Engineered Niobium Carbide MXenzyme-Integrated Self-Adaptive Coatings Inhibiting Periprosthetic Osteolysis by Orchestrating Osteogenesis-Osteoclastogenesis Balance.

Periprosthetic osteolysis induced by the ultrahigh-molecular-weight polyethylene (UHMWPE) wear particles is a major complication associated with the sustained service of artificial joint prostheses and often necessitates revision surgery. Therefore, a smart implant with direct prevention and repair abilities is urgently developed to avoid painful revision surgery. Herein, we fabricate a phosphatidylserine- and polyethylenimine-engineered niobium carbide (Nb2C) MXenzyme-coated micro/nanostructured titanium implant (PPN@MNTi) that inhibits UHMWPE particle-induced periprosthetic osteolysis. The specific mechanism by which PPN@MNTi operates involves the bioresponsive release of nanosheets from the MNTi substrate within an osteolysis microenvironment, initiated by the cleavage of a thioketal-dopamine molecule sensitive to reactive oxygen species (ROS). Subsequently, functionalized Nb2C MXenzyme could target macrophages and escape from lysosomes, effectively scavenging intracellular ROS through its antioxidant nanozyme-mimicking activities. This further achieves the suppression of osteoclastogenesis by inhibiting NF-κB/MAPK and autophagy signaling pathways. Simultaneously, based on the synergistic effect of MXenzyme-integrated coatings and micro/nanostructured topography, the designed implant promotes the osteogenic differentiation of bone mesenchymal stem cells to regulate bone homeostasis, further achieving advanced osseointegration and alleviable periprosthetic osteolysis in vivo. This study provides a precise prevention and repair strategy of periprosthetic osteolysis, offering a paradigm for the development of smart orthopedic implants.

Exosomes loaded a smart bilayer-hydrogel scaffold with ROS-scavenging and macrophage-reprogramming properties for repairing cartilage defect.

Enhancing the regeneration of cartilage defects remains challenging owing to limited innate self-healing as well as acute inflammation arising from the overexpression of reactive oxygen species (ROS) in post-traumatic microenvironments. Recently, stem cell-derived exosomes (Exos) have been developed as potential cell-free therapy for cartilage regeneration. Although this approach promotes chondrogenesis, it neglects the emerging inflammatory microenvironment. In this study, a smart bilayer-hydrogel dual-loaded with sodium diclofenac (DC), an anti-inflammatory drug, and Exos from bone marrow-derived mesenchymal stem cells was developed to mitigate initial-stage inflammation and promote late-stage stem-cell recruitment and chondrogenic differentiation. First, the upper-hydrogel composed of phenylboronic-acid-crosslinked polyvinyl alcohol degrades in response to elevated levels of ROS to release DC, which mitigates oxidative stress, thus reprogramming macrophages to the pro-healing state. Subsequently, Exos are slowly released from the lower-hydrogel composed of hyaluronic acid into an optimal microenvironment for the stimulation of chondrogenesis. Both in vitro and in vivo assays confirmed that the dual-loaded bilayer-hydrogel reduced post-traumatic inflammation and enhanced cartilage regeneration by effectively scavenging ROS and reprogramming macrophages. The proposed platform provides multi-staged therapy, which allows for the optimal harnessing of Exos as a therapeutic for cartilage regeneration.

Surficial nano-deposition locoregionally yielding bactericidal super CAR-macrophages expedites periprosthetic osseointegration.

Tracking and eradicating Staphylococcus aureus in the periprosthetic microenvironment are critical for preventing periprosthetic joint infection (PJI), yet effective strategies remain elusive. Here, we report an implant nanoparticle coating that locoregionally yields bactericidal super chimeric antigen receptor macrophages (CAR-MΦs) to prevent PJI. We demonstrate that the plasmid-laden nanoparticle from the coating can introduce S. aureus-targeted CAR genes and caspase-11 short hairpin RNA (CASP11 shRNA) into macrophage nuclei to generate super CAR-MΦs in mouse models. CASP11 shRNA allowed mitochondria to be recruited around phagosomes containing phagocytosed bacteria to deliver mitochondria-generated bactericidal reactive oxygen species. These super CAR-MΦs targeted and eradicated S. aureus and conferred robust bactericidal immunologic activity at the bone-implant interface. Furthermore, the coating biodegradability precisely matched the bone regeneration process, achieving satisfactory osteogenesis. Overall, our work establishes a locoregional treatment strategy for priming macrophage-specific bactericidal immunity with broad application in patients suffering from multidrug-resistant bacterial infection.

