HA/MgO nanocrystal-based hybrid hydrogel with high mechanical strength and osteoinductive potential for bone reconstruction in diabetic rats.

Bone repair and regeneration processes are markedly impaired in diabetes mellitus (DM). Intervening approaches similar to those developed for normal healing conditions have been adopted to combat DM-associated bone regeneration. However, limited outcomes were achieved for these approaches. Hence, together with osteoconductive hydroxyapatite (HA) nanocrystals, osteoinductive magnesium oxide (MgO) nanocrystals were uniformly mounted into the network matrix of an organic hydrogel composed of cysteine-modified γ-polyglutamic acid (PGA-Cys) to construct a hybrid and rough hydrogel scaffold. It was hypothesized that the HA/MgO nanocrystal hybrid hydrogel (HA/MgO-H) scaffold can significantly promote bone repair in DM rats via the controlled release of Mg2+. The HA/MgO-H scaffold exhibited a sponge-like morphology with porous 3D networks inside it and displayed higher mechanical strength than a PGA-Cys scaffold. Meanwhile, the HA/MgO-H scaffold gradually formed a tough hydrogel with G' of more than 1000 Pa after hydration, and its high hydration swelling ratio was still retained. Moreover, after the chemical degradation of the dispersed MgO nanocrystals, slow release of Mg2+ from the hydrogel matrix was achieved for up to 8 weeks because of the chelation between Mg2+ and the carboxyl groups of PGA-Cys. In vitro cell studies showed that the HA/MgO-H scaffold could not only effectively promote the migration and proliferation of BMSCs but could also induce osteogenic differentiation. Moreover, in the 8th week after implanting the HA/MgO-H scaffold into femur bone defect zones of DM rats, more effective bone repair was presented by micro-CT imaging. The bone mineral density (397.22 ± 16.36 mg cm-3), trabecular thickness (0.48 ± 0.07 mm), and bone tissue volume/total tissue volume (79.37 ± 7.96%) in the HA/MgO-H group were significantly higher than those in the other groups. Moreover, higher expression of COL-I and OCN after treatment with HA/MgO-H was also displayed. The bone repair mechanism of the HA/MgO-H scaffold was highly associated with reduced infiltration of pro-inflammatory macrophages (CD80+) and higher angiogenesis (CD31+). Collectively, the HA/MgO-H scaffold without the usage of bioactive factors may be a promising biomaterial to accelerate bone defect healing under diabetes mellitus.

Bone-Inspired Tube Filling Decellularized Matrix of Toad Cartilage Provided an Osteoinductive Microenvironment for Mesenchymal Stem Cells to Facilitate the Radius Defect Repair of Rabbit.

Toad bone not only contains the rich cartilage-like matrix but also presents low immunogenicity. It is inferred that decellularized toad bone matrix (dBECM) may provide the more profitable osteoinductive microenvironment for mesenchymal stem cells (MSCs) to promote the repair of bone defects. Herein, a hollow bone-inspired tube is first made from hydroxyapatite (HA) and poly (γ-glutamic acid) (PGA), and then MSCs/dBECM hydrogel is uniformly filled to its central cavity, constructing a biomimetic bone (dBECM + MSCs - PGA + HA). In vitro scratch and transwell experiments show that dBECM hydrogel not only effectively promotes migration and proliferation of MSCs but also induces their osteogenic differentiation. Moreover, the less inflammatory macrophages infiltrate at rat skin after subcutaneously injecting dBECM hydrogel, indicating its low potential for inflammatory attack. After implanting dBECM + MSCs - PGA + HA to critical radius defect of rabbit, X-ray and CT imaging shows that the cortex is effectively regenerated and the medullary cavity recanalization is completed at 20 weeks. Moreover, the expression of Collagen-II and OCN are obviously increased in the defect after implanting dBECM + MSCs - PGA + HA. The therapeutic mechanism of dBECM + MSCs - PGA + HA scaffold are highly associated with the enhanced angiogenesis. Collectively, the biomimetic dBECM + MSCs - PGA + HA scaffold may be a promising strategy to improve radius defect healing efficiency.

Homing of ICG-loaded liposome inlaid with tumor cellular membrane to the homologous xenografts glioma eradicates the primary focus and prevents lung metastases through phototherapy.

Currently, phototherapy initiated by local irradiation with a near-infrared (NIR) laser has emerged as a promising strategy for cancer treatment owing to its low toxicity. However, a key problem for effective phototherapy is how to specifically deliver a sufficient dose of photosensitizers to a tumor focus. Herein, indocyanine green (ICG), a United States Food and Drug Administration (US FDA)-approved photosensitizer, was first encapsulated in an inner aqueous compartment of liposome (ICG-LIP) to improve its stability. Thereafter, tumor cell membranes were isolated from native glioma cells and subsequently inlaid in the bilayer lipid membrane of ICG-LIP to construct cell-like liposomes (ICG-MCLs). ICG was easily encapsulated into the ICG-MCLs with a very high encapsulation efficiency, reaching 78.01 ± 0.72% and its concentration in the final formulation reached 200 µg mL-1. The ICG-MCLs displayed a spherical morphology with a hydrodynamic diameter (Dh) of 115.0 ± 0.5 nm, a PDI of 0.14, and a zeta potential of -11.2 ± 0.9 mV. Moreover, ICG-MCLs exhibited a good stability in terms of particle size and significantly improved the chemical stability of ICG in pH 7.4 PBS at 37 °C. In addition, the temperature of the ICG-MCLs rapidly increased to 63 °C after 10 min irradiation and this was maintained for a longer time. Owing to the cancer cell membrane associated protein, the ICG-MCLs were specifically internalized by homogenous glioma C6 cells in vitro, which resulted in the strong red fluorescence of ICG in cytoplasm. Moreover, in vivo imaging showed that the ICG-MCLs were effectively homed to the tumor site of C6 glioma-bearing Xenograft nude mice through vein injection, which resulted in the temperature of the tumor site rapidly rising, allowing the killing of tumor cells after local NIR irradiation. After treatment with the ICG-MCLs, the primary tumor focus was completely eradicated and lung metastases were effectively inhibited. In conclusion, liposomes inlaid with tumor cellular membranes may serve as an excellent nanoplatform for homologous-targeting phototherapy using ICG.