Application of core-shell structured nanofibers in oral tissue regeneration / 中国组织工程研究

BACKGROUND:The combination of good biomechanical properties,controlled drug release and multi-functionality of core-shell structured nanofibers is receiving more and more attention,which also makes them promising for a wide range of applications in the field of oral tissue regeneration. OBJECTIVE:To summarize the preparation,drug loading and release mechanisms of core-shell structured nanofibers and their application in the regenerative repair of oral tissues. METHODS:A computer search of the literature collected in CNKI and PubMed from January 2000 to November 2022 was applied,and the search terms in English and Chinese were"electrospinning,core-shell structures,drug delivery systems,jaw bone regeneration,cartilage regeneration,periodontal tissue regeneration". RESULTS AND CONCLUSION:(1)There are various methods for the preparation of core-shell structured nanofibers,but the coaxial and emulsion methods of electrostatic spinning have unique advantages such as simple operation,diverse material selection and good biocompatibility.(2)Core-shell structured nanofibers can be used as bacteriostatic agents,carriers of different types of drugs,and scaffolds for cell adhesion,providing new therapeutic options for oral tissue regeneration.(3)Controlled degradation and drug release rate of core-shell structured nanofibers can better adapt to the healing process of oral tissue defect repair and achieve ideal tissue regeneration.

High tibial osteotomy promotes cartilage regeneration in the treatment of knee osteoarthritis / 中国组织工程研究

BACKGROUND:For early knee osteoarthritis in which total knee arthroplasty fails to achieve satisfactory results,high tibial osteotomy that has been found to promote regeneration of damaged cartilage and alleviate symptoms in patients is considered a classic knee-preserving procedure. OBJECTIVE:To review and discuss the effectiveness,mechanism,and application prospects of high tibial osteotomy in stimulating cartilage regeneration in knee osteoarthritis and to provide a theoretical basis for the use of high tibial osteotomy in the treatment of knee osteoarthritis. METHODS:A computerized search was conducted in PubMed,Web of Science,CNKI and WanFang databases for relevant literature published from 2013 to 2023.The search terms used were"knee osteoarthritis,high tibial osteotomy,limb alignment,chondrocytes,biomechanics,intra-articular"in both English and Chinese.Finally,75 articles were included for review. RESULTS AND CONCLUSION:High tibial osteotomy correcting the lower limb alignment has been found to be effective in alleviating symptoms and potentially delaying or preventing the need for total knee arthroplasty.This is an important aspect of orthopedic step-down treatment in knee osteoarthritis.Maintaining a normal mechanical microenvironment is crucial for the proper functioning and maintenance of chondrocyte phenotype.Abnormal mechanical signals can be converted into intracellular chemical signals through mechanosensors like primary cilia,integrins,cytoskeleton and nucleoskeleton,resulting in disruptions to the balance of matrix metabolism and regulation of inflammatory responses.Chondrocytes after abnormal stress action still have the potential to revert to a normal phenotype under appropriate stress;correction of the mechanical microenvironment by high tibial osteotomy leads to spontaneous cartilage repair and remission of synovial inflammation.The combination of high tibial osteotomy and cartilage regeneration strategy holds promising prospects for patients with early knee osteoarthritis who are not candidates for total knee arthroplasty.

Applicatoin of chitosan-based hydrogel in oral tissue engineering / 中南大学学报(医学版)

