Oligopeptide-strategy of targeting at adipose tissue macrophages using ATS-9R/siCcl2 complex for ameliorating insulin resistance in GDM.

Gestational diabetes mellitus (GDM) is a pregnancy-specific disease characterized by impaired glucose tolerance during pregnancy. Although diagnosis and clinical management have improved significantly, there are still areas where therapeutic approaches need further improvement. Recent evidence suggests that CCL2, a chemokine involved in immunoregulatory and inflammatory processes, is closely related to GDM. However, the potential value for clinical therapeutic applications and the mechanism of CCL2 in adipose tissue macrophages (ATMs) of GDM remain to be elucidated. Here, we found that CCL2 was enriched in macrophages of the visceral adipose tissue from GDM women and HFD-induced GDM mice. The combination of in vitro and in vivo experiments showed that Ccl2 silencing inhibited the inflammatory response of macrophage by blocking calcium transport between ER and mitochondria and reducing excessive ROS generation. Additionally, the ATS-9R/siCcl2 oligopeptide complex targeting adipose tissue was created. Under the delivery of ATS-9R peptide, Ccl2 siRNA is expressed in ATMs, which reduces inflammation in adipose tissue and, as a result, mitigates insulin resistance. All of these findings point to the possibility that the ATS-9R/siCcl2 complex, which targets adipose tissue, is able to reduce insulin resistance in GDM and the inflammatory response in macrophages. The ATS-9R/siCcl2 oligopeptide complex targeting adipose tissue seems to be a viable treatment for GDM pregnancies.

Regulation of rheumatoid arthritis microenvironment via a self-healing injectable hydrogel for improved inflammation elimination and bone repair.

The rheumatoid arthritis (RA) microenvironment is often followed by a vicious circle of high inflammation, endogenous gas levels imbalance, and poor treatment. To break the circle, we develop a dual-gas-mediated injectable hydrogel for modulating the immune microenvironment of RA and simultaneously releasing therapeutic drugs. The hydrogel (DNRS gel) could be broken down on-demand by consuming excessive nitric oxide (NO) and releasing therapeutic hydrogen sulfide (H2S), resulting in endogenous gas restoration, inflammation alleviation, and macrophage polarization to M2 type. Additionally, the hydrogel could suppress osteoclastogenesis and enhance osteogenesis. Furthermore, the intra-articularly injected hydrogel with methotrexate (MTX/DNRS gel) significantly alleviated inflammation and clinical symptoms and promoted the repair of bone erosion in the collagen-induced arthritis rat model. As a result, in vivo results demonstrated that MTX/DNRS gel restored the microenvironment and improved the therapeutic effect of MTX. This study provides a novel understanding of developing versatile smart delivery platforms for RA treatment.

A Versatile Chitosan-Based Hydrogel Accelerates Infected Wound Healing via Bacterial Elimination, Antioxidation, Immunoregulation, and Angiogenesis.

Drug-resistant bacterial infection of cutaneous wounds causes great harm to the human body. These infections are characterized by a microenvironment with recalcitrant bacterial infections, persistent oxidative stress, imbalance of immune regulation, and suboptimal angiogenesis. Treatment strategies available to date are incapable of handling the healing dynamics of infected wounds. A Schiff base and borate ester cross-linked hydrogel, based on phenylboronic acid-grafted chitosan (CS-PBA), dibenzaldehyde-grafted poly(ethylene glycol), and tannic acid (TA), is fabricated in the present study. Customized phenylboronic acid-modified zinc oxide nanoparticles (ZnO) are embedded in the hydrogel prior to gelation. The CPP@ZnO-P-TA hydrogel effectively eliminates methicillin-resistant Staphylococcus aureus (MRSA) due to the pH-responsive release of Zn2+ and TA. Killing is achieved via membrane damage, adenosine triphosphate reduction, leakage of intracellular components, and hydrolysis of bacterial o-nitrophenyl-ß-d-galactopyranoside. The CPP@ZnO-P-TA hydrogel is capable of scavenging reactive oxygen and nitrogen species, alleviating oxidative stress, and stimulating M2 polarization of macrophages. The released Zn2+ and TA also induce neovascularization via the PI3K/Akt pathway. The CPP@ZnO-P-TA hydrogel improves tissue regeneration in vivo by alleviating inflammatory responses, stimulating angiogenesis, and facilitating collagen deposition. These findings suggest that this versatile hydrogel possesses therapeutic potential for the treatment of MRSA-infected cutaneous wounds.

