Effects of mesenchymal stem cells on solid tumor metastasis in experimental cancer models: a systematic review and meta-analysis.

BACKGROUND: It has been reported mesenchymal stem cells (MSCs) are recruited to and become integral parts of the tumor microenvironment. MSCs might have an active role in solid tumor progression, especially cancer metastasis. However, the contribution of MSCs in the process of cancer metastasis is still controversial. In this review, we performed a meta-analysis on the effects of MSCs administration on cancer metastasis based on published preclinical studies. METHODS: The PRISMA guidelines were used. A total of 42 publications met the inclusion criteria. Outcome data on the incidence and the number of cancer metastasis as well as study characteristics were extracted. Quality of the studies was assessed according to SYRCLE Risk of Bias tool. Random-effects meta-analysis was used to pool estimates. RESULTS: Of the 42 studies included, 32 reported that MSCs administration promoted outcome events (numbers or incidences of cancer metastasis), and 39 reported data suitable for meta-analysis. The median effect size (RR) was 2.04 for the incidence of cancer metastasis (95% CI 1.57-2.65, I2 = 21%), and the median effect size (SMD) was 1.23 for the number of cancer metastasis (95% CI 0.43-2.03, I2 = 89%). Heterogeneity was observed, with the greater impact based on study length and different ways of metastasis measurement and MSCs administration. CONCLUSION: Our results suggested MSCs administration increased the number and the incidence of cancer metastasis in experimental cancer models. High heterogeneity and poor reported risk of bias limit the quality of these findings. Further preclinical studies with better design and adequate reporting are still needed.

Rifampin suppresses osteoclastogenesis and titanium particle-induced osteolysis via modulating RANKL signaling pathways.

Wear particles liberated from the surface of prostheses are considered to be main reason for osteoclast bone resorption and that extensive osteoclastogenesis leads to peri-implant osteolysis and subsequent prosthetic loosening. The aim of this study was to assess the effect of rifampin on osteoclastogenesis and titanium (Ti) particle-induced osteolysis. The Ti particle-induced osteolysis mouse calvarial model and bone marrow-derived macrophages (BMMs) were used. Rifampin, at dose of 10 or 50 mg/kg/day, was respectively given intraperitoneally for 14 days in vivo. The calvariae were removed and processed for Further histological analysis. In vitro, osteoclasts were generated from mouse BMMs with receptor activator of nuclear factor-κB ligand (RANKL) and the macrophage colony stimulating factor. Rifampin at different concentrations was added to the medium. The cell viability, tartrate-resistant acid phosphatase (TRAP) staining, TRAP activity and resorption on bone slices were analysis. Osteoclast-specific genes and RANKL-induced MAPKs signaling were tested for further study of the mechanism. Rifampin inhibited Ti-induced osteolysis and osteoclastogenesis in vivo. In vitro data indicated that rifampin suppressed osteoclast differentiation and bone resorption in a dose-dependent manner. Moreover, rifampin significantly reduced the expression of osteoclast-specific markers, including TRAP, cathepsin K, V-ATPase d2, V-ATPase a3, c-Fos, and nuclear factor of activated T cells (NFAT) c1. Further investigation revealed that rifampin inhibited osteoclast formation by specifically abrogating RANKL-induced p38 and NF-κB signaling. Rifampin had significant potential for the treatment of particle-induced peri-implant osteolysis and other diseases caused by excessive osteoclast formation and function.

Identifying Patients Who Will Most Benefit from Single Photon Emission Computerized Tomography and Computerized Tomography After Femoral Neck Fracture.