Mussel-inspired alkaline phosphatase-specific coating on orthopedic implants for spatiotemporal modulating local osteoimmune microenvironment to facilitate osseointegration.

Inadequate initial osseointegration and consequent prosthesis loosening are the most severe complications after artificial arthroplasty. Proper immune responses are crucial for the successful implantation of artificial prostheses. Macrophages are central in osteoimmunomodulation because they exert distinct functions with highly plasticity. Herein, we developed an alkaline phosphatase (ALP) sensitive mussel-inspired coating on orthopedic implants for promoting osseointegration. First, the resveratrol-alendronate complexes were deposited on titanium implant surface through mussel-inspired interfacial interactions. Upon prosthesis implantation, macrophages first polarized towards M1 type to initiate inflammatory responses and bone regeneration. As osteogenesis progresses, increasing amounts of ALP secreted by osteoblasts was cleaved the resveratrol-alendronate complexes. Then, the released resveratrol further promoted osteogenic differentiation of BMSCs and induced locoregional macrophages M2 polarization. Our results demonstrated that the bioinspired osteoimmunomodulation coating remarkably facilitated the prosthesis-bone integration by spatiotemporally modulating macrophages switching from M1 to M2 polarization in response to a real-time healing signal during osteogenesis. In summary, the mussel-inspired osteoimmunomodulation coating technology may provide a new approach for promoting osseointegration after artificial arthroplasty.

Remodeling articular immune homeostasis with an efferocytosis-informed nanoimitator mitigates rheumatoid arthritis in mice.

Massive intra-articular infiltration of proinflammatory macrophages is a prominent feature of rheumatoid arthritis (RA) lesions, which are thought to underlie articular immune dysfunction, severe synovitis and ultimately joint erosion. Here we report an efferocytosis-informed nanoimitator (EINI) for in situ targeted reprogramming of synovial inflammatory macrophages (SIMs) that thwarts their autoimmune attack and reestablishes articular immune homeostasis, which mitigates RA. The EINI consists of a drug-based core with an oxidative stress-responsive phosphatidylserine (PtdSer) corona and a shell composed of a P-selectin-blocking motif, low molecular weight heparin (LMWH). When systemically administered, the LMWH on the EINI first binds to P-selectin overexpressed on the endothelium in subsynovial capillaries, which functions as an antagonist, disrupting neutrophil synovial trafficking. Due to the strong dysregulation of the synovial microvasculature, the EINI is subsequently enriched in the joint synovium where the shell is disassembled upon the reactive oxygen species stimulation, and PtdSer corona is then exposed. In an efferocytosis-like manner, the PtdSer-coroneted core is in turn phagocytosed by SIMs, which synergistically terminate SIM-initiated pathological cascades and serially reestablish intra-articular immune homeostasis, conferring a chondroprotective effect. These findings demonstrate that SIMs can be precisely remodeled via the efferocytosis-mimetic strategy, which holds potential for RA treatment.

Exosome-Functionalized Ti6Al4V Scaffolds Promoting Osseointegration by Modulating Endogenous Osteogenesis and Osteoimmunity.

Periprosthetic bone defects are the most serious problem of revision total hip arthroplasty, which can easily lead to insufficient osteointegration between the prosthesis and host bone. Bone marrow mesenchymal stem cells (BMSCs) and a moderate inflammatory response at the prosthesis-bone interface play an important role in osteointegration. Here, we developed microarc oxide titanium implant loaded engineered exosomes (S-Exos) to promote osseointegration at the prosthesis-bone interface. First, Smurf1-shRNA was transferred into the BMSCs using a viral vector to prepare S-Exos, which were subsequently immobilized to the microarc oxide titanium implant surface with positively charged polyethyleneimine. The immobilized S-Exos could be slowly and uniformly released and subsequently phagocytosed by BMSCs and macrophages. Once the S-Exos were phagocytosed, they could simultaneously activate the BMP/Smad signaling pathway in the BMSCs and promote macrophage M2 polarization, both of which enhance osseointegration. Specifically, this S-Exos coating exhibits a dual effect of promoting osseointegration, including the osseointegration of BMSCs by activating the BMP/Smad signaling pathway and the macrophage M2 polarization promoting osseointegration. In summary, the construction of S-Exos modified microarc oxide titanium implants could provide a new method for promoting osteointegration between the prosthesis and host bone in revision total hip arthroplasty.

