BACKGROUND: Regulatory dendritic cell (DCreg) subset exhibits a unique capacity for inducing immune tolerance among the variety subsets of dendritic cells (DCs) within gut-associated lymphoid tissues (GALTs). Fms-like tyrosine kinase 3 ligand (FLT3L) is involved in the differentiation of DCregs and the subsequent expansion of regulatory T-cells (Tregs) mediated by DCregs, though the precise mechanism remains poorly understood. This study aimed to explore the expansion mechanism of Treg induced by DCreg and the role of FLT3L in this process. METHODS: DCregs were distinguished from other DC subsets isolated from GALTs of BALB/c mice through a mixed lymphocyte reaction assay. The functions and mechanisms by which FLT3L promoted Treg expansion via DCregs were investigated in vitro through co-culture experiments involving DCregs and either CD4 + CD25 - T-cells or CD4 + CD25 + T-cells. Additionally, an in vivo experiment was conducted using a dextran sulfate sodium (DSS)-induced colitis model in mice. RESULTS: CD103 + CD11b + DC exhibited DCreg-like functionality and was identified as DCreg for subsequent investigation. Analysis of Foxp3 + Treg percentages within a co-culture system of CD4 + CD25 - T-cells and DCregs, with or without FLT3L, demonstrated the involvement of the FLT3/FLT3L axis in driving the differentiation of precursor T-cells into Foxp3 + Tregs induced by DCregs. Cell migration and co-culture assays revealed that the FLT3/FLT3L axis enhanced DCreg migration toward Tregs via the Rho pathway. Additionally, it was observed that DCregs could promote Treg proliferation through the Notch pathway, as inhibition of Notch signaling by DAPT (N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester) suppressed Treg expansion within the co-culture system of DCregs and CD4 + T-cells or CD4 + CD25 + T-cells. Furthermore, the FLT3/FLT3L axis influenced JAG1 expression in DCregs, indirectly modulating Treg expansion. In vivo experiments further established that FLT3L promoted DCreg expansion and restored Treg balance in DSS-induced colitis models, thereby ameliorating colitis symptoms in mice. CONCLUSION The FLT3/FLT3L axis is integral to the maintenance of DCreg function in Treg expansion.
Animals ; T-Lymphocytes, Regulatory/immunology* ; Dendritic Cells/immunology* ; Mice ; Mice, Inbred BALB C ; Membrane Proteins/metabolism* ; Receptors, Notch/metabolism* ; Lymphoid Tissue/metabolism* ; Signal Transduction/physiology* ; Coculture Techniques ; Flow Cytometry

Collagen-based materials, renowned for their biocompatibility and minimal immunogenicity, serve as exemplary substrates in a myriad of biomedical applications. Collagen-based micro/nanogels, in particular, are valued for their increased surface area, tunable degradation rates, and ability to facilitate targeted drug delivery, making them instrumental in advanced therapeutics and tissue engineering endeavors. Although extensive reviews on micro/nanogels exist, they tend to cover a wide range of biomaterials and lack a specific focus on collagen-based materials. The current review offers an in-depth look into the manufacturing technologies, drug release mechanisms, and biomedical applications of collagen-based micro/nanogels to address this gap. First, we provide an overview of the synthetic strategies that allow the precise control of the size, shape, and mechanical strength of these collagen-based micro/nanogels by controlling the degree of cross-linking of the materials. These properties are crucial for their performance in biomedical applications. We then highlight the environmental responsiveness of these collagen-based micro/nanogels, particularly their sensitivity to enzymes and pH, which enables controlled drug release under various pathological conditions. The discussion then expands to include their applications in cancer therapy, antimicrobial treatments, bone tissue repair, and imaging diagnosis, emphasizing their versatility and potential in these critical areas. The challenges and future perspectives of collagen-based micro/nanogels in the field are discussed at the end of the review, with an emphasis on the translation to clinical practice. This comprehensive review serves as a valuable resource for researchers, clinicians, and scientists alike, providing insights into the current state and future directions of collagen-based micro/nanogel research and development.
Collagen/chemistry* ; Drug Delivery Systems/methods* ; Humans ; Tissue Engineering/methods* ; Animals ; Biocompatible Materials/chemistry*