BACKGROUND Single photon emission computerized tomography and computerized tomography (SPECT/CT) is useful for assessing blood supply within the femoral head after femoral neck fracture, but its use in all femoral neck fracture patients is not feasible. Therefore, the present study aimed to identify the patients for whom SPECT/CT examination will be most beneficial. MATERIAL AND METHODS Sixty-five patients with a unilateral femoral neck fracture who underwent SPECT/CT examination of the hip and were treated via closed reduction and internal fixation with three screws were enrolled between January 2009 and March 2011. A decision tree model (C 5.0) was used to identify the factors that best reflect blood supply and to build a flowchart for identifying patients who would benefit from SPECT/CT. RESULTS Fracture type was most strongly associated with the Fracture/Normal (F/N) ratio, which reflects the blood supply to the fractured femoral head. Age and the time interval from injury to examination were also associated with the F/N ratio. SPECT/CT examination is most beneficial for patients with a displaced fracture, especially if they are over 58 years old and the time interval from injury to examination is less than 10 days. CONCLUSIONS Our results indicate that elderly people with a displaced fracture are most likely to benefit from SPECT/CT examination, which can show the blood supply to the femoral head within a relatively short window of time after the injury.

Parathyroid Hormone (PTH) Induces Autophagy to Protect Osteocyte Cell Survival from Dexamethasone Damage.

BACKGROUND Glucocorticoids (GC) have direct adverse effects on osteocytes, the most abundant bone cell type, and play an important role in osteonecrosis of the femoral head (ONFH). Teriparatide has been reported to be an effective treatment for ONFH. However, the underlying mechanism is unclear. MATERIAL AND METHODS An osteocyte cell line, MLO-Y4, was used under various doses of dexamethasone (Dex) with or without rhPTH (1-34). Cell viability, autophagy, and apoptosis markers and osteocyte characteristic mRNAs were investigated to better understand this phenomenon. RESULTS Induction of apoptosis by Dex was increased in a time- and dose-dependent manner in MLO-Y4 cells. Autophagy markers (LC3-II and Beclin-1) were increased at the low dose of Dex (10^-7 or 10^-6 M) and decreased at the high dose (10^-5 M). In MOL-Y4 cells, rhPTH (1-34) was shown to be protective against Dex-induced apoptosis. The upregulation of LC3-II and Beclin-1 and decreased level of Caspase-3 was observed in the rhPTH (1-34)-treated group compared with the Dex-only-treated group. Furthermore, the changes induced by Dex in osteocytes, such as increased SOST, RANKL, and DMP-1 mRNA level and decreased Destrin mRNA level, were reversed by rhPTH (1-34). A similar result was found in osteocyte-specific proteins sclerostin expression encoded by SOST mRNA, which acted as a bone formation inhibitor. CONCLUSIONS The self-activation of autophagy may be a protective mechanism against apoptosis induced by Dex. The protection effect of rhPTH (1-34) for GC-induced ONFH thus results, at least in part, from enhanced autophagy.

CD105 promotes chondrogenesis of synovium-derived mesenchymal stem cells through Smad2 signaling.

Mesenchymal stem cells (MSCs) are considered to be suitable for cell-based tissue regeneration. Expressions of different cell surface markers confer distinct differentiation potential to different sub-populations of MSCs. Understanding the effect of cell surface markers on MSC differentiation is essential to their targeted application in different tissues. Although CD105 positive MSCs possess strong chondrogenic capacity, the underlying mechanisms are not clear. In this study, we observed a considerable heterogeneity with respect to CD105 expression among MSCs isolated from synovium. The CD105(+) and CD105(-) synovium-derived MSCs (SMSCs) were sorted to compare their differentiation capacities and relative gene expressions. CD105(+) subpopulation had higher gene expressions of AGG, COL II and Sox9, and showed a stronger affinity for Alcian blue and immunofluorescent staining for aggrecan and collagenase II, as compared to those in CD105(-) cells. However, no significant difference was observed with respect to gene expressions of ALP, Runx2, LPL and PPARγ. CD105(+) SMSCs showed increased levels of Smad2 phosphorylation, while total Smad2 levels were similar between the two groups. There was no difference in activation of Smad1/5. These results were further confirmed by CD105-knockdown in SMSCs. Our findings suggest a stronger chondrogenic potential of CD105(+) SMSCs in comparison to that of CD105(-) SMSCs and that CD105 enhances chondrogenesis of SMSCs by regulating TGF-ß/Smad2 signaling pathway, but not Smad1/5. Our study provides a better understanding of CD105 with respect to chondrogenic differentiation.