Pulpitis, periodontitis, jaw bone defect, and temporomandibular joint damage are common oral and maxillofacial diseases in clinic, but traditional treatments are unable to restore the structure and function of the injured tissues. Due to their good biocompatibility, biodegradability, antioxidant effect, anti-inflammatory activity, and broad-spectrum antimicrobial property, chitosan-based hydrogels have shown broad applicable prospects in the field of oral tissue engineering. Quaternization, carboxymethylation, and sulfonation are common chemical modification strategies to improve the physicochemical properties and biological functions of chitosan-based hydrogels, while the construction of hydrogel composite systems via carrying porous microspheres or nanoparticles can achieve local sequential delivery of diverse drugs or bioactive factors, laying a solid foundation for the well-organized regeneration of defective tissues. Chemical cross-linking is commonly employed to fabricate irreversible permanent chitosan gels, and physical cross-linking enables the formation of reversible gel networks. Representing suitable scaffold biomaterials, several chitosan-based hydrogels transplanted with stem cells, growth factors or exosomes have been used in an attempt to regenerate oral soft and hard tissues. Currently, remarkable advances have been made in promoting the regeneration of pulp-dentin complex, cementum-periodontium-alveolar bone complex, jaw bone, and cartilage. However, the clinical translation of chitosan-based hydrogels still encounters multiple challenges. In future, more in vivo clinical exploration under the conditions of oral complex microenvironments should be performed, and the combined application of chitosan-based hydrogels and a variety of bioactive factors, biomaterials, and state-of-the-art biotechnologies can be pursued in order to realize multifaceted complete regeneration of oral tissue.

Exosomes secreted by hypoxia-preconditioned BMSCs promote cartilage regeneration / 中华骨科杂志

Objective:Observing the effect of exosomes derived from hypoxic Bone marrow mesenchymal stem cells (BMSCs) on the function of chondrocytes, and exploring the role and mechanism of exosomal miR-196b-5p. Evaluating the application prospects of hypoxic BMSCs exosomes and miR-196b-5p for cartilage regeneration.Methods:Chondrocytes were cultured in the supernatant of BMSCs cultured under normoxia or hypoxia, respectively. The proliferation of chondrocytes was detected by CCK-8 assay and the expressions of Collagen type 2 (Col2), Col1, Aggrecan and SOX9 were detected by qPCR to evaluate the effect of hypoxic BMSCs paracrine on chondrocyte functions. Obtaining normoxic and hypoxic exosomes through ultracentrifugation, and testing their effects on the proliferation and anabolic-related genes of chondrocytes through CCK-8 assay and qPCR. Verifying the expression of miR-196b-5p in hypoxic exosomes based on exosomal miRNA array. Knocking out miR-196b-5p in hypoxic BMSCs, and detecting the effect of hypoxic exosomal miR-196b-5p on the functions of chondrocytes by loss-of-function assay. Predicting the downstream of miR-196b-5p through bioinformatics tools, and exploring the mechanism of hypoxic exosomal miR-196b-5p by gain-of-function assays. Hypoxic exosomes and miR-196b-5p-knockout hypoxic exosomes were loaded on silk fibroin hydrogel and subcutaneously into nude mice. After 4 weeks of culture, histological staining of saffron O, Masson and biochemical content of sGAG and collagen were performed to assess the application prospect of hypoxic exosomes and hypoxic exosomal miR-196b-5p on cartilage regeneration. Results:The results of CCK-8 assay and qPCR indicated that the supernatant of hypoxic BMSCs significantly promoted the proliferation of chondrocytes 1.20±0.07 and the expression of cartilage-related markers (Col2 2.95±0.17, Aggrecan 2.45±0.27, SOX9 2.92±0.29) compared to normoxic BMSCs (0.94±0.04, 1.89±0.09, 1.67±0.21, 1.76±0.16), the differences were statistically significant ( P<0.05). The result of CCK-8 assay showed that hypoxic exosomes (1.28±0.04) promoted the proliferation of chondrocytes compared to normoxic exosomes 1.05±0.06, the differences were statistically significant ( P<0.05). CCK-8 assay revealed that the down-regulation of miR-196b-5p in hypoxic exosomes 0.99±0.06 attenuated the proliferation of chondrocytes compared to control group 1.20±0.07, the differences were statistically significant ( P<0.05); the expression of Col2 0.56±0.04, Aggrecan 0.74±0.09, and SOX9 0.45±0.05 in chondrocytes was reduced in the miR-196b-5p knockdown group compared to the control group (1.00±0.09, 1.00±0.12, 1.00±0.07), the differences were statistically significant ( P<0.05). Co-transfection of pmirGLO-BACH1-WT reporter vector with miR-196b-5p mimics decreased the luciferase activity 0.73±0.06, the differences were statistically significant ( P<0.05). Co-transfection of pmirGLO-BACH1-MUT reporter vector with miR-196b-5p mimics showed no change in luciferase activity. BACH1 is the target of miR-196b-5p. Subcutaneous culture in nude mice showed that hypoxic exosomes significantly promoted the deposition of sGAG 383.2±21.54 and collagen 67.40±3.45, while reducing the expression of miR-196b-5p in hypoxic exosomes weakened the deposition of sGAG 258.4±19.50 and collagen 57.15±4.95, the differences were statistically significant ( P<0.05). Conclusion:Hypoxic exosomes promoted the functions of chondrocytes by inhibiting the expression of BACH1 through miR-196b-5p. Hypoxic exosomes can be applied in cartilage regeneration.

