Down-regulation of TGF-ß1 in Fibro-adipogenic Progenitors Initiates Muscle Ectopic Mineralization.

In previous studies, we have demonstrated that stress response-induced high glucocorticoid levels could be the underlying cause of traumatic heterotopic ossification (HO), and we have developed a glucocorticoid-induced ectopic mineralization (EM) mouse model by systemic administration of a high dose of dexamethasone (DEX) to animals with muscle injury induced by cardiotoxin injection. In this model, dystrophic calcification (DC) developed into HO in a cell autonomous manner. However, it is not clear how DC is formed after DEX treatment. Therefore, in this study, we aimed to explore how glucocorticoids initiate muscle EM at a cellular and molecular level. We showed that DEX treatment inhibited inflammatory cell infiltration into injured muscle but inflammatory cytokine production in the muscle was significantly increased, suggesting that other non-inflammatory muscle cell types may regulate the inflammatory response and the muscle repair process. Accompanying this phenotype, transforming growth factor ß1 (TGF-ß1) expression in fibro-adipogenic progenitors (FAPs) was greatly down-regulated. Since TGF-ß1 is a strong immune suppressor and FAP's regulatory role has a large impact on muscle repair, we hypothesized that down-regulation of TGF-ß1 in FAPs after DEX treatment resulted in this hyperinflammatory state and subsequent failed muscle repair and EM formation. To test our hypothesis, we utilized a transgenic mouse model to specifically knock out Tgfb1 gene in PDGFRα positive FAPs to investigate if the transgenic mice could recapitulate the phenotype that was induced by DEX treatment. Our results showed that the transgenic mice completely phenocopied this hyperinflammatory state and spontaneously developed EM following muscle injury. On the contrary, therapeutics that enhanced TGF-ß1 signaling in FAPs inhibited the inflammatory response and attenuated muscle EM. In summary, these results indicate that FAPs-derived TGF-ß1 is a key molecule in regulating muscle inflammatory response and subsequent EM, and that glucocorticoids exert their effect via down-regulating TGF-ß1 in FAPs.

Heterotopic ossification (HO) is abnormal bone formation in soft tissue. Glucocorticoids, which have strong anti-inflammatory properties, have usually been used as HO therapeutics. However, our findings suggest that glucocorticoids can also promote HO formation. In this study, we tried to explain the underlying reason for these seemingly contradictory observations. We showed that glucocorticoids, in addition to exerting an anti-inflammatory effect on inflammatory cells, can also target another type of muscle cell to exert a pro-inflammatory effect. These cells are called fibro-adipogenic progenitors (FAPs), and we demonstrated that FAPs played a master regulatory role in the muscle inflammatory response by modulating the expression of transforming growth factor ß1 (TGF-ß1), a well-known immune suppressor. In summary, our findings highlighted the importance of FAP TGF-ß1 levels in affecting the progression and regression of muscle HO, and provided new treatment options for HO based on their ability to elevate TGF-ß1 levels in FAPs.

Accuracy and patient-centered results of marker-based and marker-free registrations for dynamic computer-assisted implant surgery: A randomized controlled trial.

OBJECTIVES: To compare implant placement accuracy and patient-centered results between the dynamic computer-assisted implant surgeries (d-CAISs) using marker-based and marker-free registration methods. MATERIALS AND METHODS: A double-armed, single-blinded randomized controlled trial was conducted, in which 34 patients requiring single implant placement at the esthetic zone were randomly assigned to the marker-based (n = 17) or marker-free (n = 17) groups. The marker-based registration was performed using a splint containing radiopaque markers, while the marker-free registration used natural teeth. The primary outcome assessed implant positioning accuracy via angular and linear deviations between preoperative and postoperative implant positions in CBCT. Patients were also surveyed about the intraoperative experience and oral health impact profile (OHIP). RESULTS: The global linear deviations at the implant platform (0.82 ± 0.28 and 0.85 ± 0.41 mm) and apex (1.28 ± 0.34 and 0.85 (IQR: 0.64-1.50) mm) for the marker-based and marker-free groups respectively showed no significant difference. However, the angular deviation of the marker-free group (2.77 ± 0.92 ° ) was significantly lower than the marker-based group (4.28 ± 1.58 ° ). There was no significant difference in the mean postoperative OHIP scores between the two groups (p = .758), with scores of 2.74 ± 1.21 for marker-based and 2.93 ± 2.18 for marker-free groups, indicating mild oral health-related impairment in both. Notably, patients in the marker-free group showed significantly higher satisfaction (p = .031) with the treatment procedures. CONCLUSIONS: D-CAIS with a marker-free registration method for single implantation in the anterior maxilla has advantages in improving implant placement accuracy and patients' satisfaction, without generating a significant increase in clinical time and expenses.

