Anatomical Brushite-Coated Mg-Nd-Zn-Zr Alloy Cage Promotes Cervical Fusion: One-Year Results in Goats

In this study, an anatomical brushite-coated Mg-Nd-Zn-Zr alloy cage was fabricated for cervical fusion in goats. The purpose of this study was to investigate the cervical fusion effect and degradation characteristics of this cage in goats. The Mg-Nd-Zn-Zr alloy cage was fabricated based on anatomical studies, and brushite coating was prepared. Forty-five goats were divided into three groups, 15 in each group, and subjected to C2/3 anterior cervical decompression and fusion with tricortical bone graft, Mg-Nd-Zn-Zr alloy cage, or brushite-coated Mg-Nd-Zn-Zr alloy cage, respectively. Cervical radiographs and computed tomography (CT) were performed 3, 6, and 12 months postoperatively. Blood was collected for biocompatibility analysis and Mg2+ concentration tests. The cervical spine specimens were obtained at 3, 6, and 12 months postoperatively for biomechanical, micro-CT, scanning electron microscopy coupled with energy dispersive spectroscopy, laser ablation-inductively coupled plasma-time-of-flight mass spectrometry, and histological analysis. The liver and kidney tissues were obtained for hematoxylin and eosin staining 12 months after surgery for biosafety analysis. Imaging and histological analysis showed a gradual improvement in interbody fusion over time; the fusion effect of the brushite-coated Mg-Nd-Zn-Zr alloy cage was comparable to that of the tricortical bone graft, and both were superior to that of the Mg-Nd-Zn-Zr alloy cage. Biomechanical testing showed that the brushite-coated Mg-Nd-Zn-Zr alloy cage achieved better stability than the tricortical bone graft at 12 months postoperatively. Micro-CT showed that the brushite coating significantly decreases the corrosion rate of the Mg-Nd-Zn-Zr alloy cage. In vivo degradation analysis showed higher Ca and P deposition in the degradation products of the brushite-coated Mg-Nd-Zn-Zr alloy cage, and no hyperconcentration of Mg was detected. Biocompatibility analysis showed that both cages were safe for cervical fusion surgery in goats. To conclude, the anatomical brushite-coated Mg-Nd-Zn-Zr alloy cage can promote cervical fusion in goats, and the brushite-coated Mg-Nd-Zn-Zr alloy is a potential material for developing absorbable fusion cages.

Mg-based implants with a sandwiched composite coating simultaneously facilitate antibacterial and osteogenic properties

Insufficient antibacterial effects and over-fast degradation are the main limitations of magnesium (Mg)-based orthopedic implants. In this study, a sandwiched composite coating containing a triclosan (TCS)-loaded poly(lactic acid) (PLA) layer inside and brushite (DCPD) layer outside was prepared on the surface of the Mg-Nd-Zn-Zr (denoted as JDBM) implant. In vitro degradation tests revealed a remarkable improvement in the corrosion resistance and moderate degradation rate. The drug release profile demonstrated a controllable and sustained TCS release for at least two weeks in vitro. The antibacterial rates of the implant were all over 99.8% for S. aureus, S. epidermidis, and E. coli, demonstrating superior antibacterial effects. Additionally, this coated JDBM implant exhibited no cytotoxicity but improved cell adhesion and proliferation, indicating excellent cytocompatibility. In vivo assays were conducted by implant-related femur osteomyelitis and osseointegration models in rats. Few bacteria were attached to the implant surface and the surrounding bone tissue. Furthermore, the coated JDBM implant exhibited more new bone formation than other groups due to the synergistic biological effects of released TCS and Mg2+, revealing excellent osteogenic ability. In summary, the JDBM implant with the sandwiched composite coating could significantly enhance the antibacterial activities and osteogenic properties simultaneously by the controllable release of TCS and Mg2+, presenting great potential for clinical transformation.

Enhanced Adsorption Stability and Biofunction Durability with Phosphonate-Grafted, PEGylated Copolymer on Hydroxyapatite Surface

Nonfouling surfaces are crucial in applications such as biosensors, medical implants, marine coatings, and drug delivery vehicles. However, their long-term coating stability and robust surface binding strength in physiological media remain challenging. Herein, a phosphonate-grafted, PEGylated copolymer on the hydroxyapatite (HA) surface is proposed to significantly improve the adsorption stability and thus enhance the biofunction durability accordingly. The phosphoryl (-PO3) grafted branch is employed in the functional polymer to facilitate attaching to the HA substrate. In addition, the polymer integrates the nonfouling polymer brushes of poly(ethylene glycol) (PEG) with the cell-adhesive moiety of cyclic Arg-Gly-Asp-d-Phe-Cys peptides (cRGD). A systematic study on the as-synthesized PEGylated graft copolymer indicates a synergistic binding mechanism of the NH2 and PO3 groups to HA, achieving a high surface coverage with desirable adsorption stability. The cRGD/PEGylated copolymers of optimized grafting architecture are proven to effectively adsorb to HA surfaces as a self-assembled copolymer monolayer, showing stability with minimal desorption even in a complex, physiological medium and effectively preventing nonspecific protein adsorption as examined with X-ray photoelectron spectroscopy (XPS) and a quartz crystal microbalance with dissipation (QCM-D). Direct adhesion assays further confirm that the enhanced coating stability and biofunction durability of the phosphonate-grafted, cRGD-PEGylated copolymer can considerably promote osteoblast attachment on HA surfaces, meanwhile preventing microbial adhesion. This research has resulted in a solution of self-assembly polymer structure optimization that exhibits stable nonfouling characteristics.

Clinical efficacy of percutaneous vertebroplasty versus percutaneous kyphoplasty treating osteoporotic vertebral compression fractures with kyphosis

PURPOSE

This study aimed to investigate the clinical efficacy of percutaneous vertebroplasty (PVP) and percutaneous kyphoplasty (PKP) in treating osteoporotic vertebral compression fractures (OVCFs) with kyphosis.

METHODS

The clinical data included 63 patients in the PVP group and 70 in the PKP group. The study assessed the pain visual analog scale (VAS), Oswestry Disability Index (ODI), wedge angle (WA), local kyphotic angle (LKA), and vertebral height.

RESULTS

The operative time was significantly less in the PVP group (p < 0.05). Meanwhile, more bone cement was injected into the PKP group (p < 0.05), with significantly higher surgical costs (p > 0.05). Post-operative VAS, ODI, WA, LKA, and vertebral height were significantly improved in PVP and PKP groups compared with pre-operative measurements (p < 0.05). The results revealed insignificant VAS and ODI improvement differences between the two groups at each follow-up time (p > 0.05). Vertebral height, WA, and LKA improved more significantly in the PKP group at day 1 and 3 months post-operatively (p < 0.05), with insignificant group differences at subsequent time points (p > 0.05). The improvements in VAS were unrelated to those in WA, LKA, or vertebral height in either group (p > 0.05). The improvement in VAS was unrelated to the amount of bone cement injected (p > 0.05); the PKP group demonstrated a lower incidence of cement leakage (12.9%; p < 0.05).

