Degang Yu

The promotion of cartilage defect repair using adenovirus mediated Sox9 gene transfer of rabbit bone marrow mesenchymal stem cells

Although Sox9 is essential for chondrogenic differentiation and matrix production, its application in cartilage tissue engineering has been rarely reported. In this study, the chondrogenic effect of Sox9 on bone marrow mesenchymal stem cells (BMSCs) in vitro and its application in articular cartilage repair in vivo were evaluated. Rabbit BMSCs were transduced with adenoviral vector containing Sox9. Toluidine blue, safranin O staining and real-time PCR were performed to check chondrogenic differentiation. The results showed that Sox9 could induce chondrogenesis of BMSCs both in monolayer and on PGA scaffold effectively. The rabbit model with full-thickness cartilage defects was established and then repaired by PGA scaffold and rabbit BMSCs with or without Sox9 transduction. HE, safranin O staining and immunohistochemistry were used to assess the repair of defects by the complex. Better repair, including more newly-formed cartilage tissue and hyaline cartilage-specific extracellular matrix and greater expression of several chondrogenesis marker genes were observed in PGA scaffold and BMSCs with Sox9 transduction, compared to that without transduction. Our findings defined the important role of Sox9 in the repair of cartilage defects in vivo and provided evidence that Sox9 had the potential and advantage in the application of tissue engineering.

Biomimetic sheath membrane via electrospinning for antiadhesion of repaired tendon.

The hierarchical architecture and complex biologic functions of native sheath make its biomimetic substitute a daunting challenge. In this study, a biomimetic bilayer sheath membrane consisting of hyaluronic acid-loaded poly(ε-caprolactone) (HA/PCL) fibrous membrane as the inner layer and PCL fibrous membrane as the outer layer was fabricated by a combination of sequential and microgel electrospinning technologies. This material was characterized by mechanical testing and analysis of morphology, surface wettability, and drug release. Results of an in vitro drug release study showed sustained release. The outer layer had fewer cells proliferating on its surface compared to tissue culture plates or the inner layer. In a chicken model, peritendinous adhesions were reduced and tendon gliding were improved by the application of this sheath membrane. Taken together, our results demonstrate that such a biomimetic bilayer sheath can release HA sustainably as well as promoting tendon gliding and preventing adhesion.

Strontium ranelate reduces cartilage degeneration and subchondral bone remodeling in rat osteoarthritis model.

Aim:To investigate whether strontium ranelate (SR), a new antiosteoporotic agent, could attenuate cartilage degeneration and subchondral bone remodeling in osteoarthritis (OA).Methods:Medial meniscal tear (MMT) operation was performed in adult SD rats to induce OA. SR (625 or 1800 mg·kg−1·d−1) was administered via gavage for 3 or 6 weeks. After the animals were sacrificed, articular cartilage degeneration was evaluated using toluidine blue O staining, SOX9 immunohistochemistry and TUNEL assay. The changes in microarchitecture indices and tissue mineral density (TMD), chemical composition (mineral-to-collagen ratio), and intrinsic mechanical properties of the subchondral bones were measured using micro-CT scanning, confocal Raman microspectroscopy and nanoindentation testing, respectively.Results:The high-dose SR significantly attenuated cartilage matrix and chondrocyte loss at 6 weeks, and decreased chondrocyte apoptosis, improved the expression of SOX9, a critical transcription factor responsible for the expression of anabolic genes type II collagen and aggrecan, at both 3 and 6 weeks. Meanwhile, the high-dose SR also significantly attenuated the subchondral bone remodeling at both 3 and 6 weeks, as shown by the improved microarchitecture indices, TMD, mineral-to-collagen ratio and intrinsic mechanical properties. In contrast, the low-dose SR did not significantly change all the detection indices of cartilage and bone at both 3 and 6 weeks.Conclusion:The high-dose SR treatment can reduce articular cartilage degeneration and subchondral bone remodeling in the rat MMT model of OA.

Simulated microgravity using a rotary cell culture system promotes chondrogenesis of human adipose-derived mesenchymal stem cells via the p38 MAPK pathway

Mesenchymal stem cells (MSCs) are multi-potent, and the chondrogenesis of MSCs is affected by mechanical stimulation. The aim of this study was to investigate, using a rotary cell culture system (RCCS) bioreactor, the effects of microgravity on the chondrogenic differentiation of human adipose-derived MSCs (ADSCs), which were cultured in pellets with or without the chondrogenic growth factor TGF-β1. In addition, we evaluated the role of the p38 MAPK pathway in this process. The real-time PCR and histological results show that microgravity has a synergistic effect on chondrogenesis with TGF-β1. The p38 MAPK pathway was activated by TGF-β1 alone and was further stimulated by microgravity. Inhibition of p38 activity with SB203580 suppressed chondrocyte-specific gene expression and matrix production. These findings suggest that the p38 MAPK signal acts as an essential mediator in the microgravity-induced chondrogenesis of ADSCs.

