Effect and mechanism of recombinant human fibroblast growth factor 18 on osteoporosis in OVX mice.

OBJECTIVES: This study aimed to investigate the effect and the mechanism of recombinant human fibroblast growth factor 18 (rhFGF18) on postmenopausal osteoporosis. METHODS: The effect of rhFGF18 on the proliferation and apoptosis of osteoblasts and the mechanism underlying such an effect was evaluated using an oxidative stress model of the MC3T3-E1 cell line. Furthermore, ovariectomy was performed on ICR mice to imitate estrogen-deficiency postmenopausal osteoporosis. Bone metabolism and bone morphological parameters in the ovariectomized (OVX) mice were evaluated. RESULTS: The results obtained from the cell model showed that FGF18 promoted MC3T3-E1 cell proliferation by activating the extracellular signal-regulated kinase (ERK) and p38 instead of c-Jun N-terminal kinase (JNK). FGF18 also prevented cells from damage inflicted by oxidative stress via inhibition of apoptosis. After FGF18 administration, the expression level of anti-apoptotic protein Bcl-2 in the mice was upregulated, whereas those of the pro-apoptotic proteins Bax and caspase-3 were downregulated. Administering FGF18 also improved bone metabolism and bone morphological parameters in OVX mice. CONCLUSIONS: FGF18 could effectively prevent bone loss in OVX mice by enhancing osteoblastogenesis and protecting osteoblasts from oxidative stress-induced apoptosis.

Expression of Halo-hFGF18 and study of its effect on differentiation of ATDC5 cells.

Fibroblast growth factor 18 (FGF18) is a member of the fibroblast growth factor family and important in cartilage growth and development. However, the mechanism by which FGF18 mediates its biological functions is still unclear. In our study, we expressed the rhFGF18 protein fused to a HaloTag, (Halo-rhFGF18). MTT assay results indicated that both rhFGF18 and Halo-rhFGF18 have similar biological activities in NIH3T3 cells. However, basic FGF and acidic FGF were more potent than both rhFGF18 and Halo-rhFGF18. Confocal imaging data indicated that the red fluorescence labeled Halo-rhFGF18 strongly bound to ATDC5 cells and stimulated their proliferation and differentiation, which suggests that glycosaminoglycans may be involved in mediating the biological effects of rhFGF18 in ATDC5 cells. Moreover, western blot results demonstrated that, in ATDC5 cells, ERK1/2 signaling is activated upon stimulation with rhFGF18. Our results may open doors for the use of rhFGF18 as a drug to promote cartilage growth.

Preclinical Use of FGF-18 Augmentation for Improving Cartilage Healing Following Surgical Repair: A Systematic Review.

OBJECTIVE: To evaluate the efficacy of fibroblast growth factor-18 (FGF-18) augmentation for improving articular cartilage healing following surgical repair in preclinical (in vivo) animal models. DESIGN: A systematic review was performed evaluating the efficacy of FGF-18 augmentation with cartilage surgery compared with cartilage surgery without FGF-18 augmentation in living animal models. Eligible intervention groups were FGF-18 treatment in conjunction with orthopedic procedures, including microfracture, osteochondral auto/allograft transplantation, and cellular-based repair. Outcome variables were: International Cartilage Repair Society (ICRS) score, modified O'Driscoll histology score, tissue infill score, qualitative histology, and adverse events. Descriptive statistics were recorded and summarized for each included study. RESULTS: In total, 493 studies were identified and 4 studies were included in the final analysis. All studies were randomized controlled trials evaluating in vivo use of recombinant human FGF-18 (rhFGF-18). Animal models included ovine (n = 3) and equine (n = 1), with rhFGF-18 use following microfracture (n = 3) or osteochondral defect repair (n = 1). The rhFGF-18 was delivered via intra-articular injection (n = 2), collagen membrane scaffold (n = 1), or both (n = 1). All studies reported significant, positive improvements in cartilage defect repair with rhFGF-18 compared with controls based on ICRS score (n = 4), modified O'Driscoll score (n = 4), tissue infill (n = 3), and expression of collagen type II (n = 4) (P < 0.05). No adverse events were reported with the intra-articular administration of this growth factor, indicating short-term safety and efficacy of rhFGF-18 in vivo. CONCLUSION: This systematic review provides evidence that rhFGF-18 significantly improves cartilage healing at 6 months postoperatively following microfracture or osteochondral defect repair in preclinical randomized controlled trials.

Osteochondral tissue engineering using a biphasic collagen/GAG scaffold containing rhFGF18 or BMP-7 in an ovine model.

BACKGROUND: The aim of this study was to investigate the effect of combining rhFGF18 or BMP-7 with a biphasic collagen/GAG osteochondral scaffold (Chondromimetic) on the repair of osteochondral defects in sheep. METHODS: Osteochondral defects (5.8x6mm) were created in the medial femoral condyle (MFC) and the lateral trochlea sulcus (LTS) of the stifle joint of 24 female sheep. Sheep were randomly assigned to four groups (n = 6); 1) empty defect, 2) scaffold only, 3) scaffold + rhFGF-18 (30 µg) and 4) scaffold + BMP-7 (100 µg). At 6 months the defects underwent non-destructive mechanical testing, gross assessment of repair tissue (ICRS score) and histological analysis (Modified O'Driscoll score). RESULTS: ICRS repair score: Defects treated with scaffold + rhFGF18 (mean 9.83, 95% CI 8.43-11.23) and scaffold + BMP-7 (10, 9.06-10.94) in the MFC had significantly improved ICRS scores compared to empty defects (4.2, 0-8.80) (p = 0.002). Mechanical properties: BMP-7 treated defects (mean 64.35, 95% CI 56.88-71.82) were significantly less stiff than both the rhFGF18 (mean 84.1, 95% CI 76.8-91.4) and empty defects in the LTS, compared to both contralateral limb (p = 0.003), and the perilesional articular cartilage (p < 0.001). HISTOLOGY: A statistically significant improvement in the modified O'Driscoll score was observed in the rhFGF18 treated group (mean 16.83, 95% CI 13.65-20.61) compared to the empty defects (mean 9, 95% CI 4.88-13.12) (p = 0.039) in the MFC. Excellent tissue fill, lateral integration and proteoglycan staining was observed. Only the rhFGF18 defects showed pericellular type VI collagen staining with positive type II collagen and reduced positive type I collagen staining. The majority of defects in the control and BMP-7 groups demonstrated fibrocartilagenous repair tissue. CONCLUSION: Statistically significant improvements in gross repair, mechanical properties and histological score were found over empty defects when Chondromimetic was combined with rhFGF18. These results suggest that rhFGF18 may play a significant role in articular cartilage repair applications.