CONCLUSION

PVP and PKP can restore partial vertebral height and improve kyphosis with similar clinical outcomes. PVP has a shorter operating time, is more economical, and can represent a therapeutic choice.

Molecular Imaging of Radiation-Induced Lung Injury Using [18F]AlF Labeled Polypeptide Targeting C-X-C-Chemokine-Receptor-Type-4

PURPOSE/OBJECTIVE(S)

Radiation-induced lung injury (RILI) is a severe side effect of radiotherapy (RT) for thoracic malignancies and we currently lack established means for the early detection of RILI. In this study, we synthesized a new tracer, [18F]AlF-NOTA-QHY-04, targeting C-X-C-chemokine-receptor-type-4 (CXCR4) and investigated the feasibility of using this tracer in positron emission tomography combined with computed tomography (PET/CT) for detecting RILI.

MATERIALS/METHODS

An RILI model was established using a high-dose single RT (50 Gy/Fraction) to the right lung of female Wistar rats. Experimental animals were scanned with [18F]AlF-NOTA-QHY-04 PET/CT and [18F]FDG PET/CT at various time-points post-RT. MicroCT imaging was conducted weekly till 11 weeks post-RT. Dynamic, competition, autoradiography and histopathological studies were performed on day 14 post-RT. Biodistribution study was further performed on day 18 post-RT. Lung QHY-04 uptake was analyzed in twelve patients with radiation pneumonia, developed during or after thoracic RT.

RESULTS

The yield of [18F]AlF-NOTA-QHY-04 was 28.5-43.2%, and the specific activity was 27-33 GBq/μmol. Significantly increased [18F]AlF-NOTA-QHY-04 uptake in the damaged lung compared with that in the normal lung was observed in the experimental animal model on 6 post-RT and peaked on day 14 post-RT (0.96 ± 0.06 vs. 0.50 ± 0.05 %ID/mL, P<0.05), whereas no apparent uptake of [18F]FDG was shown on day 7 and 15 post-RT. Significant intense [18F]AlF-NOTA-QHY-04 uptake was confirmed by autoradiography. No significant difference in CT density was observed between the damaged and normal lung tissues until six weeks post-RT. Immunofluorescence staining demonstrated expression of CXCR4 was significantly increased in the damaged lung tissue, which correlated with results obtained from hematoxylin-eosin and Masson's trichrome staining. Maximum standardized uptake values (SUVmax) were significantly higher in the irradiated lung compared with that in the normal lung in 12 patients with radiation pneumonia (3.07 ± 0.86 vs. 0.585 ± 0.17, P<0.001). SUVmax of patients with grade 2 RILI was significantly higher than that of patients with grade 1 RILI (3.30 ± 0.65 vs. 1.64 ± 0.08, P<0.05).

CONCLUSION

This study indicated that [18F]AlF-NOTA-QHY-04 PET/CT imaging can detect RILI noninvasively and earlier than [18F]FDG PET/CT in a rat model. Clinical studies verified its' feasibility, suggesting the clinical potential of [18F]AlF-NOTA-QHY-04 as a PET/CT tracer for early monitoring of RILI.

Efficacy and Safety of Absorb Everolimus-Eluting Bioresorbable Vascular Scaffold in Peripheral Artery Disease: A Single-Arm Meta-Analysis

PURPOSE

This study aimed to evaluate the benefits and risks of patients with peripheral artery disease (PAD) treated with Absorb everolimus-eluting bioresorbable vascular scaffold (BVS) by analyzing all the published studies on the clinical characteristics of patients with PAD.

MATERIALS AND METHODS

PubMed, Embase, and the Cochrane Library were searched for relevant studies. Efficacy, safety, and basic characteristics were analyzed.

RESULTS

Four studies were included in meta-analysis, including a total number of 155 patients with PAD. The pooled overall primary patency, freedom from target lesion revascularization (TLR), symptom resolution, and wound healing were 90%, 96%, 94%, and 86%, respectively. The pooled perioperative complication and all-cause mortality were 4% and 9%, respectively. Preoperative total occlusion was detected in 43 of 192 lesions (22%). The mean lesion length was 27.26 mm. In terms of comorbidities, the pooled percentage of hypertension, hyperlipidemia, diabetes mellitus, coronary artery disease, chronic kidney disease history, and smoking were 65%, 74%, 49%, 43%, 20%, and 57%, respectively.

CONCLUSION

Among these studies, hypertension, hyperlipidemia, and diabetes mellitus were the most common comorbidities in patients with PAD. The Absorb everolimus-eluting BVS was safe and showed the favorable clinical outcomes in both patency and TLR, especially in infrapopliteal disease with heavy calcification. The conclusions of this meta-analysis still needed to be verified by more relevant studies with more careful design, more rigorous execution, and larger sample size.

Clinical outcomes of autologous platelet-rich plasma and bone marrow mononuclear cells grafting combined with core decompression for Association Research Circulation Osseous II-IIIA stage non-traumatic osteonecrosis of the femoral head

PURPOSE

This study aimed to investigate the efficacy and safety of autologous platelet-rich plasma (PRP) and bone marrow mononuclear cells (BMMCs) grafting combined with core decompression (CD) in the treatment of Association Research Circulation Osseous (ARCO) II-IIIA stage non-traumatic osteonecrosis of the femoral head (ONFH).

METHODS

The clinical data of 44 patients (44 hips) with non-traumatic ONFH from December 2018 to December 2019 were retrospectively reviewed. Twenty-four patients underwent CD combined with autologous PRP and BMMCs grafting (PRP+BMMCs group), and 20 patients underwent core decompression alone (CD group). During a minimum follow-up of 36 months, radiographic outcomes were evaluated using X-ray, radiographic failure rates were compared, and Harris hip score (HHS) and visual analog scale (VAS) were selected to evaluate clinical outcomes. The percentage of patients with minimal clinically important difference (MCID) in both groups was analyzed. Clinical failure was defined as further total hip arthroplasty (THA) with Kaplan-Meier survival analysis. Surgical complications were recorded.

RESULTS

All patients had well healed wounds, and no complications such as infection and thrombosis occurred. HHS and VAS scores in both the PRP+BMMCs and CD groups were better than those preoperatively (P<0.05). At the last follow-up, the HHS and VAS scores of the PRP+BMMCs group were significantly better than those of the CD group (P<0.05). In ARCO II-IIIA stage, 66.7% of the PRP+BMMCs group and 30.0% of the CD group achieved the MCID (P<0.05). The clinical and imaging failure rates in the PRP+BMMCs group were 12.5% and 20.8%, respectively, compared with 40.0% and 50.0% in the CD group (P<0.05). In ARCO II stage, the MCID, clinical and imaging failure rates of PRP+BMMCs group and CD group were 66.7% and 33.3% (P<0.05), 4.8% and 33.3% (P<0.05), 14.3% and 44.4% (P<0.05), respectively. The PRP+BMMCs group had better hip survival rate compared with CD group (P<0.05).