Wnt3a knockdown promotes collagen type II expression in rat chondrocytes.

Osteoarthritis (OA) is a chronic condition caused by cartilage degradation, and there are currently no effective methods for preventing the progression of this disease; gene therapy is a relatively novel method for treating arthritis. Decreased collagen type II (Col2) expression within the cartilage matrix is an important factor for the development of OA, and Wnt3a serves a significant role in cartilage homeostasis. The present study assessed whether Wnt3a knockdown promoted Col2 expression in chondrocytes. Lentivirus-introduced small interfering RNA was used to knock down the expression of Wnt3a in primary rat chondrocytes, and then IL-1ß treatment was used to establish an OA chondrocyte model. The expression of target genes (Wnt3a, Col2, MMP-13 and ß-catenin) was analyzed using reverse transcription-quantitative PCR, western blotting and immunocytochemistry. There was significantly less MMP-13 and ß-catenin expression in the Wnt3a knockdown cells compared with the other controls. Col2 expression was significantly higher in the Wnt3a-knockdown cells compared with the control cells, indicating that knockdown of Wnt3a may promote Col2 expression. Consequently, Wnt3a was indicated to be an important factor in cartilage homeostasis, and Wnt3a knockdown may serve as a novel method for OA therapy.

Reliability of d-Dimer Determination in Diagnosis of Peri-Prosthetic Joint Infection: A Systematic Review and Meta-Analysis.

Background: Surgeons continue to seek indicators for the diagnosis of peri-prosthetic joint infection (PJI), which is a serious complication after total joint arthroplasty (TJA). Many recent studies have assessed the value of d-dimer in diagnosing PJI because of the close relation between the d-dimer value and inflammation. However, the conclusions from different studies are still disputed. Methods: We searched for studies published from 2011 to March 2020 using online databases and screened studies based on the inclusion criteria. Diagnostic parameters of d-dimer, C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR) were calculated, including the pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR) and the area under the curve (AUC). In addition, univariate meta-regression and subgroup analyses were performed to identify sources of heterogeneity. Results: A total of nine studies with 431 Patients with PJI were included. The pooled sensitivity, specificity, DOR, and AUC of d-dimer were 0.82 (95% confidence interval [CI], 0.73-0.89), 0.73 (95% CI, 0.58-0.83), 12 (95% CI, 5-30), and 0.85 (95% CI, 0.82-0.88), respectively. In addition, the sensitivity, specificity, and AUC of CRP were 0.78 (95% CI, 0.73-0.83), 0.80 (95% CI, 0.73-0.86) and 0.85 (95% CI, 0.81-0.87), respectively, whereas those of ESR were 0.68 (95% CI, 0.60-0.74), 0.83 (95% CI, 0.75-0.88), and 0.80 (95% CI, 0.76-0.83), respectively. Conclusions: d-dimer determination had similar performance to CRP and ESR in the diagnosis of PJI and may be a good addition to the current diagnostic criteria.

Simultaneously promoting adhesion and osteogenic differentiation of bone marrow-derived mesenchymal cells by a functional electrospun scaffold.

