Zhijun Pan

Osteochondral repair using porous poly(lactide-co-glycolide)/nano-hydroxyapatite hybrid scaffolds with undifferentiated mesenchymal stem cells in a rat model.

In this study, a novel three-dimensional poly (lactide-co-glycolide) (PLGA)/nano-hydroxyapatite (NHA) scaffold was fabricated by a thermally induced phase separation technique and its potential application in cartilage tissue-engineering was investigated. The PLGA scaffold was used as a control and mesenchymal stem cells (MSCs) were seeded in both scaffolds. After 12-days culture, SEM images and confocal laser scanning microscopy illustrated that MSCs attached more moderately and more cells distributed in PLGA/NHA scaffolds. MTT test and DNA assay showed that the viability and proliferation of MSCs in PLGA/NHA scaffolds were significantly superior to PLGA scaffolds during in vitro culture. Through in vivo study, the efficacy of this scaffold combining with MSCs for repairing articular osteochondral defects was evaluated in a rat model. Osteochondral defects in rats knees were left untreated, or treated with PLGA/NHA-MSCs composites or PLGA-MSCs composites. Twelve weeks after operation, histological examination revealed that the defects in the PLGA/NHA-MSCs treated group were filled with smooth and hyaline-like cartilage with abundant glycosaminoglycan and collagen type II deposition, but deficient in collagen type I at 12 weeks after operation. To investigate the final fate of MSCs transplanted into the defect areas, the fluorescent dye CM-DiI was used to prelabel cells. At 12 weeks after transplantation, we still observed the red fluorescence in the repair area. These findings suggest that the PLGA/NHA-MSCs composite may be potentially used for cartilage repair in clinical application. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res, 2010.

Stabilization of cellular properties and differentiation mutilpotential of human mesenchymal stem cells transduced with hTERT gene in a long-term culture.

Human bone marrow mesenchymal stem cells (hMSCs) are promising candidates for cell therapy and tissue engineering. The life span of hMSCs during in vitro culture is limited. Human telomerase catalytic subunit (hTERT) gene transduction can prolong the life span of hMSCs and maintain their potential of osteogenic differentiation. We established a line of hMSCs transduced with exogenous hTERT (hTERT‐hMSCs) and investigated its sustaining cellular properties in a long‐term culture. This line of hTERT‐hMSCs was cultured for 290 population doublings (PDs) without loss of contact inhibition. Under adipogenic, chondrogenic and osteogenic induction, hTERT‐hMSCs at PD 95 and PD 275 could differentiate respectively into adipocytes, chondrocytes, and osteocytes. hTERT‐hMSCs at these PDs showed no transforming activity through both in vitro assay of cell growth in soft agar and in vivo assay of tumorigenicity in NOD‐SCID mice. Karyotype analyses showed no significant chromosomal abnormalities in hTERT‐hMSCs at these PDs. These results suggested that the hTERT‐hMSCs at lower population doubling levels (PDLs) should be considered as a cell model for studies of cellular senescence, differentiation and in vitro tissue engineering experiment because of its prolonged life span and normal cellular properties. J. Cell. Biochem. 103: 1256–1269, 2008.

Selective COX-2 inhibitor versus nonselective COX-1 and COX-2 inhibitor in the prevention of heterotopic ossification after total hip arthroplasty: a meta-analysis of randomised trials

Whether selective cyclo-oxygenase-2 (COX-2) inhibitors are equally effective compared to nonselective NSAIDs for the prevention of heterotopic ossification (HO) after total hip arthroplasty (THA) is still unclear. We carried out a comprehensive search strategy, in which only randomised controlled trials were included. Two reviewers independently assessed methodological quality and extracted outcome data. Analyses were performed using Stata version 10.0. Four eligible randomised controlled trials totalling 808 patients were included. Meta-analysis results showed that no statistically significant difference was found in overall incidence of HO (RR 1.08; 95% CI 0.71–1.64), incidence of moderate severe HO (Brooker II and III) (RR 0.83; 95% CI 0.48–1.42) and any grade of Brooker classification between two groups. In summary, the selective COX-2 inhibitors are equally effective as nonselective NSAIDs for the prevention of HO after THA. Considering the gastrointestinal side effects of nonselective NSAIDs, we recommend selective COX-2 inhibitors for the prevention of HO after THA. However, future well-designed, randomised controlled trials are still needed to further confirm our results.