CONCLUSION

CD combined with autologous PRP and BMMCs grafting is a safe and effective method for the treatment of ARCO II-IIIA stage non-traumatic ONFH, especially for ARCO II stage, effectively reducing the collapse rate of the femoral head and delaying or even avoiding THA.

Comparison of clinical outcomes between posterolateral approach and modified Hardinge approach in salvage total hip arthroplasty after medial buttress plate failure for femoral neck fractures

OBJECTIVE

The purpose of this study was to investigate the clinical outcomes of salvage total hip arthroplasty (THA) after medial buttress plate surgery for femoral neck fractures via the modified Hardinge approach (MHA) and posterolateral approach (PLA) through a retrospective analysis.

PATIENTS AND METHODS

From October 2016 to October 2020, a total of 41 patients with failed femoral neck fractures treated with cannulated screws and medial buttress plates underwent unilateral salvage THA, and a retrospective study was conducted. According to the surgical approach, patients were divided into PLA group and MHA group. Clinical and radiological data were evaluated. The primary outcome indicators were the Pain Visual Analog Scale (VAS) and Hip Harris Score (HHS). Secondary outcome indicators include hemoglobin (HGB), hematocrit (HCT), creatine kinase (CK), creatine kinase-MB (CK-MB), etc. The occurrence of postoperative complications was also recorded.

RESULTS

There were no differences in demographic or clinical characteristics before surgery. There were no differences in postoperative HGB, HCT, CK-MB and radiological parameters. The surgical approach had no effect on the hospitalization period. The PLA group had earlier ambulation time, and the serum level of CK was also low. Analysis of the HHS and VAS showed that on postoperative day 3, the PLA group had superior scores. The incidence of complications did not significantly differ between groups.

CONCLUSIONS

The posterolateral approach for salvage THA provides better functional recovery with less muscle damage in the early postoperative period.

[Research advances on improving the therapeutic efficacy of mesenchymal stem cell-derived exosomes in wound repair]

How to promote high-quality wound healing is a common problem for plastic surgery and burn physicians. In recent years, numerous animal studies have demonstrated that mesenchymal stem cell-derived exosomes promote wound repair through multiple mechanisms and are promising cell-free therapeutic agents with broad prospect of application. How to enhance the therapeutic efficacy of exosomes, optimize their drug delivery strategy, and improve their biological properties are the challenges to be overcome in order to move from basic research to clinical application of exosome therapy for wound repair. This article focuses on methods to improve the wound repair potential of mesenchymal stem cell-derived exosomes, and reviews the recent research advances on improving the therapeutic efficacy of mesenchymal stem cell-derived exosomes in wound repair from three aspects, including pretreatment of parental mesenchymal stem cells, hydrogel bio-scaffold loaded with exosomes, and engineered exosomes, to provide a reference for further clinical studies.

Brushite-coated Mg-Nd-Zn-Zr alloy promotes the osteogenesis of vertebral laminae through IGF2/PI3K/AKT signaling pathway

Biodegradable magnesium (Mg) alloys have been extensively investigated in orthopedic implants due to their suitable mechanical strength and high biocompatibility. However, no studies have reported whether Mg alloys can be used to repair lamina defects, and the biological mechanisms regulating osteogenesis are not fully understood. The present study developed a lamina reconstruction device using our patented biodegradable Mg-Nd-Zn-Zr alloy (JDBM), and brushite (CaHPO₄·2H₂O, Dicalcium phosphate dihydrate, DCPD) coating was developed on the implant. Through in vitro and in vivo experiments, we evaluated the degradation behavior and biocompatibility of DCPD-JDBM. In addition, we explored the potential molecular mechanisms by which it regulates osteogenesis. In vitro, ion release and cytotoxicity tests revealed that DCPD-JDBM had better corrosion resistance and biocompatibility. We found that DCPD-JDBM extracts could promote MC3T3-E1 osteogenic differentiation via the IGF2/PI3K/AKT pathway. The lamina reconstruction device was implanted on a rat lumbar lamina defect model. Radiographic and histological analysis showed that DCPD-JDBM accelerated the repair of rat lamina defects and exhibited lower degradation rate compared to uncoated JDBM. Immunohistochemical and qRT-PCR results showed that DCPD-JDBM promoted osteogenesis in rat laminae via IGF2/PI3K/AKT pathway. This study shows that DCPD-JDBM is a promising biodegradable Mg-based material with great potential for clinical applications.

A24 INVESTIGATING THE IMPACT OF PARKINSON’S DISEASE-ASSOCIATED GENES ON INTESTINAL HOMEOSTASIS

Background

Intestinal epithelial cells (IECs) provide an essential physical barrier between harsh luminal contents and underlying host tissue. The maintenance of intestinal homeostasis in this rapidly renewing tissue must be intricately regulated through the proliferation and differentiation of intestinal stem cells (ISCs). Dysregulation of this system results in the loss of barrier function, causing pathologies in both intestinal and extra-intestinal diseases. While Parkinson’s Disease (PD) is primarily a neurodegenerative disorder, there is increasing evidence linking PD progression and gastrointestinal dysfunction. For instance, constipation and increased bowel permeability are frequently observed years prior to development of motor dysfunction in PD, people with inflammatory bowel disease are more likely to develop PD, and a positive correlation exists between gastrointestinal infections and PD incidence. Our group recently developed a model to investigate the role of the gut in PD, demonstrating that mice with genetic ablation of the PD-associated gene Pink1 exhibited motor phenotypes only when previously infected with Gram-negative Citrobacter rodentium intestinal bacteria. As Pink1 and other PD-associated genes are expressed in IECs, we hypothesize that PD-associated gene mutations directly affect the epithelium and impact early PD pathophysiology.

Purpose

Investigate the impact of Pink1 and other PD-associated genes in IECs under steady state and infection.

Method

Single-cell RNA sequencing was performed on IECs isolated from Pink1 WT and KO mice, at steady state and following in vivo C. rodentium infection. Mice were sacrificed at an early timepoint of infection (day 6) to elucidate transcriptional differences between epithelial lineages of each genotype. Additionally, ex vivo colonoids were derived from primary mouse tissue and treated with lipopolysaccharide (LPS) to determine how PINK1 loss-of-function affects the inflammatory response of the epithelium.

Result(s)

Our data revealed that loss-of-function of PINK1 profoundly affected the ISC compartment and several epithelial lineages. Specifically, ISCs from infected Pink1 KO mice demonstrated differentially regulated proliferative and cell cycle genes, while transit amplifying cells showed dysregulated expression of tight junction genes, and enterocytes displayed differentially expressed oxidative damage and apoptotic genes. Preliminary data from colonoids showed that Pink1 KO mice, when stimulated with LPS, had increased pro-inflammatory cytokine gene expression.

Conclusion(s)

In Pink1 KO intestinal epithelial cells, there is indeed an altered cellular response upon infection in vivo and LPS treatment ex vivo. However, more information is needed to decern the mechanistic role of IECs in PD. By investigating the role of PD genes in the gastrointestinal tract, these studies carry important implications for understanding the initiation and progression of PD.

