Xiao-Qing He

TLR4 Activation Promotes Bone Marrow MSC Proliferation and Osteogenic Differentiation via Wnt3a and Wnt5a Signaling

Mesenchymal stem cells (MSCs) from adult bone marrow maintain their self-renewal ability and the ability to differentiate into osteoblast. Thus, adult bone marrow MSCs play a key role in the regeneration of bone tissue. Previous studies indicated that TLR4 is expressed in MSCs and is critical in regulating the fate decision of MSCs. However, the exact functional role and underlying mechanisms of how TLR4 regulate bone marrow MSC proliferation and differentiation are unclear. Here, we found that activated TLR4 by its ligand LPS promoted the proliferation and osteogenic differentiation of MSCs in vitro. TLR4 activation by LPS also increased cytokine IL-6 and IL-1β production in MSCs. In addition, LPS treatment has no effect on inducing cell death of MSCs. Deletion of TLR4 expression in MSCs completely eliminated the effects of LPS on MSC proliferation, osteogenic differentiation and cytokine production. We also found that the mRNA and protein expression of Wnt3a and Wnt5a, two important factors in regulating MSC fate decision, was upregulated in a TLR4-dependent manner. Silencing Wnt3a with specific siRNA remarkably inhibited TLR4-induced MSC proliferation, while Wnt5a specific siRNA treatment significantly antagonized TLR4-induced MSC osteogenic differentiation. These results together suggested that TLR4 regulates bone marrow MSC proliferation and osteogenic differentiation through Wnt3a and Wnt5a signaling. These finding provide new data to understand the role and the molecular mechanisms of TLR4 in regulating bone marrow MSC functions. These data also provide new insight in developing new therapy in bone regeneration using MSCs by modulating TLR4 and Wnt signaling activity.

Distal foot coverage with reverse dorsal pedal neurocutaneous flaps

Various types of neurocutaneous flaps have been used for extremity reconstructions. However, the application of this technique to the dorsum of the foot has not been reported previously. The aim of this article is to evaluate the attempts and clinical results from dorsal pedal neurocutaneous flap procedures. Harvesting of these flaps included the medial, intermediate and lateral dorsal cutaneous nerves, the deep peroneal nerve and the nutrient arteries of these nerves. The vascular anatomy of these flaps was studied before the clinical usage of the procedure. From 2003 to 2008, 30 patients with skin defects and bone exposure of the dorsum of the distal foot were treated with 39 dorsal pedal neurocutaneous flaps in our centre. The flaps in this series ranged from 3.5 to 7.0 cm in width and 4.0 to 10.0 cm in length. Totally, 35 flaps healed uneventfully. One showed partial loss at the distal edge, and three survived entirely following continuous massage. The postoperative contour of the flaps was acceptable. The reverse dorsal pedal neurocutaneous flap has proved effective and convenient for coverage of minor- to medium-sized defects in the distal foot.

Wnt11 plays an important role in the osteogenesis of human mesenchymal stem cells in a PHA/FN/ALG composite scaffold: possible treatment for infected bone defect

BackgroundInfected bone defect poses a great challenge for orthopedists because it is difficult to cure. Tissue-engineered bone based on the human mesenchymal stem cells (hMSCs), has currently taken a promising treatment protocol in clinical practice. In a previous study, a porous hydroxyapatite/fibronectin/alginate (PHA/FN/ALG) composite scaffold displayed favorable biological properties as a novel scaffold, which was considered better than single-material scaffolds. In addition, Wnt11 has been demonstrated to play an important role in the development of osteoblasts, but until recently, its role in the osteogenic differentiation of hMSCs in infectious environment remained unclear.MethodsIn this study, we constructed a PHA/FN/ALG composite scaffold with layer-by-layer technology. Furthermore, we also constructed Wnt11-silenced (RNAi) and -overexpressing hMSCs by lentiviral transduction. The gene transduction efficacy was confirmed by quantitative PCR assay and Western blot analysis. Tissue-engineered bone was constructed with hMSCs and PHA/FN/ALG composite scaffolds, and then was implanted into an infected bone defect model for evaluating the osteogenic capacity by quantitative PCR, gross observation, micro-CT and histology analysis.ResultsAll those cells showed similar adhesion abilities and proliferation capacities in scaffolds. After tissue-engineered bone implantation, there were high levels of systemic inflammatory factors in vivo, which significantly declined three days after antibiotic therapy. One or two months after implantation, the results of osteogenic-related gene analyses, gross observation, micro-CT and histology consistently showed that the Wnt11 over-expression hMSC group displayed the strongest osteogenesis capacity, whereas the Wnt11-RNAi hMSC group displayed inferior osteogenesis capacity, when compared with the other cell-containing groups. However, the blank control group and the only composite scaffold without cell implantation group both showed extremely weak osteogenesis capacity.ConclusionOur results revealed that the Wnt11 gene plays an important role in hMSCs for enhancing the osteogenesis in an infectious environment.

