Simultaneously blocking ANGPTL3 and CD47 prevents the progression of atherosclerosis through regulating lipid metabolism, macrophagic efferocytosis and lipid peroxidation.

Atherosclerosis (AS) ultimately cause major adverse cardiovascular events (MACEs). While traditional strategies by lipid-reducing have reduced MACEs, many patients continue to face significant risks. It might attribute to the upregulation of CD47 expression in AS lesions, that mediated anti-efferocytosis of macrophages. Therefore, we propose simultaneously blocking ANGPTL3, a vital regulator of lipid metabolism, and CD47 might be a potential approach for AS therapy. Firstly, we investigate the role of a novel anti-ANGPTL3 nanobody-Fc (FD03) in AS. We found that FD03 treatment significantly decreased circulating lipids, plaque size, and lipid deposition in apoE-/- mice compared to control Ab, but there was a twofold increase in plaque formation in comparison to baseline. However, immunofluorescence indicated the upregulation of CD47 expression in the plaques even after FD03 treatment compared to normal vascular tissue. Next, a bifunctional protein containing signal regulatory protein alpha (SIRPα) and FD03 (SIRPαD1-FD03) was constructed to block CD47 and ANGPTL3 concurrently, which had high purity, robust stability, and high affinity to CD47 and ANGPTL3 with biological activity in vitro. Furthermore, SIRPαD1-FD03 fusion protein exhibited the enhanced therapeutic effect on AS compared with SIRPαD1-Fc or FD03, regressing plaque contents and the necrotic core equal to baseline. Mechanistically, SIRPαD1-FD03 reduced serum lipids, augmented the efferocytosis rate and macrophage M2 polarization, and decreased the reactive oxygen species (ROS) and lipid peroxidation level in atherosclerotic plaques. Collectively, our project suggests an effective approach for AS by simultaneously blocking ANGPTL3 and CD47 to regulate lipid metabolism, macrophage activity and lipid peroxidation.

Simultaneously blocking ANGPTL3 and IL-1ß for the treatment of atherosclerosis through lipid-lowering and anti-inflammation.

OBJECTIVE: Blood lipid levels play a critical role in the progression of atherosclerosis. However, even with adequate lipid reduction, significant residual cardiovascular risk remains. Therefore, it is necessary to seek novel therapeutic strategies for atherosclerosis that can not only lower lipid levels but also inhibit inflammation simultaneously. METHODS: The fusion protein FD03-IL-1Ra was designed by linking the Angiopoietin-like 3 (ANGPTL3) nanobody and human interleukin-1 receptor antagonist (IL-1Ra) sequences to a mutated human immunoglobulin gamma 1 (IgG1) Fc. This construct was transfected into HEK293 cells for expression. The purity and thermal stability of the fusion protein were assessed using SDS-PAGE, SEC-HPLC, and differential scanning calorimetry. Binding affinities of the fusion protein to ANGPTL3 and IL-1 receptor were measured using Biacore T200. The biological activity of the fusion protein was validated through in vitro experiments. The therapeutic efficacy of the fusion protein was evaluated in an ApoE-/- mouse model of atherosclerosis, including serum lipid level determination, histological analysis of aorta and aortic sinus sections, and detection of inflammatory and oxidative stress markers. ImageJ software was utilized for quantitative image analysis. Statistical analysis was performed using one-way ANOVA followed by Bonferroni post hoc test. RESULTS: The FD03-IL-1Ra fusion protein was successfully expressed, with no polymer formation detected, and it demonstrated good thermal and conformational stability. High affinity for both murine and human ANGPTL3 was exhibited by FD03-IL-1Ra, and it was able to antagonize hANGPTL3's inhibition of LPL activity. FD03-IL-1Ra also showed high affinity for both murine and human IL-1R, inhibiting IL-6 expression in A549 cells induced by IL-1ß stimulation, as well as suppressing IL-1ß-induced activity inhibition in A375.S2 cells. Our study revealed that the fusion protein effectively lowered serum lipid levels and alleviated inflammatory responses in mice. Furthermore, the fusion protein enhanced plaque stability by increasing collagen content within atherosclerotic plaques. CONCLUSIONS: These findings highlighted the potential of bifunctional interleukin-1 receptor antagonist and ANGPTL3 antibody fusion proteins for ameliorating the progression of atherosclerosis, presenting a promising novel therapeutic approach targeting both inflammation and lipid levels.