Disclosure of Interest

None Declared

Editing of a Specific Strain of Escherichia coli in the Mouse Gut Using Native Phages

There is a lack of methodological investigation of the in situ functions of bacterial species in microecosystems. Here, we used native phages as a microbial editing tool for eliminating Escherichia coli strain MG1655 labeled with green fluorescent protein (GFP) in the mouse gut. The virulent phages (W1 and W3) possessed host specificity at both the genus and species levels, resulting in an 8.8-log10 difference in the titer of viable bacteria after 12 h of phage treatment compared with that in the phage-free control in an in vitro test. In vivo, they reduced strain MG1655 colonizing the mouse gut at concentrations of 106 to 108 CFU g-1 to a 102 CFU g-1 level, which is almost undetectable by the plate colony-counting method. Moreover, the impact of phage treatment on the microbial community structure of the mouse gut was not significant (P > 0.05), indicating that native phages can effectively edit a target bacterium, with limited perturbation of microbial diversity and relative abundance. Therefore, we developed an engineering technique for investigation of the functions of a specific bacterium by depleting its abundance in microecosystems. IMPORTANCE This report describes a gut engineering technique for investigation of the functions of a specific bacterium. Native phages with host specificity can knock down the corresponding E. coli strain in the mouse gut with limited perturbation of microbial diversity and relative abundance, indicating that they, as a microbial editing tool, can effectively edit the abundance of a target bacterium. Such an approach is undoubtedly of interest in the context of lack of knowledge of how to methodologically study the in situ function of a specific species in a complex microecosystem.

Whole-cell biosynthesis of cytarabine by an unnecessary protein-reduced Escherichia coli that coexpresses purine and uracil phosphorylase

Currently, whole-cell catalysts face challenges due to the complexity of reaction systems, although they have a cost advantage over pure enzymes. In this work, cytarabine was synthesized by purified purine phosphorylase 1 (PNP1) and uracil phosphorylase (UP), and the conversion of cytarabine from adenine arabinoside reached 72.3±4.3%. However, the synthesis was unsuccessful by whole-cell catalysis due to interference from unnecessary proteins (UNPs) in cells. Thus, we carried out a large-scale gene editing involving 377 genes in the genome of Escherichia coli to reduce the negative effect of UNPs on substrate conversion and cytarabine production. Finally, the PNP1 and UP activities of the obtained mutant were increased significantly compared with the parental strain, and more importantly, the conversion rate of cytarabine by whole-cell catalysis reached 67.4±2.5%. The lack of 148 proteins and down-regulation of 783 proteins caused by gene editing were equivalent to partial purification of the enzymes within cells, and thus, we provided inspiration to solve the problem caused by UNP interference, which is ubiquitous in the field of whole-cell catalysis. This article is protected by copyright. All rights reserved.

Arbuscular mycorrhizal fungi enhance nutrient acquisition and reduce aluminum toxicity in Lespedeza formosa under acid rain

Lespedeza formosa is an economically important shrub in the agroecosystems of southern China, where acid rain (AR) is an increasingly serious environmental issue. However, the roles of arbuscular mycorrhizal fungi (AMF) in adapting the plants to AR stress are poorly understood. In this study, L. formosa seedlings were cultivated in a greenhouse, where the inoculated (colonization with Rhizophagus irregularis and Diversispora versiformis, alone and in combination) and non-inoculated plants were treated with three AR regimes (pH 5.6, 4.0, and 2.5) to evaluate the roles of AMF under acidic conditions. The results showed that AR individually suppressed plant growth by inhibiting photosynthetic parameters and induced Al phytotoxicity in non-mycorrhizal plants. However, mycorrhizal inoculation, especially in combination, significantly increased the total dry weight, photosynthetic capabilities, shoot nitrogen (N) concentration (average 15.8 and 16.7 mg g^-1 for non-mycorrhizal and mycorrhizal plants, respectively) and plant phosphorus (P) concentration (average 1.6 and 2.3 mg g^-1 for non-mycorrhizal and mycorrhizal plants, respectively) at pH 4.0, reduced N/P ratio (average 9.5 and 6.9 for non-mycorrhizal and mycorrhizal plants, respectively) at pH 4.0, and protected roots against Al phytotoxicity (average 2.0 and 1.4 mg g^-1 for non-mycorrhizal and mycorrhizal roots, respectively), indicating that AMF could mitigate some of the detrimental effects of AR. Moreover, our findings suggest that AMF mainly benefited the plant through the combined effects of N concentrations and N/P ratios in shoots and Al³⁺ concentrations in roots under acidic conditions.

Integrated proteome and lipidome analysis of naturally aged safflower seeds varying in vitality

Seed ageing has an important effect on germination and productivity. During natural ageing, seed vigour decreases rapidly but, to date, the molecular mechanisms underlying this decrease have not been fully elucidated. Using omics, some of the details regarding seed vigour decline during natural ageing might be elucidated through integrated analysis. Safflower seed germination and physio-biochemical changes during natural ageing (stored for 4, 16 and 28 months) were determined. Proteome and lipidome profiling during natural seed ageing was performed, and the differentially expressed proteins and lipid metabolite species analysed. The surface and internal structures of cotyledons were observed. An integrating analysis of the proteome and lipidome was also carried out. Natural seed ageing significantly decreased safflower seed germination and vigour. 4,184 proteins and 1,193 lipids were quantified, both of which show huge differences among the different naturally aged seeds. The surface of the cotyledons collapsed and cracked, and the oil bodies become looser during natural ageing. The total content of DAG and PA increased, while the content of TAG and PL (PC, PE, PS, PI and PL) significantly decreased during seeds ageing. Two lipase genes (HH-026818-RA and HH-025320) likely participated in this degradation of lipids. We conclude that the enzymes that participate in glycerolipid metabolism and fatty acid degradation probably lead to the degradation of oil bodies (TAG) and membrane lipids (PC, PE, PS, PI, PG) and, ultimately, destroy the structure, causing a decline in seed vigour during natural seed ageing.

Research and development strategy for biodegradable magnesium-based vascular stents: a review

Magnesium alloys are an ideal material for biodegradable vascular stents, which can be completely absorbed in the human body, and have good biosafety and mechanical properties. However, the rapid corrosion rate and excessive localized corrosion, as well as challenges in the preparation and processing of microtubes for stents, are restricting the clinical application of magnesium-based vascular stents. In the present work we will give an overview of the recent progresses on biodegradable magnesium based vascular stents including magnesium alloy design, high-precision microtubes processing, stent shape optimisation and functional coating preparation. In particular, the Triune Principle in biodegradable magnesium alloy design is proposed based on our research experience, which requires three key aspects to be considered when designing new biodegradable magnesium alloys for vascular stents application, i.e. biocompatibility and biosafety, mechanical properties, and biodegradation. This review hopes to inspire the future studies on the design and development of biodegradable magnesium alloy-based vascular stents.

