Injectable thermo-sensitive hydrogels composed of small intestinal submucosa (SIS) with exosomes derived from bone marrow mesenchymal stem cells (BMSCs) are desired for bone regeneration. However, poor mechanical properties limit the clinical application of SIS hydrogels. Herein, the mechanical properties of SIS hydrogels incorporated with 3-(3,4-dihydroxyphenyl) propionic acid (CA) are assessed. The results show that the mechanical properties of SIS hydrogels are improved. In addition, the retention and stability of exosomes over time at the defect site are also challenges. Fusion peptides are designed by connecting collagen-binding domines (CBDs) of collagen type I/III with exosomal capture peptides CP05 (CRHSQMTVTSRL) directly or via rigid linkers (EAAAK). In vitro experiments demonstrate that fusion peptides are contribute to promoting the positive effect of exosomes on osteogenic differentiation of BMSCs. Meanwhile, the results of hydrogels combining exosomes and fusion peptides in the treatment of rat skull defect models reveal that fusion peptides could enhance the retention and stability of exosomes, thereby strengthen the therapeutic effect for skull defects. Therefore, SIS hydrogels with CA modified by fusion peptides and exosomes appear to be a promising strategy in bone regenerative medicine.

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This work reports an experiment/simulation combination study on the magnetorheological (MR) mechanism of magnetic fluid based on Fe3O4 hollow chains. The decrease of shear stress versus the increasing magnetic field was observed in a dilute magnetic fluid. Hollow chains exhibited a higher MR effect than pure Fe3O4 hollow nanospheres under a small magnetic field. A modified particle level simulation method including the translational and rotational motion of chains was developed to comprehend the correlation between rheological properties and microstructures. Sloping cluster-like microstructures were formed under a weak external field (24 mT), while vertical column-like microstructures were observed under a strong field (240 mT). The decrease of shear stress was due to the strong reconstruction process of microstructures and the agglomeration of chains near the boundaries. The chain morphology increased the dip angle of microstructures and thus improved the MR effect under a weak field. This advantage made Fe3O4 hollow chains to be widely applied for small and low-power devices in the biomedical field. Dimensionless viscosity as a function of the Mason number was collapsed onto linear master curves. Magnetic fluid in Poiseuille flow in a microfluidic channel was also observed and simulated. A qualitative and quantitative correspondence between simulations and experiments was obtained.

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Objectives Diabetic wound healing remains a global challenge in the clinic and in research. However, the current medical dressings are difficult to meet the demands. The primary goal of this study was to fabricate a functional hydrogel wound dressing that can provide an appropriate microenvironment and supplementation with growth factors to promote skin regeneration and functional restoration in diabetic wounds. Materials and Methods Small extracellular vesicles (sEVs) were bound to the porcine small intestinal submucosa‐based hydrogel material through peptides (SC‐Ps‐sEVs) to increase the content and achieve a sustained release. NIH3T3 cell was used to evaluate the biocompatibility and the promoting proliferation, migration and adhesion abilities of the SC‐Ps‐sEVs. EA.hy926 cell was used to evaluate the stimulating angiogenesis of SC‐Ps‐sEVs. The diabetic wound model was used to investigate the function/role of SC‐Ps‐sEVs hydrogel in promoting wound healing. Results A functional hydrogel wound dressing with good mechanical properties, excellent biocompatibility and superior stimulating angiogenesis capacity was designed and facilely fabricated, which could effectively enable full‐thickness skin wounds healing in diabetic rat model. Conclusions This work led to the development of SIS, which shows an unprecedented combination of mechanical, biological and wound healing properties. This functional hydrogel wound dressing may find broad utility in the field of regenerative medicine and may be similarly useful in the treatment of wounds in epithelial tissues, such as the intestine, lung and liver.

Guided bone regeneration (GBR) technology is the most widely used and stable method for bone defect repair. However, infectious bone defect limits the application of this technique. Herein, a small intestinal submucosa (SIS) membrane modified by chimeric peptides as a new type of GBR membrane is developed for efficacious tissue regeneration. Based on the main components of SIS membrane are I and III collagen, collagen binding peptides TKKTLRT and KELNLVY sequences are used to construct chimeric peptides with healing‐promoting peptide Hst1 or antibacterial osteogenic peptide JH8194, so as to realize the specifically target of SIS. This method achieves the fast and efficient multifunctional modification of SIS membrane. The chimeric peptides modified SIS (pSIS) membrane has satisfactory biocompatibility and a certain degree of antibacterial activity. Moreover, pSIS promotes the osteogenic related factors expression of rat bone mesenchymal stem cells and demonstrates great bone regeneration in rat skull defect model. Furthermore, pSIS accelerates the migration of oral epithelial cells in vitro and activate integrin α3β1 signal pathway contribute to wound healing. This study presents a novel biomaterial design of GBR membrane, specifically for the treatment of infectious bone defects.

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