A novel nanobody-heavy chain antibody against Angiopoietin-like protein 3 reduces plasma lipids and relieves nonalcoholic fatty liver disease.

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) is a metabolic disease mainly on account of hypercholesterolemia and may progress to cirrhosis and hepatocellular carcinoma. The discovery of effective therapy for NAFLD is an essential unmet need. Angiopoietin-like protein 3 (ANGPTL3), a critical lipid metabolism regulator, resulted in increased blood lipids and was elevated in NAFLD. Here, we developed a nanobody-heavy chain antibody (VHH-Fc) to inhibit ANGPTL3 for NAFLD treatment. RESULTS: In this study, we retrieved an anti-ANGPTL3 VHH and Fc fusion protein, C44-Fc, which exhibited high affinities to ANGPTL3 proteins and rescued ANGPLT3-mediated inhibition of lipoprotein lipase (LPL) activity. The C44-Fc bound a distinctive epitope within ANGPTL3 when compared with the approved evinacumab, and showed higher expression yield. Meanwhile, C44-Fc had significant reduction of the triglyceride (~ 44.2%), total cholesterol (~ 36.6%) and LDL-cholesterol (~ 54.4%) in hypercholesterolemic mice and ameliorated hepatic lipid accumulation and liver injury in NAFLD mice model. CONCLUSIONS: We discovered a VHH-Fc fusion protein with high affinity to ANGPTL3, strong stability and also alleviated the progression of NAFLD, which might offer a promising therapy for NAFLD.

A Novel Bifunctional Fusion Protein (Anti-IL-17A-sST2) Protects against Acute Liver Failure, Modulating the TLR4/MyD88 Pathway and NLRP3 Inflammasome Activation.

Acute liver failure (ALF) is a serious inflammatory disorder with high mortality rates, which poses a significant threat to human health. The IL-33/ST2 signal is a crucial regulator in inflammation responses associated with lipopolysaccharide (LPS)-induced macrophages. The IL-17A signaling pathway promotes the release of chemokines and inflammatory cytokines, recruiting neutrophils and T cells under LPS stimulation, thus facilitating inflammatory responses. Here, the potential therapeutic benefits of neutralizing the IL-17A signal and modulating the IL-33/ST2 signal in ALF were investigated. A novel dual-functional fusion protein, anti-IL-17A-sST2, was constructed, which displayed high purity and biological activities. The administration of anti-IL-17A-sST2 resulted in significant anti-inflammatory benefits in ALF mice, amelioration of hepatocyte necrosis and interstitial congestion, and reduction in TNF-α and IL-6. Furthermore, anti-IL-17A-sST2 injection downregulated the expression of TLR4 and NLRP3 as well as important molecules such as MyD88, caspase-1, and IL-1ß. The results suggest that anti-IL-17A-sST2 reduced the secretion of inflammatory factors, attenuated the inflammatory response, and protected hepatic function by regulating the TLR4/MyD88 pathway and inhibiting the NLRP3 inflammasome, providing a new therapeutic approach for ALF.

The Effects of Combined Treatments of Laser Engraving, Plasma Spraying and Resin Pre-Coating on Improving the Bonding Strength of Titanium Alloy and Carbon Fiber-Reinforced Polymer.

This study focused on effective methods of laser engraving treatment (LET), plasma spraying, and resin pre-coating (RPC) to manufacture the reinforced adhesive joints of titanium alloy and carbon fiber-reinforced polymer (TA-CFRP) composites. The combined treatments contributed to the creation of a better adhesive bonding condition and offer a vertical gap between circular protrusions to form epoxy pins and carbon nanotube (CNT)-reinforced epoxy pins. The bonding strength of the TA-CFRP composite was reinforced by 130.6% via treatments with a twice-engraving unit of 0.8 mm, plasma spraying, and RPC. The original debonding failure on the TA surface was changed into the cohesive failure of the epoxy adhesive and delamination-dominated failure of the CFRP panel. Overall, laser engraving has been confirmed as an effective and controllable treatment method to reinforce the bonding strength of the TA-CFRP joint combined with plasma spraying and RPC. It may be considered as an alternative in industry for manufacturing high-performance metal-CFRP composites.