Treatment of pre-collapse non-traumatic osteonecrosis of the femoral head through Orthopdische Chirurgie München approach combined with autologous bone mixed with β-tricalcium phosphate porous bioceramic bone graft: a retrospective study of mid-term results

Background

This study aimed to evaluate the clinical efficacy of femoral head and neck fenestration combined with autologous bone mixed with β-tricalcium phosphate porous bioceramic bone (light bulb procedure) through Orthopdische Chirurgie München approach (OCM approach) for pre-collapse non-traumatic osteonecrosis of the femoral head(ONFH).

Methods

The clinical data of 47 patients (47 hips) with ONFH were retrospectively reviewed. The Harris hip score (HHS) was used to evaluate the clinical outcomes. Imaging was assessed by X-ray. Clinical failure was defined as postoperative total hip arthroplasty (THA) or the HHS was poor (< 70). The Kaplan–Meier survival curve was used to conduct a univariate analysis of risk factors. The analysis factors included gender, age, International Association Research Circulation Osseous (ARCO) stage, etiology, body mass index (BMI), 25-hydroxyvitamin D (25(OH)D), and type I collagen carboxy-terminal peptide (CTX). The COX multivariate risk model was used to analyze the risk factors.

Results

All the 47 hips were followed up for 24–58 months, with an average of 45 months. The Harris score (76.29 ± 10.38) at the last follow-up was significantly higher than the preoperative HHS (64.45 ± 2.93) (P < 0.05). The postoperative HHS was excellent with a success rate of 36.17%. Postoperative imaging evaluation showed that 9 hips improved, 28 hips stabilized, and 10 hips progressed. Moreover, 17 out of 47 hips were defined as a postoperative clinical failure and the success rate was 63.83%. 25(OH)D and preoperative ARCO stage were risk factors for postoperative clinical failure (P < 0.05). The COX multivariate risk model analysis showed that IIIA stage was an independent risk factor for postoperative clinical failure (P < 0.05).

Conclusions

The head and neck fenestration and bone grafting via the OCM approach in the treatment of non-traumatic ONFH in the pre-collapse stage can achieve good clinical outcomes. 25(OH)D deficient patients and ARCO IIIA patients had a higher failure rate of bone graft using this approach.

[Effects of normobaric hyperoxia intervention on renal ischemia-reperfusion injury in rats]

Objective: To investigate the effects of normobaric hyperoxia intervention on renal ischemia-reperfusion injury in rats and its possible mechanism. Methods: Twenty-one adult male SD rats were enrolled and their right kidneys were excised. After two weeks, they were randomly assigned to 3 groups, with 7 rats in each group, namely sham-operated group (Group S), ischemia-reperfusion group (Group I/R), and normobaric hyperoxia+ischemia-reperfusion group (Group NBHO+I/R). In group S, only the left renal pedicle was isolated, but no ischemic treatment was performed. However, in group I/R and group NBHO+I/R, left renal pedicles were separated and left renal ischemia was induced by noninvasive arterial clamp for 45 min, and after 24 h of reperfusion, rats in group S and group I/R inhaled regular concentration of oxygen (21%), while rats in group NBHO+I/R inhaled high concentration of oxygen (60%), 2 h at each time, once a day for 7 days. On the 7th day after surgery, blood urea nitrogen (BUN) and creatinine (Cr) levels were measured by taking blood from the orbital veins of rats. The content of malondialdehyde (MDA) and superoxide dismutase (SOD) was detected from the left kidney tissues. The mRNA and protein contents of Keap1 and Nrf2 gene in kidney tissues were determined by qPCR and Western Blotting, respectively. Hematoxylin-eosin staining (HE) was employed to observe the pathological changes of kidney tissue. Immunohistochemical staining was used to measure the protein expression of Keap1 and Nrf2 in kidney tissues. Results: Compared with group S, the serum BUN [(10.7±1.7) mmol/L, (8.4±1.0) mmol/L vs (6.1±1.3) mmol/L, both P<0.05] and Cr [(81.0±3.7) μmol/L, (62.9±3.4) μmol/L vs (48.3±2.9) μmol/L, both P<0.05] levels of rats in the group I/R and group NBHO+I/R increased, and the I/R group had the most significant increase. Compared with group S, the MDA content of kidney tissue in the rats of group I/R and NBHO+I/R increased [(10.5±1.0) μmol/L, (8.6±0.8) μmol/L vs (6.5±0.5) μmol/L, both P<0.05], but the MDA content in group NBHO+I/R was lower than that of group I/R (P<0.05). Compared with group S, the SOD content in the kidney tissues of rats in both group I/R and group NBHO+I/R decreased. However, the SOD content of group NBHO+I/R was higher than that of group I/R (P<0.05). Compared with group S, the mRNA and protein contents of Keap1 gene in kidney tissues of group I/R and group NBHO+I/R decreased, and group NBHO+I/R had the most significant decrease (P<0.05). However, compared with group S, mRNA and protein expressions of Nrf2 gene increased in kidney tissues of group I/R and group NBHO+I/R, and NBHO+I/R group had the most significant increase (P<0.05). Postoperative pathological results suggested that compared with group S, the pathological damage of kidney tissues in group I/R and group NBHO+I/R increased, but the degree of damage in group NBHO+I/R was lower than that in group I/R. Conclusion: Normobaric hyperoxia intervention may have protective effects on renal ischemia-reperfusion injury in rats by activating Keap1-Nrf2 signaling pathway.

Multi-omics integration identifies key upstream regulators of pathomechanisms in hypertrophic cardiomyopathy due to truncating MYBPC3 mutations

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is the most common genetic disease of the cardiac muscle, frequently caused by mutations in MYBPC3. However, little is known about the upstream pathways and key regulators causing the disease. Therefore, we employed a multi-omics approach to study the pathomechanisms underlying HCM comparing patient hearts harboring MYBPC3 mutations to control hearts.

RESULTS

Using H3K27ac ChIP-seq and RNA-seq we obtained 9310 differentially acetylated regions and 2033 differentially expressed genes, respectively, between 13 HCM and 10 control hearts. We obtained 441 differentially expressed proteins between 11 HCM and 8 control hearts using proteomics. By integrating multi-omics datasets, we identified a set of DNA regions and genes that differentiate HCM from control hearts and 53 protein-coding genes as the major contributors. This comprehensive analysis consistently points toward altered extracellular matrix formation, muscle contraction, and metabolism. Therefore, we studied enriched transcription factor (TF) binding motifs and identified 9 motif-encoded TFs, including KLF15, ETV4, AR, CLOCK, ETS2, GATA5, MEIS1, RXRA, and ZFX. Selected candidates were examined in stem cell-derived cardiomyocytes with and without mutated MYBPC3. Furthermore, we observed an abundance of acetylation signals and transcripts derived from cardiomyocytes compared to non-myocyte populations.

CONCLUSIONS

By integrating histone acetylome, transcriptome, and proteome profiles, we identified major effector genes and protein networks that drive the pathological changes in HCM with mutated MYBPC3. Our work identifies 38 highly affected protein-coding genes as potential plasma HCM biomarkers and 9 TFs as potential upstream regulators of these pathomechanisms that may serve as possible therapeutic targets.