Micronano Titanium Accelerates Mesenchymal Stem Cells Aging through the Activation of Senescence-Associated Secretory Phenotype.

Stem cell senescence is one of the most representative events of organism aging and is responsible for many physiological abnormalities and disorders. In the scenario of orthopedic disease treatment, stem cell aging may affect the implantation outcome and even lead to operation failure. To explore whether stem cell aging will affect the osteointegration effect of titanium implant, a widely used micronano titanium (MNT) was fabricated. We first verified the expected osteointegration effect of the MNT, which could be attributed to the improvement of stem cell adhesion and osteogenic differentiation. Then, we obtained aged-derived bone marrow mesenchymal stem cells (BMSCs) and studied their biological behaviors on MNT both in vitro and in vivo. We found that compared with normal rats, MNT did not significantly improve the osteointegration in aged rats. Compared with normal rats, fewer endogenous stem cells were observed at the implant-host interface, and the expression of p21 (senescence marker) was also higher. We further confirmed that MNT promoted the nuclear localization of NF-κB in senescent stem cells through the activation of p38 MAPK, thereby inducing the occurrence of the senescence-associated secretory phenotype (SASP) and ultimately leading to the depletion of the stem-cell pool at the implant-host interface. However, the activation of p38 MAPK can still promote the osteogenic differentiation of nonsenescent BMSCs. These results showed an interesting paradoxical balance between osteogenesis and senescence on MNT surfaces and also provided insights for the design of orthopedic implants for aging patients.

Elimination of methicillin-resistant Staphylococcus aureus biofilms on titanium implants via photothermally-triggered nitric oxide and immunotherapy for enhanced osseointegration.

BACKGROUND: Treatment of methicillin-resistant Staphylococcus aureus (MRSA) biofilm infections in implant placement surgery is limited by the lack of antimicrobial activity of titanium (Ti) implants. There is a need to explore more effective approaches for the treatment of MRSA biofilm infections. METHODS: Herein, an interfacial functionalization strategy is proposed by the integration of mesoporous polydopamine nanoparticles (PDA), nitric oxide (NO) release donor sodium nitroprusside (SNP) and osteogenic growth peptide (OGP) onto Ti implants, denoted as Ti-PDA@SNP-OGP. The physical and chemical properties of Ti-PDA@SNP-OGP were assessed by scanning electron microscopy, X-ray photoelectron spectroscope, water contact angle, photothermal property and NO release behavior. The synergistic antibacterial effect and elimination of the MRSA biofilms were evaluated by 2',7'-dichlorofluorescein diacetate probe, 1-N-phenylnaphthylamine assay, adenosine triphosphate intensity, o-nitrophenyl-ß-D-galactopyranoside hydrolysis activity, bicinchoninic acid leakage. Fluorescence staining, assays for alkaline phosphatase activity, collagen secretion and extracellular matrix mineralization, quantitative real­time reverse transcription­polymerase chain reaction, and enzyme-linked immunosorbent assay (ELISA) were used to evaluate the inflammatory response and osteogenic ability in bone marrow stromal cells (MSCs), RAW264.7 cells and their co-culture system. Giemsa staining, ELISA, micro-CT, hematoxylin and eosin, Masson's trichrome and immunohistochemistry staining were used to evaluate the eradication of MRSA biofilms, inhibition of inflammatory response, and promotion of osseointegration of Ti-PDA@SNP-OGP in vivo. RESULTS: Ti-PDA@SNP-OGP displayed a synergistic photothermal and NO-dependent antibacterial effect against MRSA following near-infrared light irradiation, and effectively eliminated the formed MRSA biofilms by inducing reactive oxygen species (ROS)-mediated oxidative stress, destroying bacterial membrane integrity and causing leakage of intracellular components (P < 0.01). In vitro experiments revealed that Ti-PDA@SNP-OGP not only facilitated osteogenic differentiation of MSCs, but also promoted the polarization of pro-inflammatory M1 macrophages to the anti-inflammatory M2-phenotype (P < 0.05 or P < 0.01). The favorable osteo-immune microenvironment further facilitated osteogenesis of MSCs and the anti-inflammation of RAW264.7 cells via multiple paracrine signaling pathways (P < 0.01). In vivo evaluation confirmed the aforementioned results and revealed that Ti-PDA@SNP-OGP induced ameliorative osseointegration in an MRSA-infected femoral defect implantation model (P < 0.01). CONCLUSIONS: These findings suggest that Ti-PDA@SNP-OGP is a promising multi-functional material for the high-efficient treatment of MRSA infections in implant replacement surgeries.