Lipid Nanoparticle-Mediated Delivery of CRISPR-Cas9 Against Rubicon Ameliorates NAFLD by Modulating CD36 Along with Glycerophospholipid Metabolism.

Non-alcoholic fatty liver disease (NAFLD) is a prominent cause of various chronic metabolic hepatic diseases with limited therapeutics. Rubicon, an essential regulator in lysosomal degradation, is reported to exacerbate hepatic steatosis in NAFLD mice and patients, indicating its probability of being a therapeutic target for NAFLD treatment. In this study, the therapeutic potential of Rubicon blockage is investigated. Lipid nanoparticles carrying Rubicon-specific CRISPR-Cas9 components exhibited liver accumulation, cell internalization, and Rubicon knockdown. A single administration of the nanoparticles results in attenuated lipid deposition and hepatic steatosis, with lower circulating lipid levels and decreased adipocyte size in NAFLD mice. Furthermore, the increase of phosphatidylcholine and phosphatidylethanolamine levels can be observed in the NAFLD mice livers after Rubicon silencing, along with regulatory effects on metabolism-related genes such as CD36, Gpcpd1, Chka, and Lpin2. The results indicate that knockdown of Rubicon improves glycerophospholipid metabolism and thereby ameliorates the NAFLD progression, which provides a potential strategy for NAFLD therapy via the restoration of Rubicon.

Targeting IL-33 reprograms the tumor microenvironment and potentiates antitumor response to anti-PD-L1 immunotherapy.

BACKGROUND: The main challenge against patients with cancer to derive benefits from immune checkpoint inhibitors targeting PD-1/PD-L1 appears to be the immunosuppressive tumor microenvironment (TME), in which IL-33/ST2 signal fulfills critical functions. However, whether IL-33 limits the therapeutic efficacy of anti-PD-L1 remains uncertain. METHODS: Molecular mechanisms of IL-33/ST2 signal on anti-PD-L1 treatment lewis lung carcinoma tumor model were assessed by RNA-seq, ELISA, WB and immunofluorescence (IF). A sST2-Fc fusion protein was constructed for targeting IL-33 and combined with anti-PD-L1 antibody for immunotherapy in colon and lung tumor models. On this basis, bifunctional fusion proteins were generated for PD-L1-targeted blocking of IL-33 in tumors. The underlying mechanisms of dual targeting of IL-33 and PD-L1 revealed by RNA-seq, scRNA-seq, FACS, IF and WB. RESULTS: After anti-PD-L1 administration, tumor-infiltrating ST2+ regulatory T cells (Tregs) were elevated. Blocking IL-33/ST2 signal with sST2-Fc fusion protein potentiated antitumor efficacy of PD-L1 antibody by enhancing T cell responses in tumor models. Bifunctional fusion protein anti-PD-L1-sST2 exhibited enhanced antitumor efficacy compared with combination therapy, not only inhibited tumor progression and extended the survival, but also provided long-term protective antitumor immunity. Mechanistically, the superior antitumor activity of targeting IL-33 and PD-L1 originated from reducing immunosuppressive factors, such as Tregs and exhausted CD8+ T cells while increasing tumor-infiltrating cytotoxic T lymphocyte cells. CONCLUSIONS: In this study, we demonstrated that IL-33/ST2 was involved in the immunosuppression mechanism of PD-L1 antibody therapy, and blockade by sST2-Fc or anti-PD-L1-sST2 could remodel the inflammatory TME and induce potent antitumor effect, highlighting the potential therapeutic strategies for the tumor treatment by simultaneously targeting IL-33 and PD-L1.

Correction: Yang et al. Growing Carbon Nanotubes In Situ Surrounding Carbon Fiber Surface via Chemical Vapor Deposition to Reinforce Flexural Strength of Carbon Fiber Composites. Polymers 2023, 15, 2309.

In the original publication [...].

Growing Carbon Nanotubes In Situ Surrounding Carbon Fiber Surface via Chemical Vapor Deposition to Reinforce Flexural Strength of Carbon Fiber Composites.