Meniscal Fibrocartilage Repair Based on Developmental Characteristics: A Proof-of-Concept Study.

BACKGROUND: Unlike the adult meniscus, the fetal meniscus possesses robust healing capacity. The dense and stiff matrix of the adult meniscus provides a biophysical barrier for cell migration, which is not present in the fetal meniscus. Inspired by developmental characteristics, modifying the matrix of the adult meniscus into a fetal-like, loose and soft microenvironment holds opportunity to facilitate repair, especially in the avascular zone. HYPOTHESIS: Modifying the dense and stiff matrix of the adult meniscus into a fetal-like, loose and soft microenvironment could enhance cell migration to the tear interface and subsequent robust healing capacity. STUDY DESIGN: Controlled laboratory study. METHODS: Fresh porcine menisci were treated with hyaluronidase or collagenase. The density and arrangement of collagen fibers were assessed. The degradation of proteoglycans and collagen was evaluated histologically. Cell migration within the meniscus or the infiltration of exogenous cells into the meniscus was examined. Dendritic silica nanoparticles with relatively large pores were used to encapsulate hyaluronidase for rapid release. Mesoporous silica nanoparticles with relatively small pores were used to encapsulate transforming growth factor-beta 3 (TGF-ß3) for slow release. A total of 24 mature male rabbits were included. A longitudinal vertical tear (0.5 cm in length) was prepared in the avascular zone of the medial meniscus. The tear was repaired with suture, repaired with suture in addition to blank silica nanoparticles, or repaired with suture in addition to silica nanoparticles releasing hyaluronidase and TGF-ß3. Animals were sacrificed at 12 months postoperatively. Meniscal repair was evaluated macroscopically and histologically. RESULTS: The gaps between collagen bundles increased after hyaluronidase treatment, while collagenase treatment resulted in collagen disruption. Proteoglycans degraded after hyaluronidase treatment in a dose-dependent manner, but collagen integrity was maintained. Hyaluronidase treatment enhanced the migration and infiltration of cells within meniscal tissue. Last, the application of fibrin gel and the delivery system of silica nanoparticles encapsulating hyaluronidase and TGF-ß3 enhanced meniscal repair responses in an orthotopic longitudinal vertical tear model. CONCLUSION: The gradient release of hyaluronidase and TGF-ß3 removed biophysical barriers for cell migration, creating a fetal-like, loose and soft microenvironment, and enhanced the fibrochondrogenic phenotype of reparative cells, facilitating the synthesis of matrix and tissue integration. CLINICAL RELEVANCE: Modifying the adult matrix into a fetal-like, loose and soft microenvironment via the local gradient release of hyaluronidase and TGF-ß3 enhanced the healing capacity of the meniscus.

Accuracy and patient-centered results of static and dynamic computer-assisted implant surgery in edentulous jaws: a retrospective cohort study.

