Chondrogenesis of periodontal ligament stem cells by transforming growth factor-β3 and bone morphogenetic protein-6 in a normal healthy impacted third molar

The periodontal ligament-derived mesenchymal stem cell is regarded as a source of adult stem cells due to its multipotency.However, the proof of chondrogenic potential of the cells is scarce.Therefore,we investigated the chondrogenic differentiation capacity of periodontal ligament derived mesenchymal stem cells induced by transforming growth factor(TGF)-p3 and bone morphogenetic protein(BMP)-6.After isolation of periodontal ligament stem cells(PDLSCs) from human periodontal ligament,the cells were cultured in Dulbecco’s modified Eagle’s medium(DMEM) with 20%fetal bovine serum(FBS).A mechanical force initiated chondrogenic differentiation of the cells.For chondrogenic differentiation,10μg·LTGF-β3 or 100μg·LBMP-6 and the combination treating group for synergistic effect of the growth factors.We analyzed the PDLSCs by fluorescence-activated cell sorting and chondrogenesis were evaluated by glycosaminoglycans assay,histology,immunohistochemistry and genetic analysis.PDLSCs showed mesenchymal stem cell properties proved by FACS analysis.Glycosaminoglycans contents were increased 217%by TGF-β3 and 220%by BMP-6. The synergetic effect of TGF-β3 and BMP-6 were shown up to 281%compared to control.The combination treatment increased Sox9, aggrecan and collagen II expression compared with not only controls,but also TGF-P3 or BMP-6 single treatment dramatically.The histological analysis also indicated the chondrogenic differentiation of PDLSCs in our conditions.The results of the present study demonstrate the potential of the dental stem cell as a valuable cell source for chondrogenesis,which may be applicable for regeneration of cartilage and bone fracture in the field of cell therapy.

Induction of Chondrogenesis of Adipose-derived Stem Cells by Novel Recombinant TGF-β3 Fusion Protein

Summary： A new type of TGF-β3 fusion protein with targeted therapy function was constructed, and its feasibility and target specificity of inducing chondrogenesis were investigated by transfecting LAP-MMP-mTGF-β3 gene into adipose-derived stem cells （ADSCs）. The recombinant pIRES- EGFP-MMP was constructed by inserting the sense and antisense DNA of encoding the amino acid of the synthetic MMP enzyme cutting site into the eukaryotic expression vector pIRES-EGFE LAP and mTGF-β3 fragments were obtained by using RT-PCR and inserted into the upstream and downstream of MMP from pIRES-EGFP-MMP respectively, and the recombinant plasmid of pIRES-EGFP- LAP-MMP-mTGF-β3 was constructed, which was transferred to ADSCs. The ADSCs were cultured and divided in three groups： experimental group （MMP group）, negative control group （no MMP） and non-transfection group. The morphological changes were observed microscopically, and the expression of proteoglycan and type II collagen （Col II） was detected by using Alcian blue staining and immuno- histochemistry staining at 7th, 14th and 21st day after culture. The recombinant plasmid of pIRES-EGFP-LAP-MMP-mTGF-β3 was correctly constructed by methods of enzyme cutting and se- quencing analysis. The mTGF-β3 fusion protein was successfully expressed after transfection, and in the presence of the MMP, active protein mTGF-β3 was generated, which significantly promoted differ- entiation of ADSCs into chondrocytes and the expression of cartilage matrix. The novel fusion protein LAP-MMP-mTGF-β3 can targetedly induce differentiation of ADSCs into chondrocytes, which would open up prospects for target therapy of cartilage damage repair in future.