Ultrasonic-controlled "explosive" hydrogels to precisely regulate spatiotemporal osteoimmune disturbance.

Spatiotemporal Immune disorder is a key factor leading to the failure of bone tissue healing. It is of vital importance to accurately suppress excessive peak immune response within 24-48 h of the injury and so regulate the spatiotemporal osteoimmune disturbance of bones. In this study, Ultrasound Controlled "Explosive" (UCE) hydrogels were prepared from gelatin-hyaluronic acid methacrylate hydrogels loaded with resveratrol nanobubbles produced by double emulsification through a condensation reaction. Such materials innovatively enable ultrasound-controlled RES release for precise regulation of spatiotemporal osteoimmune disorders. Under an ultrasonic power level of 1.5 W/cm2, the rate of effectively released RES through the blast of UCE hydrogels reached 38.14 %. And compared with the control group, the in vivo inhibition of inflammation and osteogenesis effects of UCE hydrogels were more effective, respectively. As suggested by the results, the excessive local inflammatory response was inhibited by the release of resveratrol, the temporospatial disorder of bone immune was precisely regulated, and as a result, the process of bone repair was accelerated. Altogether, this study confirms that the newly created UCE Hydrogels effectively promote bone repair by intervening peak inflammation during the early phase of fracture healing.

Nitric Oxide Scavenging and Hydrogen Sulfide Production Synergistically Treat Rheumatoid Arthritis.

To restore the disordered endogenous gas levels is an efficient alternative for the treatment of rheumatoid arthritis (RA). Both insufficient hydrogen sulfide (H2 S) and excessive nitric oxide (NO) contribute to synovial inflammation. Herein, a new block polymer PEG10 -b-PNAPA30 -b-PEG10 composed of an NO-responsive monomer and a cysteine-triggered H2 S donor, which can simultaneously scavenge NO and release therapeutic H2 S for RA treatment, is reported. In vitro experiments demonstrate that the polymer exhibits a synergistic effect on suppressing reactive oxygen species levels and pro-inflammatory cytokine production via NF-κB signaling pathway. It leads to the polarization of macrophages from M1 to M2 phenotype. Moreover, the released H2 S further restrains NO production by suppressing the expression of iNOS. In vivo experiments with an RA rat model show that the system markedly mitigates the synovial inflammation, osteoporosis, and clinical symptoms of RA rats, which is attributed to the combination therapy of H2 S release and NO depletion. This work provides new insight into the synergistic treatment of RA and endogenous gas-related diseases.

ROS-responsive hydrogel coating modified titanium promotes vascularization and osteointegration of bone defects by orchestrating immunomodulation.

Ideal titanium implants are required to participate in bone repair actively to improve in situ osteointegration. However, the traditional surface functionalization methods of titanium implants are difficult to both achieve the active regulation and long-term stability of bioactive components. Here, a novel functionalized titanium which loaded with thymosin ß4 (Tß4) and covered by a hydrogel coating was designed and evaluated. A strong adhesion between the coating and the titanium substrate was realized by the synergistic action of borate ester bonds and surface topological structure. The hydrogel coating also achieved an in vivo adhesion between implant and tissue through hydrogen bonds and borate bonds. In addition, based on the ROS response property of borate bonds, the implant can release Tß4 in response to the immune reaction of bone healing by regulating the polarization of macrophages, thereby reducing the fibrosis formation around the implant interface and promoting vascularization and osteointegration of bone defects.

