RESUMEN
Objective To investigate the correlation between mechanical properties and hemostatic ability of the sealing hydrogels. Methods The gelation time, elastic modulus, viscous modulus, bursting strength and hemostatic ability of the hyaluronic acid/gelatin hydrogels were measured. Compared with fibrin sealant, gelation time and mechanical parameters were proposed to judge the feasibility of sealing hydrogels to be used for hemostasis in clinic. Results Hydrogels with a long gelation time, low elastic modulus, low viscous modulus and small bursting strength were merely suitable for hemostasis in minor bleeding. The hydrogels with short gelation time, high elastic and viscous modulus and large bursting strength could effectively reduce the blood loss in the cases of massive bleeding. Conclusions The hemostatic ability of a hydrogel was correlated to its gelation time, elastic modulus, viscous modulus and bursting strength. To achieve hemostasis as effective as fibrin sealant, the gelation time of a sealing hydrogel should be less than 120 s, its elastic and viscous modulus should exceed 600 Pa and 120 Pa, respectively. For the damage with diameter of 2 mm in the tissue model, the burst strength should exceed 10.7 kPa and preferably be larger than 16.0 kPa.
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Objective: To construct a novel antibacterial and injectable hydrogel (BMP/Gel/SH-Ag) loaded with bone morphogenetic protein-2 (BMP-2) microspheres, and investigate its biocompatibility, antibacterial properties and bone-promoting properties. Methods: The photocrosslinked gelatin microspheres loaded with BMP-2 were prepared by microfluidics. The microspheres were mixed with 4-arm thiol-terminated poly (ethylene glycol) (4SH-PEG) and crosslinked with Ag+ to prepare injectable sulfhydrylated PEG hydrogels (BMP/Gel/SH-Ag). The micromorphology of microspheres and hydrogels was observed by light microscope and scanning electron microscope. The drug release profile was investigated at 37℃ in a shaker (100 r/min). The injectability of BMP/Gel/SH-Ag was evaluated by injecting hydrogel using a syringe with a tip diameter of 0.5 mm. The antibacterial activity of BMP/Gel/SH-Ag against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) was evaluated by agar diffusion test. The biocompatibility of BMP/Gel/SH-Ag was verified by CCK-8, and the bone-promoting activity was evaluated by alkaline phosphatase (ALP) assay and calcium nodule staining in bone marrow mesenchymal stem cells (BMSCs). Results: Gelatin microspheres had smooth appearance and uniform particle size distribution (~ 350 μm). BMP/Gel/SH-Ag had porous micro-structure and can be injected with a syringe needle with a diameter of up to 0.5 mm in diameter to produce hydrogel filament. The cumulative release of BMP-2 from BMP/Gel/SH-Ag was (81.8±3.6)% after being incubated for 8 d. BMP/Gel/SH-Ag had obvious inhibitory effect on S. aureus and E. coli. CCK-8 results showed that BMP/Gel/SH-Ag had good biocompatibility. BMP/Gel/SH-Ag can increase the expression of ALP and the content of calcium nodules in rat BMSCs. Conclusion: The BMP/Gel/SH-Ag has good performance in promoting osteogenesis and an-ti-infection.
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PURPOSE: In this study, we investigated the potential of injectable hydrogel scaffolds for the regeneration of nucleus pulposus. MATERIALS AND METHODS: We prepared injectable hydrogels [Chitosan-Pluronic (CP), CP/Osteogenic Protein-1 (CP/OP-1), CP/Gly-Arg-Gly-Asp-Ser (CP/GRGDS), CP/GRGDS/OP-1] for this study. One of the four potential materials was selected through the cell viability tests. For each material, primary cultured nucleus pulposus (NP) cells from New Zealand rabbits were seeded onto each material. For the investigation of the effects of mechanical stimulation, the commercially available bioreactor was used. 0.2 MPa of intermittent hydrostatic pressure was imposed for 3 days after 7th day of seeding with the pattern of 2 min and 15 min for stimulating and resting, respectively. The specimens were harvested at 1, 10, 14 day after seeding for analyses. RESULTS: The MTT assay for 5 days revealed that CP/OP-1 group showed significant increase. The other two groups (CP/GRGDS and CP/GRGDS/OP-1) showed that the proliferation rate increased until 3 days after culture, while it decreased on day 5. The mechanical stimuli induced higher amounts of DNA measured in CP/OP- 1 on day 5 after culture. However, no significant difference was observed between two groups. CONCLUSION: We came to the conclusions that the biochemical environment as well as mechanical stimulation may play an important role in regenerating nucleus pulposus matrix, especially in CP/OP-1 in this study. However, further study are recommended in relation to mechanical effects as well as biochemical conditions.