Electrospinning is a common technology to construct tissue engineering scaffolds for bone regeneration. However, pure electrospun scaffolds do not enrich seed cells or promote their osteogenic differentiation. Biological functionalization of tissue engineering scaffolds is currently a hot research topic. Therefore, in this study, the bone marrow-derived mesenchymal cells (BM-MSC)-specific affinity peptide E7 and a bone morphogenic protein 2 (BMP-2) mimetic peptide were concomitantly conjugated onto the surface of an electrospun scaffold to construct a functional PEB scaffold. Characterization of PEB scaffolds revealed that both E7 and BMP-2 mimetic peptides were successfully conjugated onto the surface of electrospun scaffolds. With regard to biological activity, the PEB scaffold could synchronously promote adhesion and osteogenic differentiation of BM-MSC as a result of the co-delivery of E7 and BMP-2 mimetic peptides, which proved superior compared with the other three scaffolds. Consequently, the PEB scaffold offers a new concept for the construction of bone tissue engineering scaffolds.

A specific affinity cyclic peptide enhances the adhesion, expansion and proliferation of rat bone mesenchymal stem cells on ß­tricalcium phosphate scaffolds.

Osteonecrosis of the femoral head (ONFH) is a common osteological disease. Treatment of ONFH prior to the collapse of the femoral head is critical for increasing therapeutic efficiency. Tissue engineering therapy using bone mesenchymal stem cells (BMSCs) combined with a scaffold is a promising strategy. However, it is currently unclear how to improve the efficiency of BMSC recruitment under such conditions. In the present study, a specific cyclic peptide for Sprague­Dawley rat BMSCs, CTTNPFSLC (known as C7), was used, which was identified via phage display technology. Its high affinity for BMSCs was demonstrated using flow cytometry and fluorescence staining. Subsequently, the cyclic peptide was placed on ß­tricalcium phosphate (ß­TCP) scaffolds using absorption and freeze­drying processes. Adhesion, expansion and proliferation of BMSCs was investigated in vitro on the C7­treated ß­TCP scaffolds and compared with pure ß­TCP scaffolds. The results revealed that C7 had a promoting effect on the adhesion, expansion and proliferation of BMSCs on ß­TCP scaffolds. Therefore, C7 may be effective in future tissue engineering therapy for ONFH.

Biopanning of mouse bone marrow mesenchymal stem cell affinity for cyclic peptides.

Osteonecrosis of the femoral head (ONFH) is a refractory disease present worldwide. In the development of therapies for this disease, mesenchymal stem cells (MSC) are a promising candidate cell source in tissue engineering (TE) and regenerative medicine. MSCs harvested from bone marrow (BM) are the gold standard. A significant barrier for BMMSC­based therapies is the inability and decreased number of BMMSCs in the tissues of interest. The ability to recruit BMMSCs efficiently to defective or injured sites in tissues or organs, for example the necrotic area of the femoral head in vivo, has been a major concern. In the present study, a peptide sequence (CDNVAQSVC), termed D7, was identified through phage display technology using C57BL/6 mouse BMMSCs. Subsequent analysis suggested that the identified loop­constrained heptapeptide exhibited a high specific affinity for mouse BMMSCs. Due to this specific affinity for BMMSCs, the present study provides a selective method to improve MSC­based TE strategies for the treatment of ONFH.

Enhanced adhesion and proliferation of bone marrow mesenchymal stem cells on ß­tricalcium phosphate modified by an affinity peptide.

Mesenchymal stem cells (MSCs) are often used in orthopedic tissue engineering, and bone marrow­derived mesenchymal stem cells (BMSCs) are currently considered the gold standard. One of the most important issues in MSC­based tissue engineering therapy is the low number of MSCs in pathological tissues. Achieving efficient recruitment of MSCs to defective or damaged tissues in vivo has been a difficult hurdle. The aim of the present study was to construct a biomaterial that can effectively recruit BMSCs to facilitate the repair of pathological tissues. So functional ß­tricalcium phosphate (ß­TCP) was synthesized using the BMSC affinity peptide DPIYALSWSGMA (DPI) adsorbed onto ß­TCP through an adsorption/freeze­drying strategy. C57BL/6 mouse­derived BMSCs were seeded onto the DPI peptide­modified ß­TCP (ß­TCP­DPI); in vitro experiments demonstrated that ß­TCP­DPI enhanced BMSC adhesion and proliferation compared with unmodified ß­TCP. Results from the present study indicated that functional ß­TCP may be used as an ideal scaffold in tissue engineering and in regenerative medicine.

A gold nanocluster chemical tongue sensor array for Alzheimer's disease diagnosis.