This study employed novel joint treatments to strengthen the carbon fiber reinforced polymer (CFRP) composites. Vertically aligned carbon nanotubes (VACNTs) were prepared in situ on the catalyst-treated CF surface via the chemical vapor deposition (CVD) method, intertwining into three-dimensional fiber-nets and fully surrounding CF to form an integrated structure. The resin pre-coating (RPC) technique was further used to guide diluted epoxy resin (without hardener) to flow into nanoscale and submicron spaces to eliminate void defects at the root of VACNTs. Three-point bending testing results showed the "growing CNTs and RPC"-treated CFRP composites yielded the best flexural strength, a 27.1% improvement over the specimens without treatment, while the failure modes indicated that the original delamination failure was changed into "flexural failure" with through-the-thickness crack propagation. In brief, growing VACNTs and RPC on the CF surface enabled toughening of the epoxy adhesive layer, reducing potential void defects and constructing the integrated quasi-Z-directional fiber bridging at the CF/epoxy interface for stronger CFRP composites. Therefore, the joint treatments of growing VACNTs in situ via the CVD method and RPC technique are very effective and have great potential in manufacturing high-strength CFRP composites for aerospace applications.

Inhibition of Hedgehog signaling ameliorates foam cell formation by promoting autophagy in early atherosclerosis.

Macrophages are the origin of most foam cells in the early stage of atherosclerotic plaques. However, the mechanism involved in the formation of macrophage-derived foam cell formation remains unclear. Here, we revealed that the hedgehog (Hh) signaling is critical in autophagy-lysosome pathway regulation and macrophage-derived foam cell formation. Inhibition of Hh signaling by vismodegib ameliorated lipid deposition and oxidative stress level in atherosclerotic plaques in high-fat diet-fed apoE-/- mice. For mechanistic study, how the Hh signaling modulate the process of foam cell formation were accessed afterward. Unexpectedly, we found that suppression of Hh signaling in apoE-/- mice had no significant impact on circulating cholesterol levels, indicating that Hh pathway modulate the procession of atherosclerotic plaque not through a traditional lipid-lowing mechanism. Instead, vismodegib was found to accelerate autophagosomes maturation as well as cholesterol efflux in macrophage-derived foam cell and in turn improve foam cell formation, while autophagy inhibitors (LY294002 or CQ) administration significantly attenuated vismodegib-induced cholesterol efflux and reversed the effect on foam cell formation. Therefore, our result demonstrated that inhibition of the Hh signaling pathway increases cholesterol efflux and ameliorates macrophage-derived foam cell formation by promoting autophagy in vitro. Our data thus suggested a novel therapeutic target of atherosclerosis and indicated the potential of vismodegib to treat atherosclerosis.

Simultaneous blockade of VEGF-B and IL-17A ameliorated diabetic kidney disease by reducing ectopic lipid deposition and alleviating inflammation response.

The pathogenesis of diabetic kidney disease (DKD) is complicated. Current clinical treatments fail to achieve satisfactory efficacy in the prevention of DKD progression, it urgently needs novel and effective treatment for DKD. In this study, we firstly demonstrated that renal lipid metabolism abnormality and inflammation significantly changed in DKD conditions by mining public transcriptomic data of DKD patient samples. KEGG analysis further exhibited the critical role of vascular endothelial growth factor B (VEGF-B) and interleukin 17A (IL-17A) signal pathways in DKD progression, indicating that VEGF-B and IL-17A might be the promising targets for DKD treatment. Then the potential of a novel combination therapy, anti-VEGF-B plus anti-IL-17A antibody, was evaluated for DKD treatment. Our results demonstrated that simultaneous blockade of VEGF-B and IL-17A signaling with their neutralizing antibodies alleviated renal damage and ameliorated renal function. The therapeutic effectiveness was not only related to the reduced lipid deposition especially the neutral lipids in kidney but also associated with the decreased inflammation response. Moreover, the therapy alleviated renal fibrosis by reducing collagen deposition and the expression of fibronectin and α-SMA in kidney tissues. RNA-seq analysis indicated that differential expression genes (DEGs) in db/db mice were significantly clustered into lipid metabolism, inflammation, fibrosis and DKD pathology-related pathways, and 181 of those DEGs were significantly reversed by the combinatory treatment, suggesting the underlying mechanism of administration of anti-VEGF-B and anti-IL-17A antibodies in DKD treatment. Taken together, this study identified that renal lipid metabolism abnormality and inflammation were critically involved in the progression of DKD, and simultaneous blockade of VEGF-B and IL-17A signaling represents a potential DKD therapeutic strategy.