Ex vivo expansion and pluripotential differentiation of cryopreserved human bone marrow mesenchymal stem cells

This study is aimed at investigating the potentials of ex vivo expansion and pluri-differentiation of cryopreservation of adult human bone marrow mesenchymal stem cells (hMSCs) into chondrocytes, adipocytes and neurocytes. Cryopreserved hMSCs were resuscitated and cultured for 15 passages, and then induced into chondrocytes, adipocytes and neurocytes with corresponding induction medium. The induced cells were observed for morphological properties and detected for expressions of type II collagen, triglyceride or neuron-specific enolase and nestin. The result showed that the resuscitated cells could differentiate into chondrocytes after exposure to transforming growth factor β1 (TGF-β1), insulin-like growth factor I (IGF-I) and vitamin C (VC), and uniformly changed morphologically from a spindle-like fibroblastic appearance to a polygonal shape in three weeks. The induced cells were heterochromatic to safranin O and expressed cartilage matrix-procollagenal (II) mRNA. The resuscitated cells cultured in induction medium consisting of dexamethasone, 3-isobutyl-1-methylxanthine, indomethacin and IGF-I showed adipogenesis, and lipid vacuoles accumulation was detectable after 21 d. The resuscitated hMSCs were also induced into neurocytes and expressed nestin and neuron specific endolase (NSE) that were special surface markers associated with neural cells at different stage. This study suggested that the resuscitated hMSCs should be still a population of pluripotential cells and that it could be used for establishing an abundant hMSC reservoir for further experiment and treatment of various clinical diseases.

Proliferation and osteogenesis of immortalized bone marrow-derived mesenchymal stem cells in porous polylactic glycolic acid scaffolds under perfusion culture

Human bone marrow mesenchymal stem cells (hMSCs) are promising candidates for cell therapy and tissue engineering. However, the life span of hMSCs during in vitro culture is limited. Human telomerase catalytic subunit (hTERT) gene transduction could prolong the life span of hMSCs and maintain their potential of osteogenic differentiation. Therefore, hMSCs transduced with hTERT (hTERT-hMSCs) could be used as a cell model for in vitro tissue engineering experiment because of its prolonged life span and normal cellular properties. A perfusion culture system for proliferation and osteogenesis of hTERT-hMSCs or primary hMSCs in porous polylactic glycolic acid (PLGA) scaffolds is described here. A cell suspension of hTERT-hMSCs or primary hMSCs (5 x 10(5) cells/250 microL) was seeded and then cultured for 12 days in porous PLGA scaffolds (10 mm in diameter, 3 mm in height) under both static and perfusion culture systems. The seeding efficiency, proliferation, distribution and viability, and osteogenesis of cells in scaffolds were evaluated. The perfusion method generated higher scaffold cellularity and proliferation of cells in scaffolds, and hTERT-hMSCs showed the higher proliferation potential than primary hMSCs. Results from fluorescein diacetate (FDA) staining and scanning electron microscopy (SEM) demonstrated homogeneous seeding, proliferation, and viability of hTERT-hMSCs throughout the scaffolds in the perfusion culture system. On the contrary, the static culture yielded polarized proliferation favoring the outer and upper scaffold surfaces, and resulted in decreasing of cells in the central section of the scaffolds. A flow rate of 0.5 mL/min had an effect on osteogenic differentiation of cells in scaffolds. However, the osteogenic medium promoted the osteogenic efficiency of cells. Scaffolds with hTERT-hMSCs had the higher osteogenesis than scaffolds with primary hMSCs. Thus, these results suggest that the flow condition not only allow a better seeding efficiency and homogeneity but also facilitate uniform proliferation and osteogenic differentiation of hTERT-hMSCs in scaffolds. hTERT-hMSCs could be used as stem cell candidates for bone tissue engineering experiments.

Could the effect of modeled microgravity on osteogenic differentiation of human mesenchymal stem cells be reversed by regulation of signaling pathways

Abstract Microgravity (MG) results in a reduction in bone formation. Bone formation involves osteogenic differentiation from mesenchymal stem cells (hMSCs) in bone marrow. We modeled MG to determine its effects on osteogenesis of hMSCs and used activators or inhibitors of signaling factors to regulate osteogenic differentiation. Under osteogenic induction, MG reduced osteogenic differentiation of hMSCs and decreased the expression of osteoblast gene markers. The expression of Runx2 was also inhibited, whereas the expression of PPARγ2 increased. MG also decreased phosphorylation of ERK, but increased phosphorylation of p38MAPK. SB203580, a p38MAPK inhibitor, was able to inhibit the phosphorylation of p38MAPK, but did not reduce the expression of PPARγ2. Bone morphogenetic protein (BMP) increased the expression of Runx2. Fibroblast growth factor 2 (FGF2) increased the phosphorylation of ERK, but did not significantly increase the expression of osteoblast gene markers. The combination of BMP, FGF2 and SB203580 significantly reversed the effect of MG on osteogenic differentiation of hMSCs. Our results suggest that modeled MG inhibits the osteogenic differentiation and increases the adipogenic differentiation of hMSCs through different signaling pathways. Therefore, the effect of MG on the differentiation of hMSCs could be reversed by the mediation of signaling pathways.

