Fabrication of Interleukin-4 Encapsulated Bioactive Microdroplets for Regulating Inflammation and Promoting Osteogenesis

Abstract

Background Despite the inherent regenerative ability of bone, large bone defect regeneration remains a major clinical challenge for orthopedic surgery. Therapeutic strategies medicated by M2 phenotypic macrophages or M2 macrophage inducer have been widely used to promote tissue remodeling. In this study, ultrasound-responsive bioactive microdroplets (MDs) encapsulated with bioactive molecule interleukin-4 (IL4, hereafter designated MDs-IL4) were fabricated to regulate macrophage polarization and potentiate the osteogenic differentiation of human mesenchymal stem cells (hBMSCs). Materials and Methods The MTT assay, live and dead staining, and phalloidin/DAPI dual staining were used to evaluate biocompatibility in vitro. H&E staining was used to evaluate biocompatibility in vivo. Inflammatory macrophages were further induced via lipopolysaccharide (LPS) stimulation to mimic the pro-inflammatory condition. The immunoregulatory role of the MDs-IL4 was tested via macrophage phenotypic marker gene expression, pro-inflammatory cytokine level, cell morphological analysis, and immunofluorescence staining, etc. The immune-osteogenic response of hBMSCs via macrophages and hBMSCs interactions was further investigated in vitro. Results The bioactive MDs-IL4 scaffold showed good cytocompatibility in RAW 264.7 macrophages and hBMSCs. The results confirmed that the bioactive MDs-IL4 scaffold could reduce inflammatory phenotypic macrophages, as evidenced by changing in morphological features, reduction in pro-inflammatory marker gene expression, increase of M2 phenotypic marker genes, and inhibition of pro-inflammatory cytokine secretion. Additionally, our results indicate that the bioactive MDs-IL4 could significantly enhance the osteogenic differentiation of hBMSCs via its potential immunomodulatory properties. Conclusion Our results demonstrate that the bioactive MDs-IL4 scaffold could be used as novel carrier system for other pro-osteogenic molecules, thus having potential applications in bone tissue regeneration.

Development of bioactive and ultrasound-responsive microdroplets for preventing ovariectomy (OVX)-induced osteoporosis

“…44 Therefore, in this study, we evaluated macrophage viability following incubation with MDs-NFATc1 by conducting MTT assays at 1 day and 3 days time points. 28 The MTT assay is one of the most frequently used methods to analyze cell proliferation, viability, and cytotoxicity. 45 As shown in Fig.…”

“…To induce inflammatory macrophage polarization, macrophages were stimulated with 1000 ng mL −1 of lipopolysaccharide (LPS, Escherichia coli 0111: B4, Sigma, China), as established in our previous study. 28…”

Three-dimensional printed titanium mesh combined with iliac cancellous bone in the reconstruction of mandibular defects secondary to ameloblastoma resection

“…Factors contributing to reduced graft volume include autoimmune-induced osteoclastic resorption [ 25 ] and alterations in bone density in the reconstruction area [ 26 ]. Bone resorption commonly correlates with chronic inflammation, M1 macrophages activation, increased generation of reactive oxygen species (ROS), and extended periods of inflammation while bone is being regenerated [ 27 , 28 ]. Moreover, the grafted cancellous bone not only offers mechanical support but also a vast reservoir of bone marrow-derived mesenchymal stem cells (BMSCs) [ 29 ].…”

Microdroplets Encapsulated with NFATc1-siRNA and Exosomes-Derived from MSCs Onto 3D Porous PLA Scaffold for Regulating Osteoclastogenesis and Promoting Osteogenesis

“…The ultrasound stimulation of MDs-NFATc1 was performed following the established protocol in our previous study. 37 In summary, FITC-labeled MDs-NFATc1 were first diluted into PBS. Subsequently, they were exposed to ultrasound stimulation utilizing a portable home use ultrasound pain therapy device, which operated at an acoustic frequency of 1 MHz and a power of 1 W/cm 2 for a duration of 10 minutes (MYCHWAY, China).…”