Alzheimer's disease (AD) is a common neurodegenerative disorder in elderly people, and is associated with a heavy financial burden on our society. The use of serologic biomarkers is an attractive method to diagnose AD. Although the determination of blood-based biomarkers for AD has been explored in many studies, few practical diagnosis methods have been used in the clinic. In this work, we constructed a "chemical tongue" sensor array that is easy to use and based on four kinds of fluorescent gold nanoclusters (Au NCs) for discriminating between multiple proteins at nanomolar concentrations. The device utilizes a linear discrimination analysis based on fluorescence intensity response patterns. Using this chemical tongue sensor array, multiple proteins can be confidently identified even in complex biological systems, such as human urine. Most importantly, sera of AD patients could be effectively discriminated from those of osteoarthritis patients, or of healthy people. Also, the results obtained for the AD patients by the chemical tongue sensor array were validated by CSF determination. We conclude that the chemical tongue sensor array manufactured in this work paves the way for designing an auxiliary diagnosis method for AD that is less invasive and more convenient for the large-scale screening of patients.

E7 peptide-functionalized Ti6Al4V alloy for BMSC enrichment in bone tissue engineering.

Ti6Al4V alloy is widely used for hip joint prostheses, however owing to its lack of biomimetic surface properties, it often suffers from poor osseointegration. It is well known that bone mesenchymal stem cells (BMSCs) play an important role in the osseointegration of the host bone and joint prostheses. One promising approach to improving the osseointegration of joint prostheses is to enrich the number of BMSCs at the periprosthetic site. Previous studies have reported that BMSC specific affinity peptide E7, can specifically enrich BMSCs. However, to date, few studies have reported the use of E7 in bone tissue engineering. In this study, we conjugated E7 peptide to Ti6Al4V alloy to fabricate a scaffold (BTS) to improve the biocompatibility of the alloy. E7 peptide efficiently improved the adhesion of BMSCs to Ti6Al4V alloy. In addition, the BTS scaffold was more conducive to osteogenesis than the RGD-functionalized and non-functionalized control scaffolds. The functional BTS scaffold could pave the way for designing functional joint prostheses, which promote osseointegration between the host bone and implant.

Inhibitory effect of quercetin on titanium particle-induced endoplasmic reticulum stress (ERS)-related apoptosis and in vivoosteolysis.

Wear particle-induced periprosthetic osteolysis is the main cause of aseptic loosening of orthopaedic implants. The aim of this study is to determine the protective effect of quercetin (QUE) against titanium (Ti) particle-induced ERS-related apoptosis and osteolysis. In this study, RAW264.7 cells were pretreated with different concentrations (40, 80, and 160 µmol/l) of QUE for 30 min and then treated with Ti particle (5 mg/ml) for 24 h. Cell viability and apoptosis were determined using MTT assay and Annexin V-FITC apoptosis detection kit, respectively. Protein and mRNA expressions of ERS-related genes were examined by western blot and real-time PCR, respectively. The release of inflammatory cytokines was detected by ELISA. Then a mouse calvarial osteolysis model was established. Histological sections of calvaria were stained with H&E or TRAP. The results showed that Ti particle reduced cell viability and induced apoptosis in RAW264.7 macrophages. The cytotoxic effects of Ti particle were dramatically inhibited by QUE pretreatment. Interestingly, we found that QUE also significantly reduced Ti particle-induced up-regulation of the expression levels of PERK, IRE1, GRP78, CHOP, caspase-12 and caspase-3 and enhanced the down-regulation of Bcl-2. In addition, QUE decreased Ti particle-induced inflammatory cytokines release from RAW264.7 cells. Moreover, treatment with QUE markedly decreased osteoclast number. In a mouse calvarial osteolysis model, QUE inhibited Ti particle-induced osteolysis in vivo by inhibiting osteoclast formation and expressions of ERS-related genes. In conclusion, QUE can protect RAW264.7 cells from Ti particle-induced ERS-related apoptosis and suppress calvarial osteolysis in vivo.

Calcitonin protects chondrocytes from lipopolysaccharide-induced apoptosis and inflammatory response through MAPK/Wnt/NF-κB pathways.