Injectable hydrogel microspheres experimental research for the treatment of osteoarthritis / 中国修复重建外科杂志

OBJECTIVE@#To prepare a novel hyaluronic acid methacrylate (HAMA) hydrogel microspheres loaded polyhedral oligomeric silsesquioxane-diclofenac sodium (POSS-DS) patricles, then investigate its physicochemical characteristics and in vitro and in vivo biological properties.@*METHODS@#Using sulfhydryl POSS (POSS-SH) as a nano-construction platform, polyethylene glycol and DS were chemically linked through the "click chemistry" method to construct functional nanoparticle POSS-DS. The composition was analyzed by nuclear magnetic resonance spectroscopy and the morphology was characterized by transmission electron microscopy. In order to achieve drug sustained release, POSS-DS was encapsulated in HAMA, and hybrid hydrogel microspheres were prepared by microfluidic technology, namely HAMA@POSS-DS. The morphology of the hybrid hydrogel microspheres was characterized by optical microscope and scanning electron microscope. The in vitro degradation and drug release efficiency were observed. Cell counting kit 8 (CCK-8) and live/dead staining were used to detect the effect on chondrocyte proliferation. Moreover, a chondrocyte inflammation model was constructed and cultured with HAMA@POSS-DS. The relevant inflammatory indicators, including collagen type Ⅱ, aggrecan (AGG), matrix metalloproteinase 13 (MMP-13), recombinant A disintegrin and metalloproteinase with thrombospondin 5 (Adamts5), and recombinant tachykinin precursor 1 (TAC1) were detected by immunofluorescence staining and real-time fluorescence quantitative PCR, with normal cultured chondrocytes and the chondrocyte inflammation model without treatment as control group and blank group respectively to further evaluate their anti-inflammatory activity. Finally, by constructing a rat model of knee osteoarthritis, the effectiveness of HAMA@POSS-DS on osteoarthritis was evaluated by X-ray film and Micro-CT examination.@*RESULTS@#The overall particle size of POSS-DS nanoparticles was uniform with a diameter of about 100 nm. HAMA@POSS-DS hydrogel microspheres were opaque spheres with a diameter of about 100 μm and a spherical porous structure. The degradation period was 9 weeks, during which the loaded POSS-DS nanoparticles were slowly released. CCK-8 and live/dead staining showed no obvious cytotoxicity at HAMA@POSS-DS, and POSS-DS released by HAMA@POSS-DS significantly promoted cell proliferation (P<0.05). In the chondrocyte anti-inflammatory experiment, the relative expression of collagen type Ⅱ mRNA in HAMA@POSS-DS group was significantly higher than that in control group and blank group (P<0.05). The relative expression level of AGG mRNA was significantly higher than that of blank group (P<0.05). The relative expressions of MMP-13, Adamts5, and TAC1 mRNA in HAMA@POSS-DS group were significantly lower than those in blank group (P<0.05). In vivo experiments showed that the joint space width decreased after operation in rats with osteoarthritis, but HAMA@POSS-DS delayed the process of joint space narrowing and significantly improved the periarticular osteophytosis (P<0.05).@*CONCLUSION@#HAMA@POSS-DS can effectively regulate the local inflammatory microenvironment and significantly promote chondrocyte proliferation, which is conducive to promoting cartilage regeneration and repair in osteoarthritis.