OBJECTIVES: This study aimed to compare implant positioning accuracy and patient-centered results between static and dynamic computer-assisted implant surgery (s-CAIS and d-CAIS) in edentulous jaws. MATERIAL AND METHODS: The current study retrospectively evaluated a total of 110 implants placed in 22 fully edentulous patients via s-CAIS or d-CAIS (n = 11). The accuracy of implant positioning was assessed by measuring the implant's angular deviation and deviation at the platform and apex from the preoperative design postoperatively. Patient-centered results, including preoperative and intraoperative patient-reported experiences and postoperative patient-reported outcomes, were extracted from the medical records. The nested t test and chi-square test were used to compare accuracy and patient-centered results between s-CAIS and d-CAIS postoperatively. RESULTS: The implants in the s-CAIS group showed significantly smaller angular deviation (2.32 ± 1.23°) than those in the d-CAIS group (3.87 ± 2.75°). In contrast, the platform and apical deviation were significantly larger in s-CAIS (1.56 ± 1.19 mm and 1.70 ± 1.09 mm, respectively) than d-CAIS (1.02 ± 0.45 mm and 1.00 ± 0.51 mm, respectively). Furthermore, the implants in the s-CAIS group deviated significantly (p < 0.001) more toward the coronal direction than those in the d-CAIS group. Notably, all patients in the s-CAIS group reported an obvious foreign body sensation during surgery, representing a significant difference from the d-CAIS group. CONCLUSIONS: Compared to s-CAIS, d-CAIS is a reliable technique for the placement of multiple implants in fully edentulous patients with less linear deviation and less foreign body sensation. TRIAL REGISTRATION: The retrospective study was registered on the Chinese Clinical Trial Registry on August 8th, 2022, with registration number No. ChiCTR2200062484. CLINICAL RELEVANCE: Despite the increasing use of computer- assisted implant surgery in fully edentulous patients, clinical evidence comparing implant positioning accuracy and patient-centered results between static and dynamic CAIS systems is scarce. Our study demonstrated that compared to s-CAIS, d-CAIS is a reliable technique for the placement of multiple implants in fully edentulous patients with less linear deviation.

A Systematic Review of Bone Marrow Stromal Cells and Periosteum-Derived Cells for Bone Regeneration.

Bone marrow stromal cells (BMSCs) and periosteum-derived cells (PDCs) represent promising skeletal stem cell sources to treat critical-size bone defects. However, the large number of preclinical tests with a variety of in vivo data complicates the selection of cells for further clinical translation. This systematic review aims to analyze the in vivo bone-forming efficacy of BMSCs- and PDCs-based approaches in all published preclinical experiments until November 2020. For this purpose, four databases (PubMed, Embase, Cochrane Central Register of Controlled Trial, and Web of Science) were searched for eligible literature, which yielded a total of 94 full-text articles for systematic review. This review generated an evidence-based list of BMSC- or PDC-based approaches, which have been evaluated for bone formation in different animal models. Among them, 74 studies were included for pairwise and network meta-analysis. The results revealed that both PDC and BMSC had beneficial bone-forming efficacy compared to bare scaffold. In addition, BMSC- and PDC-based approaches had no significant difference regarding in vivo bone-forming efficacy. However, BMSC-based approach had a higher probability to be ranked better than PDC-based approach. Furthermore, the review discusses (i) the possible risk of bias of the in vivo evaluation of cell-based approaches, (ii) the difficulty in replication of such experiments due to frequent poor reporting of the methods and results, and (iii) the clinical relevance of the currently utilized BMSC- and PDC-based approaches. Systematic review registration: The study was prospectively registered in PROSPERO, Registration No. CRD42021270922.

Comparison Between Treadmill and Bicycle Ergometer Exercises in Terms of Safety of Cardiopulmonary Exercise Testing in Patients With Coronary Heart Disease.

Background: Cardiopulmonary exercise testing (CPET) is used widely in the diagnosis, exercise therapy, and prognosis evaluation of patients with coronary heart disease (CHD). The current guideline for CPET does not provide any specific recommendations for cardiovascular (CV) safety on exercise stimulation mode, including bicycle ergometer, treadmill, and total body workout equipment. Objective: The aim of this study was to explore the effects of different exercise stimulation modes on the occurrence of safety events during CPET in patients with CHD. Methods: A total of 10,538 CPETs, including 5,674 performed using treadmill exercise and 4,864 performed using bicycle ergometer exercise at Peking University Third Hospital, were analyzed retrospectively. The incidences of CV events and serious adverse events during CPET were compared between the two exercise groups. Results: Cardiovascular events in enrolled patients occurred during 355 CPETs (3.4%), including 2 cases of adverse events (0.019%), both in the treadmill group. The incidences of overall events [235 (4.1%) vs. 120 (2.5%), P < 0.001], premature ventricular contractions (PVCs) [121 (2.1%) vs. 63 (1.3%), P = 0.001], angina pectoris [45 (0.8%) vs. 5 (0.1%), P < 0.001], and ventricular tachycardia (VT) [32 (0.6%) vs. 14 (0.3%), P = 0.032] were significantly higher in the treadmill group compared with the bicycle ergometer group. No significant difference was observed in the incidence of bradyarrhythmia and atrial arrhythmia between the two groups. Logistic regression analysis showed that the occurrence of overall CV events (P < 0.001), PVCs (P = 0.007), angina pectoris (P < 0.001), and VT (P = 0.008) was independently associated with the stimulation method of treadmill exercise. In male subjects, the occurrence of overall CV events, PVCs, angina pectoris, and VT were independently associated with treadmill exercise, while only the overall CV events and angina pectoris were independently associated with treadmill exercise in female subjects. Conclusion: In comparison with treadmill exercise, bicycle ergometer exercise appears to be a safer exercise stimulation mode for CPET in patients with CHD.