Effects of composition and hierarchical structures of calcium phosphate coating on the corrosion resistance and osteoblast compatibility of Mg alloys

Magnesium and its alloys have been recently used in biomedical applications such as orthopedic implants, whereas the weak corrosion resistance undermines their clinical efficacy. Herein, to address this critical challenge, the preparation of hierarchically structured hydroxyapatite-based coatings was proposed. Compact coatings were fabricated on a Mg alloy through a facile two-step method of chemical deposition of brushite precursor and subsequent hydrothermal conversion. A series of HA-based coatings were obtained with kinetic conversion process with formation mechanism revealed. The hydroxyapatite coating demonstrated the greatest corrosion resistance for Mg in electrochemical and long-term immersion tests, especially against pitting corrosion, attributable to its compact structure, alkaline degradation environment and self-induced growth capacity. The in vitro cytocompatibility and osteoinductivity were dictated. Additionally, anti-corrosion mechanisms were compared among different coating compositions and structures, along with their correlation with cellular response. Our study brings hints for a tailored surface design for resorbable biomedical device applications.

Exposure to high levels of magnesium disrupts bone mineralization in vitro and in vivo

Background

The removal of permanent internal fixation devices by secondary surgery could be avoided if these devices were made of degradable magnesium and magnesium alloys. Before such implants can be used clinically, however, the biological effect of magnesium exposure on surrounding bone must be evaluated. Previous studies have focused on bone formation; few have examined the effects of magnesium on the bone quality that affect many biomechanical properties.

Methods

Using bone quality parameters, we analyzed in vivo changes in bone properties and biomechanics after exposure to locally high levels of magnesium.

Results

Local bone mineralization was significantly disrupted following exposure to a porous rod of pure magnesium. Normal crystal formation and crystallinity were inhibited and the mineral-to-matrix ratio decreased. These results were consistent with those of in vitro experiments, in which high levels of magnesium inhibited mineral deposition by mesenchymal stem cells (MSCs) but increased alkaline phosphatase (ALP) expression. The same mineralization inhibition was observed around magnesium implants via micro-computerized tomography (micro-CT) and von Kossa staining. Such reduced bone quality around degrading magnesium rods could negatively impact bone biomechanics.

Conclusions

This study showed that exposure to the local high magnesium levels that arise from rapidly degrading magnesium devices may significantly disrupt bone mineralization and negatively impact bone biomechanics.

Nano-micrometer surface roughness gradients reveal topographical influences on differentiating responses of vascular cells on biodegradable magnesium

Distinctively directing endothelial cells (ECs) and smooth muscle cells (SMCs), potentially by surface topography cue, is of central importance for enhancing bioefficacy of vascular implants. For the first time, surface gradients with a broad range of nano-micrometer roughness are developed on Mg, a promising next-generation biodegradable metal, to carry out a systematic study on the response of ECs and SMCs. Cell adhesion, spreading, and proliferation are quantified along gradients by high-throughput imaging, illustrating drastic divergence between ECs and SMCs, especially in highly rough regions. The profound role of surface topography overcoming the biochemical cue of released Mg²⁺ is unraveled at different roughness ranges for ECs and SMCs. Further insights into the underlying regulatory mechanism are gained at subcellular and gene levels. Our work enables high-efficient exploration of optimized surface morphology for modulating favored cell selectivity of promoting ECs and suppressing SMCs, providing a potential strategy to achieve rapid endothelialization for Mg.

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Surface topography stimuli was engineered on Mg with varying roughness gradients.

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Ridge/valley network feature on Mg overperforms the influence of Mg²⁺.

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Optimized roughness facilitates proliferation of ECs while suppressing SMCs.

Degradation and osteogenic induction of a SrHPO4-coated Mg-Nd-Zn-Zr alloy intramedullary nail in a rat femoral shaft fracture model

Magnesium and Mg-based alloys are promising biomaterials for orthopedic implants because of their degradability, osteogenic effects, and biocompatibility. However, the drawbacks of these materials include high hydrogen gas production, unexpected corrosion resistance, and insufficient mechanical strength duration. Surface modification can protect these biomaterials and induce osteogenesis. In this work, a SrHPO₄ coating was developed for our patented biodegradable Mg-Nd-Zn-Zr alloy (abbr. JDBM) through a chemical deposition method. The coating was characterized by in vitro immersion, ion release, and cytotoxicity tests, which showed a slower corrosion behavior and excellent cell viability. RNA sequencing of MC3T3E1 cells treated with SrHPO₄-coated JDBM ion release test extract showed increased Tlr4, followed by the activation of the downstream PI3K/Akt signaling pathway, causing proliferation and growth of pre-osteoblasts. An intramedullary nail (IMN) was implanted in a femoral fracture rat model. Mechanical test, radiological and histological analysis suggested that SrHPO₄-coated JDBM has superior mechanical properties, induces more bone formation, and decreases the degradation rate compared with uncoated JDBM and the administration of TLR4 inhibitor attenuated the new bone formation for fracture healing. SrHPO₄ is a promising coating for JDBM implants, particularly for long-bone fractures.

The Characterization of Dissolved Organic Matter in Reclaimed Water and Its Influence on Copper Toxicity

Water samples were collected from five phases of treatment in a municipal sewage reclaimed water plant and the DOM was characterized. Results indicated that the components and properties of DOM varied notably with sequential treatments, such as the fluorescence intensity, the molecular weight and the total acidity. Meanwhile the accumulation of Cu in Daphnia magna was analyzed following exposure to samples spiked with 50 µg/L copper, which were decreased by the presence of DOM in those water samples. Furthermore, this study found significant associations between fluorescence intensity and Cu accumulation (r² = 0.778, p < 0.05), while increased total acidity was found to enhance the unit total organic carbon-Cu accumulation (r² = 0.979, p < 0.01). This study provides useful information on the safety and effective management of reclaimed water as a potential water resource.

Effect of TAGLN2 in the regulation of meningioma tumorigenesis and development

OBJECTIVE

To explore the role of transgelin-2 TAGLN2 in the development and progression of meningioma and the potential regulatory.

MATERIALS AND METHODS

TAGLN2 knockdown expression and overexpression in vitro models were constructed using lentivirus in meningioma cell line CH157; their corresponding transfection efficiencies were verified by qRT-PCR and Western Blot. Actions of TAGLN2 on the proliferation of meningioma cells were explored by CCK8 and colony formation assays. The effect of TAGLN2 on invasion of meningioma cells was analyzed by transwell cell invasion assay. Biological function of TAGLN2 on apoptosis of meningioma cells was determined by flow cytometry. Finally, Western Blot was used to investigate the detailed mechanism of TAGLN2 on regulating the biological functions of meningioma cells.