Effects of the timing of tourniquet release in cemented total knee arthroplasty: a systematic review and meta-analysis of randomized controlled trials

BackgroundThe aim of this study is to evaluate the effects of tourniquet release before wound closure for hemostasis or after wound closure in cemented total knee arthroplasty (TKA).MethodsWe conducted a meta-analysis and review work on relevant clinical outcomes to evaluate the effects of the timing of tourniquet release in cemented TKA. Electronic databases were searched for relevant randomized controlled trials (RCTs) that compared outcomes of tourniquet release before wound closure for hemostasis with tourniquet release after wound closure. The methodological quality of each included RCT was assessed in terms of the 12-item scale. The meta-analysis was performed with STATA 12.0 software.ResultsEleven RCTs involving 651 patients with 670 TKAs were included in this meta-analysis. Of these, 332 patients (342 knees) were in an early tourniquet release group and 319 patients (328 knees) in the late tourniquet release group. The results showed that there were no significant differences in overt blood loss, hemoglobin drop, and blood transfusions, whereas the tourniquet release after wound closure might increase the risks of overall complications and major complications.ConclusionsTourniquet release before wound closure for hemostasis might reduce the rate of complications, but it could not limit overall blood loss. The current evidences are not enough to indicate that tourniquet release before wound closure is superior to its release after wound closure in cemented TKA.

Rat Cartilage Repair Using Nanophase PLGA/HA Composite and Mesenchymal Stem Cells

Biodegradable polymer/bioceramic composite poly(lactide- coglycolide)/hydroxyapatite(PLGA/HA) was studied for bone tissue engineering. The PLGA/HA composite was evaluated as a scaffold with the ability for mesenchymal stem cells (MSC) to participate in cartilage repair. The PLGA/HA composite and the PLGA/HA composite cultured with MSC were transplanted into cartilage defects created in rats. The PLGA/HA-MSC and PLGA/HA had better tissue morphology, structure integrity, matrix staining, and much thicker newly formed cartilage than the control group. The histological score for PLGA/ HA-MSC better than that for PLGA/HA; it appears that the MSC plays an important role in tissue repair. Based on these results, using PLGA/HA as the tissue scaffold and the addition of MSC significantly enhances cartilage repair.Biodegradable polymer/bioceramic composite poly(lactidecoglycolide)/hydroxyapatite(PLGA/HA) was studied for bone tissue engineering. The PLGA/HA composite was evaluated as a scaffold with the ability for mesenchymal stem cells (MSC) to participate in cartilage repair. The PLGA/HA composite and the PLGA/HA composite cultured with MSC were transplanted into cartilage defects created in rats. The PLGA/HA-MSC and PLGA/HA had better tissue morphology, structure integrity, matrix staining, and much thicker newly formed cartilage than the control group. The histological score for PLGA/ HA-MSC better than that for PLGA/HA; it appears that the MSC plays an important role in tissue repair. Based on these results, using PLGA/HA as the tissue scaffold and the addition of MSC significantly enhances cartilage repair.

Reamed and unreamed intramedullary nailing for the treatment of open and closed tibial fractures: a subgroup analysis of randomised trials.

The choice between reamed and unreamed intramedullary nailing for the treatment of open and closed tibial fractures is an ongoing controversy. We carried out a comprehensive search strategy. Six eligible randomised controlled trials were included. Three reviewers independently assessed methodological quality and extracted outcome data. Analyses were performed using Review Manager 5.0. The results showed lower risks of tibial fracture nonunion and implant failures with reamed nails compared to unreamed nails in closed tibial fractures [relative risk (RR): 0.41, 95% confidence interval (CI): 0.21–0.89, P = 0.008 for nonunion and RR: 0.35, 95% CI: 0.22–0.56, P < 0.0001 for implant failures], but no statistical differences in risk reduction of malunion, compartment syndrome, embolism and infection. Our results suggested no statistical differences in risk reduction of all the complications evaluated between reamed and unreamed nails in open tibial fractures. In conclusion, our study recommended reamed nails for the treatment of closed tibial fractures. But the choice for open tibial fractures remains uncertain.

Barbed versus traditional sutures for wound closure in knee arthroplasty: a systematic review and meta-analysis

Sutures are an increasing focus of research in knee arthroplasty (KA). Whether knotless barbed sutures (KBS) are safe and efficient in KA remains controversial. The objective of our study is to compare the clinical outcomes of KA according to wound closure method: KBS versus knotted traditional sutures (KTS). To clarify this, we conducted a systematic review and meta-analysis. Nine articles involving 10 studies were included in this study. The dataset consisted of 1729 patients with 1754 KA. Among these, 814 patients’ wounds were closed with KBS and 915 with KTS. Our analysis indicates that KBS is preferable for KA wound closure given its shorter wound closure time and lower total cost; postoperative Knee Society scores and complication rates were similar to those of surgeries using KTS. The subgroup analysis revealed that closure of arthrotomy with KBS appears to be associated with a lower risk of complications. This meta-analysis indicates that use of KBS in KA reduces operative time and cost. KBS is the preferred option for wound closures, including arthrotomy and reattachment of subcutaneous and subcuticular tissues. Given the possible biases, adequately powered and better-designed studies with longer follow-up are required to reach a firmer conclusion.