Prognostic value of malignant T cell-amplified sequence 1 in head and neck squamous cell carcinoma.

Aim: To explore the expression profile and prognostic value of MCTS1 in head and neck squamous cell carcinoma (HNSC). Materials & methods: This study used the data from TCGA to HNSC database, GEO database and the data and specimens collected from the patients in our hospital to conduct a comprehensive bioinformatic analysis of MCTS1 in HNSC. Results:MCTS1 was significantly upregulated. MCTS1 mRNA expression level is a potential prognostic biomarker for overall survival and recurrence-free survival. We revealed the potential interactions of MCTS1 with other molecules and potential relationship with ubiquitination, translation initiation and mRNA splicing in HNSC. Conclusion:MCTS1 was significantly upregulated in primary HNSC. The correlation of MCTS1 with poor prognosis suggested its potential as a prognostic marker for HNSC patients.

Secondary Effects of the Rupture and Reconstruction of the Interosseous Talocalcaneal Ligament on the Peritalar Joints.

BACKGROUND The interosseous talocalcaneal ligament (ITCL) is the main soft-tissue contributor to subtalar joint stability. The role of ITCL reconstruction in retaining this stability is minimally reported. Therefore, we conducted this study to investigate the effects of rupture and reconstruction of the ITCL on the subtalar and peritalar joints. MATERIAL AND METHODS This experimental study randomly divided 72 rabbits into 3 equal groups of 24 rabbits each. Group I underwent reconstruction surgery, group II underwent resection, and group III was the control group. The cartilages between the talocrural and calcaneocrural joints, and between the subtalar and talonavicular joints on both sides were assessed by gross observation, ink staining, histology, and immunohistochemistry at weeks 4, 8, 16, and 32, postoperatively. RESULTS In group II, the quantitative ink staining analysis revealed degeneration of the articular cartilages on the talonavicular joint (T=2.070, P=0.038) and the posterior subtalar joint (T=2.121, P=0.034) compared with the 2 sides of the same rabbit at 4 and 8 postoperative weeks. Comparing the operated sides of all the groups showed the posterior subtalar joints (Hc=9.563, P=0.008) and talonavicular joints (Hc=9.714, P=0.008) had an obvious difference at postoperative week 4; and in the calcaneocrural joints (Hc=6.750, P=0.034), it was noticed at postoperative week 8. Histology and immunohistochemistry findings confirm these observations. CONCLUSIONS An ITCL resection can lead to the progressive degeneration of the talonavicular and posterior subtalar joints, while an ITCL reconstruction can be beneficial in restoring the stability of these joints, preventing or postponing their degeneration, and protecting the articular cartilages.

Highly efficient wurtzite/zinc blende CdS visible light photocatalyst with high charge separation efficiency and stability.

Mixed phase TiO2 (Degussa P25) exhibits superior photocatalytic performance and stability due to the formation of the hetero-phase junction between anatase and rutile. However, the large bandgap limits its visible light activity. CdS is a photocatalyst with a broad light absorption band up to 550 nm. Constructing a hetero-phase junction will greatly promote the photocatalytic activity of CdS. In this work, the one-step solvothermal method was used to synthesize CdS hetero-phase junction with both hexagonal wurtzite (WZ) and cubic zinc blende (ZB) phases. The ratio of WZ and ZB phases can be tuned by adjusting the solvent ratio and reaction time to construct type I junction and effectively separate the photogenerated electron-hole pair. Under visible-light illumination, the optimal photocatalytic activity of the prepared material reaches 7.96 mmol h-1 g-1, and the quantum efficiency is 36.7% at 420 nm, which is three times higher than that of any single-phase sample (cubic or hexagonal phase) and maintains high photocatalytic stability as well. It is expected that this work will provide a feasible prospect for the practical application of high-efficiency homogeneous junction photocatalysts.