Multifunctional silicon calcium phosphate composite scaffolds promote stem cell recruitment and bone regeneration.

A scaffold is one of the most significant implants for treating bone injury, while the precise control of stem cell proliferation and differentiation within a scaffold is still challenging. In this work, a composite scaffold was designed to be capable of recruiting endogenous stem cells, stimulating osteogenic differentiation and achieving significant bone repair function. The designed SiCP + SF@PFS silica-calcium phosphate composite scaffold was obtained by mixing the peptide PFS containing silk fibroin solution with the SiCP scaffold, and treating with horseradish peroxidase and H2O2. The results showed that the composite scaffold was able to release the PFS peptide continuously to induce the migration of mesenchymal stem cells. Meanwhile, cell proliferation and osteogenic differentiation were also improved after being seeded on the scaffold. In the cranial defect rat model, the composite scaffold was able to recruit CD29+ and CD90+ cells one week after implantation around the injury sites. The results of Micro-CT, H&E staining, Masson's staining and immunohistochemical staining indicated that the composite scaffold was able to promote new bone formation significantly.

Surface modification of titanium substrate via combining photothermal therapy and quorum-sensing-inhibition strategy for improving osseointegration and treating biofilm-associated bacterial infection.

Insufficient osseointegration and biofilm-associated bacterial infection are important challenges for clinical application of titanium (Ti)-based implants. Here, we constructed mesoporous polydopamine (MPDA) nanoparticles (NPs) loaded with luteolin (LUT, a quorum sensing inhibitor), which were further coated with the shell of calcium phosphate (CaP) to construct MPDA-LUT@CaP nanosystem. Then, MPDA-LUT@CaP NPs were immobilized on the surface of Ti implants. Under acidic environment of bacterial biofilm-infection, the CaP shell of MPDA-LUT@CaP NPs was rapidly degraded and released LUT, Ca2+ and PO4 3- from the surface of Ti implant. LUT could effectively inhibit and disperse biofilm. Furthermore, under near-infrared irradiation (NIR), the thermotherapy induced by the photothermal conversion effect of MPDA destroyed the integrity of the bacterial membrane, and synergistically led to protein leakage and a decrease in ATP levels. Combined with photothermal therapy (PTT) and quorum-sensing-inhibition strategy, the surface-functionalized Ti substrate had an antibacterial rate of over 95.59% against Staphylococcus aureus and the elimination rate of the formed biofilm was as high as 90.3%, so as to achieve low temperature and efficient treatment of bacterial biofilm infection. More importantly, the modified Ti implant accelerated the growth of cell and the healing process of bone tissue due to the released Ca2+ and PO4 3-. In summary, this work combined PTT with quorum-sensing-inhibition strategy provides a new idea for surface functionalization of implant for achieving effective antibacterial and osseointegration capabilities.

A pH-responsive hyaluronic acid hydrogel for regulating the inflammation and remodeling of the ECM in diabetic wounds.

Diabetes is a universal disease in the world. In the wounds of diabetic individuals, chronic inflammation and an inefficient fibrogenic process hinder the formation and deposition of the ECM, which delays the process of wound healing. To reconstruct the ECM of a diabetic patient's wound, in this work, we designed a pH-responsive "Double H-bonds" (hydrogen bond and hydrazone bond) hyaluronic acid-collagen hydrogel. This hydrogel can be self-gelled quickly in neutral and alkaline environments. But the weakly acidic inflammatory environment of diabetic wounds may accelerate the degradation of the hydrogel and the release of metformin. The in vitro results showed that the hydrogel can enhance the adhesion and infiltration of fibroblasts while inhibiting the growth of macrophages. Meanwhile, metformin could be released and polarize macrophages from M1 to M2, thereby accelerating the migration of fibroblasts and the production of collagen in a high glucose environment. The in vivo results proved that this hydrogel could remodel the ECM in diabetic mice wounds.

Fabrication of gelatin-based and Zn2+-incorporated composite hydrogel for accelerated infected wound healing.