Systematic review on the use of autologous matrix-induced chondrogenesis for the repair of articular cartilage defects in patients

AIM To systematically review the results of studies looking at autologous matrix-induced chondrogenesis(AMIC) in humans. METHODS A literature search was performed, adhering to the PRISMA guidelines, to review any studies using such techniques in humans. Our initial search retrieved 297 articles listed on MEDLINE, Google Scholar, CINHal and EMBASE. From these studies, 15 studies meeting the eligibility criteria were selected and formed the basis of our systematic review.RESULTS The study designs, surgical techniques and outcome measures varied between the studies. Although all studies reported improvements in patient outcome measures, this was not necessarily correlated with magnetic resonance imaging findings. Although there were many additional procedures performed, when AMIC was performed in isolation, the results tended to peak at 24 mo before declining. CONCLUSION Although short-term studies suggest improved patient reported outcomes with a variety of scaffolds, surgical techniques and rehabilitation regimes, the literature remains equivocal on whether the defect size and location, and patient factors affect the outcome. Patientbenefit appears to be maintained in the short-tomedium term but more high level studies with extensive and robust validated outcome measures should be conducted to evaluate the medium-and long-term effect of the AMIC procedure.

Accelerated chondrogenesis in nanofiber polymeric scaffolds embedded with BMP-2 genetically engineered chondrocytes

This study evaluated chondrogenesis within a nanofiber polymeric scaffold seeded with isolated untreated chondrocytes, isolated chondrocytes genetically engineered with adenoviral (Ad) bone morphogenetic protein (BMP)-2, or isolated chondrocytes genetically engineered with green fluorescent protein (Ad-GFP). Electrospun polycaprolactone scaffolds (150-200 m thickness, 700 m fiber diameter, 30 m pore size) were optimally seeded with 1 x 107 isolated chondrocytes by using a 20% serum gradient culture system. Chondrocyte-scaffold constructs (untreated, Ad-B- MP-2 and Ad-GFP) were generated from 5 adult horses, cultured in triplicate for 7 or 14 days, and quantitatively analyzed for cell proliferation (DNA content;Hoechst assay), viability, morphology (confocal microscopy), matrix production (proteoglycan content;DMMB assay), and mRNA expression of collagen I, collagen II, and aggrecan. Chondrocytes transduced with Ad-BMP-2 demonstrated greater cell numbers and significantly greater expression of chondrogenic markers including aggrecan, collagen II, and proteoglycan through 14 days of culture as compared to untransduced or Ad-GFP controls. This study demons- trated that chondrocytes can be driven to seed a polycaprolactone nanofiber scaffold by serum gradient and a polycaprolactone nanofiber scaffold containing Ad-BMP2 transduced chondrocytes resulted in grea- ter and accelerated chondrogenesis than controls. This cell engineered construct has potential use in one-step cartilage repair in vivo.

Bone morphogenetic protein 2 promotes transforming growth factor β3-induced chondrogenesis of human osteoarthritic synovium-derived stem cells

Background Synovium-derived stem cells （SDSCs） with higher chondrogenic potential are attracting considerable attention as a cell source for cartilage regeneration. We investigated the effect of bone morphogenetic protein 2 （BMP-2） on transforming growth factor beta3 （TGF-β3）-induced chondrogenesis of SDSCs isolated from human osteoarthritic synovium in a pellet culture system. Methods The clonogenicity, stem cell marker expression and multi-differentiation potential of isolated SDSCs were determined by colony forming unit assay, flow cytometry and specific staining including alizarin red S, Oil red O and alcian blue staining, respectively. SDSCs pellet was cultured in chondrogenic medium with or without TGF-β3 or/and BMP-2. At day 21, the diameter and the weight of the pellets were measured. Chondrogenic differentiation of SDSCs was evaluated by Safranin O staining, immunohistochemical staining of collagen type Ⅱ, sulfated glycosaminoglycan （sGAG） synthesis and mRNA expression of collagen type Ⅱ, aggrecan, SOX9, link-protein, collagen type X and BMP receptor Ⅱ. Results Cells isolated under the optimized culturing density （104/60 cm2） showed clonogenicity and multi-differentiation potential. These cells were positive （〉99%） for CD44, CD90, CD105 and negative （〈10%） for CD34 and CD71. SDSCs differentiated to a chondrocytic phenotype in chondrogenic medium containing TGF-β3 with or without BMP-2. Safranin O staining of the extracellular matrix was positive and the expression of collagen type Ⅱ was detected. Cell pellets treated with TGF-β3 and BMP-2 were larger in diameter and weight, produced more sGAGs, and expressed higher levels of collagen type Ⅱ and other chondrogenic markers, except COL10A1, than medium with TGF-β3 alone. Conclusions SDSCs could be isolated from human osteoarthritic synovium. Supplementation with BMP-2 significantly promoted the in vitro TGF-β3-induced chondrogenic differentiation of SDSCs.