A digital method of measuring cartilage defects under an arthroscope.

Measurements of cartilage defect size under an arthroscope are essential for prognosis and treatment decisions. A new method called arthroscopic measurement by computer graphics (ACG) was developed to accurately calculate the size of the cartilage under an arthroscope. This study aimed to validate the accuracy and utility of this method. In this controlled laboratory study, the ACG method was validated by measuring the sizes of three cartilage defects in a knee joint of a pig, using the following techniques: traditional arthroscopic measurement by ruler (TAR), ACG, incised measurement by computer graphics (ICG), and incised measurement by ruler (IR, control, gold standard). Measurements were conducted by two blinded trained observers. Intra- and inter-observer variabilities were determined by calculating the intra-class correlation coefficient (ICC). Consistency among TAR, ACG, ICG and IR was analyzed using the command "Concord" in Stata. For arthroscopic measurements using ACG and ICG, the overall ICC intra- and inter-observer values were 0.99 and 0.98, respectively, which showed excellent reproductivity. The concord value showed consistency of various approaches relative to the gold standard method. The average concord value for TAR was 0.813, and the average concord value for ACG and ICG was 0.886 and 0.917, respectively. ACG utilizes computer graphics for measuring the size of cartilage defects of any size under an arthroscope, without reconditioning the injured cartilage. ACG showed excellent intra- and inter-observer reproducibility and satisfactory accuracy. This method would make it possible to more accurately match the graft with the defect, thereby facilitating cartilage repair.

One-step strategy for cartilage repair using acellular bone matrix scaffold based in situ tissue engineering technique in a preclinical minipig model.

Cartilage defects are most commonly seen in the knee joint. However, due to the limited self-recovery ability of cartilage, the repair of articular cartilage defects is still a great challenge despite that various approaches have been proposed. We designed a strategy to induce cartilage repair using acellular bone matrix (ABM), thereby creating an appropriate microenvironment for the in-situ cells with an easy surgical application. An in vitro system demonstrated that the ABM scaffold could promote cell adhesion, growth, proliferation, and chondrogenesis of mesenchymal stem cells. This experiment was performed in a minipig cartilage repair model. The repaired tissue was hyaline-like cartilage according to the morphological and histological results. The mechanical properties of the repaired tissue were similar to those of normal cartilage. The integration of repaired tissue and normal tissue in the ABM+M group was better than those of other two groups. The ABM-based, one-stage, minimally invasive, in situ procedure for cartilage regeneration can potentially improve the treatment of articular cartilage defects.

Effects of wine-cap Stropharia cultivation on soil nutrients and bacterial communities in forestlands of northern China.

BACKGROUND: Cultivating the wine-cap mushroom (Stropharia rugosoannulata) on forestland has become popular in China. However, the effects of wine-cap Stropharia cultivation on soil nutrients and bacterial communities are poorly understood. METHODS: We employed chemical analyses and high-throughput sequencing to determine the impact of cultivating the wine-cap Stropharia on soil nutrients and bacterial communities of forestland. RESULTS: Cultivation regimes of Stropharia on forestland resulted in consistent increases of soil organic matter (OM) and available phosphorus (AP) content. Among the cultivation regimes, the greatest soil nutrient contents were found in the one-year interval cultivation regime, and the lowest total N and alkaline hydrolysable N contents were observed in the current-year cultivation regime. No significant differences were observed in alpha diversity among all cultivation regimes. Specific soil bacterial groups, such as Acidobacteria, increased in abundance after cultivation of Stropharia rugosoannulata. DISCUSSION: Given the numerous positive effects exerted by OM on soil physical and chemical properties, and the consistent increase in OM content for all cultivation regimes, we suggest that mushroom cultivation is beneficial to forest soil nutrient conditions through increasing OM content. Based on the fact that the one-year interval cultivation regime had the highest soil nutrient content as compared with other cultivation regimes, we recommend this regime for application in farming practice. The spent mushroom compost appeared to be more influential than the hyphae of S. rugosoannulata on the soil nutrients and bacterial communities; however, this requires further study. This research provides insight into understanding the effects of mushroom cultivation on the forest soil ecosystem and suggests a relevant cultivation strategy that reduces its negative impacts.