GPRC5B protects osteoarthritis by regulation of autophagy signaling

Osteoarthritis (OA) is one of the most common chronic diseases in the world. However, current treatment modalities mainly relieve pain and inhibit cartilage degradation, but do not promote cartilage regeneration. In this study, we show that G protein-coupled receptor class C group 5 member B (GPRC5B), an orphan G-protein-couple receptor, not only inhibits cartilage degradation, but also increases cartilage regeneration and thereby is protective against OA. We observed that Gprc5b deficient chondrocytes had an upregulation of cartilage catabolic gene expression, along with downregulation of anabolic genes in vitro. Furthermore, mice deficient in Gprc5b displayed a more severe OA phenotype in the destabilization of the medial meniscus (DMM) induced OA mouse model, with upregulation of cartilage catabolic factors and downregulation of anabolic factors, consistent with our in vitro findings. Overexpression of Gprc5b by lentiviral vectors alleviated the cartilage degeneration in DMM-induced OA mouse model by inhibiting cartilage degradation and promoting regeneration. We also assessed the molecular mechanisms downstream of Gprc5b that may mediate these observed effects and identify the role of protein kinase B (AKT)-mammalian target of rapamycin (mTOR)-autophagy signaling pathway. Thus, we demonstrate an integral role of GPRC5B in OA pathogenesis, and activation of GPRC5B has the potential in preventing the progression of OA.

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 intra-articular drug delivery systems (DDSs) in the future.

Role and application of bone morphogenetic proteins in articular cartilage regeneration / 中国组织工程研究

BACKGROUND: Articular cartilage degeneration is the main cause of osteoarthritis. Bone morphogenetic proteins play an important role in cartilage regeneration and repair. OBJECTIVE: To review the research progress of bone morphogenetic protein in the process of articular cartilage regeneration. METHODS: A computer-based online search of PubMed and Elsevier databases was performed using the keywords “bone morphogenetic proteins, BMPs, arthritis, osteoarthritis, OA, cartilage, chondrocyte” in English. A total of 272 papers were retrieved, 96 of which were included in final analysis. Another 27 papers related to concepts were also included. Therefore, 123 papers are finally included. RESULTS AND CONCLUSION: Bone morphogenetic proteins participate in many biological processes including cell proliferation, differentiation, migration, and apoptosis, and play an important role in the formation of bone and cartilage. Bone morphogenetic proteins participate in a variety of signaling pathway cascades by binding to different receptors, which can protect articular cartilage from cartilage destruction caused by inflammation and trauma. Bone morphogenetic proteins alone or in combination with other cytokines can repair cartilage defects improve degenerative lesions, and promote the differentiation and regeneration of articular chondrocytes. However, there are still some practical problems that need to be solved for the widespread use of bone morphogenetic proteins in cartilage regeneration, such as the safety of drug transporters, the lack of effective biological scaffold materials, the optimal dosage and time point of use of biological agents, and their toxic and side effects. Future research will focus on how to solve the above problems. The widespread application of bone morphogenetic proteins will open a new era for targeted treatment of cartilage damage and cartilage degenerative diseases represented by osteoarthritis.

Effect of quercetin on chondrocyte phenotype and extracellular matrix expression / 中国天然药物

Due to the poor repair ability of cartilage tissue, regenerative medicine still faces great challenges in the repair of large articular cartilage defects. Quercetin is widely applied as a traditional Chinese medicine in tissue regeneration including liver, bone and skin tissues. However, the evidence for its effects and internal mechanisms for cartilage regeneration are limited. In the present study, the effects of quercetin on chondrocyte function were systematically evaluated by CCK8 assay, PCR assay, cartilaginous matrix staining assays, immunofluorescence assay, and western blotting. The results showed that quercetin significantly up-regulated the expression of chondrogenesis genes and stimulated the secretion of GAG (glycosaminoglycan) through activating the ERK, P38 and AKT signalling pathways in a dose-dependent manner. Furthermore, in vivo experiments revealed that quercetin-loaded silk protein scaffolds dramatically stimulated the formation of new cartilage-like tissue with higher histological scores in rat femoral cartilage defects. These data suggest that quercetin can effectively stimulate chondrogenesis in vitro and in vivo, demonstrating the potential application of quercetin in the regeneration of cartilage defects.