Calcitonin (CT) is an anti-absorbent, which has long been used for treatment of osteoporosis. However, little information is available about the effects of CT on osteoarthritis (OA). This study was mainly aimed to explore the effects of CT on the treatment of OA, as well as the underlying mechanisms. Chondrocytes were isolated from immature mice and then were incubated with lipopolysaccharide (LPS), CT, small interfering (si) RNA against bone morphogenetic protein (BMP)-2, and/or the inhibitors of MAPK/Wnt/NF-κB pathway. Thereafter, cell viability, apoptosis, nitric oxide (NO) and inflammatory factors productions, and expression levels of cartilage synthesis protein key factors, cartilage-derived morphogenetic protein (CDMP) 1, SRY (sex-determining region Y)-box 9 protein (SOX9), and MAPK/Wnt/NF-κB pathways key factors were determined. CT significantly reversed LPS-induced cell viability decrease, apoptosis increase, the inflammatory factors and NO secretion, the abnormally expression of cartilage synthesis proteins and the activation of MAPK/Wnt/NF-κB pathways (P<0.05). In addition, we observed that administration of the inhibitors of MAPK/Wnt/NF-κB pathways statistically further increased the levels of CDMP1 and SOX9 (P<0.05). Suppression of BMP-2 decreased the levels of CDMP1 and SOX9 and activated MAPK/Wnt/NF-κB pathways, and could partially abolish CT-modulated the expression changes in CDMP1 and SOX9, and MAPK/Wnt/NF-κB pathways key factors (P<0.05). The results showed that CT protects chondrocytes from LPS-induced apoptosis and inflammatory response by regulating BMP-2 and thus blocking MAPK/Wnt/NF-κB pathways.

Silencing of Wnt5a prevents interleukin-1ß-induced collagen type II degradation in rat chondrocytes.

Osteoarthritis (OA) is a joint disease, and few treatments to date have been able to delay OA progression. The degradation of collagen type II (COL2) in the cartilage matrix is an important initiating factor for OA progression; the upregulation of Wnt5a protein activates COL2 degradation. In the present study, small interfering RNA of Wnt-5a was delivered by a lentiviral vector (LV-Wnt5a-RNAi) to silence Wnt-5a mRNA and prevent COL2 degradation. To determine the function of LV-Wnt5a-RNAi, the OA chondrocyte model (OA-like chondrocytes) were constructed using interleukin (IL)-1ß. Detected using reverse transcription-quantitative polymerase chain reaction (RT-qPCR), Wnt-5a mRNA in the OA-like chondrocytes were upregulated in a time-dependent manner, indicating that OA-like chondrocytes were successfully constructed. The bioactivity of OA-like chondrocytes was determined using Live-Dead staining, and the result illustrated that the OA-like chondrocytes stimulated with IL-1ß for 6 h remained viable, and these were used in Wnt5a silencing. The OA-like chondrocytes were divided into three groups: Group I, cultivated with common medium; group II, cultivated with common medium supplemented with empty lentiviral vector; group III, cultivated with common medium supplemented with LV-Wnt5a-RNAi. The efficiency of LV-Wnt5a-RNAi transfection was determined using fluorescence microscopy, the result of which indicated that LV-Wnt5a-RNAi could efficiently be transfected into the OA-like chondrocytes. The LV-Wnt5a-RNAi efficiency for the Wnt5a mRNA silencing was determined using RT-qPCR. The result illustrated that the mRNA of Wnt5a in group III was significantly lower in group I compared with that in group II (P<0.05), indicating that the LV-Wnt5a-RNAi could successfully silence Wnt5a mRNA. To further verify whether the silencing of Wnt5a mRNA could prevent COL2 degradation, western blotting and immunohistochemical analyses were performed. The results demonstrated that COL2 in group III was significantly higher compared with that in groups I and II (P<0.05), which illustrated that the silencing of Wnt5a mRNA could prevent COL2 degradation. In conclusion, LV-Wnt5a-RNAi was formed successfully and could efficiently silence Wnt5a mRNA expressed by OA-like chondrocytes. In addition, the silencing of Wnt5a mRNA could prevent the degradation of COL2 in OA-like chondrocytes, confirming that LV-Wnt5a-RNAi may be used as a novel tool for OA treatment.