Gelatin-based hydrogels have a broad range of biomedical fields due to their biocompatibility, convenience for chemical modifications, and degradability. However, gelatin-based hydrogels present poor antibacterial ability that hinders their applications in treating infected wound healing. Herein, a series of multifunctional hydrogels (Gel@Zn) were fabricated through free-radical polymerization interaction based on gelatin methacrylate (GelMA) and dopamine methacrylate (DMA), and then immersed them into zinc nitrate solutions based on the metal coordination and ionic bonding interaction. These designed hydrogels wound dressings show strong antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) by increasing intracellular reactive oxygen species (ROS) level and changing bacterial membrane permeability. Meanwhile, the hydrogels exhibit good cytocompatibility, enhance the adhesion, proliferation, and migration of NIH-3T3 cells. Furthermore, Gel@Zn-0.08 (0.08 â€‹M Zn2+ immersed with Gel sample) presents a good balance between antibacterial effect, cell viability, and hemolytic property. Compared with 3 â€‹M commercial dressings, Gel@Zn-0.04, and Gel@Zn-0.16, the Gel@Zn-0.08 could significantly improve the healing process of S. aureus-infected full-thickness wounds via restrained the inflammatory responses, enhanced epidermis and granulation tissue information, and stimulated angiogenesis. Our study indicates that the Zn-incorporated hydrogels are promising bioactive materials as wound dressings for infected full-thickness wound healing and skin regeneration.

Gallium (Ga)-strontium (Sr) layered double hydroxide composite coating on titanium substrates for enhanced osteogenic and antibacterial abilities.

Bacterial infection and poor osteogenic capacity can result in the loosing or failure of titanium (Ti)-based implants in the clinic. Therefore, it is urgent to design an effective approach to enhance the osteogenic property and restrict bacterial activity. In this study, a layered double hydroxide (LDH) composed of Ga and Sr ions on Ti substrates by a hydrothermal method, then calcined in 250°C and denoted as LDH250. The scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were confirmed that the LDH films were successfully formed on the Ti substrates. Importantly, the obtained LDH films can induce an alkaline microenvironment around the Ti surface and regulate the behaviors of osteogenic cells and bacteria. In vitro cellular experiments, the LDH250 can enhance the differentiation of both MC3T3-E1 cells and osteoblasts, stimulate alkaline phosphatase activity (ALP), collagen secretion, and mineralization levels. Meanwhile, antimicrobial assay against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) demonstrated that the LDH250 samples had strong antibacterial abilities, which attributed to the release profile of Ga3+ could act as a "Trojan horse" to destroy the bacterial iron metabolism, inducing of local alkaline environment, and producing reactive oxygen species. Hence, this study provides an effective method for reducing antibacterial infection and enhancing the bone integrative capacity of Ti-based implants for orthopedic applications.

FGF19 protects against obesity-induced bone loss by promoting osteogenic differentiation.

Human fibroblast growth factor 19 (FGF19) has become a potential therapeutic target for metabolic-related diseases. However, the effects of FGF19 on obesity-induced bone loss have not been completely elucidated. The aim of this study was to investigate the protective effects of FGF19 in high-fat diet (HFD)-fed obese mice and palmitic acid (PA)-treated osteoblasts and to further explore its underlying mechanisms. In vivo, we found that FGF19 alleviated the decreased bone mineral density (BMD) induced by HFD. Micro-CT analysis of femur samples and histological analysis indicated that FGF19 alleviated HFD-induced loss of bone trabeculae and damage to the bone trabecular structure. In vitro, the results suggested that FGF19 ameliorated the PA-induced decline in osteoblast proliferation, increased cell death and impaired cell morphology. Additionally, FGF19 protected against the decline in activation of alkaline phosphatase (ALP) and protein expression of Collagen-1, Runx-2, and osteopontin (OPN) induced by PA. Furthermore, FGF19 might enhance osteogenic differentiation via the Wnt/ß-catenin pathway and inhibit osteoclastogenesis by regulating the osteoprotegerin (OPG)/receptor activator of NF-κB ligand (RANKL) axis, thus attenuating the negative effect of PA in osteoblasts. In conclusion, our results suggested that FGF19 might promote osteogenic differentiation partially through activation of the Wnt/ß-catenin pathway and alleviate obesity-induced bone loss.

Effects of a novel self-assembling peptide scaffold on bone regeneration and controlled release of two growth factors.

