Zhe Xing

Objectives: An infectious trigger can initiate a systemic inflammatory response, which in turn activates immune cells and causes the release of various mediators. Local mediators, such as resolvin D1 (RvD1), actively interact with immune cells to promote the resolution of inflammation. This study aimed to determine the impact of RvD1 on the inflammatory response mediated by monocytes in response to LPS. Methods: To investigate the mechanism by which RvD1 affects the monocyte-mediated inflammatory response to LPS, human THP-1 monocytic cells were treated with LPS, RvD1, or vehicle for 24 h. Inflammatory cytokines, interleukin-1β (IL-1β) and tumor necrosis factor (TNF-α), were measured using enzyme-linked immunosorbent assay (ELISA). RNA sequencing (RNA-seq) was used to identify differentially expressed genes (DEGs). The NF-κB and MAPK p38 signaling pathways were validated using real-time quantitative PCR (RT-qPCR) and Western blotting (WB). Results: RvD1 diminished the levels of IL-1β and TNF-α in LPS-induced inflammation. RvD1 significantly enhanced the mRNA expression of CREB, NRF2, and BCL-2. In addition, RvD1 significantly decreased the mRNA expression of CASP3. RvD1 regulated the inflammatory process in human monocytic THP-1 cells via the NF-κB p65 (MyD88, p65) and p38 MAPK signaling pathways (p38, BCL-2) and further suppressed the expression of apoptotic factors (PI3K, caspase-3). Conclusions: RvD1 has been shown to exert pro-resolving effects by regulating the anti-apoptotic gene BCL-2 and activating the NF-κB p65 and MAPK p38 signaling pathways.

Medication-related osteonecrosis of the jaw (MRONJ) is a severe complication associated with antiresorptive therapy, characterized by compromised bone and soft tissue integrity. However, the underlying tissue-level mechanisms remain poorly understood. To uncover cell functions and spatial organization surrounding ONJ lesions, imaging mass cytometry is used to profile lesions at single-cell resolution across epithelial, stromal, and vascular regions. Widespread immune infiltration is observed, with regulatory T cells, M2-like macrophages, exhausted T cells, and natural killer cells shifting from dispersed to clustered spatial patterns, indicating altered immune organization. Epithelial regions show reduced epithelial marker expression and disrupted architecture despite elevated proliferation-related markers, while fibroblasts and endothelial cells display signs of activation. Functional profiling reveals concurrent proliferative, apoptotic, and stress-associated signatures across multiple cell populations. This comprehensive spatial and functional atlas provides insights into the pathophysiology of MRONJ and may inform future therapeutic strategies aimed at restoring tissue homeostasis and promoting effective healing.

Objectives: Periodontitis is a multifactorial inflammatory disease initiated by pathogenic bacteria, such as Porphyromonas gingivalis. Resolvin D1 (RvD1) plays a pivotal role in inflammation resolution. This study aimed to identify the mechanism of the regulatory effects of RvD1 on the inflammatory response of human periodontal ligament cells (hPDLCs). Methods: To investigate the mechanism of RvD1’s impact on the hPDLCs, RNA-sequencing (RNA-seq) was used and differentially expressed genes (DEGs) were identified. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed to assess the signaling pathways in which NF-κB and MAPK were determined to play a significant role. Alterations in NF-κB and MAPK pathways were verified by immunofluorescence (IF), quantitative real-time PCR (qRT-PCR), and Western blotting (WB). The expression of RvD1 and lipoxin A4/formyl peptide receptor 2 (ALX/FPR2) was assessed by IF and WB. Inflammatory cytokine interleukin (IL) 6 and IL-1β release was measured by ELISA. Results: GO and KEGG analyses indicated that RvD1 regulates the inflammatory process in PDLCs primarily via TLR4-MyD88-mediated NF-κB and MAPK signaling. RvD1 suppressed lipopolysaccharide (LPS)-induced TLR4 and MyD88 expression, inhibited phosphorylation of NF-κB p65 and its inhibitor IKBKB, and attenuated phosphorylation of p38 MAPK, ERK, and JNK. ALX/FPR2 was expressed on hPDLCs and was further upregulated upon treatment with RvD1. RvD1 significantly down-regulated the IL-6 and IL-1β levels in LPS-stimulated hPDLCs. Conclusions: RvD1 regulates the inflammatory response of LPS-stimulated hPDLCs by the TLR4-MyD88-MAPK and TLR4-MyD88-NF-κB signaling pathways, suggesting the potential role of RvD1 in restoring periodontal tissue homeostasis by regulating PDLC response to inflammatory and infectious stimuli.