Diterpenoid ferruginol is a key intermediate in biosynthesis of active ingredients such as tanshinone and carnosic acid.However, the traditional process of obtaining ferruginol from plants is often cumbersome and inefficient. In recent years, the increasingly developing gene editing technology has been gradually applied to the heterologous production of natural products, but the production of ferruginol in microbe is still very low, which has become an obstacle to the efficient biosynthesis of downstream chemicals, such as tanshinone. In this study, miltiradiene was produced by integrating the shortened diterpene synthase fusion protein,and the key genes in the MVA pathway were overexpressed to improve the yield of miltiradiene. Under the shake flask fermentation condition, the yield of miltiradiene reached about(113. 12±17. 4)mg·L~(-1). Subsequently, this study integrated the ferruginol synthase Sm CYP76AH1 and Sm CPR1 to reconstruct the ferruginol pathway and thereby realized the heterologous synthesis of ferruginol in Saccharomyces cerevisiae. The study selected the best ferruginol synthase(Il CYP76AH46) from different plants and optimized the expression of pathway genes through redox partner engineering to increase the yield of ferruginol. By increasing the copy number of diterpene synthase, CYP450, and CPR, the yield of ferruginol reached(370. 39± 21. 65) mg·L~(-1) in the shake flask, which was increased by 21. 57-fold compared with that when the initial ferruginol strain JMLT05 was used. Finally, 1 083. 51 mg·L~(-1) ferruginol was obtained by fed-batch fermentation, which is the highest yield of ferruginol from biosynthesis so far. This study provides not only research ideas for other metabolic engineering but also a platform for the construction of cell factories for downstream products.
Saccharomyces cerevisiae/genetics* ; Diterpenes/metabolism* ; Metabolic Engineering ; Fermentation ; Abietanes

Callicarpa is an important medicinal plant in China, which has hemostatic, antibacterial, and antioxidant pharmacological effects, and the efficacy of astringing and arresting bleeding, clearing heat and detoxification, activating blood, and resolving stasis is outstanding. At the same time, Callicarpa can be used as an ornamental plant because of its gorgeous flowers and fruits. Callicarpa has good market development prospects, but the long seed reproduction cycle directly limits the large demand for seedlings in its industrial development. Asexual reproduction technology is the basis for the industrialization development of Callicarpa, which is helpful in producing high-quality seedlings and medicinal materials. Although Chinese and foreign scholars have achieved remarkable results in the study of asexual reproduction of Callicarpa, there is no report on the large-scale production of seedlings of Callicarpa. Integrating and improving its asexual reproduction technology can promote the development and utilization of Callicarpa, improve its medicinal value, and create significant economic benefits. Therefore, the authors reviewed the effects of cutting, season, plant growth regulators, substrates, environment, and management measures on the cutting of Callicarpa and the research progress of tissue culture propagation affected by explants, basic media, exogenous additives, subculture cycles, culture conditions, and transplanting substrates. The mechanism of adventitious root formation was reviewed at the cellular, physiological, and biochemical levels, so as to put forward the problems and corresponding solutions in the study of asexual propagation technology and regulatory mechanism of Callicarpa and point out the future research directions. The study aims to provide a reference for in-depth research on the asexual propagation technology of Callicarpa and the commercial production of its high-quality seedlings.
Reproduction, Asexual ; Plants, Medicinal/physiology* ; Seedlings/growth & development* ; Tissue Culture Techniques

In this study, Saccharomyces cerevisiae R0 was used as the chassis cell to synthesize oleanolic acid from scratch through the heterologous expression of β-amyrin synthase(β-AS) from Glycyrrhiza uralensis, cytochrome P450 enzyme CYP716A154 from Catharanthus roseus, and cytochrome P450 reductase AtCPR from Arabidopsis thaliana. The engineered strain R1 achieved shake flask titres of 5.19 mg·L~(-1). By overexpressing enzymes in the pentose phosphate pathway(PPP)(ZWF1, GND1, TKL1, and TAL), the NADH kinase gene in the mitochondrial matrix(POS5), truncated 3-hydroxy-3-methylglutaryl-CoA reductase(tPgHMGR1) from Panax ginseng, and farnesyl diphosphate synthase gene(SmFPS) from Salvia miltiorrhiza, the precursor supply and intracellular reduced nicotinamide adenine dinucleotide phosphate(NADPH) supply were enhanced, resulting in an 11.4-fold increase in squalene yield and a 3.6-fold increase in oleanolic acid yield. Subsequently, increasing the copy number of the heterologous genes tPgHMGR1, β-AS, CYP716A154, and AtCPR promoted the metabolic flow towards the final product, oleanolic acid, and increased the yield by three times. Shake flask fermentation data showed that, by increasing the copy number, precursor supply, and intracellular NADPH supply, the final engineered strain R3 could achieve an oleanolic acid yield of 53.96 mg·L~(-1), which was 10 times higher than that of the control strain R1. This study not only laid the foundation for the green biosynthesis of oleanolic acid but also provided a reference for metabolic engineering research on other pentacyclic triterpenoids in S. cerevisiae.
Oleanolic Acid/biosynthesis* ; Saccharomyces cerevisiae/metabolism* ; Industrial Microbiology ; Microorganisms, Genetically-Modified/metabolism* ; Plants/enzymology* ; Fermentation ; Metabolic Engineering