Biodegradable composite scaffolds of bioactive glass/chitosan/carboxymethyl cellulose for hemostatic and bone regeneration.

Hemostasis in orthopedic osteotomy or bone cutting requires different methods and materials. The bleeding of bone marrow can be mostly stopped by bone wax. However, the wax cannot be absorbed, which leads to artificial prosthesis loosening, foreign matter reaction, and infection. Here, a bioactive glass/chitosan/carboxymethyl cellulose (BG/CS/CMC) composite scaffold was designed to replace traditional wax. WST-1 assay indicated the BG/CS/CMC composite resulted in excellent biocompatibility with no cytotoxicity. In vivo osteogenesis assessment revealed that the BG/CS/CMC composite played a dominant role in bone regeneration and hemostasis. The BG/CS/CMC composite had the same hemostasis effect as bone wax; in addition its biodegradation also led to the functional reconstruction of bone defects. Thus, BG/CS/CMC scaffolds can serve as a potential material for bone repair and hemostasis in critical-sized bone defects.

One-stage freehand minimally invasive pedicle screw fixation combined with mini-access surgery through OLIF approach for the treatment of lumbar tuberculosis.

OBJECTIVE: To compare one-stage freehand minimally invasive pedicle screw fixation (freehand MIPS) combined with mini-access surgery through OLIF approach with posterior approach for treatment of lumbar tuberculosis (TB), and evaluate its feasibility, efficacy and safety in debridement, bone graft fusion and internal fixation. METHODS: 48 patients with single segment lumbar TB from June 2014 to June 2017 were included. Among them, 22 patients underwent one-stage freehand MIPS combined with mini-access surgery through OLIF approach (group 1), 26 patients were treated with posterior open surgery (group 2). Duration of operation, blood loss, and stay time in hospital were compared. Pre- and postoperative visual analog scale (VAS) pain scores, Oswestry disability index (ODI), erythrocyte sedimentation rate, complications and images were also recorded. RESULTS: Patients in group 1 showed significantly less blood loss (165 ± 73 ml vs 873 ± 318 ml, P < 0.001), shorter stay time in hospital (6/4-8 days vs 12/8-15 days, P < 0.001), while longer duration of operation (185 ± 14 min vs 171 ± 12 min, P < 0.001) than group 2 did. VAS scores significantly decreased after surgery in both groups, however, VAS scores of group 1 were significantly lower than that of group 2 immediately after surgery and during follow-ups (P < 0.001). ODI of group 1 was also significantly lower than that of group 2 at 12-month after surgery (P < 0.001). CONCLUSION: One-stage freehand MIPS combined with mini-access surgery through OLIF approach is a feasible, efficient and safe method in treating single segment lumbar TB. It shows advantages of less surgical trauma and faster postoperative recovery.

Percutaneous transforaminal endoscopic surgery combined with mini-incision OLIF and anterolateral screws rod fixation vs. MIS-TLIF for surgical treatment of single-level lumbar spondylolisthesis.

Objective: Oblique lumbar interbody fusion (OLIF) has been used to treat lumbar spine spondylolisthesis. However, it usually needs posterior pedicle screws fixation for biomechanical stability and possible posterior direct decompression for relieving neurologic symptoms. We use percutaneous transforaminal endoscopic surgery (PTES) combined with mini-incision OLIF and anterolateral screws rod fixation for surgical treatment of lumbar spondylolisthesis. The purpose of study is to evaluate the feasibility, efficacy, and safety of this method compared with minimally invasive surgery-transforaminal lumbar interbody fusion (MIS-TLIF). Methods: From July 2016 to May 2018, 65 patients of lumbar spondylolisthesis (L2-4) with neurologic symptoms were treated using PTES combined with mini-incision OLIF and anterolateral screws rod fixation (31 cases, group A) or MIS-TLIF (34 cases, group B) in this study. Operative duration, blood loss, incision length, fluoroscopy frequency, and hospital stay are compared. Preoperative and postoperative visual analog scale (VAS) pain scores of back and legs, Oswestry disability index (ODI), intervertebral space height, lumbar lordotic angle, operative segmental lordotic angle, and complications are recorded. The fusion status is assessed according to Bridwell's fusion grades. Results: The VAS score of back and leg pain and ODI significantly dropped after surgery in both groups (p < 0.001). There was no statistical difference of back and leg VAS score and ODI between two groups except that back VAS scores in group A were significantly lower than that of group B immediately after surgery (p = 0.000). Group A had significantly more intervertebral space height and operative segmental lordotic angle than group B postoperatively (p = 0.022, p = 0.002). Twenty-three segments (74.2%) were grade I and 8 segments (25.8%) were grade II in group A; 20 segments (58.8%) were grade I and 14 segments (41.2%) were grade II in group B at a 2-year follow-up (p = 0.194). No difference was observed in the complication rate between the two groups (6.5% vs. 5.9%, p = 0.924). Conclusion: The long-term clinical efficacy and complication rates of both groups are comparable. PTES combined with mini-incision OLIF and anterolateral screws rod fixation is a good choice of minimally invasive surgery for lumbar spondylolisthesis, which hardly destroys the paraspinal muscles and bone structures.