RADA16 is a self-assembling peptide material with good bioactivity. To improve the bioactivity of a material, some specific functional motifs can be added to its peptide sequence. Here, we report a self-assembling peptide nanogel, RADA16-RGD, that has better bioactivity than RADA16 and can simultaneously carry and control the release of two growth factors, VEGF and BMP-2, which have synergistic effects on bone formation. The peptide materials were characterized by transmission electron microscopy and scanning electron microscopy. The mechanical properties of the peptides were evaluated by the rheology test. The biocompatibility of the materials was evaluated via the use of the CCK-8 test, live/dead staining and confocal laser scanning microscopy. Osteogenesis capability in vitro was evaluated by means of ALP staining, extracellular matrix mineralization and detection of osteogenic markers. The controlled release of growth factors was examined by ELISA. The results showed that RADA16-RGD exhibited a better ability than RADA16 to promote cell proliferation, adhesion and bone formation. In addition, RADA16-RGD had good biocompatibility and exhibited effective controlled release of VEGF and BMP-2. More importantly, compared with RADA16-RGD loaded with single growth factor or without growth factors, RADA16-RGD loaded with two growth factors exhibited a stronger ability to promote cell proliferation and osteogenesis. This study provides a promising strategy for the application of self-assembling peptides to promote osteogenesis and controlled release of proteins.

Self-renewal or quiescence? Orchestrating the fate of mesenchymal stem cells by matrix viscoelasticity via PI3K/Akt-CDK1 pathway.

To control the fate of mesenchymal stem cells (MSCs) in a 3D environment by adjusting the mechanical parameters of MSC-loading scaffolds, is one of the hot topics in the field of regenerative biomaterials. However, a thorough understanding of the relevant MSCs behaviors affected by viscoelasticity, a dynamic physical parameter of scaffolds, is still lacking. Herein, we established an alginate hydrogel system with constant stiffness and tunable stress relaxation rate, which is a key parameter for the viscoelastic property of material. MSCs were cultured inside three groups of alginate hydrogels with various stress relaxation rates, and then RNA-seq analysis of cells was performed. Results showed that the change of stress relaxation rates of hydrogels regulated the most of the different expression genes of MSCs, which were enriched in cell proliferation-related pathways. MSCs cultured in hydrogels with fast stress relaxation rate presented a high self-renewal proliferation profile via activating phosphatidylinositol 3- kinase (PI3K)/protein kinase B (Akt) pathway. In contrast, a slow stress relaxation rate of hydrogels induced MSCs to enter a reversible quiescence state due to the weakened PI3K/Akt activation. Combined with a further finite element analysis, we speculated that the quiescence of MSCs could be served as a positive strategy for MSCs to deal with the matrix with a low deformation to keep stemness. Based on the results, we identified that stress relaxation rate of hydrogel was a potential physical factor of hydrogel to regulate the self-renewal or quiescence of MSCs. Thus, our findings provide a significant guiding principle for the design of MSCs-encapsulated biomaterials.

Calcium Peroxide Nanoparticles-Embedded Coatings on Anti-Inflammatory TiO2 Nanotubes for Bacteria Elimination and Inflammatory Environment Amelioration.

Implant-associated bacterial infections significantly impair the integration between titanium and soft tissues. Traditional antibacterial modifications of titanium implants are able to eliminate bacteria, but the resulting pro-inflammatory reactions are usually ignored, which still poses potential risks to human bodies. Here, a dual drug-loading system on titanium has been developed via the adhesion of a catechol motif-modified methacrylated gelatin hydrogel onto TiO2 nanotubes. Then synthesized CaO2 nanoparticles (NPs) are embedded into the hydrogel, and interleukin-4 (IL-4) is loaded into the nanotubes to achieve both antibacterial and anti-inflammatory properties. The dual drug-loading system can eliminate Staphylococcus aureus (S. aureus) rapidly, attributed to the H2 O2 release from CaO2 NPs. The potential cytotoxicity of CaO2 NPs is also remarkably reduced after being embedded into the hydrogel. More importantly, with the gradual release of IL-4, the dual drug-loading system is capable of modulating pro-inflammatory reactions by inducing M2 phenotype polarization of macrophages. In a subcutaneous infection model, the S. aureus contamination is effectively resolved after 2 days, and the resulting pro-inflammatory reactions are also inhibited after 7 days. Finally, the damaged tissue is significantly recovered. Taken together, the dual drug-loading system exhibits great therapeutic potential in effectively killing pathogens and inhibiting the resulting pro-inflammatory reactions.