Targeting CD47 enhanced the antitumor immunity of PD-L1 blockade in B-cell lymphoma.

Background: Only a subset of B-cell lymphoma (BCL) patients can benefit from immune checkpoint inhibitors targeting PD-1/PD-L1. Materials & methods: In the A20 model, SIRPα-Fc and anti-PD-L1 were employed to target CD47 and PD-L1 simultaneously. Flow cytometry, immunofluorescence and quantitative polymerase chain reaction were used to unravel the potential mechanisms. Results: Simultaneously targeting CD47 and PD-L1 activated CD8+ T cells with an increased release of effector molecules. Furthermore, infiltration of F4/80+iNOS+ M1 macrophages was enhanced by the dual therapy. Conclusion: Anti-CD47 therapy could sensitize BCL tumors to anti-PD-L1 therapy in a CD8+ T-cell- and M1-macrophage-dependent manner by promoting cytotoxic lymphocyte infiltration, which may provide a potential strategy for BCL treatment by simultaneously targeting CD47 and PD-L1.

Immune checkpoint inhibitors targeting PD-1/PD-L1 have become effective agents for cancer treatment. However, only a minority of patients benefit from this treatment in the clinic because of the limited response rate. Targeting CD47/SIRPα restores macrophage function and improves the response of antitumor immunity. Here, combination immunotherapy targeting CD47/SIRPα and PD-1/PD-L1 was investigated to increase the response rate and antitumor effect of PD-L1 monotherapy in B-cell lymphoma (BCL). This study broadens the application of the combination therapy and provided a promising strategy for B-cell lymphoma treatment by simultaneous targeting of PD-1/PD-L1 and CD47/SIRPα axis.

A novel fusion protein consisting of anti-ANGPTL3 antibody and interleukin-22 ameliorates diabetic nephropathy in mice.

Introduction: The pathogenic mechanisms of diabetic nephropathy (DN) include podocyte injury, inflammatory responses and metabolic disorders. Although the antagonism of Angiopoietin-like protein 3 (ANGPTL3) can alleviate proteinuria symptoms by inhibiting the activation of integrin αvß3 on the surface of podocytes, it can not impede other pathological processes, such as inflammatory responses and metabolic dysfunction of glucolipid. Interleukin-22 (IL-22) is considered to be a pivotal molecule involved in suppressing inflammatory responses, initiating regenerative repair, and regulating glucolipid metabolism. Methods: Genes encoding the mIL22IgG2aFc and two chains of anti-ANGPTL3 antibody and bifunctional protein were synthesized. Then, the DN mice were treated with intraperitoneal injection of normal saline, anti-ANGPTL3 (20 mg/kg), mIL22Fc (12 mg/kg) or anti-ANGPTL3 /IL22 (25.3 mg/kg) and irrigation of positive drug losartan (20mg/kg/d) twice a week for 8 weeks. Results: In this research, a novel bifunctional fusion protein (anti-ANGPTL3/IL22) formed by the fusion of IL-22 with the C-terminus of anti-ANGPTL3 antibody exhibited favorable stability and maintained the biological activity of anti-ANGPTL3 and IL-22, respectively. The fusion protein showed a more pronounced attenuation of proteinuria and improved dysfunction of glucolipid metabolism compared with mIL22Fc or anti-ANGPTL3. Our results also indicated that anti-ANGPTL3/IL22 intervention significantly alleviated renal fibrosis via inhibiting the expression of the inflammatory response-related protein nuclear factor kappa light-chain enhancer of activated B cells (NF-κB) p65 and NOD-like receptor family pyrin domain-containing protein 3 (NLRP3) inflammasome. Moreover, transcriptome analysis revealed the downregulation of signaling pathways associated with injury and dysfunction of the renal parenchymal cell indicating the possible protective mechanisms of anti-ANGPTL3/IL22 in DN. Conclusion: Collectively, anti-ANGPTL3/IL22 bifunctional fusion protein can be a promising novel therapeutic strategy for DN by reducing podocyte injury, ameliorating inflammatory response, and enhancing renal tissue recovery.

AKR1C3 and ß-catenin expression in non-small cell lung cancer and relationship with radiation resistance.