RESULTS

After down-regulating the expression of TAGLN2, there were significantly decreased capacities of cells proliferation and colony formation of meningioma cells, meanwhile, cell invasion was significantly decreased but the apoptosis rate was increased. On the contrary, up-regulation of TAGLN2 expression, the proliferation, colony formation ability were significantly increased as well as the invasion capacity, whilst apoptosis rate was decreased. Western Blot showed that expressions of p-PI3K and p-AKT were inhibited after knockdown of TAGLN2, which were significantly increased after TAGLN2 was overexpressed.

CONCLUSIONS

TAGLN2 can affect the proliferation, invasion and apoptosis of meningioma cells and may participate in the development of meningioma through regulating the PI3K/AKT signaling pathway.

Structure and mode of action of a novel antibacterial peptide from the blood of Andrias davidianus

Andrias davidianus is widely recognized in traditional medicine as a cure-all to treat a plethora of ailments. In a previous study, a novel antibacterial peptide named andricin B was isolated from A. davidianus blood. In this study, we investigated andricin B structure and its mode of action. Circular dichroism spectra suggested that andricin B adopts a random coil state in aqueous solution and a more rigid conformation in the presence of bacteria. Moreover propidium iodide/fluorescein diacetate double staining indicated that bacteria treated with andricin B were not immediately eliminated. Rather, there is a gradual bacterial death, followed by a sublethal stage. Scanning electronic microscope imaging indicates that andricin B might form pores on cell membranes, leading to the release of cytoplasmic contents. These results were consistent with flow cytometry analysis. Furthermore, Fourier transform infrared spectroscopy suggests that andricin B induces changes in the chemical properties in the areas surrounding these "pores" on the cell membranes. SIGNIFICANCE AND IMPACT OF THE STUDY: The results of this study suggested the new perspectives about the mode of action of antimicrobial peptide (AMP) active against sensitive bacteria. The AMP was able to be in a random coiled state in aqueous solution but to change to a more rigid one in the presence of sensitive bacteria. Exposure to AMP might not lead to immediate death of treated bacteria, rather bacteria concentration decreased gradually flattening at a sublethal stage. These findings will help people to understand better how the AMPs activate against sensitive bacteria.

Degradation Products of Polydopamine Restrained Inflammatory Response of LPS-Stimulated Macrophages Through Mediation TLR-4-MYD88 Dependent Signaling Pathways by Antioxidant

Polydopamine (PDA) has a promising application as coating of biomaterials due to its favorable degradability and bioadaptability. However, its bioactivity, such as anti-inflammatory capacity, was still little known. Herein, we investigated whether degradable products of PDA could affect inflammatory response in lipopolysaccharide (LPS)-stimulated human THP-1-derived macrophages. The supernatants containing degradation products of PDA, annotated as PDA extracts, were collected after PDA being immersed in cell culture medium for 3 days. Wherein, the composition of the degradation products was analyzed by HPLC assay. Collected PDA extracts were diluted into 100%, 50%, and 25% of original concentration, respectively, to evaluate their anti-inflammatory ability on LPS-induced macrophages from the expression levels of pro-inflammatory cytokines to associated molecular mechanism. Our results showed that the PDA extracts were mainly composed of dopamine, quinine, and PDA segments. Furthermore, macrophages showed no cytotoxicity after PDA extract treatment with or without LPS, while the release levels of TNF-α and IL-6 by LPS-induced macrophages were decreased in dose-dependent by PDA extract treatment. Additionally, TLR-4 and MYD88 expression in protein and RNA level were downregulated by PDA extracts in LPS-induced macrophages. Similarly, PDA extracts effectively inhibited LPS-induced NF-κB trans-locating into nuclear by inactivation of the phosphorylation of IKK-α/β and IKβ-α. Of note, the production of LPS-induced ROS was reduced by PDA extracts in macrophages, while HO-1 expression, a critical protein of antioxidant signaling pathway, was increased. Based on these results, we proposed a potential mechanism by which degradation products of PDA suppressed inflammation of macrophages via downregulation TLR-4-MYD88-NFκB pathway and simultaneous activation HO-1 pathway, which might be a possible therapeutic target.

A comprehensive analysis of candidate gene signatures in oral squamous cell carcinoma

This study aimed to unravel the molecular mechanism of oral squamous cell carcinoma (OSCC). With microarray dataset GSE30784, differentially expressed genes (DEGs) were identified between OSCC and control samples. The DEGs overlapped with genes obtained from online database MalaCards were determined as OSCCDEG, followed by Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. A total of 5177 up-regulated and 6081 down-regulated DEGs were identified between OSCC and control. Out of the DEGs, 451 genes were overlapped with the 704 genes gained from MalaCards and regarded as "OSCCDEG". Up-regulated OSCCDEG were associated with cell cycle pathway, while down-regulated OSCCDEG were linked to ErbB pathway. ANGPT1, ANGPT2 and 3 hub proteins (EGFR, HSP90AA1, RB1) in the PPI network were associated with the survival rates of several tumors. The largest network module with the hub protein EGFR was associated with positive regulation of cell communication. The second largest module with the hub node FN1 was related to angiogenesis. For the third network module in connection with DNA metabolism, the hub protein was PCNA. ErbB and cell cycle pathways were crucial for OSCC. EGFR, FN1, PCNA, ANGPT1 and ANGPT2 might be potential biomarkers for OSCC. These findings help provide guidelines for treating OSCC.

Increased intrinsic connectivity for structural atrophy and functional maintenance after acute ischaemic stroke

BACKGROUND AND PURPOSE

Significant clinical recovery has commonly been observed in ischaemic stroke patients with irreversible brain structural damage. However, brain mechanisms that help to maintain clinical function remain unclear.

METHODS

Sixty-two patients with acute ischaemic stroke underwent longitudinal clinical assessments and magnetic resonance scanning. The clinical recovery trajectory was evaluated using a hierarchical linear model and intrinsic connectivity was analysed with a seed-based approach to examine its changing pattern based on the regional volume changes calculated using voxel-wise analysis.

RESULTS

It was observed that clinical outcome measures improved mainly in the short-term period (baseline versus 3 weeks) and then remained stable. Grey matter volume was reduced significantly in the bilateral caudate over the entire 3-year long-term period. Significant intrinsic connectivity increases were observed in the caudate-middle cingulum over the short-term period and in the caudate-precuneus and caudate-calcarine over the long-term period. Finally, it was found that increased caudate-calcarine connectivity was associated with reduced right caudate volume, and a positive correlation was found between increased caudate-middle cingulum connectivity and the amount of modified Rankin score changes.

CONCLUSIONS

The increased intrinsic connectivity found in this study tends to be a compensatory mechanism for post-stroke structural damage, associated with clinical recovery. The study helps in understanding the significance of enhanced intrinsic connectivity in post-stroke long-term assessment and rehabilitation.

Prevalence and characteristics of adults with fetal alcohol spectrum disorder in corrections: a Canadian case ascertainment study

BACKGROUND

Individuals with fetal alcohol spectrum disorder (FASD) experience a range of cognitive, affective, and physical deficits following prenatal alcohol exposure. They are thought to be overrepresented in criminal justice settings. However, limited evidence is available to inform prevalence. We sought to estimate the prevalence of FASD in a Northern Canadian correctional population.