A novel rabbit model of early osteoarthritis exhibits gradual cartilage degeneration after medial collateral ligament transection outside the joint capsule.

Though many surgical animal models have been used to induce osteoarthritis (OA) of the knee joint, they always open the capsule of the joint. Any surgical procedures that incises the capsule may cause inflammation, pain, and possibly altered gait. One common disadvantage of these surgically induced animal models is that they may affect the initial structures and synovial fluid in joint. These animal models may not be suitable for research into synovial fluid changes during early OA. This study aimed to create an animal model of early OA by resecting the medial collateral ligament (MCL) outside of the capsule. At 1, 2, 3, 4, 5 and 6 weeks after surgery, eight knees from each group were harvested. The joint gap was measured on posteroanterior radiographs after MCL-transection (MCLT). Gross examination and histological analysis were performed to evaluate cartilage damage to the medial femoral condyles, and knee joints were scanned using a Micro-CT system. The MCLT group experienced early stage OA from 3 to 6 weeks according to the histological scores. IL-6, MMP-1 and MMP-13 content in the synovial fluid were higher after MCLT than anterior cruciate ligament transection (ACLT) at 1 and 2 weeks.

Transplantation of allogenic chondrocytes with chitosan hydrogel-demineralized bone matrix hybrid scaffold to repair rabbit cartilage injury.

Cartilage tissue engineering is the hotspot of cartilage repair. The allogenic chondrocytes appear to be a promising source of seed cells in cartilage tissue engineering. In this study, we aimed to transplant allogenic chondrocytes with chitosan hydrogel (CS)-demineralized bone matrix (DBM) hybrid scaffold (CS/DBM) to repair rabbit cartilage injury with one-step operation. After the CS/DBM scaffold was successfully fabricated, it showed that the porous CS filled the large pores of DBM, which improved the distribution of seed cells in the CS/DBM scaffold. The allogenic chondrocytes at second passage were transplanted with different scaffolds to repair rabbit cartilage injury. Twenty-four weeks after surgery, the cartilage defect in the CS/DBM group was successfully filled as shown by MRI. Moreover, the histological score of CS/DBM group was significantly higher than that of the other groups. On the aspect of biomechanical property, the regenerated cartilage in the CS/DBM group were superior to those in the other groups as determined by nanoindentation. Meanwhile, no obvious inflammatory response was observed after the transplantation of allogenic chondrocytes at 24 weeks post-surgery. Furtherly, gene expression profile for cells within the repair tissue was compared with the allogenic chondrocytes before transplantation using Agilent microarray and RT-qPCR. The results showed that some genes beneficial to cartilage regeneration, such as BMP-7, HGF, and IGF-1, were upregulated one month after transplantation. Consequently, our study demonstrated that the transplantation of allogenic chondrocytes with CS/DBM scaffold successfully repaired rabbit cartilage injury with only one-step operation, thereby providing new insights into cartilage tissue engineering.

In Vitro Bioactivity Study of RGD-Coated Titanium Alloy Prothesis for Revision Total Hip Arthroplasty.

Total hip arthroplasty (THA) is a common procedure for the treatment of end-stage hip joint disease, and the demand for revision THA will double by 2026. Ti6Al4V (Titanium, 6% Aluminum, and 4% Vanadium) is a kind of alloy commonly used to make hip prothesis. To promote the osseointegration between the prothesis and host bone is very important for the revision THA. The peptide Arg-Gly-Asp (RGD) could increase cell attachment and has been used in the vascular tissue engineering. In this study, we combined the RGD with Ti6Al4V alloy using the covalent cross-linking method to fabricate the functional Ti6Al4V alloy (FTA). The distribution of RGD oligopeptide on the FTA was even and homogeneous. The FTA scaffolds could promote mouse osteoblasts adhesion and spreading. Furthermore, the result of RT-qPCR indicated that the FTA scaffolds were more beneficial to osteogenesis, which may be due to the improvement of osteoblast adhesion by the RGD oligopeptide coated on FTA. Overall, the FTA scaffolds developed herein pave the road for designing and building more efficient prothesis for osseointegration between the host bone and prothesis in revision THA.