Minghao Zheng

Scaffolds for tendon and ligament repair: review of the efficacy of commercial products.

Driven by market demand, many biological and synthetic scaffolds have been developed during the last 15 years. Both positive and negative results have been reported in clinical applications for tendon and ligament repair. To obtain data for this review, multiple electronic databases were used (e.g., Pubmed and ScienceDirect), as well as the US FDA website and the reference lists from clinical trials, review articles and company reports, in order to identify studies relating to the use of these commercial scaffolds for tendon and ligament repair. The commercial names of each scaffold and the keywords ‘tendon’ and ‘ligament’ were used as the search terms. Initially, 378 articles were identified. Of these, 47 were clinical studies and the others were reviews, editorials, commentaries, animal studies or related to applications other than tendons and ligaments. The outcomes were reviewed in 47 reports (six on Restore™, eight on Graftjacket®, four on Zimmer®, one on TissueMend®, five on Gore-Tex®, six on Lars®, 18 on Leeds–Keio® and one study used both Restore and Graftjacket). The advantages, disadvantages and future perspectives regarding the use of commercial scaffolds for tendon and ligament treatment are discussed. Both biological and synthetic scaffolds can cause adverse events such as noninfectious effusion and synovitis, which result in the failure of surgery. Future improvements should focus on both mechanical properties and biocompatibility. Nanoscaffold manufactured using electrospinning technology may provide great improvement in future practice.

Prevention of Wear Particle-Induced Osteolysis by a Novel V-ATPase Inhibitor Saliphenylhalamide through Inhibition of Osteoclast Bone Resorption

Wear particle-induced peri-implant loosening (Aseptic prosthetic loosening) is one of the most common causes of total joint arthroplasty. It is well established that extensive bone destruction (osteolysis) by osteoclasts is responsible for wear particle-induced peri-implant loosening. Thus, inhibition of osteoclastic bone resorption should prevent wear particle induced osteolysis and may serve as a potential therapeutic avenue for prosthetic loosening. Here, we demonstrate for the first time that saliphenylhalamide, a new V-ATPase inhibitor attenuates wear particle-induced osteolysis in a mouse calvarial model. In vitro biochemical and morphological assays revealed that the inhibition of osteolysis is partially attributed to a disruption in osteoclast acidification and polarization, both a prerequisite for osteoclast bone resorption. Interestingly, the V-ATPase inhibitor also impaired osteoclast differentiation via the inhibition of RANKL-induced NF-κB and ERK signaling pathways. In conclusion, we showed that saliphenylhalamide affected multiple physiological processes including osteoclast differentiation, acidification and polarization, leading to inhibition of osteoclast bone resorption in vitro and wear particle-induced osteolysis in vivo. The results of the study provide proof that the new generation V-ATPase inhibitors, such as saliphenylhalamide, are potential anti-resorptive agents for treatment of peri-implant osteolysis.

EGFL6 Promotes Endothelial Cell Migration and Angiogenesis through the Activation of Extracellular Signal-regulated Kinase

Angiogenesis is required for bone development, growth, and repair. It is influenced by the local bone environment that involves cross-talks between endothelial cells and adjacent bone cells. However, data regarding factors that directly contribute to angiogenesis by bone cells remain poorly understood. Here, we report that EGFL6, a member of the epidermal growth factor (EGF) repeat superfamily proteins, induces angiogenesis by a paracrine mechanism in which EGFL6 is expressed in osteoblastic-like cells but promotes migration and angiogenesis of endothelial cells. Co-immunoprecipitation assays revealed that EGFL6 is secreted in culture medium as a homodimer protein. Using scratch wound healing and transwell assays, we found that conditioned medium containing EGFL6 potentiates SVEC (a simian virus 40-transformed mouse microvascular endothelial cell line) endothelial cell migration. In addition, EGFL6 promotes the endothelial cell tube-like structure formation in Matrigel assays and angiogenesis in a chick embryo chorioallantoic membrane. Furthermore, we show that EGFL6 recombinant protein induces phosphorylation of ERK in SVEC endothelial cells. Inhibition of ERK impaired EGFL6-induced ERK activation and endothelial cell migration. Together, these results demonstrate, for the first time, that osteoblastic-like cells express EGFL6 that is capable of promoting endothelial cell migration and angiogenesis via ERK activation. Thus, the EGLF6 mediates a paracrine mechanism of cross-talk between vascular endothelial cells and osteoblasts and might offer an important new target for the potential treatment of bone diseases, including osteonecrosis, osteoporosis, and fracture healing.