Evaluation of cartilage regeneration by arthroscopy after high tibial osteotomy / 中国骨伤

OBJECTIVE@#To evaluate the cartilage regeneration in the knee joint by arthroscopy after high tibial osteotomy.@*METHODS@#Eleven patients were included in the study who were treated with high tibial osteotomy and underwent microscopy when the internal fixation was unloaded from September 2017 to September 2019. Among them, there were 2 males and 9 females, aged from 55 to 64 years old. The internal and external compartment pictures of the knee were taken before and after surgery of removing the internal fixation and the International Cartilage Repair Society (ICRS) grading systerm was used to evaluate the degree of cartilage damage on the medial and lateral femoralcondyles and tibial plateau. The Westrn Ontarioand Mcmaster Universities osteoarthritis index (WOMAC) and the weight bearing line (WBL) were used to evaluate the function of the knee and the alignment of the lower limb.@*RESULTS@#All 8 patients were followed up for more than 12 months, ranging from 12 to 22 months. The degenerated cartilage of the medial femoral condyle and medial tibial plateau was covered by newly regenerated cartilage. WOMAC score decreased from 102-127 to 41-52 and WBL was improved from 17%-34% to 58%-64%. All incisions healed in stageⅠ, and no complications such as internal fixation rupture and infection occurred during and after the operation.@*CONCLUSION@#High tibial osteotomy can relieve the pain of the knee and the dysfunction by adjusting lower limb alignment, and the degenerated cartilage could be regenerated in the medial femoral condyle and medial tibial plateau.

Future hot spots for cartilage repair: Laminin promotes stem cell proliferation / 中国组织工程研究

BACKGROUND: The characteristics of laminin that can promote the proliferation of stem cells have been widely concerned. OBJECTIVE: To review the interactions between laminin and many different stem cells, and provide reliable theoretical basis for chondrogenic research and application of stem cells. METHODS: Wanfang, CNKI, PubMed and Web of Science databases were searched for articles related to mechanism of laminin, changes in stem cell behaviors, and cartilage regeneration published from January 2010 to October 2019. The retrieval terms were “laminin” and “steam cells” in Chinese and English. Duplicated and poorly related articles were excluded, and finally 57 articles were included for review. RESULTS AND CONCLUSION: (1) The structural characteristics of laminin were summarized. The spatiotemporal changes of laminin during cartilage development and degradation were analyzed. At the same time, the distribution of laminin expression in natural cartilage tissue and tissue engineered cartilage tissue was compared. (2) The effects of laminin on the proliferation of various stem cells, including embryonic stem cells, induced pluripotent stem cells and adult stem cells, were described. (3) The possible hotspots on the combination of laminin and stem cells for cartilage regeneration were proposed, with the attempt of providing theoretical basis for cartilage repair and regeneration in the future.

Perspective on Intra-articular Injection Cell Therapy for Osteoarthritis Treatment

BACKGROUND: Osteoarthritis (OA), the most common arthritis, is one of the most frequently encountered orthopaedic conditions. As a small number of large joints such as knee and hip are affected in OA, OA is an ideal target for local therapy. Although corticosteroid and hyaluronic acid have been traditionally used for joints through intra-articular (IA) injection, IA injection also provides a minimally invasive route to apply cell therapy to treat OA. IA cell therapy has drawn attention because it may provide regeneration of articular cartilage in addition to palliative anti-inflammatory effects. METHODS: Current progress of IA injection therapy and the author's perspective on this issue are described narratively. RESULTS: It is too premature to have any conclusion on the eventual efficacy of IA cell therapy concerning regeneration of articular cartilage based on current data. Prospective radiological and histological data from larger numbers of patients are needed to prove cost effectiveness of IA cell therapy. CONCLUSION: Expanding research in this field will produce further evidences to provide guidance on the eventual effectiveness of IA cell therapy in the future.