Multifaceted signaling regulators of chondrogenesis:Implications in cartilage regeneration and tissue engineering

Defects of articular cartilage present a unique clinical challenge due to its poor self-healing capacity and avascular nature.Current surgical treatment options do not ensure consistent regeneration of hyaline cartilage in favor of fibrous tissue.Here,we review the current understanding of the most important biological regulators of chondrogenesis and their interactions,to provide insight into potential applications for cartilage tissue engineering.These include various signaling pathways,including fibroblast growth factors(FGFs),transforming growth factor b(TGF-b)/bone morphogenic proteins(BMPs),Wnt/b-catenin,Hedgehog,Notch,hypoxia,and angiogenic signaling pathways.Transcriptional and epigenetic regulation of chondrogenesis will also be discussed.Advances in our understanding of these signaling pathways have led to promising advances in cartilage regeneration and tissue engineering.

Compound screening platform using human induced pluripotent stem cells to identify small molecules that promote chondrogenesis

Articular cartilage,which is mainly composed of collagen Ⅱ,enables smooth skeletal movement.Degeneration of collagen Ⅱ can be caused by various events,such as injury,but degeneration especially increases over the course of normal aging.Unfortunately,the body does not fully repair itself from this type of degeneration,resulting in impaired movement.Microfracture,an articular cartilage repair surgical technique,has been commonly used in the clinic to induce the repair of tissue at damage sites.Mesenchymal stem cells(MSC)have also been used as cell therapy to repair degenerated cartilage.However,the therapeutic outcomes of all these techniques vary in different patients depending on their age,health,lesion size and the extent of damage to the cartilage.The repairing tissues either form fibrocartilage or go into a hypertrophic stage,both of which do not reproduce the equivalent functionality of endogenous hyaline cartilage.One of the reasons for this is inefficient chondrogenesis by endogenous and exogenous MSC.Drugs that promote chondrogenesis could be used to induce self-repair of damaged cartilage as a non-invasive approach alone,or combined with other techniques to greatly assist the therapeutic outcomes.The recent development of human induced pluripotent stem cell(iPSCs),which are able to self-renew and differentiate into multiple cell types,provides a potentially valuable cell resource for drug screening in a“more relevant”cell type.Here we report a screening platform using human iPSCs in a multi-well plate format to identify compounds that could promote chondrogenesis.

Effect of different aged cartilage ECM on chondrogenesis of BMSCs in vitro and in vivo

Extracellular matrix(ECM)-based biomaterials are promising candidates in cartilage tissue engineering by simulating the native microenvironment to regulate the chondrogenic differentiation of bone marrow mesenchymal stem cells(BMSCs)without exogenous growth factors.The biological properties of ECM scaffolds are primarily depended on the original source,which would directly influence the chondrogenic effects of the ECM materials.Despite the expanding investigations on ECM scaffolds in recent years,the selection of optimized ECM materials in cartilage regeneration was less reported.In this study,we harvested and compared the articular cartilage ECM from newborn,juvenile and adult rabbits.The results demonstrated the significant differences in the mechanical strength,sulphated glycosaminoglycan and collagen contents of the different aged ECM,before and after decellularization.Consequently,different compositional and mechanical properties were shown in the three ECM-based collagen hydrogels,which exerted age-dependent chondrogenic inducibility.In general,both in vitro and in vivo results suggested that the newborn ECM promoted the most chondrogenesis of BMSCs but led to severe matrix calcification.In contrast,BMSCs synthesized the lowest amount of cartilaginous matrix with minimal calcification with adult ECM.The juvenile ECM achieved the best overall results in promoting chondrogenesis of BMSCs and preventing matrix calcification.Together,this study provides important information to our current knowledge in the design of future ECM-based biomaterials towards a successful repair of articular cartilage.