A co-culture system of rat synovial stem cells and meniscus cells promotes cell proliferation and differentiation as compared to mono-culture.

A meniscus tear often happens during active sports. It needs to be repaired or replaced surgically to avoid further damage to the articular cartilage. To address the shortage of autologous meniscal cells, we designed a co-culture system of synovial stem cells (SMSCs) and meniscal cells (MCs) to produce a large cell number and to maintain characteristics of MCs. Different ratios of SMSCs and MCs at 3:1, 1:1, and 1:3 were tested. Mono-culture of SMSCs or MCs served as control groups. Proliferation and differentiation abilities were compared. The expression of extracellular matrix (ECM) genes in MCs was assessed using an ECM array to reveal the mechanism at the gene level. The co-culture system of SMSCs/MCs at the ratio of 1:3 showed better results than the control groups or those at other ratios. This co-culture system may be a promising strategy for meniscus repair with tissue engineering.

The potential of using semitendinosus tendon as autograft in rabbit meniscus reconstruction.

Since transplantation of meniscal allograft or artificial menisci is limited by graft sources and a series of adverse events, substitution for meniscus reconstruction still needs to be explored. Natural biomaterials, which can provide a unique 3-D microenvironment, remain a promising alternative for tissue engineering. Among them, autograft is a preferred option for its safety and excellent biocompatibility. In this study, we utilized semitendinosus tendon autograft in meniscus reconstruction to investigate its fibrochondrogenic metaplasticity potential and chondroprotective effect. Tendon-derived stem cells (TDSCs) and synovial-derived mesenchymal stem cells (SMSCs), two most important stem cell sources in our strategy, exhibited excellent viability, distribution, proliferation and fibrochondrogenic differentiation ability in decellularized semitendinosus tendon (DST) scaffolds in vitro. Histologic evaluation of the tendon grafts in vivo suggested endogenous stem cells differentiated into fibrochondrocytes, synthesized proteoglycan, type II collagen and radial type I collagen at 12 weeks and 24 weeks post-surgery. As for elastic modulus and hardness of the grafts, there were no significant differences between native meniscus and regenerated meniscus at 24 weeks. The protection of condylar cartilage from degeneration was significantly better in the reconstruction group comparing to control group. Overall, semitendinosus tendon autograft seems to be a promising substitution in meniscus reconstruction.

A composite scaffold of MSC affinity peptide-modified demineralized bone matrix particles and chitosan hydrogel for cartilage regeneration.

Articular cartilage injury is still a significant challenge because of the poor intrinsic healing potential of cartilage. Stem cell-based tissue engineering is a promising technique for cartilage repair. As cartilage defects are usually irregular in clinical settings, scaffolds with moldability that can fill any shape of cartilage defects and closely integrate with the host cartilage are desirable. In this study, we constructed a composite scaffold combining mesenchymal stem cells (MSCs) E7 affinity peptide-modified demineralized bone matrix (DBM) particles and chitosan (CS) hydrogel for cartilage engineering. This solid-supported composite scaffold exhibited appropriate porosity, which provided a 3D microenvironment that supports cell adhesion and proliferation. Cell proliferation and DNA content analysis indicated that the DBM-E7/CS scaffold promoted better rat bone marrow-derived MSCs (BMMSCs) survival than the CS or DBM/CS groups. Meanwhile, the DBM-E7/CS scaffold increased matrix production and improved chondrogenic differentiation ability of BMMSCs in vitro. Furthermore, after implantation in vivo for four weeks, compared to those in control groups, the regenerated issue in the DBM-E7/CS group exhibited translucent and superior cartilage-like structures, as indicated by gross observation, histological examination, and assessment of matrix staining. Overall, the functional composite scaffold of DBM-E7/CS is a promising option for repairing irregularly shaped cartilage defects.

Different tenogenic differentiation capacities of different mesenchymal stem cells in the presence of BMP-12.