Background/Objectives: Constant inflammation can be a detrimental response in bone regeneration. To regulate of the inflammatory response and synchronically promote rapid tissue regeneration is a vital clinical challenge. The urinary bladder matrix (UBM) and small intestinal submucosa (SIS) composite are commonly used extracellular matrix (ECM) materials. We designed a novel drug-loaded membrane by integrating the biological matrix (BM) composed of UBM and SIS composites with Resolvin D1 (RvD1), an endogenous pro-resolving lipid mediator, using the lyophilization process. This membrane is referred to as BRL, an acronym for BM-RvD1-Lyophilization. Methods: In this study, the physicochemical properties of the membranes were characterized. Fluorescence staining and the CCK8 assay kit were utilized to assess biocompatibility. To evaluate the inflammatory resolution properties and osteogenic ability of osteoblasts, real-time quantitative PCR and ELISA were conducted. Results: BRL exhibited a more pronounced three-dimensional pore structure, demonstrating excellent physicochemical properties and enabling the slow release of RvD1. This approach improved the viability of MG63 osteoblast-like cells, reduced LPS-induced inflammation, and upregulated osteogenesis-related genes significantly. Conclusions: By integrating inflammation control capabilities into tissue regeneration materials, BRL effectively regulates the tissue regeneration microenvironment, thereby enhancing regeneration efficiency and positioning itself as an exceptional candidate for future tissue regeneration membranes.

Objective: To evaluate the drug release, cytocompatibility with periodontal ligament cells (PDLCs), and therapeutic efficacy of GelMA hydrogel loaded with resolvin D1 (RvD1) in treating rat periodontal inflammation and alveolar bone damage. Methods: An RvD1 complexed with GelMA was prepared, and its release kinetics and compatibility with PDLCs were assessed. Rats with induced periodontitis were treated weekly with topical applications of vehicle, GelMA, RvD1, or RvD1 complexed with GelMA for four weeks. Periodontal inflammation and tissue regeneration were evaluated using quantitative PCR (qPCR) and histochemical staining, while alveolar bone repair and regeneration were analyzed through micro-CT. Results: The RvD1 complexed with GelMA effectively released RvD1 and enhanced the proliferation and viability of PDLCs. Compared to RvD1 alone, treatment with RvD1 complexed with GelMA significantly reduced inflammatory cell infiltration, TNF-α and RANKL expression, and osteoclast formation in periodontal tissues. Additionally, it promoted the expression of specific anti-inflammatory and regenerative markers. Micro-CT analysis confirmed significant new bone formation in the RvD1 complexed with GelMA-treated group. Conclusions: RvD1 complexed with GelMA provides sustained drug release and biocompatibility, effectively resolves periodontal inflammation, and promotes tissue regeneration in periodontitis.

The primary goal of bone tissue engineering is to fabricate scaffolds that can provide a microenvironment similar to that of natural bone. Therefore, various scaffolds have been designed to replicate the bone structure. Although most tissues exhibit complicated structures, their basic structural unit includes stiff platelets arranged in a staggered micro-array. Therefore, many researchers have designed scaffolds with staggered patterns. However, relatively few studies have comprehensively analyzed this type of scaffold. In this review, we have analyzed scientific research pertaining to staggered scaffold designs and summarized their effects on the physical and biological properties of scaffolds. Compression tests or finite element analysis are typically used to evaluate the mechanical properties of scaffolds, and most studies have performed experiments in cell cultures. Staggered scaffolds improve mechanical strength and are beneficial for cell attachment, proliferation, and differentiation in comparison with conventional designs. However, very few have been studied in vivo experiments. Additionally, studies on the effect of staggered structures on angiogenesis or bone regeneration in vivo, particularly in large animals, are required. Currently, with the prevalence of artificial intelligence (AI)-based technologies, highly optimized models can be developed, resulting in better discoveries. In the future, AI can be used to deepen our understanding on the staggered structure, promoting its use in clinical applications.