Do Postoperative Platelet-Rich Plasma Injections Accelerate Early Tendon Healing and Functional Recovery After Arthroscopic Supraspinatus Repair? A Randomized Controlled Trial

Background: Tendon-bone healing after rotator cuff repair directly correlates with a successful outcome. Biological therapies that elevate local growth-factor concentrations may potentiate healing after surgery. Purpose: To ascertain whether postoperative and repeated application of platelet-rich plasma (PRP) to the tendon repair site improves early tendon healing and enhances early functional recovery after double-row arthroscopic supraspinatus repair. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: A total of 60 patients underwent arthroscopic double-row supraspinatus tendon repair. After randomization, half the patients received 2 ultrasound-guided injections of PRP to the repair site at postoperative days 7 and 14. Early structural healing was assessed with MRI at 16 weeks, and cuff appearances were graded according to the Sugaya classification. Functional scores were recorded with the Oxford Shoulder Score; Quick Disability of the Arm, Shoulder and Hand; visual analog scale for pain; and Short Form–12 quality-of-life score both preoperatively and at postoperative weeks 6, 12, and 16; isokinetic strength and active range of motion were measured at 16 weeks. Results: PRP treatment did not improve early functional recovery, range of motion, or strength or influence pain scores at any time point after arthroscopic supraspinatus repair. There was no difference in structural integrity of the supraspinatus repair on MRI between the PRP group (0% full-thickness retear; 23% partial tear; 77% intact) and the control group (7% full-thickness retear; 23% partial tear; 70% intact) at 16 weeks postoperatively (P = .35). Conclusion: After arthroscopic supraspinatus tendon repair, image-guided PRP treatment on 2 occasions does not improve early tendon-bone healing or functional recovery.

In chronic lateral epicondylitis, apoptosis and autophagic cell death occur in the extensor carpi radialis brevis tendon.

HYPOTHESIS Despite its common occurrence, lateral epicondylitis is poorly understood from a cellular and molecular perspective. We hypothesize that apoptosis and autophagic cell death are involved in the development of chronic lateral epicondylitis. MATERIALS AND METHODS In 10 patients undergoing surgery for chronic recalcitrant lateral epicondylitis, tendon samples were taken from the extensor carpi radialis brevis (ECRB) tendon and were processed for hematoxylin and eosin, terminal deoxynucleotidyl transferase-mediated deoxy uridine triphosphate nick-end labeling (TUNEL) assay, and immunostaining. Extracellular matrix structure was graded I to III according to collagen fiber structure and arrangement. Apoptotic rate, autophagic cell death rate, cell density, and type I collagen content were measured and compared between areas with different collagen grade. RESULTS Apoptotic and autophagic cell death occur in the ECRB tendon and varied with the grade of collagen structure. In grade I matrix with relatively less disrupted collagen structure, the apoptosis rate was 23.2% +/- 4.8% and the autophagy cell death rate was 7.6% +/- 2.2%. In grade II matrix with more advanced breakdown of collagen structure, the apoptosis rate increased to 34.4% +/- 4% (P < .05) and the autophagic cell death rate to 13.7% +/- 3% (P < .05). DISCUSSION This study demonstrated that apoptosis and autophagic cell death occur in the ECRB tendon in chronic lateral epicondylitis. The markedly elevated apoptotic rate and autophagic cell death rate in the grade II matrix may be responsible for the decrease in cellularity and further deterioration of collagen quality seen in end-stage grade III matrix, and this eventually compromised the tendons ability to maintain its integrity and resulted in tendon tear. CONCLUSION Both apoptosis and autophagic cell death play an important role in the development of tendon degeneration in chronic lateral epicondylitis.

Tctex-1, a Novel Interaction Partner of Rab3D, Is Required for Osteoclastic Bone Resorption

ABSTRACT Vesicular transport along microtubules must be strictly regulated to sustain the unique structural and functional polarization of bone-resorbing osteoclasts. However, the molecular mechanisms bridging these vesicle-microtubule interactions remain largely obscure. Rab3D, a member of the Rab3 subfamily (Rab3A/B/C/D) of small exocytotic GTPases, represents a core component of the osteoclastic vesicle transport machinery. Here, we identify a new Rab3D-interacting partner, Tctex-1, a light chain of the cytoplasmic dynein microtubule motor complex, by a yeast two-hybrid screen. We demonstrate that Tctex-1 binds specifically to Rab3D in a GTP-dependent manner and co-occupies Rab3D-bearing vesicles in bone-resorbing osteoclasts. Furthermore, we provide evidence that Tctex-1 and Rab3D intimately associate with the dynein motor complex and microtubules in osteoclasts. Finally, targeted disruption of Tctex-1 by RNA interference significantly impairs bone resorption capacity and mislocalizes Rab3D vesicles in osteoclasts, attesting to the notion that components of the Rab3D-trafficking pathway contribute to the maintenance of osteoclastic resorptive function.