Development of cartilage extracellular matrix in cartilage tissue engineering / 华西口腔医学杂志

Cartilage tissue engineering, an effective way to repair cartilage defects, requires an ideal scaffold to promote the regeneration performance of stem cells. Cartilage extracellular matrix (CECM) can imitate the living environment of cartilage cells to the greatest extent. CECM not only exhibits good biocompatibility with chondrocytes and stem cells, which can meet the basic requirements of scaffolds, but also promotes chondrocytes to secrete matrix and induce stem cells to differentiate into chondrocytes; as such, this matrix is a better scaffold and has more advantages than existing ones. The promotion and induction effects could be related to various cartilage-related proteins inside. However, the practical application of this technique is hindered by problems, such as poor mechanical properties and insufficient cell penetration of CECM. Association with other materials can compensate for these inadequacies to a certain degree, and finding a combination mode with optimized performance is the application trend of CECM. This review focuses on research of CECM materials in cartilage tissue engineering.

Promotion effect of cartilage regenerated scaffolds combined with exosomes derived from mutant type of HIF-1α modified BMSCs in repairing advanced cartilage defects / 吉林大学学报(医学版)

Objective: To explore the protective effect of exosomes secreted from bone mesenchymal stem cells (BMSCs) modified by hypoxia inducible factor-1α (HIF-1α) on the chondrocytes, and to elucidate the possible mechanism of its combination with cartilage regenerated scaffolds in promoting the repair of advanced cartilage defects. Methods: The exosomes (BMSCs-ExoWT and BMSCs-ExoMU) were extracted from the BMSCs modified by wild type of HIF-1α and mutant type of HIF-1α by ultracentrifugation method and identified in the meantime. In vitro the inflammatory response of chondrocytes were induced by interleukin-1β (IL-1β), the same amount of PBS, BMSCs-ExoWT (80 μg · ml-1), BMSCs-ExoMU (80 μg · m-1) were respectively cultivated with the chondrocytes under the inflammatory reaction and blank group, inflammation group, BMSCs-ExoWT group and BMSCs-ExoMU group were set up; Hoechst33342 staining was used to detect the number of apoptotic bodies of chondrocytes in various groups. The Western blotting method was used to detect the expression levels of AKT/p-AKT, ERK/p-ERK and p38/p-p38 in the chondrocytes in various groups. Twelve New Zealand white rabbits were randomly divided into 4 groups and the models of rabbit knee cartilage defects were consructed; the equal volume of physiological saline, scaffold + physiological saline, scaffold + BMSCs-ExoWT and scaffold + BMSCs-ExoMU were respectively injected into the cartilage defects of rabbits. Six weeks after operation, gross conference, HE and safranin O staining were used to observe and compare the repair effects of cartilage defects in each group. Results: BMSCs-ExoWT and BMSCs-ExoMU were successfully extracted and identified, and the exosomes were observed to be nearly circular with diameter of about 40-100 nm; the Western blotting results showed that they expressed special proteins CD63 and CD81, respectively. Invitro, the number of apoptotic bodies of chondrocytes in BMSCs-ExoMU group was lower than those in inflammation group and BMSCs-ExoWT group (P<0.01). The Western blotting results revealed that the expression levels of p-ERK1/2 in BMSCs-ExoMU and BMSCs-ExoWT groups were lower than that in inflammation group (P<0.05); the expression levels of p-AKT and p-p38 were higher (P<0.05); the effect in BMSCs-ExoMU group was stronger than BMSCs-ExoWT group, and the difference was statistically significant (P<0.05). In the advanced cartilage defect models of rabbit knee joint, the repair effect in scaffold + BMSCs-ExoMU group was better than those in blank group, scaffold group and scaffold + BMSCs-ExoWT group. Conclusion: Cartilage scaffold combined with BMSCs-ExoMU can promote the repair of cartilage defects.