Many triterpenoid compounds have been successfully heterologously synthesized in Saccharomyces cerevisiae. To increase the yield of triterpenoids, various metabolic engineering strategies have been developed. One commonly applied strategy is to enhance the supply of precursors, which has been widely used by researchers. Squalene, as a precursor to triterpenoid biosynthesis, plays a crucial role in the synthesis of these compounds. This study primarily investigates the effect of different squalene levels in chassis strains on the synthesis of triterpenoids(oleanolic acid and ursolic acid), and the underlying mechanisms are further explored using real-time quantitative PCR(qPCR) analysis. The results demonstrate that the chassis strain CB-9-5, which produces high levels of squalene, inhibits the synthesis of oleanolic acid and ursolic acid. In contrast, chassis strains with moderate to low squalene production, such as Y8-1 and CNPK, are more conducive to the synthesis of oleanolic acid and ursolic acid. The qPCR analysis reveals that the expression levels of ERG1, βAS, and CrCYP716A154 in the oleanolic acid-producing strain CB-OA are significantly lower than those in the control strains C-OA and Y-OA, suggesting that high squalene production in the chassis strains suppresses the transcription of certain genes, leading to a reduced yield of triterpenoids. Our findings indicate that when constructing S. cerevisiae strains for triterpenoid production, chassis strains with high squalene content may suppress the expression of certain genes, ultimately lowering their production, whereas chassis strains with moderate squalene levels are more favorable for triterpenoid biosynthesis.
Squalene/analysis* ; Saccharomyces cerevisiae/genetics* ; Triterpenes/metabolism* ; Metabolic Engineering ; Oleanolic Acid/biosynthesis* ; Ursolic Acid

As a high-quality moxibustion material, Artemisia stolonifera has high economic value and research prospects. However, due to difficulties in seed germination, its wild germplasm resources are sparsely distributed in China. This study used young stem segments grown in the current year to investigate the effects of explant sterilization, different combinations and concentrations of plant growth regulators on the proliferation and rooting of adventitious shoots, with the aim of constructing an in vitro rapid propagation technology system for A. stolonifera. The results showed that the lowest contamination rate of 25.83% was achieved when sterilizing the stem segments by rinsing with running water for 30 min, soaking in 75% ethanol for 30 s, followed by a 5 min treatment with 0.1% HgCl_2, 10 min with 8% NaClO, and 10 min with 0.6% phytosaniline. There was no browning of the stem segments, and surface sterilization of the A. stolonifera stem segments was successfully achieved. In the induction culture phase, when the concentration of kinetin(KT) was 0.05 mg·L~(-1) and 6-benzylaminopurine(6-BA) was 0.05 mg·L~(-1), the adventitious shoot proliferation coefficient was 2.02, effectively promoting the proliferation and growth of A. stolonifera. In the rooting culture phase, 0.1 mg·L~(-1) 1-naphthaleneacetic acid(NAA) effectively induced A. stolonifera test-tube seedlings to root within a short period, achieving a rooting rate of 100%. The addition of a small amount of activated charcoal also promoted rooting and strengthened seedling growth. The survival rate of A. stolonifera seedlings transplanted into a substrate consisting of 90% nutrient soil and 10% perlite was 100%. This study established an efficient in vitro rapid propagation system for A. stolonifera, overcoming difficulties with seed germination, shortening the breeding cycle, and reducing production and planting costs. It provides technical support for the introduction, domestication, seedling propagation, germplasm conservation, and industrial development of A. stolonifera.
Artemisia/drug effects* ; Tissue Culture Techniques/methods* ; Plant Growth Regulators/pharmacology* ; Plant Stems/drug effects* ; Plant Shoots/drug effects*