PURPOSE: To search the AKR1C3 and ß-catenin expression in non-small cell lung cancer (NSCLC) and to explore the correlation between AKR1C3 and ß-catenin and radiation resistance. METHODS: Paraffin specimens from 61 patients with NSCLC were evaluated. These patients could not receive operation but received radical radiotherapy. The patients were divided into effective group and ineffective group with reference to RECIST evaluation criteria. The sites and intensity of AKR1C3 and ß-catenin protein expression were detected by immunohistochemistry. The relationship between AKR1C3 and ß-catenin and radiation resistance was analyzed by Mann-Whitney U test. The correlation between AKR1C3 and ß-catenin was analyzed by Spearman's correlation test. Mann-Whitney U test was used to analyze the AKR1C3 overall expression in the effective group and the ineffective group after radiotherapy. RESULTS: The nuclear expression in the two groups was statistically significant (p=0.033). The ß-catenin protein was mainly expressed in the cytoplasm and the nucleus of tissues with NSCLC. The ß-catenin nuclear expression was different between the two groups, with statistical significance (p=0.008). AKR1C3 nuclear expression was positively correlated with ß-catenin nuclear expression (rs=0.382, p=0.002). CONCLUSIONS: High AKR1C3 nuclear expression in NSCLC is related to radiation resistance. The higher the AKR1C3 nucleus expression, the worse short-term curative effects after radiotherapy. High ß-catenin nuclear expression is related to radiation resistance, and the higher the ß-catenin nuclear expression, the worse the short-term curative effects after radiotherapy. The nuclear aggregation of AKR1C3 during radiation resistance of non-small cell lung cancer (NSCLC) may have some synergistic relationship with nuclear aggregation of ß-catenin.

Margin failures in brittle dome structures: relevance to failure of dental crowns.

Margin cracks in loaded brittle dome structures are investigated. Dome structures consisting of glass shells filled with polymer resin, simulating the essential features of brittle crowns on tooth dentin, provide model test specimens. Disk indenters of diminishing elastic modulus are used to apply axisymmetric loading to the apex of the domes. Previous studies using hard indenters have focused on fractures initiating in the near-contact region of such specimens, including radial cracks at the glass undersurface directly below the contact axis. Here, we focus on fractures initiating at the remote support margins. Margin cracks can become dominant when loading forces are distributed over broad contact areas, as in biting on soft matter, here simulated by balsa wood disks. Cracks preinitiated at the dome edges during the specimen preparation propagate under load around the dome side into segmented, semilunar configurations reminiscent of some all-ceramic crown failures. Finite element analysis is used to determine the basic stress states within the dome structures, and to confirm a shift in maximum tensile stress from the near-contact area to the dome sides with more compliant indenters.

Co-expression of the recombined alcohol dehydrogenase and glucose dehydrogenase and cross-linked enzyme aggregates stabilization.

As the key chiral precursor of Crizotinib (S)-1-(2,6-dichloro-3-fluorophenyl) phenethyl alcohol can be prepared from 1-(2,6-dichloro-3-fluorophenyl) acetophenone by the reductive coupling reactions of alcohol dehydrogenase (ADH) and glucose dehydrogenases (GDH). In this work the heterologous expression plasmids harbouring the encoding genes of ADH and GDH were constructed respectively and co-expressed in the same E. coli strain. After optimization, a co-cross-linked enzyme aggregates (co-CLEAs) of both ADH and GDH were prepared from crude enzyme extracts by cross-linking with the mass ratio of Tween 80, glutaraldehyde and total protein (0.6:1:2) which rendered immobilized biocatalysts that retained 81.90% (ADH) and 40.29% (GDH) activity retention. The ADH/GDH co-CLEAs show increased thermal stability and pH stability compared to both enzymes. The ADH/GDH co-CLEAs also show 80% (ADH) and 87% (GDH) residual activity after seven cycles of repeated use. These results make the ADH/GDH co-CLEAs a potential biocatalyst for the industrial preparation of (S)-1-(2,6-dichloro-3-fluorophenyl) phenethyl alcohol.

"Steel-Concrete" Inspired Biofunctional Layered Hybrid Cage for Spine Fusion and Segmental Bone Reconstruction.