A multifunctional hydrogel coating to direct fibroblast activation and infected wound healing via simultaneously controllable photobiomodulation and photodynamic therapies.

Bacterial infection treatment and subsequent tissue rebuilding are the main tasks of biomaterial research. To endow implants with antibacterial activity and biological functions, the material systems are usually very complicated and ineffective. Recently, the concept of photobiomodulation (PBM), or low-level laser therapy (LLLT), has attracted increasing attention in tissue repair applications but still has not obtained wide acceptance. Because of the same laser resource, PBM could simultaneously work with 660 nm laser triggered photodynamic therapy (PDT), which will significantly simplify the material system and achieve the multiple functions of antibacterial activity and biological modulation effects. Herein, we attempt to validate the effectiveness of PBM and combine PBM with a PDT-based material system. A catechol motif-modified methacrylated gelatin containing photosensitizer Chlorin e6-loaded mesoporous polydopamine nanoparticles was fabricated (GelMAc/MPDA@Ce6). This hydrogel could be tightly adhered to titanium surfaces to serve as surface coating materials or directly used as dressings. Because of the 660 nm laser-triggered ROS generation property of Ce6, GelMAc/MPDA@Ce6 exhibited a remarkable and rapid antibacterial activity when the laser power was 1 W cm-2. After bacterial elimination, when the power was adjusted to 100 mW cm-2, daily irradiation brought an excellent PBM effect: the fibroblast activation was realized to accelerate wound repair. According to our in vitro and in vivo results, the fabricated hydrogel coating possessed both antibacterial activity and fibroblast activation ability only by adjusting the power of laser irradiation, which will greatly strengthen the confidence of using PBM in broader fields and give a good example to combine PBM with traditional biomaterial design.

LIPUS inhibits inflammation and catabolism through the NF-κB pathway in human degenerative nucleus pulposus cells.

BACKGROUND: Low-intensity pulsed ultrasound (LIPUS) is a safe and noninvasive rehabilitative physical therapy with anti-inflammatory effects. The current study investigated the effect of LIPUS on the inflammation of nucleus pulposus (NP) cells and its underlying mechanism. METHODS: Human NP cells were acquired from lumbar disc herniation tissue samples and cultured for experiments. Human NP cells were treated with LPS and then exposed to LIPUS (15 mW/cm2, 30 mW/cm2 and 60 mW/cm2) for 20 min daily for 3 days to determine the appropriate intensity to inhibit the expression of the inflammatory factors TNF-α and IL-1ß. The gene and protein expression of aggrecan, collagen II, MMP-3 and MMP-9 was measured by real-time PCR and western blotting, respectively. The activity of the nuclear factor-kappa B (NF-κB) pathway was examined by western blotting and immunofluorescence. After pretreatment with the NF-κB inhibitor PDTC, the expression of TNF-α, IL-1ß, MMP-3 and MMP-9 was measured by real-time PCR. RESULTS: LIPUS at intensities of 15 mW/cm2, 30 mW/cm2 and 60 mW/cm2 inhibited LPS-induced NP cell expression of the inflammatory factors TNF-α and IL-1ß, especially at 30 mW/cm2. LIPUS significantly upregulated the gene and protein expression of aggrecan and collagen II and downregulated the gene and protein expression of MMP-3 and MMP-9 in LPS-induced NP cells. The NF-κB signaling pathway was inhibited by LIPUS through inhibiting the protein expression of p-P65 and the translocation of P65 into the nucleus in LPS-induced NP cells. In addition, LIPUS had similar effects as the NF-κB inhibitor PDTC by inhibiting the NF-κB signaling pathway, inflammation and catabolism in LPS-induced human degenerative nucleus pulposus cells. CONCLUSION: LIPUS inhibited inflammation and catabolism through the NF-κB pathway in human degenerative nucleus pulposus cells.