BACKGROUND: Mesenchymal stem cells (MSCs) are regarded as a promising cell-based therapeutic tool for tendon repair. This study aimed to compare the different tenogenic differentiation capacities of the three types of MSCs in the presence of bone morphogenic protein 12 (BMP-12). METHODS: MSCs were isolated from rat bone marrow (BM), inguinal adipose tissue (AD), and synovium (SM) from the knee joint. MSCs were characterized by morphology, proliferation, trilineage differentiation, and surface marker analysis. Tenogenic differentiation potential was initially assessed using real-time polymerase chain reaction, Western blot, and enzyme-linked immunosorbent assay in vitro. Histological assessments were also performed after subcutaneous implantation of BMP-12 recombinant adenovirus-infected MSCs in nude mice in vivo. RESULTS: The three types of MSCs exhibited similar fibroblast-like morphology and surface markers but different differentiation potentials toward adipogenic, osteogenic, and chondrogenic lineage fates. Bone marrow-derived MSCs (BM-MSCs) showed the most superior in vitro tenogenic differentiation capacity, followed by synovial membrane-derived MSCs (SM-MSCs) and then adipose-derived MSCs (AD-MSCs). After implantation, all three types of MSC masses infected with BMP-12 recombinant adenovirus emerged in the form of fiber-like matrix, especially in 6-week specimens, compared with the control MSCs in vivo. BM-MSCs and SM-MSCs revealed more intense staining for collagen type I (Col I) compared with AD-MSCs. Differences were not observed between BM-MSCs and SM-MSCs. However, SM-MSCs demonstrated higher proliferation capacity than BM-MSCs. CONCLUSION: BM-MSCs exhibited the most superior tenogenic differentiation capacity, followed by SM-MSCs. By contrast, AD-MSCs demonstrated the inferior capacity among the three types of MSCs in the presence of BMP-12 both in vivo and in vitro.

Dextran-coated fluorapatite crystals doped with Yb3+/Ho3+ for labeling and tracking chondrogenic differentiation of bone marrow mesenchymal stem cells in vitro and in vivo.

Upconversion fluorescent nanoparticles are becoming more widely used as imaging contrast agents, owing to their high resolution and penetration depth, and avoidance of tissue auto-fluorescence and photodamage to cells. Here, we synthesized upconversion fluorescent crystals from rare-earth Yb3+ and Ho3+ co-doped fluorapatite (FA:Yb3+/Ho3+) suitable for long-term tracking and monitoring cartilage development (chondrogenesis) in bone marrow mesenchymal stem cells (BMSCs) in vitro and in vivo. We initially determined the structure, morphology and luminescence of the products using X-ray powder diffraction, transmission electron microscopy and two-photon confocal microscopy. When excited at 980 nm, FA:Yb3+/Ho3+ crystals exhibited distinct upconversion fluorescence peaks at 543 nm and 654 nm. We then conjugated FA:Yb3+/Ho3+ crystals with dextran to enhance hydrophilicity, biocompatibility and cell penetration. Next, we employed the dextran-coated FA:Yb3+/Ho3+ crystals in labeling and tracking chondrogenic differentiation processes in BMSCs stably expressing green fluorescent protein (BMSCsGFP) in vitro and in vivo. Labeled BMSCsGFP were shown to reproducibly exhibit chondrogenic differentiation potential in RT-PCR analysis, histological assessment and immunohistochemistry. We observed continuous luminescence from the FA:Yb3+/Ho3+ upconversion crystals at 4 weeks and 12 weeks post transplantation in BMSCsGFP, while GFP fluorescence in both control and crystal-treated groups significantly decreased at 12 weeks after BMSCsGFP transplantation. We therefore demonstrate the high biocompatibility and stability of FA:Yb3+/Ho3+ crystals in tracking and monitoring BMSCs chondrogenesis in vitro and in vivo, highlighting their excellent cell labeling potential in cartilage tissue engineering.

A functional biphasic biomaterial homing mesenchymal stem cells for in vivo cartilage regeneration.

