Gadolinium-hyaluronic acid nanoparticles as an efficient and safe magnetic resonance imaging contrast agent for articular cartilage injury detection

Accurate detection of cartilage injuries is critical for their proper treatment because these injuries lack the selfhealing ability and lead to joint dysfunction.However,the low longitudinal T1 relaxivity(r1)and non-specificity of contrast agents(such as gadolinium(III)-diethylenetriamine-pentaacetic acid(Gd-DTPA))significantly limit the efficiency of clinical magnetic resonance imaging(MRI)applications.To overcome these drawbacks,we integrated hyaluronic acid(HA)with Gd to synthesize a Gd-DTPA-HA composite,which was subsequently freeze-dried to produce nanoparticles(NPs).The resultant Gd-HA NPs demonstrated a greater r1 value(12.51 mM^-1 s^-1)compared with the bulk Gd-DTPA-HA(8.37 mM^-1 s^-1)and clinically used Gd-DTPA(3.88 mM^-1 s^-1).Moreover,the high affinity of HA to the cartilage allowed these NPs to penetrate deeper beyond the cartilage surface.As a result,Gd-HA NPs considerably increased the quality of cartilage and lesion MR images via their intra-articular injection in vivo.Specifically,2 h after NP administration,the signal-to-noise ratio at the injured cartilage site was 2.3 times greater than the value measured before the injection.In addition,Gd-HA NPs exhibited good biosafety properties due to the absence of adverse effects in the blood or on the main organs.It was also showed that Gd NPs were first metabolized by the kidney and liver and then excreted from the body with urine.Thus,Gd-HA NPs can potentially serve as an efficient MRI contrast agent for improved detection of cartilage injuries.

High-precision,gelatin-based,hybrid,bilayer scaffolds using melt electro-writing to repair cartilage injury

Articular cartilage injury is a common disease in the field of orthopedics.Because cartilage has poor self-repairing ability,medical intervention is needed.Using melt electro-writing(MEW)technology,tissue engineering scaffolds with high porosity and high precision can be prepared.However,ordinary materials,especially natural polymer materials,are difficult to print.In this study,gelatin was mixed with poly(lactic-co-glycolic acid)to prepare high-concentration and high-viscosity printer ink,which had good printability and formability.A composite scaffold with full-layer TGF-β1 loading mixed with hydroxyapatite was prepared,and the scaffold was implanted at the cartilage injury site;microfracture surgery was conducted to induce the mesenchyme in the bone marrow.Quality stem cells thereby promoted the repair of damaged cartilage.In summary,this study developed a novel printing method,explored the molding conditions based on MEW printing ink,and constructed a bioactive cartilage repair scaffold.The scaffold can use autologous bone marrow mesenchymal stem cells and induce their differentiation to promote cartilage repair.

Does progress in microfracture techniques necessarily translate into clinical effectiveness?

BACKGROUND Multitudinous advancements have been made to the traditional microfracture(MFx)technique,which have involved delivery of various acellular 2nd generation MFx and cellular MFx-III components to the area of cartilage defect.The relative benefits and pitfalls of these diverse modifications of MFx technique are still not widely understood.AIM To comparatively analyze the functional,radiological,and histological outcomes,and complications of various generations of MFx available for the treatment of cartilage defects.METHODS A systematic review was performed using PubMed,EMBASE,Web of Science,Cochrane,and Scopus.Patients of any age and sex with cartilage defects undergoing any form of MFx were considered for analysis.We included only randomized controlled trials(RCTs)reporting functional,radiological,histological outcomes or complications of various generations of MFx for the management of cartilage defects.Network meta-analysis(NMA)was conducted in Stata and Cochrane’s Confidence in NMA approach was utilized for appraisal of evidence.RESULTS Forty-four RCTs were included in the analysis with patients of mean age of 39.40(±9.46)years.Upon comparing the results of the other generations with MFX-I as a constant comparator,we noted a trend towards better pain control and functional outcome(KOOS,IKDC,and Cincinnati scores)at the end of 1-,2-,and 5-year time points with MFx-III,although the differences were not statistically significant(P>0.05).We also noted statistically significant Magnetic resonance observation of cartilage repair tissue score in the higher generations of microfracture(weighted mean difference:17.44,95%confidence interval:0.72,34.16,P=0.025;without significant heterogeneity)at 1 year.However,the difference was not maintained at 2 years.There was a trend towards better defect filling on MRI with the second and third generation MFx,although the difference was not statistically significant(P>0.05).CONCLUSION The higher generations of traditional MFx technique utilizing acellular and cellular components to augment its potential in the management of cartilage defects has shown only marginal improvement in the clinical and radiological outcomes.