To assess the implantation effectiveness of porous scaffolds, it is essential to consider not only their mechanical properties but also their biological performance. Given the high cost, long duration and low reproducibility of biological experiments, simulation studies as a virtual alternative, have become a widely adopted and efficient evaluation method. In this study, based on the secondary development environment of finite element analysis software, the strain energy density growth criterion for bone tissue was introduced to simulate and analyze the cell proliferation-promoting effects of four different lattice porous scaffolds under cyclic compressive loading. The biological performance of these scaffolds was evaluated accordingly. The computational results indicated that in the early stages of bone growth, the differences in bone tissue formation among the scaffold groups were not significant. However, as bone growth progressed, the scaffold with a porosity of 70% and a pore size of 900 μm demonstrated markedly superior bone formation compared to other porosity groups and pore size groups. These results suggested that the scaffold with a porosity of 70% and a pore size of 900 μm was most conducive to bone tissue growth and could be regarded as the optimal structural parameter for bone repair scaffold. In conclusion, this study used a visualized simulation approach to pre-evaluate the osteogenic potential of porous scaffolds, aiming to provide reliable data support for the optimized design and clinical application of implantable scaffolds.
Tissue Scaffolds/chemistry* ; Porosity ; Finite Element Analysis ; Tissue Engineering/methods* ; Computer Simulation ; Bone Development ; Osteogenesis ; Humans ; Cell Proliferation

The three-dimensional (3D) printed bone tissue repair guide scaffold is considered a promising method for treating bone defect repair. In this experiment, chitosan (CS), sodium alginate (SA), and mineralized collagen (MC) were combined and 3D printed to form scaffolds. The experimental results showed that the printability of the scaffold was improved with the increase of chitosan concentration. Infrared spectroscopy analysis confirmed that the scaffold formed a cross-linked network through electrostatic interaction between chitosan and sodium alginate under acidic conditions, and X-ray diffraction results showed the presence of characteristic peaks of hydroxyapatite, indicating the incorporation of mineralized collagen into the scaffold system. In the in vitro collagen release experiments, a weakly alkaline environment was found to accelerate the release rate of collagen, and the release amount increased significantly with a lower concentration of chitosan. Cell experiments showed that scaffolds loaded with mineralized collagen could significantly promote cell proliferation activity and alkaline phosphatase expression. The subcutaneous implantation experiment further verified the biocompatibility of the material, and the implantation of printed scaffolds did not cause significant inflammatory reactions. Histological analysis showed no abnormal pathological changes in the surrounding tissues. Therefore, incorporating mineralized collagen into sodium alginate/chitosan scaffolds is believed to be a new tissue engineering and regeneration strategy for achieving enhanced osteogenic differentiation through the slow release of collagen.
Chitosan/chemistry* ; Alginates/chemistry* ; Tissue Scaffolds/chemistry* ; Printing, Three-Dimensional ; Osteogenesis ; Collagen/chemistry* ; Cell Differentiation ; Animals ; Tissue Engineering/methods* ; Cell Proliferation ; Biocompatible Materials ; Glucuronic Acid/chemistry* ; Hexuronic Acids/chemistry*

OBJECTIVE: To summarize the research progress of bioactive scaffolds in the repair and regeneration of osteoporotic bone defects. METHODS: Recent literature on bioactive scaffolds for the repair of osteoporotic bone defects was reviewed to summarize various types of bioactive scaffolds and their associated repair methods. RESULTS: The application of bioactive scaffolds provides a new idea for the repair and regeneration of osteoporotic bone defects. For example, calcium phosphate ceramics scaffolds, hydrogel scaffolds, three-dimensional (3D)-printed biological scaffolds, metal scaffolds, as well as polymer material scaffolds and bone organoids, have all demonstrated good bone repair-promoting effects. However, in the pathological bone microenvironment of osteoporosis, the function of single-material scaffolds to promote bone regeneration is insufficient. Therefore, the design of bioactive scaffolds must consider multiple factors, including material biocompatibility, mechanical properties, bioactivity, bone conductivity, and osteogenic induction. Furthermore, physical and chemical surface modifications, along with advanced biotechnological approaches, can help to improve the osteogenic microenvironment and promote the differentiation of bone cells. CONCLUSION With advancements in technology, the synergistic application of 3D bioprinting, bone organoids technologies, and advanced biotechnologies holds promise for providing more efficient bioactive scaffolds for the repair and regeneration of osteoporotic bone defects.
Humans ; Tissue Scaffolds/chemistry* ; Bone Regeneration ; Osteoporosis/therapy* ; Tissue Engineering/methods* ; Biocompatible Materials/chemistry* ; Printing, Three-Dimensional ; Calcium Phosphates/chemistry* ; Osteogenesis ; Ceramics ; Cell Differentiation ; Hydrogels ; Bioprinting ; Bone and Bones