Non-contact Coculture Reveals a Comprehensive Response of Chondrocytes Induced by Mesenchymal Stem Cells Through Trophic Secretion

Coculture between mesenchymal stem cells (MSCs) and chondrocytes has significant implications in cartilage regeneration. However, a conclusive understanding remains elusive. Previously, we reported that rabbit bone marrow-derived MSCs (rbBMSCs) could downregulate the differentiated phenotype of rabbit articular chondrocytes (rbACs) in a non-contact coculture system for the first time. In the present study, a systemic investigation was performed to understand the biological characteristics of chondrocytes in coculture with MSCs. Firstly, cells (MSCs and chondrocytes) from different origins were cocultured in transwell system. Different chondrocytes, when cocultured with different MSCs respectively, consistently demonstrated stimulated proliferation, transformed morphology and declined glycosaminoglycan secretion of chondrocytes. Next, cell surface molecules and the global gene expression of rbACs were characterized. It was found that cocultured rbACs showed a distinct surface molecule profile and global gene expression compared to both dedifferentiated rbACs and rbBMSCs. In the end, cocultured rbACs were passaged and induced to undergo the chondrogenic redifferentiation. Better growth and chondrogenesis ability were confirmed compared with control cells without coculture. Together, chondrocytes display comprehensive changes in coculture with MSCs and the cocultured rbACs are beneficial for cartilage repair.

Promotion effect of cartilage regenerated scaffolds combined with exosomes derived from mutant type of HIF-1α modified BMSCs in repairing advanced cartilage defects / 吉林大学学报(医学版)

Objective:To explore the protective effect of exosomes secreted from bone mesenchymal stem cells (BMSCs)modified by hypoxia inducible factor-1α(HIF-1α)on the chondrocytes,and to elucidate the possible mechanism of its combination with cartilage regenerated scaffolds in promoting the repair of advanced cartilage defects.Methods:The exosomes(BMSCs-ExoWTand BMSCs-ExoMU)were extracted from the BMSCs modified by wild type of HIF-1α and mutant type of HIF-1α by ultracentrifugation method and identified in the meantime.In vitro the inflammatory response of chondrocytes were induced by interleukin-1β(IL-1β),the same amount of PBS, BMSCs-ExoWT(80 μg · mL-1),BMSCs-ExoMU(80 μg · mL-1)were respectively cultivated with the chondrocytes under the inflammatory reaction and blank group,inflammation group,BMSCs-ExoWTgroup and BMSCs-ExoMUgroup were set up;Hoechst33342 staining was used to detect the number of apoptotic bodies of chondrocytes in various groups.The Western blotting method was used to detect the expression levels of AKT/p-AKT,ERK/p-ERK and p38/p-p38 in the chondrocytes in various groups.Twelve New Zealand white rabbits were randomly divided into 4 groups and the models of rabbit knee cartilage defects were consructed;the equal volume of physiological saline,scaffold +physiological saline,scaffold +BMSCs-ExoWTand scaffold +BMSCs-ExoMUwere respectively injected into the cartilage defects of rabbits.Six weeks after operation,gross conference, HE and safranin O staining were used to observe and compare the repair effects of cartilage defects in each group. Results:BMSCs-ExoWTand BMSCs-ExoMUwere successfully extracted and identified,and the exosomes were observed to be nearly circular with diameter of about 40-100 nm;the Western blotting results showed that they expressed special proteins CD63 and CD81,respectively.In vitro,the number of apoptotic bodies of chondrocytes in BMSCs-ExoMUgroup was lower than those in inflammation group and BMSCs-ExoWTgroup(P<0.01).The Western blotting results revealed that the expression levels of p-ERK1/2 in BMSCs-ExoMUand BMSCs-ExoWT groups were lower than that in inflammation group(P<0.05);the expression levels of p-AKT and p-p38 were higher(P<0.05);the effect in BMSCs-ExoMUgroup was stronger than BMSCs-ExoWTgroup,and the difference was statistically significant(P<0.05).In the advanced cartilage defect models of rabbit knee joint,the repair effect in scaffold+ BMSCs-ExoMUgroup was better than those in blank group,scaffold group and scaffold+BMSCs-ExoWTgroup.Conclusion:Cartilage scaffold combined with BMSCs-ExoMUcan promote the repair of cartilage defects.