Dynamic Observation of Cartilage Damage and Serum IL-1β, TNF-α, IL-6 and IL-17 in Post-traumatic Rat Osteoarthritis Model

The pathogenesis of animal osteoarthritis(OA)is not clear.The aim of this study was to investigate the dynamic changes of cartilage lesions and serum IL-1β,TNF-α,IL-6 and IL-17 inflammatory factors in a post-traumatic osteoarthritis model in rats,and to explore their values in monitoring the progression of osteoarthritis.Forty male SD rats were randomly divided into the control group(n=20)and the model group(n=20).The OA model was established by anterior cruciate ligament transection combined with partial medial meniscus resection(ACLT+PMMx)in the model group,and sham operation was performed in the control group.On the 0th,10th,20th and 30th days after modeling,the degree of joint swelling and the number of white blood cells in the peripheral blood were evaluated,and tibia samples were taken for macroscopic observation score and pathological observation.The serum levels ofIL-1β,TNF-α,IL-6 and IL-17 concentration were detected by enzyme-linked immunosorbent assay(ELISA).The results showed that the cartilage damage in the tibial surface and pathological observations of rats in the model group gradually increased with time,the eye scores increased and increased significantly on the 20th and 30th days(P<0.01),and the joints of the rats were swollen.And the swelling was extremely significant on the 30th day(P<0.01).Compared with the control group,the number of white blood cells in the peripheral blood of the model group gradually increased,and the increase was extremely significant on the 20th and 30th days(P<0.01).The serum IL-17 concentration in the model group tended to increase,and the increase was significant on the 20th day(P<0.05)and extremely significant on the 30th day(P<0.01);the serum TNF-αand IL-1βconcentrations in the model group showed an increasing trend,and the increase was extremely significant on the 10th,20th and 30th days(P<0.01);IL-6 concentration in the serum of the model group showed an increasing trend,and it increased significantly on the 30th day(P<0.05).The results showed that in the rat model of traumatic OA,the degree of joint damage gradually increased,and the expression of blood inflammatory indexes IL-1β,TNF-α,IL-17 and IL-6 increased.The research provided a basis for prompting and monitoring the timing of OA treatment and the development of the disease in animal clinical.

Arthroscopic Assessment of Intra-Articular Injury in Patients with Acute Unstable Malleolar Fracture

Introduction: Purpose to study prevalence of the intraarticular chondral lesion in the malleolar fracture by using ankle arthroscopy to fully understand the severity and complexity of the injury. Methods: Cross sectional study of 32 patients diagnosed with ankle fracture and undergone open reduction and internal fixation with arthroscopic assessment performed stimultaneously. The mechanism of injury, patterns of injury and intraarticular chondral injury were documented. Results: Mean age was 38 years (SD = 14.1, range 18 - 68 years). Eighteen were female and 14 were male. Fifteen involved syndesmostic distruption, 22 had Danis-Weber B injury and 16 had supination external rotation (SER). Ten (31.2%) had positive intraoperative cartilage injury. Significant correlation between the Lauge-Hansen classifications with positive findings with 6 had SER, 2 had pronation adduction and 2 had pronation external rotation. Conclusion: The prevalence of chondral injury in ankle fracture was quite high and may leads to poor outcome. Arthroscopy procedure allow surgeon to assess intraarticular surface and reduction of the ankle fracture which prompt further intervention that may improve the clinical outcomes and prognosis of the patients.

Biomimetic melatonin-loaded silk fibroin/GelMA scaffold strengthens cartilage repair through retrieval of mitochondrial functions

Articular cartilage injury induced by collision or trauma is a common sports-related condition that may progress to pain,dysfunction,and secondary osteoarthritis(OA).Limited by self-renewal potential,cartilage regeneration faces a quandary while bio-inspired novel strategies are urgently required.In this study,by a soft freezing method and surface modification technique,a multi-functional silk fibroin(SF)plus gelatin methacrylate(GelMA)scaffold laden with melatonin(MT)was prepared.SF-GelMA@MT scaffold demonstrated enhanced biomechanical characteristics and long-acting melatonin release.In vitro treatment with SF-GelMA@MT induced the synthesis of cartilage extracellular matrix(ECM)components.Mechanistically,sustained release of melatonin yielded robust chondroprotective effects via improving mitochondrial polarization and antioxidant properties.SF-GelMA@MT implantation boosted cartilage renascence in a full-thickness cartilage defect model via mitochondria-associated sirtuins 1(SIRT1)-superoxide dismutase 2(SOD2)signaling pathway in vivo.In summary,this research proposed a welldesigned bionic composite scaffold that promotes cartilage regeneration via mitochondrial function enhancement,which is of tremendous potential for cartilage tissue engineering.

