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Because tissue responses to implants determine the success or failure of tissue engineering products, fibroin/sericin-based scaffolds including bionic silk scaffolds, native silk fibers, fibroin fibers, and regenerated fibroin have been fabricated, and their biocompatibility was investigated. Fibroin/sericin-based scaffolds were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Bionic silk scaffolds were beneficial to silk fiber formation through self-assembly. Histological and immunofluorescent staining analysis demonstrated that bionic silk scaffolds did not show significant inflammatory responses. Immunization analysis showed that soluble fibroin and sericin did not show obvious immunogenicity. This work supplied an effective approach to design fibroin/sericin-based scaffolds for tissue engineering and drug delivery.

Spinal cord injury (SCI) is an incurable trauma that frequently results in partial or complete loss of motor and sensory function. Massive neurons are damaged after the initial mechanical insult. Secondary injuries, which are triggered by immunological and inflammatory responses, also result in neuronal loss and axon retraction. This results in defects in the neural circuit and a deficiency in the processing of information. Although inflammatory responses are necessary for spinal cord recovery, conflicting evidence of their contributions to specific biological processes have made it difficult to define the specific role of inflammation in SCI. This review summarizes our understanding of the complex role of inflammation in neural circuit events following SCI, such as cell death, axon regeneration and neural remodeling. We also review the drugs that regulate immune responses and inflammation in the treatment of SCI and discuss the roles of these drugs in the modulation of neural circuits. Finally, we provide evidence about the critical role of inflammation in facilitating spinal cord neural circuit regeneration in zebrafish, an animal model with robust regenerative capacity, to provide insights into the regeneration of the mammalian central nervous system.

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Increasing evidence shows that the physical properties of biomaterials play an important role in regulating cell behavior and function, especially the mechanical properties of biomaterials. Macrophages can also be multidirectionally regulated by mechanical factors in the microenvironment, which simultaneously mediate biomaterials response that triggered by foreign body reactions (FBR). However, how the stiffness of biomaterials regulates macrophages and the underlying mechanisms are still not well understood. Our study demonstrates that chitosan freeze-dried scaffolds with different elastic modulus can modulate the proliferative capacity, growth morphology and polarization behavior of macrophages. The compression tests and morphology observation confirmed that the prepared lyophilized chitosan scaffolds possessed varied stiffness. The fluorescence staining experiments showed that the RAW macrophage cell lines exhibited differences in proliferation and morphology on the freeze-dried scaffolds with different stiffness. Macrophages in the 5% group (elastic modulus of 106.7 kPa) had the largest number and mean cell area. Furthermore, ELISA and qPCR results illustrated that macrophage polarization towards the M1/M2 phenotype was strongly influenced by the stiffness of the lyophilized scaffolds. The study may provide new insights and references for designing the elastic moduli of biomaterials for regulating immune responsiveness.