RESUMO
An effective method for controlling the corrosion rate of Mg-based implants must be urgently developed to meet the requirements of clinical applications. As a naturally occurring osteoid material, nacre offers a strategy to endow biomedical Mg alloys with excellent biocompatibility, and corrosion resistance. In this study, pearl powder and NaH2PO4 were used as precursors to deposit coatings on AZ91D alloy substrates hydrothermally based on Na2EDTA-assisted induction. Na2EDTA-induced nacre coatings were fabricated at various pH values, and its chemical composition and microstructure were analyzed via energy-dispersive X-ray, scanning electron microscopy, and X-ray diffraction spectroscopy. The corrosion-resistant performance and cytocompatibility of the samples were evaluated via electrochemical measurements and in vitro cell experiments. Results showed that the samples hydrothermally treated under faint acid conditions present excellent corrosion resistance, whereas the samples treated under slight alkaline conditions demonstrate improved biocompatibility due to high Ca and P content and large Ca/P atomic ratio. This study provides substantial evidence of the potential value of nacre coatings in expanding the biological applications of implanted biomaterials.
RESUMO
BACKGROUND: Restenosis remains a clinical problem; drug-coated balloons (DCBs) have demonstrated high efficiency in this situation. DCBs prevent neointimal hyperplasia by inhibiting cell proliferation and migration. Tetramethylpyrazine (TMP) is a traditional Chinese medicine originally isolated from the rhizome of Ligusticum Walliichii, which can inhibit platelet aggregation and smooth muscle cell proliferation. We hypothesized that TMP-coated balloons (TCB) could reduce neointimal hyperplasia through the NF-κB signalling pathway. METHODS: Twenty-one New-Zealand White rabbits (2.5-3.0 kg, male) were fed high-fat diets; 36 bilateral iliac artery stenosis models were successfully established by balloon straining. Rabbits were randomly treated with TCB (n=20) or plain balloons (PBA, n=16) (3 died during model construction). Angiographies were recorded at baseline, the immediate period, and 4 weeks later. Animals were euthanized and arteries collected for histological analysis and immunohistochemical staining. Protein expression of proliferating cell nuclear antigen (PCNA) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) p65 of the vessel samples were analyzed using Western blotting. RESULTS: No difference existed in the baseline lesion characteristics or procedural results. Angiographic follow-up was successfully performed on 18 rabbits (TCB: n=20, PBA: n=16), except for 3 deaths related to the operation. Treatment with TCB was superior to that with PBA, with lower late lumen loss (0.45±0.23 vs. 0.84±0.17 mm, P<0.01). Pathological analysis confirmed the efficiency of TCB through decreasing the area stenosis rate compared with PBA (46.48%±8.22% vs. 75.24%±6.10%, P<0.01). As determined by Western blotting, significant reductions occurred in PCNA and NF-κB p65 protein intensity in the TCB group versus the PBA group (all P<0.01). TCB efficiently mitigated restenosis in the rabbit iliac artery model. CONCLUSIONS: This study elucidated that TCB could restrain intimal hyperplasia of vessels by inhibiting the activation of the NF-κB pathway to reduce inflammatory response and decrease the rate of cell proliferation through suppressing PCNA expression.