METHODS

Using an active case ascertainment approach we recruited a representative sample of 80 justice-involved adults (ages 18-40, 85% male) over an 18-month period from 2013 to 2015. Participants completed interdisciplinary clinical assessments comprising medical and psychological evaluations that adhered to the 2005 Canadian FASD Diagnostic Guidelines.

RESULTS

We identified a high rate of FASD (17.5, 95% CI [9.2, 25.8%]) in this sample, and this rate could have been as high as 31.2% with confirmation of prenatal alcohol exposure. Most participants in this study presented with significant neurodevelopmental and cognitive deficits in at least two domains of functioning, irrespective of diagnosis, with only five of 80 participants (6.3%) demonstrating no cognitive impairment.

CONCLUSIONS

Findings showed disproportionately high estimated FASD prevalence in this representative sample compared to general population estimates in both Canada and the U.S. (2-5%), underscoring the need for improved FASD screening and diagnosis in correctional settings, and education for clinicians working in the justice context. Strengthened health prevention and intervention efforts to support the needs of individuals with FASD outside the criminal justice context are needed.

The degradation and transport mechanism of a Mg-Nd-Zn-Zr stent in rabbit common carotid artery: A 20-month study

Mg-based stent is a promising candidate of the next generation fully degradable vascular stents. The latest progress includes the CE approval of the Magmaris ® WE43 based drug eluting stent. However, so far, the long term (more than 1 year implantation) in vivo degradation and the physiological effects caused by the degradation products were still unclear. In this study, a 20 month observation was carried out after the bare Mg-Nd-Zn-Zr (abbr. JDBM) stent prototype was implanted into the common carotid artery of New Zealand white rabbit in order to evaluate its safety, efficacy and especially degradation behavior. The degradation of the main second phase Mg₁₂Nd was also studied. Results showed that the bare JDBM stent had good safety and efficacy with a complete re-endothelialization within 28 days. The JDBM stent struts were mostly replaced in situ by degradation products in 4 month. The important finding was that the volume and Ca concentration of the degradation products decreased in the long term, eliminating the clinicians' concern of possible vessel calcification. In addition, the alloying elements Mg and Zn in the stent could be safely metabolized as continuous enrichment in any of the main organs were not detected although Nd and Zr showed an abrupt increase in spleen and liver after 1 month implantation. Collectively, the long term in vivo results showed the rapid re-endothelialization of JDBM stent and the long term safety of the degradation products, indicating its great potential as the backbone of the fully degradable vascular stent.

STATEMENT OF SIGNIFICANCE

Mg-based stent is a promising candidate of the next generation fully degradable stents, especially after the recent market launch of one of its kind (Magmaris). However the fundamental question about the long term degradation and metabolic mechanism of Mg-based stent and its degradation products remain unanswered. We implanted our patented Mg-Nd-Zn-Zr bare stent into the common carotid artery of rabbits and conducted a 20 months observation. We found that the Ca containing degradation products could be further degraded in vivo. All the alloying elements showed no continuous enrichment in the main organs of rabbits. These findings eliminate the clinicians' concern of possible vessel calcification and element enrichment after the implantation of Mg alloy based stents to some extent.

Dual modulation of bone formation and resorption with zoledronic acid-loaded biodegradable magnesium alloy implants improves osteoporotic fracture healing: An in vitro and in vivo study

Osteoporotic fracture (OPF) remains a major clinical challenge for skeletal regeneration. Impaired osteogenesis and excessive remodeling result in prolonged and poor quality of fracture healing. To augment bone formation and inhibit excessive resorption simultaneously, we constructed a biodegradable magnesium-based implant integrated with the anti-catabolic drug zoledronic acid (ZA); this implant exhibits controllable, sustained release of magnesium degradation products and ZA in vitro. The extracts greatly stimulate the osteogenic differentiation of rat-bone marrow-derived mesenchymal stem cells (rBMSCs), while osteoclastogenesis is inhibited by ZA. Implantation of intramedullary nails to fix femur fracture in ovariectomy-induced osteoporotic rats for up to 12 weeks demonstrates magnesium implants alone can enhance OPF repair through promoting callus formation compared to conventional stainless steel, while the combinatory treatment with local ZA release from implant coating further increases bone regeneration rate and callus size, remarkably improves bone quality and mechanical strength and suppresses osteoclasts and bone remodeling, due to the synergistic effect of both agents. The slow and uniform degradation of the implant ensures a steady decrease in bending force, which meets clinical requirements. In summary, biodegradable magnesium-based implants can locally co-deliver magnesium degradation products and zoledronic acid in a controlled manner, and can be superior alternatives for the reconstruction of osteoporosis-related fracture.

STATEMENT OF SIGNIFICANCE

Management of osteoporotic fracture has posed a major challenge in orthopedics, as the imbalance between diminished osteogenesis and excessive bone remodeling often leads to delayed and compromised fracture repair. Among various efforts expended on augmenting osteoporotic fracture healing, herein we reported a new strategy by engineering and utilizing a biodegradable magnesium-based implant integrated with local drug delivery, specifically, zoledronic acid (ZA)-loaded polylactic acid/brushite bilayer coating on a biodegradable Mg-Nd-Zn-Zr alloy (denoted as Mg/ZA/CaP), aiming to combine the favorable properties of Mg and zoledronic acid for simultaneous modulation of bone formation and bone resorption. In vitro and in vivo studies demonstrated its superior treatment efficacy along with adequate degradation. It stimulated new bone formation while suppressing remodeling, ascribed to the local release of magnesium degradation products and zoledronic acid. To our knowledge, the enhanced fracture repair capability of Mg-based implants was for the first time demonstrated in an osteoporotic fracture animal model. This innovative biodegradable Mg-based orthopedic implant presents great potential as a superior alternative to current internal fixation devices for treating osteoporotic fracture.

In vitro and in vivo degradation of rapamycin-eluting Mg-Nd-Zn-Zr alloy stents in porcine coronary arteries

In this work, rapamycin-eluting poly (d, l-lactic acid) coating (PDLLA/RAPA) was prepared on biodegradable Mg-Nd-Zn-Zr alloy (JDBM) for both in vitro and in vivo investigation of the degradation behaviors of the magnesium alloy stent platform. Electrochemical tests and hydrogen evolution test demonstrated significant in vitro protection of the polymeric coating against magnesium degradation both in short and long term. The 3-month in vivo study on the RAPA-eluting JDBM stent implanted into porcine coronary arteries confirmed its favorable safety, and in the meanwhile revealed similar neointima proliferation compared to the second generation DES Firebird 2 with no occurrence of adverse complications. Moreover, Micro-CT examination combined with IVUS and OCT detection indicated a remarkably lower degradation rate and prolonged radial supporting duration of the drug-eluting JDBM stent as compared to the bare, attributable to the protection of the coating in vivo. Hence, rapamycin-eluting JDBM stents exhibit great potential for clinical application.