the ß-TCP group.

Improved Healing by Adjuvant Osteoconductive Therapy Using a Novel Cotton-Like Hydroxyapatite Sheet After Median Sternotomy.

The union rate of wire fixation after median sternotomy remains unsatisfactory. We developed a novel osteoconductive sheet composed of hydrophilized hydroxyapatite and evaluated its osteogenetic effect when interposed between sternal halves in a canine model. Eighteen canines were divided equally into groups based on the hemostatic agent used: osteoconductive sheet (S), none (C), and bone wax (BW). After median sternotomy, the sternal halves were closed by wire fixation. In each group, 3 canines were euthanized at 1 month, while 3 were euthanized at 2 months. Resected sternums were mechanically assessed by the 3-point bending test, radiographically assessed by micro-CT, and pathologically assessed to quantify the osteogenesis between sternal halves. Compared with the BW group, the S group had a greater maximum stress at 1 month (S: 322.9 ± 107.7 N, C: 233.0 ± 62.7 N, BW: 124.9 ± 88.4 N; P = 0.025), and greater maximum shear force at 1 month (S: 1.92 ± 0.67 N/m2; C: 1.23 ± 0.28 N/m2; BW: 0.68 ± 0.41 N/m2; P = 0.025). Micro-CT revealed that the S group had more osteogenesis than the BW group at 1 month (25.7% ± 9.8% vs 6.9% ± 9.2%), and 2 months (34.0% ± 15.1% vs 14.8% ± 9.4%); the respective values in the C group were 17.1% ± 7.2% and 29.7% ± 9.3%. Pathologic examination revealed that the S group had the greatest osteogenetic area at 2 months (S: 38.8% ± 18.8%; C: 24.5% ± 6.9%; BW: 24.7% ± 18.6%). Adjuvant osteoconductive therapy using a cotton-like hydroxyapatite sheet in addition to wire fixation significantly improved sternal healing compared with BW. This new material also showed relatively better outcome than the C group.

Enhancement of phagocytosis and cytotoxicity in macrophages by tumor-derived IL-18 stimulation.

Inoculation of mice with the murine NFSA cell line caused the formation of large tumors with necrotic tumor cores. FACS analysis revealed accumulations of CD11b(+) cells in the tumors. Microarray analysis indicated that the NFSA cells expressed a high level of the pro-inflammatory factor interleukin-18 (il-18), which is known to play a critical role in macrophages. However, little is known about the physiological function of IL-18-stimulated macrophages. Here, we provide direct evidence that IL-18 enhances the phagocytosis of RAW264 cells and peritoneal macrophages, accompanied by the increased expression of tumor necrosis factor (tnf-α), interleukin-6 (il-6) and inducible nitric oxide synthase (Nos2). IL-18-stimulated RAW264 cells showed an enhanced cytotoxicity to endothelial F-2 cells via direct cell-to-cell interaction and the secretion of soluble mediators. Taken together, our results demonstrate that tumor-derived IL-18 plays an important role in the phagocytosis of macrophages and that IL-18-stimulated macrophages may damage tumor endothelial cells.

Role of FGF10 on tumorigenesis by MS-K.

Murine MS-K and NFSA cell lines formed tumor after inoculation into mouse and both cell lines expressed high level of vascular endothelial growth factor-A (vegf-A) and produced same level of VEGF-A. However, poor blood vessel formation, and necrosis was significantly observed in NFSA-tumor, contrary to well-developed blood vessel formation in MS-K tumor. The microarray analysis showed high expression of fibroblast growth factor-10 (fgf-10) in MS-K than NFSA. In this report, the role of fgf-10 on tumor growth was studied. MS-K enhanced more proliferation of endothelial cells by direct co-culture than NFSA, and rFGF10 supported the proliferation of HUVEC in combination with VEGF-A. fgf-10-knocked down MS-K, MS-K (fgf-10-KD), proliferated slower in vitro and the tumorigenicity of them was also slower than control. The blood vessel formation in these MS-K (fgf-10-KD) clones was reduced compared with the MS-K (normal). qPCR analysis showed the suppression of vegf-A, vegf-C and fgfr-1-expression in the MS-K (fgf-10-KD) clones. Taken together, these results indicated that FGF10, which was produced from tumor cells, was essential for the proliferation of tumor cell itself and also supports proliferation of endothelial cells. Thus, FGF10 plays an important role for tumor growth by both paracrine and autocrine manner.