Proteome analysis of human mesenchymal stem cells undergoing chondrogenesis when exposed to the products of various magnesium-based materials degradation

Treatment of physeal fractures(15%–30%of all paediatric fractures)remains a challenge as in approximately 10%of the cases,significant growth disturbance may occur.Bioresorbable Magnesium-based implants represent a strategy to minimize damage(i.e.,load support until bone healing without second surgery).Nevertheless,the absence of harmful effects of magnesium-implants and their degradation products on the growth plate should be confirmed.Here,the proteome of human mesenchymal stem cells undergoing chondrogenesis was evaluated when exposed to the products of various Magnesium-based materials degradation.The results of this study indicate that the materials induced regulation of proteins associated with cell chondrogenesis and cartilage formation,which should be beneficial for cartilage regeneration.

The role of Nkx3.2 in chondrogenesis

Transcription factor, Nkx3.2, is a member of the NK family of developmental genes and is expressed during embryogenesis in a variety of mammalian model organisms, including chicken and mouse. It was first identified in Drosophila as the Bagpipe （bap） gene, where it has been demonstrated to be essential during formation of the midgut musculature. However, mammalian homolog Nkx3.2 has been shown to play a significant role in axial and limb skeletogenesis; in particular, the human skeletal disease, spondylo-megaepiphyseal-metaphyseal dysplasia （SMMD）, is associated with mutations of the Nkx3.2 gene. In this review, we highlight the role of Nkx3.2 during musculoskeletal development, with an emphasis on the factor＇s role in determining chondrogenic cell fate and its subsequent role in endochondral ossification and chondrocyte survival.

Opposite Regulation of Chondrogenesis and Angiogenesis in Cartilage Repair ECM Materials under Hypoxia

Although cartilage tissue engineering has been developed for decades, it is still unclear whether angio- genesis was the accompaniment of chondrogenesis in cartilage regeneration. This study aimed to explore the process of anti-angiogenesis during cartilage regenerative progress in cartilage repair extracellular matrix （ECM） materials under Hypoxia. C3H10T1/2 cell line, seeded as pellet or in ECM materials, was added with chondrogenic medium or DMEM medium for 21 days under hypoxia or normoxia environment. Genes and miRNAs related with chondrogenesis and angiogenesis were detected by RT-qPCR technique on Days 7, 14, and 21. Dual-luciferase report system was used to explore the regulating roles of miRNAs on angiogenesis. Results showed that the chondrogenic medium promotes chondrogenesis both in pellet and ECM materials culture. HIF1α was up-regulated under hypoxia compared with normoxia （P 〈 0.05）. Meanwhile, hypoxia enhanced chondrogenesis, miR-140-Sp exhibited higher expression while miR-146b exhibited lower expression. The chondrogenic phenotype was more stabilized in the ECM materials in chondrogenic medium than DMEM medium, with lower VEGFα expression even under hypoxia. Dual-luciferase report assays demonstrated that miR-140-5p directly targets VEGFct by binding its 3＇- UTR. Taken together, chondrogenic cytokines, ECM materials and hypoxia synergistically promoted chondrogenesis and inhibited angiogenesis, miR-140-5p olaved an imnortant role in this process.

Adipose-derived mesenchymal stem cell-incorporated PLLA porous microspheres for cartilage regeneration

Background:In facial plastic surgery,patients with nasal deformity are often treated by rib cartilage transplantation.In recent years,cartilage tissue engineering has developed as an alternative to complex surgery for patients with minor nasal defects via injection of nasal filler material.In this study,we prepared an injectable nasal filler material containing poly-L-l actic acid(PLLA)porous microspheres(PMs),hyaluronic acid(HA)and adipose-derived mesenchymal stem cells(ADMSCs).Methods:We seeded ADMSCs into as-prepared PLLA PMs using our newly invented centrifugation perfusion technique.Then,HA was mixed with ADMSC-i ncorporated PLLA PMs to form a hydrophilic and injectable cell delivery system(ADMSCincorporated PMH).Results:We evaluated the biocompatibility of PMH in vitro and in vivo.PMH has good injectability and provides a favorable environment for the proliferation and chondrogenic differentiation of ADMSCs.In vivo experiments,we observed that PMH has good biocompatibility and cartilage regeneration ability.Conclusion:In this study,a injectable cell delivery system was successfully constructed.We believe that PMH has potential application in cartilage tissue engineering,especially in nasal cartilage regeneration.