Promotion of Chondrogenesis of Marrow Stromal Stem Cells by TGF-β3 Fusion Protein In Vitro

The purpose of this study was to investigate the repair of the osteoarthritis（OA）-induced car- tilage injury by transfecting the new TGF-β3 fusion protein （LAP-MMP-mTGF-β3） with targeted ther- apy function into the bone marrow-derived mesenchymal stem cells （MSCs） in rats. The recombinant of plRES-EGFP-MMP was constructed by combination of DNA encoding MMP enzyme cutting site and eukaryotic expression vector plRES-EGFP. LAP and mTGF-β3 fragments were obtained from rat em- bryos by RT-PCR and inserted into the upstream and downstream of MMP from plRES-EGFP-MMP respectively, so as to construct the recombinant plasmid ofplRES-EGFP-LAP-MMP-mTGF-β3, plRES- EGFP-LAP-MMP-mTGF-β3 was transfected into rat MSCs. The genetically modified MSCs were cul- tured in medium with MMP-1 or not. The transfected MSCs were transplanted in the rat OA models. The OA animal models were surgically induced by anterior cruciate ligament transaction （ACLT）. The pathological changes were observed under a microscope by HE staining, Alcian blue, Safranin-fast Gre- en and graded by Mankin＇s scale, plRES-EGFP-LAP-MMP-mTGF-β3 was successfully constructed by means of enzyme cutting and sequencing, and the mTGF-β3 fusion protein （39 kD） was certified by Western blotting. Those genetically modified MSCs could differentiate into chondrocytes induced by MMP and secrete the relevant-matrix. The transfected MSCs could promote chondrogenesis and matrix production in rat OA models in vivo. It was concluded that a new fusion protein LAP-MMP-mTGF-β3 was constructed successfully by gene engineering, and could be used to repair the OA-induced cartilage injury.

Advancing drug delivery to articular cartilage:From single to multiple strategies

Articular cartilage(AC) injuries often lead to cartilage degeneration and may ultimately result in osteoarthritis(OA) due to the limited self-repair ability. To date, numerous intra-articular delivery systems carrying various therapeutic agents have been developed to improve therapeutic localization and retention, optimize controlled drug release profiles and target different pathological processes. Due to the complex and multifactorial characteristics of cartilage injury pathology and heterogeneity of the cartilage structure deposited within a dense matrix, delivery systems loaded with a single therapeutic agent are hindered from reaching multiple targets in a spatiotemporal matched manner and thus fail to mimic the natural processes of biosynthesis, compromising the goal of full cartilage regeneration. Emerging evidence highlights the importance of sequential delivery strategies targeting multiple pathological processes. In this review, we first summarize the current status and progress achieved in single-drug delivery strategies for the treatment of AC diseases. Subsequently, we focus mainly on advances in multiple drug delivery applications, including sequential release formulations targeting various pathological processes, synergistic targeting of the same pathological process, the spatial distribution in multiple tissues, and heterogeneous regeneration. We hope that this review will inspire the rational design of intraarticular drug delivery systems(DDSs) in the future.

Working conditions of bipolar radiofrequency on human articular cartilage repair following thermal injury during arthroscopy