Cartilage regeneration after trauma is still a great challenge for clinicians and researchers due to many reasons, such as joint load-bearing, synovial movement and the paucity of endogenous repair cells. To overcome these limitations, we constructed a functional biomaterial using a biphasic scaffold platform and a bone-derived mesenchymal stem cells (BMSCs)-specific affinity peptide. The biphasic scaffold platform retains more cells homogeneously within the sol-gel transition of chitosan and provides sufficient solid matrix strength. This biphasic scaffold platform is functionalized with an affinity peptide targeting a cell source of interest, BMSCs. The presence of conjugated peptide gives this system a biological functionality towards BMSC-specific homing both in vitro and in vivo. The functional biomaterial can stimulate stem cell proliferation and chondrogenic differentiation during in vitro culture. Six months after in vivo implantation, compared with routine surgery or control scaffolds, the functional biomaterials induced superior cartilage repair without complications, as indicated by histological observations, magnetic resonance imaging and biomechanical properties. Beyond cartilage repair, this functional biphasic scaffold may provide a biomaterial framework for one-step tissue engineering strategy by homing endogenous cells to stimulate tissue regeneration.

The effects of co-delivery of BMSC-affinity peptide and rhTGF-ß1 from coaxial electrospun scaffolds on chondrogenic differentiation.

Electrospinning is a promising technology for the fabrication of scaffolds in cartilage tissue engineering. Two other important elements for tissue engineering are seed cells and bioactive factors. Bone marrow-derived stem cells (BMSCs) and rhTGF-ß1 are extensively studied for cartilage regeneration. However, little is known about scaffolds that can both specifically enrich BMSCs and release rhTGF-ß1 to promote chondrogenic differentiation of the incorporated BMSCs. In this study, we first fabricated coaxial electrospun fibers using a polyvinyl pyrrolidone/bovine serum albumin/rhTGF-ß1 composite solution as the core fluid and poly(ε-caprolactone) solution as the sheath fluid. Structural analysis revealed that scaffold fibers were relatively uniform with a diameter of 674.4 ± 159.6 nm; the core-shell structure of coaxial fibers was homogeneous and proteins were evenly distributed in the core. Subsequently, the BMSC-specific affinity peptide E7 was conjugated to the coaxial electrospun fibers to develop a co-delivery system of rhTGF-ß1 and E7. The results of (1)H nuclear magnetic resonance indicate that the conjugation between the E7 and scaffolds was covalent. The rhTGF-ß1 incorporated in E7-modified scaffolds could maintain sustained release and bioactivity. Cell adhesion, spreading, and DNA content analyses indicate that the E7 promoted BMSC initial adhesion, and that the scaffolds containing both E7 and rhTGF-ß1 (CBrhTE) were the most favorable for BMSC survival. Meanwhile, CBrhTE scaffolds could promote the chondrogenic differentiation ability of BMSCs. Overall, the CBrhTE scaffold could synchronously improve all three of the basic components required for cartilage tissue engineering in vitro, which paves the road for designing and building more efficient tissue scaffolds for cartilage repair.

Directing chondrogenic differentiation of mesenchymal stem cells with a solid-supported chitosan thermogel for cartilage tissue engineering.

Hydrogels are attractive for cartilage tissue engineering because of their high plasticity and similarity with the native cartilage matrix. However, one critical drawback of hydrogels for osteochondral repair is their inadequate mechanical strength. To address this limitation, we constructed a solid-supported thermogel comprising a chitosan hydrogel system and demineralized bone matrix. Scanning electron microscopy, the equilibrium scanning ratio, the biodegradation rate, biomechanical tests, biochemical assays, metabolic activity tests, immunostaining and cartilage-specific gene expression analysis were used to evaluate the solid-supported thermogel. Compared with pure hydrogel or demineralized matrix, the hybrid biomaterial showed superior porosity, equilibrium swelling and degradation rate. The hybrid scaffolds exhibited an increased mechanical strength: 75% and 30% higher compared with pure hydrogels and demineralized matrix, respectively. After three days culture, bone-derived mesenchymal stem cells (BMSCs) maintained viability above 90% in all three materials; however, the cell retention of the hybrid scaffolds was more efficient and uniform than the other materials. Matrix production and chondrogenic differentiation of BMSCs in the hybrid scaffolds were superior to its precursors, based on glycosaminoglycan quantification and hyaline cartilage marker expression after three weeks in culture. Its easy preparation, favourable biophysical properties and chondrogenic capacity indicated that this solid-supported thermogel could be an attractive biomaterial framework for cartilage tissue engineering.