Enhanced microfracture techniques in cartilage knee surgery: Fact or fiction?

The limited intrinsic healing potential of human articular cartilage is a well-known problem in orthopedic surgery. Thus a variety of surgical techniques have been developed to reduce joint pain, improve joint function and delay the onset of osteoarthritis. Microfractures as a bone marrow stimulation technique present the most common applied articular cartilage repair procedure today. Unfortunately the deficiencies of fibrocartilaginous repair tissue inevitably lead to breakdown under normal joint loading and clinical results deteriorate with time. To overcome the shortcomings of microfracture, an enhanced microfracture technique was developed with an additional collagen Ⅰ/Ⅲ membrane(Autologous, Matrix-Induced Chondrogenesis, AMIC). This article reviews the pre-clinical rationale of microfractures and AMIC, presents clinical studies and shows the advantages and disadvantages of these widely usedtechniques. PubM ed and the Cochrane database were searched to identify relevant studies. We used a comprehensive search strategy with no date or language restrictions to locate studies that examined the AMIC technique and microfracture. Search keywords included cartilage, microfracture, AMIC, knee, ChondroGide. Besides this, we included our own experiences and study authors were contacted if more and non published data were needed. Both cartilage repair techniques represent an effective and safe method of treating full-thickness chondral defects of the knee in selected cases. While results after microfracture deteriorate with time, mid-term results after AMIC seem to be enduring. Randomized studies with long-term followup are needed whether the grafted area will maintain functional improvement and structural integrity over time.

Effects of various antimicrobial agents on multi-directional differentiation potential of bone marrow-derived mesenchymal stem cells

Antimicrobial drugs of several classes play an important role in the treatment of bone and joint infections. In addition to fighting pathogenic microorganisms, the effects of drugs on local tissues and cells are also related to the course and prognosis of bone and joint infections. The multi-directional differentiation potential of bone marrow-derived mesenchymal stem cells (MSCs) is essential for tissue repair after local injury, which is directly related to the recovery of bone, cartilage, and medullary adipose tissue. Our previous studies and the literature indicate that certain antimicrobial agents can regulate the differentiation potential of bone marrow-derived MSCs. Here, in order to systematically analyze the effects of various antimicrobial drugs on local tissue regeneration, we comprehensively review the studies on the effects of these drugs on MSC differentiation, and classify them according to the three differentiation directions (osteogenesis, chondrogenesis, and adipogenesis). Our review demonstrates the specific effects of different antimicrobial agents on bone marrow-derived MSCs and the range of concentrations at which they work, and provides a basis for drug selection at different sites of infection.

Construction of Self-Assembled Cartilage Tissue from Bone Marrow Mesenchymal Stem Cells Induced by Hypoxia Combined with GDF-5

It is widely known that hypoxia can promote chondrogenesis of human bone marrow de- rived mesenchymal stem cells （hMSCs） in monolayer cultures. However, the direct impact of oxygen tension on hMSC differentiation in three-dimensional cultures is still unknown. This research was de- signed to observe the direct impact of oxygen tension on the ability of hMSCs to ＂self assemble＂ into tissue-engineered cartilage constructs, hMSCs were cultured in chondrogenic medium （CM） containing 100 ng/mL growth differentiation factor 5 （GDF-5） at 5% （hypoxia） and 21% （normoxia） 02 levels in monolayer cultures for 3 weeks. After differentiation, the cells were digested and employed in a self- assembly process to produce tissue-engineered constructs under hypoxic and normoxic conditions in vi- tro. The aggrecan and type ]I collagen expression, and type X collagen in the self-assembled con- structs were assessed by using immunofluorescent and immunochemical staining respectively. The methods of dimethylmethylene blue （DMMB）, hydroxyproline and PicoGreen were used to measure the total collagen content, glycosaminoglycan （GAG） content and the number of viable cells in each con- struct, respectively. The expression of type II collagen and aggrecan under hypoxic conditions was in- creased significantly as compared with that under normoxic conditions. In contrast, type X collagen expression was down-regulated in the hypoxic group. Moreover, the constructs in hypoxic group showed more significantly increased total collagen and GAG than in normoxic group, which were more close to those of the natural cartilage. These findings demonstrated that hypoxia enhanced chondro- genesis of in vitro, scaffold-free, tissue-engineered constructs generated using hMSCs induced by GDF-5. In hypoxic environments, the self-assembled constructs have a Thistological appearance and biochemical parameters similar to those of the natural cartilage.