Freehand Minimally Invasive Pedicle Screw Fixation and Minimally Invasive Decompression for a Thoracic or Lumbar Vertebral Metastatic Tumor From Hepatocellular Carcinoma.

Objective: To compare freehand minimally invasive pedicle screw fixation (freehand MIPS) combined with percutaneous vertebroplasty (PVP), minimally invasive decompression, and partial tumor resection with open surgery for treatment of thoracic or lumbar vertebral metastasis of hepatocellular carcinoma (HCC) with symptoms of neurologic compression, and evaluate its feasibility, efficacy, and safety. Methods: Forty-seven patients with 1-level HCC metastatic thoracolumbar tumor and neurologic symptoms were included between February 2015 and April 2017. Among them, 21 patients underwent freehand MIPS combined with PVP, minimally invasive decompression, and partial tumor resection (group 1), while 26 patients were treated with open surgery (group 2). Duration of operation, blood loss, times of fluoroscopy, incision length, and stay in hospital were compared between the two groups. Pre- and postoperative visual analog scale (VAS) pain score, Oswestry Disability Index (ODI), American Spinal Injury Association (ASIA) grade, ambulatory status, and urinary continence were also recorded. The Cobb angle and central and anterior vertebral body height were measured on lateral radiographs before surgery and during follow-ups. Results: Patients in group 1 showed significantly less blood loss (195.5 ± 169.1 ml vs. 873.1 ± 317.9 ml, P = 0.000), shorter incision length (3.4 ± 0.3 vs. 13.6 ± 1.8 cm, P = 0.000), shorter median stay in hospital (4-8/6 vs. 8-17/12 days, P = 0.000), more median times of fluoroscopy (5-11/6 vs. 4-7/5 times, P = 0.000), and longer duration of operation (204.8 ± 12.1 vs. 171.0 ± 12.0 min, P = 0.000) than group 2. Though VAS significantly decreased after surgery in both groups, VAS of group 1 was significantly lower than that of group 2 immediately after surgery and during follow-ups (P < 0.05). Similar results were found in ODI. No differences in the neurological improvement and spinal stability were observed between the two groups. Conclusion: Freehand MIPS combined with PVP, minimally invasive decompression, and partial tumor resection is a safe, effective, and minimally invasive method for treating thoracolumbar metastatic tumors of HCC, with less blood loss, better pain relief, and shorter length of midline incision and stay in hospital.

Development of a Prognostic Scoring System for Hepatocellular Carcinoma Patients With Main Portal Vein Tumor Thrombus Undergoing Conventional Transarterial Chemoembolization: An Analysis of 173 Patients.