Resolvin D1 (RvD1) is a pro‐resolving lipid mediator of inflammation, endogenously synthesized from omega‐3 docosahexaenoic acid. The purpose of this study was to investigate the effect of RvD1 on bone regeneration using a rat calvarial defect model. Collagen 3D nanopore scaffold (COL) and Pluronic F127 hydrogel (F127) incorporated with RvD1 (RvD1‐COL‐F127 group) or COL and F127 (COL‐F127 group) were implanted in symmetrical calvarial defects. After implantation, RvD1 was administrated subcutaneously every 7 days for 4 weeks. The rats were sacrificed at weeks 1 and 8 post‐implantation. Tissue samples were analyzed by real‐time reverse transcriptase‐polymerase chain reaction and histology at week 1. Radiographical and histological analyses were done at week 8. At week 1, calvarial defects treated with RvD1 exhibited decreased numbers of inflammatory cells and tartrate‐resistant acid phosphatase (TRAP) positive cells, greater numbers of newly formed blood vessels, upregulated gene expression of vascular endothelial growth factor and alkaline phosphatase, and downregulated gene expression of receptor activator of nuclear factor‐κB ligand, interleukin‐1β and tumor necrosis factor‐α. At week 8, the radiographical results showed that osteoid area fraction of the RvD1‐COL‐F127 group was higher than that of the COL‐F127 group, and histological examination exhibited enhanced osteoid formation and newly formed blood vessels in the RvD1‐COL‐F127 group. In conclusion, this study showed that RvD1 enhanced bone formation and vascularization in rat calvarial defects.

It has been recently reported that, in a rat calvarial defect model, adding endothelial cells (ECs) to a culture of bone marrow stromal cells (BMSCs) significantly enhanced bone formation. The aim of this study is to further investigate the ossification process of newly formed osteoid and host response to the poly(L-lactide-co-1,5-dioxepan-2-one) [poly(LLA-co-DXO)] scaffolds based on previous research. Several different histological methods and a PCR Array were applied to evaluate newly formed osteoid after 8 weeks after implantation. Histological results showed osteoid formed in rat calvarial defects and endochondral ossification-related genes, such as dentin matrix acidic phosphoprotein 1 (Dmp1) and collagen type II, and alpha 1 (Col2a1) exhibited greater expression in the CO (implantation with BMSC/EC/Scaffold constructs) than the BMSC group (implantation with BMSC/Scaffold constructs) as demonstrated by PCR Array. It was important to notice that cartilage-like tissue formed in the pores of the copolymer scaffolds. In addition, multinucleated giant cells (MNGCs) were observed surrounding the scaffold fragments. It was concluded that the mechanism of ossification might be an endochondral ossification process when the copolymer scaffolds loaded with co-cultured ECs/BMSCs were implanted into rat calvarial defects. MNGCs were induced by the poly(LLA-co-DXO) scaffolds after implantation, and more specific in vivo studies are needed to gain a better understanding of host response to copolymer scaffolds.

Background: Recent studies have suggested that both poly(l-lactide-co-1,5-dioxepan-2-one) (or poly(LLA-co-DXO)) and poly(l-lactide-co-ε-caprolactone) (or poly(LLA-co-CL)) porous scaffolds are good candidates for use as biodegradable scaffold materials in the field of tissue engineering; meanwhile, their surface properties, such as hydrophilicity, need to be further improved. Methods: We applied several different concentrations of the surfactant Tween 80 to tune the hydrophilicity of both materials. Moreover, the modification was applied not only in the form of solid scaffold as a film but also a porous scaffold. To investigate the potential application for tissue engineering, human bone marrow mesenchymal stem cells (hMSCs) were chosen to test the effect of hydrophilicity on cell attachment, proliferation, and differentiation. First, the cellular cytotoxicity of the extracted medium from modified scaffolds was investigated on HaCaT cells. Then, hMSCs were seeded on the scaffolds or films to evaluate cell attachment, proliferation, and osteogenic differentiation. The results indicated a significant increasing of wettability with the addition of Tween 80, and the hMSCs showed delayed attachment and spreading. PCR results indicated that the differentiation of hMSCs was stimulated, and several osteogenesis related genes were up-regulated in the 3% Tween 80 group. Poly(LLA-co-CL) with 3% Tween 80 showed an increased messenger Ribonucleic acid (mRNA) level of late-stage markers such as osteocalcin (OC) and key transcription factor as runt related gene 2 (Runx2). Conclusion: A high hydrophilic scaffold may speed up the osteogenic differentiation for bone tissue engineering.