Mechanical loading of adipose derived stromal cells causes cell alignment

Osteoarthritis is a debilitating disease that affects hundreds of millions of people worldwide. Current research involving growth and characterization of adipose derived stromal cells (ADSC) in vitro offers a potential solution for the treatment of cartilage de-fects that will allow patients to return to the physical activities they were involved in. Studies have shown that fibroblast cells grown in vitro respond to cyclic mechanical stretching by orienting in a direction perpendicular to the direction of stretch. ADSCs were isolated from human peripatellar adipose tissue discards. Cells were cultured until confluent and seeded at a density of approximately 105 cells in silicone wells pretreated with ProNectin-F Plus. After stret-ching, relative alignment of the cells was ascertained using imaging software. Stretching cells for 3, 4, 8 and 12 hours resulted in noticeable cellular alignment of approximately 60? relative to the direction of loading. Cell alignment is crucial for developing tis-sue-engineered cartilage that has similar mechanical properties to native cartilage. Mechanically loading cells is one method to achieve cell alignment. Since cell differentiation will be initiated after alignment, the resulting chondrocytes will be aligned, leading to organized collagen formation and resulting in a hya-line-like cartilage structure.

From skeletal to non skeletal: The intriguing roles of BMP-9: A literature review

In the well-known superfamily of transforming growth factors beta (TGF-b), bone morphogenetic proteins (BMPs) are one of the most compelling cytokines for their major role in regulation of cell growth and differentiation in both embryonic and adult tissues. This subfamily was first described for its ability of potentiating bone formation, but nowadays, the power of BMPs is well beyond the bone healing scope. Some of the BMPs have been well studied and described in the literature, but the BMP9 is still worthy of attention. It has been shown by many authors that it is the most potent osteogenic BMP. Moreover, it has been described as one of the rare circulating BMPs. In this paper, we will review the recent literature on BMP9 and the different avenues for future research in that field. Our primary scope is to review its relation to bone formation and to elaborate on the available literature on other systems.

Boosting cartilage repair with silk fibroin-DNA hydrogel-based cartilage organoid precursor

Osteoarthritis(OA),a common degenerative disease,is characterized by high disability and imposes substantial economic impacts on individuals and society.Current clinical treatments remain inadequate for effectively managing OA.Organoids,miniature 3D tissue structures from directed differentiation of stem or progenitor cells,mimic native organ structures and functions.They are useful for drug testing and serve as active grafts for organ repair.However,organoid construction requires extracellular matrix-like 3D scaffolds for cellular growth.Hydrogel microspheres,with tunable physical and chemical properties,show promise in cartilage tissue engineering by replicating the natural microenvironment.Building on prior work on SF-DNA dual-network hydrogels for cartilage regeneration,we developed a novel RGD-SF-DNA hydrogel microsphere(RSD-MS)via a microfluidic system by integrating photopolymerization with self-assembly techniques and then modified with Pep-RGDfKA.The RSD-MSs exhibited uniform size,porous surface,and optimal swelling and degradation properties.In vitro studies demonstrated that RSD-MSs enhanced bone marrow mesenchymal stem cells(BMSCs)proliferation,adhesion,and chondrogenic differentiation.Transcriptomic analysis showed RSD-MSs induced chondrogenesis mainly through integrin-mediated adhesion pathways and glycosaminoglycan biosynthesis.Moreover,in vivo studies showed that seeding BMSCs onto RSD-MSs to create cartilage organoid precursors(COPs)significantly enhanced cartilage regeneration.In conclusion,RSD-MS was an ideal candidate for the construction and long-term cultivation of cartilage organoids,offering an innovative strategy and material choice for cartilage regeneration and tissue engineering.