Efficacy of zoledronic acid in treatment of teoarthritis is dependent on the disease progression stage in rat medial meniscal tear model

Aim:To investigate whether the stage of osteoarthritis (OA) progression influenced the efficacy of the third-generation bisphosphonate zoledronic acid in a rat medial meniscal tear model.Methods:Medial meniscal tear (MMT) was surgically induced in adult male Sprague Dawley rats. Zoledronic acid (ZOL, 100 μg/kg, sc, twice a week) was administered starting immediately, early (from 4 weeks) or late (from 8 weeks) after OA induction. The degeneration of articular cartilage was evaluated with toluidine blue O staining. Subchondral bone remodeling was evaluated with X-ray micro-CT scanning. Joint pain was measured with respect to weight-bearing asymmetry. Calcitonin gene-related peptide (CGRP) expression in dorsal root ganglia (DRGs) was examined using immunofluorescence analysis. The afferent neurons in DRGs innervating the joint were identified by retrograde labeling with fluorogold.Results:Progressive cartilage loss was observed during 12 weeks after OA induction. Subchondral bone remodeling manifested as increased bone resorption at early stage (4 weeks), but as increased bone accretion at advanced stages (8 weeks). Immediately and early ZOL administration significantly improved subchondral microstructural parameters, attenuated cartilage degeneration, reduced weight-bearing asymmetry and CGRP expression, whereas the late ZOL administration had no significant effects.Conclusion:The stage of OA progression influences the efficacy of ZOL in treating joint degeneration and pain. To obtain the maximum efficacy, bisphosphonate treatment should be initiated in rat with early stages of OA pathogenesis.

The utility of digital templating in Total Hip Arthroplasty with Crowe type II and III dysplastic hips

With the superiority of digital imaging, conventional preoperative acetate templating is gradually being replaced by digital templating in total hip arthroplasty (THA). The purpose of this study was to assess the utility of digital templating for patients with Crowe type II and III dysplastic hips. In this study, 41 THA patients with Crowe type II or III dysplastic hips and 48 THA patients with other primary diseases were retrospectively reviewed. All patients were fitted with cementless prostheses in 2008. For the THA patients with dysplastic hips, we attempted to restore their hip centres to the position of the true acetabulum. Digital templating was the method chosen to achieve hip centre restoration. The prosthesis prediction accuracy (within ± one size using digital templating) was 20 (48.8%) for the cup size and 30 (73.2%) for the stem size. Meanwhile, for patients with other primary diseases, the accuracy for the cup size within ± one size was 34 (70.8%) and for the stem size accuracy was within ± one size in 38 (79.2%). Between the two patient groups, there was a significant difference in the predicted cup size. In patients with dysplastic hips, the low accuracy of the predicted cup size may have resulted from difficulty in predicting the vertical location of the hip centre. Despite this limitation, preoperative planning using digital templating is a convenient technique for THA patients with Crowe type II and III dysplastic hips.

Fabrication of silver nanoparticle-doped hydroxyapatite coatings with oriented block arrays for enhancing bactericidal effect and osteoinductivity

Implant-associated infection is a common postoperative complication and remains a serious problem in orthopedic surgery. This work describes the synthesis of silver nanoparticle-doped hydroxyapatite coatings with oriented block arrays (AgNP-BHAC). The resulting nanostructure was investigated using scanning electron microscopy, energy-dispersive spectrometry, transmission electron microscopy, X-ray powder diffraction, and Fourier transform infrared spectroscopy. AgNP-BHAC exhibited excellent antimicrobial activity toward gram-negative Escherichia coli and gram-positive Staphylococcus aureus owing to the antibacterial effects of the silver nanoparticles. Human bone marrow stromal cells (hBMSC) culture revealed that the AgNP-BHAC exhibited better biocompatibility, and permitted improved cell proliferation, attachment, and osteoinductivity than uncoated Ti-6Al-4V titanium alloy, the favored material for biomedical applications. In summary, this study presents a convenient and effective method for the incorporation of silver into HA coatings with block morphology. This method can be utilized to modify a variety of metallic implant surfaces to improve their antimicrobial effects and reduce potential long-term cytotoxicity.