A Prospective, Randomized Comparison of Traditional and Accelerated Approaches to Postoperative Rehabilitation following Autologous Chondrocyte Implantation 2-Year Clinical Outcomes

Objective: To determine the safety and efficacy of “accelerated” postoperative load-bearing rehabilitation following matrix-induced autologous chondrocyte implantation (MACI). Design: A randomized controlled study design was used to investigate clinical outcomes in 70 patients following MACI, in conjunction with either accelerated or traditional approaches to postoperative weight-bearing (WB) rehabilitation. Both interventions sought to protect the implant for an initial period and then incrementally increase WB. Under the accelerated protocol, patients reached full WB at 8 weeks postsurgery, compared to 11 weeks for the traditional group. Clinical outcomes were assessed presurgery and at 3, 6, 12, and 24 months postsurgery. Results: A significant effect ( P < 0.017) for time existed for all clinical measures, demonstrating improvement up to 24 months in both groups. A significant interaction effect (P < 0.017) existed for pain severity and the 6-minute walk test, with accelerated group patients reporting significantly less severe pain and demonstrating superior 6-minute walk distance over the period. Although there was a significant group effect (P < 0.017) for maximal active knee extension range in favor of the accelerated regime, no further significant differences existed. There was no incidence of graft delamination up to 24 months that resulted directly from the 3-month postoperative rehabilitation program. Conclusion: The accelerated load-bearing approach that reduced the length of time spent ambulating on crutches produced comparable if not superior clinical outcomes up to 24 months postsurgery in the accelerated rehabilitation group, without compromising graft integrity. This accelerated regime is safe and effective and demonstrates a faster return to normal function postsurgery.

A conceptual framework for computational models of Achilles tendon homeostasis

Computational modeling of tendon lags the development of computational models for other tissues. A major bottleneck in the development of realistic computational models for Achilles tendon is the absence of detailed conceptual and theoretical models as to how the tissue actually functions. Without the conceptual models to provide a theoretical framework to guide the development and integration of multiscale computational models, modeling of the Achilles tendon to date has tended to be piecemeal and focused on specific mechanical or biochemical issues. In this paper, we present a new conceptual model of Achilles tendon tissue homeostasis, and discuss this model in terms of existing computational models of tendon. This approach has the benefits of structuring the research on relevant computational modeling to date, while allowing us to identify new computational models requiring development. The critically important functional issue for tendon is that it is continually damaged during use and so has to be repaired. From this follows the centrally important issue of homeostasis of the load carrying collagen fibrils within the collagen fibers of the Achilles tendon. Collagen fibrils may be damaged mechanically—by loading, or damaged biochemically—by proteases. Upon reviewing existing computational models within this conceptual framework of the Achilles tendon structure and function, we demonstrate that a great deal of theoretical and experimental research remains to be done before there are reliably predictive multiscale computational model of Achilles tendon in health and disease. WIREs Syst Biol Med 2013, 5:523–538. doi: 10.1002/wsbm.1229

Sanguinarine inhibits osteoclast formation and bone resorption via suppressing RANKL-induced activation of NF-κB and ERK signaling pathways

Sanguinarine is a natural plant extract that has been supplemented in a number of gingival health products to suppress the growth of dental plaque. However, whether sanguinarine has any effect on teeth and alveolar bone health is still unclear. In this study, we demonstrated for the first time that sanguinarine could suppress osteoclastic bone resorption and osteoclast formation in a dose-dependent manner. Sanguinarine diminished the expression of osteoclast marker genes, including TRAP, cathepsin K, calcitonin receptor, DC-STAMP, V-ATPase d2, NFATc1 and c-fos. Further investigation revealed that sanguinarine attenuated RANKL-mediated IκBα phosphorylation and degradation, leading to the impairment of NF-κB signaling pathway during osteoclast differentiation. In addition, sanguinarine also affected the ERK signaling pathway by inhibiting RANKL-induced ERK phosphorylation. Collectively, this study suggested that sanguinarine has protective effects on teeth and alveolar bone health.

LIS1 Regulates Osteoclast Formation and Function through Its Interactions with Dynein/Dynactin and Plekhm1

Microtubule organization and lysosomal secretion are both critical for the activation and function of osteoclasts, highly specialized polykaryons that are responsible for bone resorption and skeletal homeostasis. Here, we have identified a novel interaction between microtubule regulator LIS1 and Plekhm1, a lysosome-associated protein implicated in osteoclast secretion. Decreasing LIS1 expression by shRNA dramatically attenuated osteoclast formation and function, as shown by a decreased number of mature osteoclasts differentiated from bone marrow macrophages, diminished resorption pits formation, and reduced level of CTx-I, a bone resorption marker. The ablated osteoclast formation in LIS1-depleted macrophages was associated with a significant decrease in macrophage proliferation, osteoclast survival and differentiation, which were caused by reduced activation of ERK and AKT by M-CSF, prolonged RANKL-induced JNK activation and declined expression of NFAT-c1, a master transcription factor of osteoclast differentiation. Consistent with its critical role in microtubule organization and dynein function in other cell types, we found that LIS1 binds to and colocalizes with dynein in osteoclasts. Loss of LIS1 led to disorganized microtubules and aberrant dynein function. More importantly, the depletion of LIS1 in osteoclasts inhibited the secretion of Cathepsin K, a crucial lysosomal hydrolase for bone degradation, and reduced the motility of osteoclast precursors. These results indicate that LIS1 is a previously unrecognized regulator of osteoclast formation, microtubule organization, and lysosomal secretion by virtue of its ability to modulate dynein function and Plekhm1.