In this paper we report a "steel-concrete" inspired layered hybrid spine cage combining a titanium mesh and a bioceramic scaffold, which were welded together through a bioglass bonding layer using a novel multistep manufacturing methodology including three-dimensional slip deposition, gel casting, freeze-drying, and cosintering. The interfacial welding strength achieved 27 ± 0.7 MPa, indicating an excellent structural integrity of the hybrid cage construct. The biocramic scaffold layer consisting of wollastonite and hydroxyapatite had an interconnected, highly porous structure with a pore size of 100-500 µm and a porosity of >85%, well fufilling the structural requirements of bone regeneration. Simulated body fluid immersion assay showed that the hybrid cage exhibited excellent biodegradability to facilitate rapid bone-like apatite formation. In vitro studies demonstrated that the bioceramic scaffold on the hybrid cage supported attachment, spreading, growth, and migration of bone/vessel-forming cells and triggered osteogenic differentiation of human mesenchymal stem cells. In vivo studies further suggested that the bioceramic scaffold on the hybrid cage could actively promote fast generation of new bone tissues within 12 weeks of implantation in a rabbit femoral condyle model. This study has provided a new design and fabrication methodology of hybrid cages by integrating strong mechanical properties with excellent biological activities including osteoinductivity and bone regeneration ability, for spine fusion and segmental bone reconstruction.

Effect of off-axis concentrated loading on failure of curved brittle layer structures.

A study is made of the effects of superposed tangential force by off-axis indentation loading on curved bilayers consisting of brittle shells filled with polymer support material. Such loadings are pertinent to all-ceramic crown structures on tooth dentin in occlusal function. Layer flexure places the ceramic undersurfaces in tension, leading to fracture by initiation and propagation of radial cracks. Following an earlier study, model specimens with curved surfaces are prepared by pressing glass plates 1 mm thick onto steel spherical dies with radius of curvature 20 mm to 8 mm at elevated temperatures, and bonding the resultant hemispherical shells onto an epoxy support base. The specimens are tested by indentation with spheres loaded vertically but off-center, with the contact center located at 30 degrees to the hemisphere axis. The applied loads to initiate radial cracks are little affected by the resultant tangential component, but the loads to propagate the same cracks to the specimen edges are substantially reduced. Finite element calculations are used to evaluate stress states in the specimens for correlation with the experimental data.

Characterizing depth-dependent refractive index of articular cartilage subjected to mechanical wear or enzymic degeneration.

Utilizing a laser scanning confocal microscope system, the refractive indices of articular cartilage (AC) with mechanical or biochemical degenerations were characterized to investigate whether potential correlations exist between refractive index (RI) and cartilage degeneration. The cartilage samples collected from the medial femoral condyles of kangaroo knees were mechanically degenerated under different loading patterns or digested in trypsin solution with different concentrations. The sequences of RI were then measured from cartilage surface to deep region and the fluctuations of RI were quantified considering combined effects of fluctuating frequency and amplitude. The compositional and microstructural alterations of cartilage samples were assessed with histological methods. Along with the loss of proteoglycans, the average RI of cartilage increased and the local fluctuation of RI became stronger. Short-term high-speed test induced little influence to both the depth fluctuation and overall level of RI. Long-term low-speed test increased the fluctuation of RI but the average RI was barely changed. The results substantially demonstrate that RI of AC varies with both compositional and structural alterations and is potentially an indicator for the degeneration of AC.

Design optimization of a radial functionally graded dental implant.

In this work, we use FEA to test the hypothesis that a low-modulus coating of a cylindrical zirconia dental implant would reduce the stresses in the peri-implant bone and we use design optimization and the rule of mixture to estimate the elastic modulus and the porosity of the coating that provides optimal stress shielding. We show that a low-modulus coating of a dental implant significantly reduces the maximum stresses in the peri-implant bone without affecting the average stresses thus creating a potentially favorable biomechanical environment. Our results suggest that a resilient coating is capable of reducing the maximum compressive and tensile stresses in the peri-implant bone by up to 50% and the average stresses in the peri-implant bone by up to 15%. We further show that a transitional gradient between the high-modulus core and the low-modulus coating is not necessary and for a considered zirconia/HA composite the optimal thickness of the coating is 100 µ with its optimal elastic at the lowest value considered of 45 GPa.