BACKGROUND: Patients with hepatocellular carcinoma (HCC) with main portal vein tumor thrombus (mPVTT) have poor prognosis. Promising systemic therapies, such as target therapies, have limited benefits. The purpose of this study is to retrospectively evaluate the benefits of conventional TACE (c-TACE) and to establish a prognostic stratification of HCC patients with mPVTT. METHODS: This is a single center retrospective study conducted over 5 years (duration of performing c-TACE), on consecutive HCC patients with mPVTT receiving c-TACE. Univariable and multivariable analysis were used to explore factors independently associated with overall survival (OS). Based on Cox-regression analysis, prognostic models were developed and internally validated by bootstrap methods. Discrimination and performance were measured by Akaike information criterion, concordance index, and likelihood ratio test. RESULTS: A total of 173 patients were included. Median OS was 6.0 months (95%CI: 3.92~8.08). The independent variables correlated with survival were largest tumor diameter, tumor number, mPVTT extension, and AFP. In the final model, patients were assigned 2 points if largest tumor diameter ≥8 cm, or tumor number ≥2, 1point if main trunk was complete obstructed, or AFP ≥400 ng/ml. By summing up these points, patients were divided into three risk groups according to the score at the 15rd and 85th percentiles, in which median OS were 18, 7, and 3.5months, respectively (p<0.001). The model shown optimal discrimination, performance, and calibration. CONCLUSIONS: c-TACE could provide survival benefits in HCC patients with mPVTT and the proposed prognostic stratification may help to identify good candidates for the treatment, and those for whom c-TACE may be futile.

Injectable double-crosslinked hydrogels with kartogenin-conjugated polyurethane nano-particles and transforming growth factor ß3 for in-situ cartilage regeneration.

Articular cartilage has a limited ability for self-repair after injury. Implantation of scaffolds functionalized with bioactive molecules that could induce the migration and chondrogenesis of endogenous mesenchymal stem cells (MSCs) provides a convenient alternative for in-situ cartilage regeneration. In this study, we found the synergistic effects of kartogenin (KGN) and transforming growth factor ß3 (TGF-ß3) on chondrogenesis of MSCs in vitro, indicating that KGN and TGF-ß3 are a good match for cartilage regeneration. Furthermore, we confirmed that KGN promoted the chondrogenesis of MSCs through attenuating the degradation of Runx1, which physically interacted with p-Smad3 in nuclei of MSCs. Meanwhile, we designed an injectable double-crosslinked hydrogel with superior mechanical property and longer support for cartilage regeneration by modifying sodium alginate and gelatin. When loaded with KGN conjugated polyurethane nanoparticles (PN-KGN) and TGF-ß3, this hydrogel showed biological functions by the release of KGN and TGF-ß3, which promoted the MSC migration and cartilage regeneration in one system. In conclusion, the cell-free hydrogel, along with PN-KGN and TGF-ß3, provides a promising strategy for cartilage repair by attracting endogenous MSCs and inducing chondrogenesis of recruited cells in a single-step procedure.

Serum Biomarkers Related to Glucocorticoid-Induced Osteonecrosis of the Femoral Head: A Prospective Nested Case-Control Study.

Early diagnosis and prevention of glucocorticoid (GC)-induced osteonecrosis of the femoral head (ONFH) continues to be a challenging problem for clinicians and researchers. However, the role of circulating biomarkers for GC-induced ONFH, which may reveal individual susceptibility and facilitate earlier diagnosis, remains to be determined. The aim of this study was to identify potential biomarkers that may predict early GC-induced ONFH. A total of 123 patients scheduled for initial systemic GC therapy were enrolled in this prospective nested case-control study. The serum concentrations of 13 potential biomarkers were measured in seven patients with GC-induced ONFH, diagnosed instantly after short-term use of GCs and in 20 controls who did not develop osteonecrosis despite similar GC therapy. Biomarkers were measured both before and after taking GCs to identify any differences in marker levels and the changes during GC therapy between two groups. Type I collagen cross-linked C-telopeptide (ß-CTX; p = 0.000) was significantly lower, high-density lipoprotein cholesterol (p = 0.092) and apolipoprotein (apo)-B/apo-A1 (p = 0.085) tended to be lower and higher, respectively, before GC treatment in osteonecrosis group. After GC therapy, ß-CTX (p = 0.014) was significantly lower and amino terminal telopeptide of procollagen type I (PINP; p = 0.068) tended to be lower in the osteonecrosis group. As secondary outcomes, we observed remarkable changes in nine potential biomarkers following short-term GC therapy in both groups. In conclusion, we found that ß-CTX, could potentially be used to predict GC-induced ONFH before GC therapy. Lower ß-CTX and PINP are promising biomarkers for the early diagnosis of GC-induced ONFH. These findings need to be confirmed in large-scale prospective studies. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2348-2357, 2019.