The Inhibition of Subchondral Bone Lesions Significantly Reversed the Weight-Bearing Deficit and the Overexpression of CGRP in DRG Neurons, GFAP and Iba-1 in the Spinal Dorsal Horn in the Monosodium Iodoacetate Induced Model of Osteoarthritis Pain

Background Chronic pain is the most prominent and disabling symptom of osteoarthritis (OA). Clinical data suggest that subchondral bone lesions contribute to the occurrence of joint pain. The present study investigated the effect of the inhibition of subchondral bone lesions on joint pain. Methods Osteoarthritic pain was induced by an injection of monosodium iodoacetate (MIA) into the rat knee joint. Zoledronic acid (ZOL), a third generation of bisphosphonate, was used to inhibit subchondral bone lesions. Joint histomorphology was evaluated using X-ray micro computed tomography scanning and hematoxylin-eosin staining. The activity of osteoclast in subchondral bone was evaluated using tartrate-resistant acid phosphatase staining. Joint pain was evaluated using weight-bearing asymmetry, the expression of calcitonin gene-related peptide (CGRP) in the dorsal root ganglion (DRG), and spinal glial activation status using glial fibrillary acidic protein (GFAP) and ionized calcium binding adaptor molecule-1 (Iba-1) immunofluorescence. Afferent neurons in the DRGs that innervated the joints were identified using retrograde fluorogold labeling. Results MIA injections induced significant histomorphological alterations and joint pain. The inhibition of subchondral bone lesions by ZOL significantly reduced the MIA-induced weight-bearing deficit and overexpression of CGRP in DRG neurons, GFAP and Iba-1 in the spinal dorsal horn at 3 and 6 weeks after MIA injection; however, joint swelling and synovial reaction were unaffected. Conclusions The inhibition of subchondral bone lesions alleviated joint pain. Subchondral bone lesions should be a key target in the management of osteoarthritic joint pain.

Total hip replacement for high dislocated hips without femoral shortening osteotomy

When performing total hip replacement (THR) in high dislocated hips, the presence of soft-tissue contractures means that most surgeons prefer to use a femoral shortening osteotomy in order to avoid the risk of neurovascular damage. However, this technique will sacrifice femoral length and reduce the extent of any leg-length equalisation. We report our experience of 74 THRs performed between 2000 and 2008 in 65 patients with a high dislocated hip without a femoral shortening osteotomy. The mean age of the patients was 55 years (46 to 72) and the mean follow-up was 42 months (12 to 78). All implants were cementless except for one resurfacing hip implant. We attempted to place the acetabular component in the anatomical position in each hip. The mean Harris hip score improved from 53 points (34 to 74) pre-operatively to 86 points (78 to 95) at final follow-up. The mean radiologically determined leg lengthening was 42 mm (30 to 66), and the mean leg-length discrepancy decreased from 36 mm (5 to 56) pre-operatively to 8.5 mm (0 to 18) postoperatively. Although there were four (5%) post-operative femoral nerve palsies, three had fully resolved by six months after the operation. No loosening of the implant was observed, and no dislocations or infections were encountered. Total hip replacement without a femoral shortening osteotomy proved to be a safe and effective surgical treatment for high dislocated hips.

Comparison of the cytotoxic and inflammatory responses of titanium particles with different methods for endotoxin removal in RAW264.7 macrophages

It is generally accepted that periprosthetic bone resorption is initiated through aseptic inflammation aggravated by wear particles that are generated from artificial joint. However, some studies have demonstrated that “endotoxin-free” wear particles are almost completely unable to stimulate the macrophage-mediated production of proinflammatory cytokines. Here, we compare the titanium particles with different methods of endotoxin removal. The results indicated that different titanium particle preparation dosages did not significantly change particle size, morphology, and chemical composition. But it could cause variations in the endotoxin concentration of titanium particles and inflammatory responses in RAW264.7 macrophages. The particles with higher endotoxin levels correlated with more extensive inflammatory responses. When testing endotoxins using the supernatant of particle suspensions, it would lead to false negative results compared with testing the particle themselves. And when using the particles themselves, all the particles should be removed by centrifugation to avoid particle interference before the absorbance value was determined. Therefore, we suggest that research concerning wear particles should completely describe the endotoxin testing process, including endotoxin removal from particles and the details of endotoxin testing. Moreover, future research should focus on the surface of wear particles (the potential role of adherent endotoxin) rather than the particles themselves.