Background The thermal injury during bipolar radiofrequercy results in chondrocyte death that limits cartilage repair.The purpose was to determine the effects of various factors of bipolar radiofrequency on human articular cartilage after thermal injury,offering suitable working conditions for bipolar radiofrequency during arthroscopy.Methods Osteochondral explants from 28 patients undergoing total knee arthroplasty （TKA） in Department of Orthopaedic,Peking University Reople＇s Hospital from October 2013 to May 2014,were harvested and treated using bipolar radiofrequency in a light contact mode under the following conditions：various power setting of levels 2,4 and 6; different durations of 2 seconds,5 seconds and 10 seconds; irrigation with fluids of different temperatures of 4℃,22℃,and 37℃; two different bipolar radiofrequency probes ArthroCare TriStar 50 and Paragon T2.The percentage of cell death and depth of cell death were quantified with laser confocal microscopy.The content of proteoglycan elution at different temperatures was determined by spectrophotometer at 530 nm.Results Chondrocyte mortality during the treatment time of 2 seconds and power setting of level 2 was significantly lower than that with long duration or in higher level groups （time：P=0.001; power：P=0.001）.The percentage of cell death after thermal injury was gradually reduced by increasing the temperature of the irrigation solutions （P=0.003）,the depth of dead chondrocytes in the 37℃ solution group was significantly less than those in the 4℃ and 22℃ groups （P=0.001）.The proteoglycan elution was also gradually reduced by increasing the temperature （P=0.004）.Compared with the ArthroCare TriStar 50 group,the percentage of cell death in the Paragon T2 group was significantly decreased （P=0.046）.Conclusions Thermal chondroplasty with bipolar radiofrequency resulted in defined margins of chondrocyte death under controlled conditions.The least cartilage damage during thermal chondroplasty could be achieved with lower power,shorter duration,suitable temperature of irrigation solutions and chondroprotective probes.The recommendations for the use of bipolar radiofrequency to minimize cartilage damage could be achieved with a power setting of level 2,treatment duration of 2 seconds,suitable fluid temperature （closer to body temperature of 37℃） and chondroprotective Paragon T2 probes.

Recruitment of endogenous progenitor cells by erythropoietin loaded particles for in situ cartilage regeneration

Cartilage injury affects millions of people throughout the world,and at this time there is no cure.While transplantation of stem cells has shown some success in the treatment of injured cartilage,such treatment is limited by limited cell sources and safety concerns.To overcome these drawbacks,a microscaffolds system was developed capable of targeting,reducing the inflammatory response and recruiting endogenous progenitor cells to cartilage-defect.Erythropoietin(EPO)-loaded-hyaluronic acid(HA)microscaffolds(HA+EPO)were fabricated and characterized.HA-microscaffolds showed good cell-compatibility and could target chondrocytes via CD44 receptors.HA+EPO was designed to slowly release EPO while recruiting progenitor cells.Finally,the ability of HA+EPO to repair cartilage-defects was assessed using a rabbit model of full-thickness cartilagedefect.Our results showed that the intra-articular administration of EPO,HA,and EPO+HA reduced the number of inflammatory cells inside the synovial-fluid,while EPO+HA had the greatest anti-inflammatory effects.Furthermore,among all groups,EPO+HA achieved the greatest progenitor cell recruitment and subsequent chondrogenesis.The results of this work support that,by targeting and localizing the release of growthfactors,HA+EPO can reduce inflammatory responses and promote progenitor cells responses.This new platform represents an alternative treatment to stem-cell transplantation for the treatment of cartilage injury.

Osteochondral scaffolds for early treatment of cartilage defects in osteoarthritic joints:from bench to clinic

Osteoarthritis is a degenerative joint disease,typified by the loss in the quality of cartilage and bone at the interface of a synovial joint,resulting in pain,stiffness and reduced mobility.The current surgical treatment for advanced stages of the disease is joint replacement,where the non-surgical therapeutic options or less invasive surgical treatments are no longer effective.These are major surgical procedures which have a substantial impact on patients’quality of life and lifetime risk of requiring revision surgery.Treatments using regenerative methods such as tissue engineering methods have been established and are promising for the early treatment of cartilage degeneration in osteoarthritis joints.In this approach,3-dimensional scaffolds(with or without cells)are employed to provide support for tissue growth.However,none of the currently available tissue engineering and regenerative medicine products promotes satisfactory durable regeneration of large cartilage defects.Herein,we discuss the current regenerative treatment options for cartilage and osteochondral(cartilage and underlying subchondral bone)defects in the articulating joints.We further identify the main hurdles in osteochondral scaffold development for achieving satisfactory and durable regeneration of osteochondral tissues.The evolution of the osteochondral scaffolds–from monophasic to multiphasic constructs–is overviewed and the osteochondral scaffolds that have progressed to clinical trials are examined with respect to their clinical performances and their potential impact on the clinical practices.Development of an osteochondral scaffold which bridges the gap between small defect treatment and joint replacement is still a grand challenge.Such scaffold could be used for early treatment of cartilage and osteochondral defects at early stage of osteoarthritis and could either negate or delay the need for joint replacements.