Mechanically Reinforced Extracellular Matrix Scaffold for Application of Cartilage Tissue Engineering

Scaffolds with cartilage-like environment and suitable physical properties are critical for tissue-engineered cartilage repair. In this study, decellularized porcine cartilage-derived extracellular matrix (ECM) was utilized to fabricate ECM scaffolds. Mechanically reinforced ECM scaffolds were developed by combining salt-leaching and crosslinking for cartilage repair. The developed scaffolds were investigated with respect to their physicochemical properties and their cartilage tissue formation ability. The mechanically reinforced ECM scaffold showed similar mechanical strength to that of synthetic PLGA scaffold and expressed higher levels of cartilage-specific markers compared to those expressed by the ECM scaffold prepared by simple freeze-drying. These results demonstrated that the physical properties of ECM-derived scaffolds could be influenced by fabrication method, which provides suitable environments for the growth of chondrocytes. By extension, this study suggests a promising approach of natural biomaterials in cartilage tissue engineering.

Magnetic Resonance Imaging (MRI) of a Hypertrophy of Cartilage and Simultaneous Regeneration of a Damaged Meniscus after Autologous Bone Marrow Aspirates Concentrate (BMAC) Transplantation: a Case Report and Literature Review

Bone marrow aspirates concentrate (BMAC) transplantation is a well-known technique for cartilage regeneration with good clinical outcomes for symptoms in patients with osteoarthritis (OA). Magnetic resonance imaging (MRI) has an important role in evaluating the degree of cartilage repair in cartilage regeneration therapy instead of a second assessment via an arthroscopy. We experienced a case of hypertrophic regeneration of the cartilage and a presumed simultaneous regeneration of the posterior horn of the lateral meniscus after BMAC transplantation for a cartilage defect at the lateral tibial and femoral condyle. This report provides the details of a case of an unusual treatment response after a BMAC transplant. This report is the first of its kind to demonstrate a MR image that displays the simultaneous regeneration of the cartilage and meniscus with a differentiation ability of the mesenchymal stem cell to the desired cell lineage.

Alginate-Hyaluronic Acid-Collagen Composite Hydrogel Favorable for the Culture of Chondrocytes and Their Phenotype Maintenance

Articular cartilage has limited regeneration capacity, thus significant challenge has been made to restore the functions. The development of hydrogels that can encapsulate and multiply cells, and then effectively maintain the chondrocyte phenotype is a meaningful strategy to this cartilage repair. In this study, we prepared alginate-hyaluronic acid based hydrogel with type I collagen being incorporated, namely Alg-HA-Col composite hydrogel. The incorporation of Col enhanced the chemical interaction of molecules, and the thermal stability and dynamic mechanical properties of the resultant hydrogels. The primary chondrocytes isolated from rat cartilage were cultured within the composite hydrogel and the cell viability recorded revealed active proliferation over a period of 21 days. The mRNA levels of chondrocyte phenotypes, including SOX9, collagen type II, and aggrecan, were significantly up-regulated when the cells were cultured within the Alg-HA-Col gel than those cultured within the Alg-HA. Furthermore, the secretion of sulphated glycosaminoglycan, a cartilage-specific matrix molecule, was recorded higher in the collagen-added composite hydrogel. Although more in-depth studies are required such as the in vivo functions, the currently-prepared Alg-HA-Col composite hydrogel is considered to provide favorable 3-dimensional matrix conditions for the cultivation of chondrocytes. Moreover, the cell-cultured constructs may be useful for the cartilage repair and tissue engineering.

Research progress of platelet-rich plasma in cartilage regeneration / 国际生物医学工程杂志

Cartilage is vulnerable to traumatic injury and unable to facilitate a satisfactory healing response due to its poor vascularity and inability to access mesenchymal stem cells.Continuous defects in the joint surfaces cause pain,swelling,and mechanical symptoms that result in functional impairment and limitation of athletic participation.Commonly used repair techniques include marrow stimulation,structural osteo-articular autografts or chondrocyte implantation.Platelet-rich plasma (PRP) is a concentrate extract of platelets from autologous blood,which is rich in growth factors and other cytokines and provides local environment for tissue regeneration and lends a possible option for the stimulation and acceleration of cartilage regeneration.This review gives summarization on the current state of the use of PRP for cartilage regeneration.