Correction: The treatment of femoral neck fracture using VEGF-loaded nanographene coated internal fixation screws.

[This corrects the article DOI: 10.1371/journal.pone.0187447.].

Intra-articular injection of kartogenin-conjugated polyurethane nanoparticles attenuates the progression of osteoarthritis.

Osteoarthritis (OA) is the most common form of joint disease and a leading cause of physical disability, there is an urgent need to attenuate the progression of OA. Intra-articular (IA) injection is an effective treatment for joints diseases, however, the therapeutic effects mostly depend on the efficacy of drug duration in joints. Drug delivery system can provide drug-controlled release and reduce the number of IA injection. In this study, amphiphilic polyurethanes with pendant amino group were synthesized and amide bonds were formed between the amine group of polyurethane and the carboxyl group of kartogenin (KGN), a small molecular reported to show both regenerative and protective effects on cartilage. Our results showed that KGN-conjugated polyurethane nanoparticles (PN-KGN) were spherical and regular in shape with an average size of 25 nm and could sustained and controlled release of KGN in vitro. PN-KGN showed no cytotoxicity and pro-inflammatory effects on chondrocytes. The therapeutic effects in OA model showed that IA injection of KGN could attenuate the progress of OA, however, the cartilage degeneration became obviously at 12 weeks with matrix loss and vertical fissures. By contrast, IA injection of PN-KGN showed less cartilage degeneration with significant lower OARSI scores even at 12 weeks, indicating PN-KGN could further arrest the development of OA. Immunohistochemistry also validated that IA injection of PN-KGN retained the normal compositions of cartilage matrix, with much stronger Col II staining and less Col I staining. In conclusion, IA injection of PN-KGN is a better potential strategy to treat OA, with long-time cartilage protection and less IA injections.

The treatment of femoral neck fracture using VEGF-loaded nanographene coated internal fixation screws.

PURPOSE: Previous studies have proved that vascular endothelial growth factor (VEGF) has a dual role in the promotion of new bone formation and blood vessel repair during fracture healing. However, how to introduce VEGF to a fracture site safely and effectively is still a challenge. This study aimed to prepare a VEGF-loaded nanographene coated internal fixation screw and to evaluate its effects in the treatment of femoral neck fracture. METHODS: Nanographene coated screws were prepared by direct liquid-phase exfoliation of the graphite method, and the surface characteristics were observed through scanning electron microscopy (SEM). VEGF was loaded on nanographene coatings through physical adsorption, and the VEGF controlled release was examined by ELISA. Then a canine femoral neck fracture model was built to examine both the angiogenic and osteogenic properties of the VEGF-loaded coated screws. X-ray, micro-CT-based microangiography, and histopathologic evaluation were used to assess the fracture healing progress. RESULTS: The results demonstrated that nanographene could load VEGF effectively, and the accumulative release of VEGF clearly increased during the entire testing period (9 days) without burst release. In canine fracture models, the results of X-ray, microangiography, and histopathologic examination proved that the speed of fracture healing, new bone formation area, and revascularization of the fractured femoral heads in the VEGF-loaded coated screws groups were significantly higher than in the control groups. CONCLUSION: Our study proved that VEGF-loaded nanographene coated screws were effective in the treatment of femoral neck fracture and prevention of avascular necrosis of femoral head.

Aspirin inhibits the proliferation of synovium-derived mesenchymal stem cells by arresting the cell cycle in the G0/G1 phase.