Novel injectable adhesive hydrogel loaded with exosomes for holistic repair of hemophilic articular cartilage defect

Hemophilic articular cartilage damage presents a significant challenge for surgeons,characterized by recurrent intraarticular bleeding,a severe inflammatory microenvironment,and limited self-repair capability of cartilage tissue.Currently,there is a lack of tissue engineering-based integrated therapies that address both early hemostasis,anti-inflammation,and long-lasting chondrogenesis for hemophilic articular cartilage defects.Herein,we developed an adhesive hydrogel using oxidized chondroitin sulfate and gelatin,loaded with exosomes derived from bone marrow stem cells(BMSCs)(Hydrogel-Exos).This hydrogel demonstrated favorable injectability,self-healing,biocompatibility,biodegradability,swelling,frictional and mechanical properties,providing a comprehensive approach to treating hemophilic articular cartilage defects.The adhesive hydrogel,featuring dynamic Schiff base bonds and hydrogen bonds,exhibited excellent wet tissue adhesiveness and hemostatic properties.In a pig model,the hydrogel could be smoothly injected into the knee joint cartilage defect site and gelled in situ under fluid-irrigated arthroscopic conditions.Our in vitro and in vivo experiments confirmed that the sustained release of exosomes yielded anti-inflammatory effects by modulating macrophage M2 polarization through the NF-κB pathway.This immunoregulatory effect,coupled with the extracellular matrix components provided by the adhesive hydrogel,enhanced chondrogenesis,promoted the cartilage repair and joint function restoration after hemophilic articular cartilage defects.In conclusion,our results highlight the significant application potential of Hydrogel-Exos for early hemostasis,immunoregulation,and long-term chondrogenesis in hemophilic patients with cartilage injuries.This innovative approach is well-suited for application during arthroscopic procedures,offering a promising solution for addressing the complex challenges associated with hemophilic articular cartilage damage.

Cartilage lacuna-biomimetic hydrogel microspheres endowed with integrated biological signal boost endogenous articular cartilage regeneration

Despite numerous studies on chondrogenesis,the repair of cartilage—particularly the reconstruction of cartilage lacunae through an all-in-one advanced drug delivery system remains limited.In this study,we developed a cartilage lacuna-like hydrogel microsphere system endowed with integrated biological signals,enabling sequential immunomodulation and endogenous articular cartilage regeneration.We first integrated the chondrogenic growth factor transforming growth factor-β3(TGF-β3)into mesoporous silica nanoparticles(MSNs).Then,TGF-β3@MSNs and insulin-like growth factor 1(IGF-1)were encapsulated within microspheres made of polydopamine(pDA).In the final step,growth factor-loaded MSN@pDA and a chitosan(CS)hydrogel containing platelet-derived growth factor-BB(PDGF-BB)were blended to produce growth factors loaded composite microspheres(GFs@μS)using microfluidic technology.The presence of pDA reduced the initial acute inflammatory response,and the early,robust release of PDGF-BB aided in attracting endogenous stem cells.Over the subsequent weeks,the continuous release of IGF-1 and TGF-β3 amplified chondrogenesis and matrix formation.μS were incorporated into an acellular cartilage extracellular matrix(ACECM)and combined with a polydopamine-modified polycaprolactone(PCL)structure to produce a tissue-engineered scaffold that mimicked the structure of the cartilage lacunae evenly distributed in the cartilage matrix,resulting in enhanced cartilage repair and patellar cartilage protection.This research provides a strategic pathway for optimizing growth factor delivery and ensuring prolonged microenvironmental remodeling,leading to efficient articular cartilage regeneration.