Mesenchymal stem cells (MSCs) provide promising applications for clinical treatments. However, patients often take medications that affect the viability of transplanted MSCs. The aim of this study was to assess the effects and underlying mechanism of action of aspirin on the proliferation of MSCs. We showed that aspirin inhibited the growth of MSCs in a concentration- and time-dependent manner. Analysis of cell-cycle distributions showed significantly increased cell populations in the G0/G1 phase and decreased cell populations in the S phase and G2/M phase with increasing concentrations of aspirin. We further analyzed the expression of cyclins and found that the level of cyclin D1 was significantly reduced after aspirin treatment, while there was no obvious effect on the levels of cyclin A2 and cyclin E1. Because we showed that the expression of miRNA145 was significantly increased after aspirin treatment, we further transfected MSCs with an miRNA145 mimic or miRNA145 inhibitor. Transfection with the miRNA145 mimic resulted in decreased expression of cyclin D1, while transfection with miRNA145 inhibitor resulted in increased expression of cyclin D1. Transfection with miRNA145 inhibitor abolished the downregulation of cyclin D induced by aspirin. The results suggested that aspirin inhibited the proliferation of MSCs and caused cell-cycle arrest in the G0/G1 phase through downregulation of cyclin D1, which could be related to the increased expression of miRNA145.

Stromal cell-derived factor-1α and transforming growth factor-ß1 synergistically facilitate migration and chondrogenesis of synovium-derived stem cells through MAPK pathways.

The clinical translation of tissue engineering methods is confined by the limited external cell sources, which is hopefully to be addressed by the cell guidance approach as cytokine-induced homing and differentiation of the patients' autologous cells. Synovium-derived stem cells (SDSCs) are a potent cell source for cartilage restoration due to its intrinsic proximity and tissue-specific chondrogenic capacity. In this study, stromal cell-derived factor-1α (SDF-1α) in combination with transforming growth factor ß1 (TGF-ß1) were used to induce SDSCs migration and chondrogenesis in vitro. The migration capacity was evaluated by transwell assay and for chondrogenic evaluation, the expression of Sox9, ACAN and COL2A1 were assessed by quantitative RT-PCR while the expression of sulfated GAG and collagen II were evaluated by Alcian Blue stain and immunohistochemistry respectively. Our data showed that SDF-1α/CXC chemokine receptor 4 (CXCR4) was involved in SDSCs migration through phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) pathway. Exogenous TGF-ß1 enhanced SDF-1α-induced SDSCs migration in a concentration and time-dependent manner through CXCR4, evidenced as complete blockage by AMD3100, the CXCR4 antagonist and this effect was mediated by extracellular regulated protein kinases (ERK) activation. Moreover, the addition of SDF-1α augmented the TGF-ß1-induced SDSCs chondrogenesis, evidenced by the increased pellet sizes and the expressions of COL 2A1, ACAN and Sox9. This effect was related to c-Jun N-terminal kinase (JNK) activation. Collectively, these results suggest that SDF-1α and TGF-ß1 interacts with each other and synergistically enhance the SDSCs migration and chondrogenesis through MAPK pathways.

Fabrication of modified dextran-gelatin in situ forming hydrogel and application in cartilage tissue engineering.

Hydrogels play a very important role in cartilage tissue engineering. Here, we oxidized dextran (Odex) and modified gelatin (Mgel) to fabricate a fast forming hydrogel without the addition of a chemical crosslinking agent. The dynamic gelling process was measured through rheological measurements. The microstructure was examined by lyophilizing to get porous scaffolds. Biological assessment was performed through CCK-8 assays by using synovium-derived mesenchymal cells (SMSCs) at 1, 3, 7 and 14 days. In vivo evaluation for application in cartilage tissue engineering was performed 8 weeks after subcutaneous injection of SMSC-loaded Odex/Mgel hydrogels combined with TGF-ß3 in the dorsa of nude mice. According to the results, a fast forming hydrogel was obtained by simply modifying dextran and gelatin. Moreover, the Odex/Mgel hydrogel exhibited good biocompatibility in cultures of SMSCs and a homogeneous distribution of live cells was achieved inside the hydrogels. After 8 weeks, newly formed cartilage was achieved in the dorsa of nude mice; no inflammatory reaction was observed and high production of GAGs was shown. The method provides a strategy for the design and fabrication of fast in situ forming hydrogels. The Odex/Mgel hydrogel could be used for the regeneration of cartilage in tissue engineering.