Staphylococcus Aureus Induces Osteoclastogenesis via the NF-κB Signaling Pathway

Background Osteomyelitis is one of the refractory diseases encountered in orthopedics, while Staphylococcus aureus (S. aureus) is the most common causative organism in osteomyelitis. However, the precise mechanisms underlying the bone loss caused by S. aureus infection have not been well defined. Here, we investigated the effect of S. aureus on osteoclast differentiation and the probable molecular mechanism. Material/Methods RAW 264.7 cells were treated for 5 days with live S. aureus, inactivated S. aureus, and S. aureus filtrate. Then, the formation of osteoclast-like cells and resorption pits was observed, and the expression of osteoclast-specific genes (TRAP, MMP-9, cathepsin K, CTR and Atp6v0d2) was detected by real-time PCR. Moreover, key proteins in the signaling pathway associated with osteoclast differentiation were detected with Western blot. Results The data showed that live S. aureus, inactivated S. aureus, and S. aureus filtrate induced osteoclast formation, promoted bone resorption, and increased the expression of osteoclast-specific genes in a dose-dependent manner in the absence RANKL. In addition, we found that the S. aureus-induced osteoclastogenesis was related to the degradation of IκB-α, phosphorylation of NF-κB p65, and increased expression of NFATc1. Thus, we used JSH-23 to inhibit NF-κB transcriptional activity. The effect of the S. aureus-induced osteoclastogenesis and the expression of osteoclast-specific genes and NFATc1 were inhibited, which indicated that the NF-κB signaling pathway plays a role in S. aureus-induced osteoclastogenesis. Conclusions This study demonstrated that S. aureus induces osteoclastogenesis through its cell wall compound and secretion of small soluble molecules, and the NF-κB signaling pathway plays a role in this process.

The Role of the Distal Runoff Vessel of the Descending Branch of the Lateral Circumflex Femoral System in Anterolateral Thigh Flap Surgery: A Case Series and Literature Review.

BackgroundAs a distal portion of the descending branch of the lateral circumflex femoral system (LCFS), the role of the distal runoff vessel in anterolateral thigh (ALT) flap surgery has long been overlooked. Recently, however, the distal runoff vessel has been increasingly used in many aspects of ALT flap surgery, and it has exhibited superior properties in solving some difficult problems. MethodsFourteen ALT flaps using the distal runoff vessel of the descending branch of the LCFS for extremity defects were retrospectively reviewed, and recent reports on using the distal runoff vessel were reviewed to determine the role of this vessel in ALT flap surgery. ResultsIn our series, the distal runoff vessel was used as a flow-through pattern in 10 cases, as a recombined chimeric flap in 2 cases, and as a backup vessel for flap salvage in 2 cases. All of the ALT flaps completely survived. None of the donor sites presented with additional morbidity as a result of harvesting the distal runoff vessel. In the literature review, the following are 5 other options for using the distal runoff vessel: in interposition artery and vein grafts, as the pedicle of the reverse-flow ALT flap, as the recipient vessel, to avoid twisting, and as a monitoring method. ConclusionsThe distal runoff vessel of the descending branch of the LCFS could be used for many aspects of the ALT flap surgery, and this vessel plays an irreplaceable role in some difficult reconstruction surgeries.

Traumatic Forefoot Reconstructions With Free Perforator Flaps

The forefoot is critical to normal walking; thus, any reconstruction of forefoot defects, including the soft tissues, must be carefully done. The free perforator flap, with its physiologic circulation, lower donor site morbidity, and minimal thickness is the most popular technique in plastic and microsurgery, and is theoretically the most suitable for such forefoot reconstruction. However, these flaps are generally recognized as more difficult and time-consuming to create than other flaps. In 41 patients with traumatic forefoot defects, we reconstructed the forefoot integument using 5 types of free perforator flaps. The overall functional and cosmetic outcomes were excellent. Three flaps required repeat exploration; one survived. The most common complications were insufficient perfusion and the need for second debulking. The key to our success was thoroughly debriding devitalized bone and soft tissue before attaching the flap. Forefoot reconstruction with a free perforator flap provides better function, better cosmesis, better weightbearing, and better gait than the other flaps we have used.

Implant-related infection in the tibia: surgical revision strategy with vancomycin cement.

The development of a deep wound infection in the presence of internal hardware presents a clinical dilemma. The purpose of the present study was to evaluate the treatment outcomes of vancomycin cement with other advances of surgical techniques for implant-related infection (IRI) in the tibia. This study included 217 consecutive patients who had sustained IRI of the tibia. Of them, 152 patients had soft tissue defects and the internal hardware was exposed. Repeated debridement and negative pressure assisted closure were used. All the infected internal hardware was removed. External fixations and flaps were used. Custom-made vancomycin cement was inserted into the dead space of the wounds and left in site for a month. The follow-up was from 12 months to 108 months, averaging 37.5 months. For all the 217 patients, the general osteomyelitis healing rate and bone union rate were 86.6% and 97.2%, respectively. This study shows high rates of healing of IRI in the tibia if the new advances of surgery could be effectively combined into the treatment strategy with vancomycin cement as an important treatment.

CHI3L1 regulation of inflammation and the effects on osteogenesis in a Staphylococcus aureus‐induced murine model of osteomyelitis

Osteomyelitis is an inflammation of the bone and bone marrow that occurs as a consequence of infections mainly attributed to Staphylococcus aureus. In a previous study, we found that expression of the chitinase 3‐like 1 (CHI3L1) gene affected mineralization of MC3T3‐E1 cells infected with S. aureus and there was increased expression of CHI3L1 in the blood of osteomyelitis patients. In the present study, to further investigate the role of CHI3L1 in osteomyelitis, we developed an S. aureus‐induced murine model of the disease. We found that the expression of CHI3L1 was significantly up‐regulated in femurs of mice infected with S. aureus compared with mice inoculated with a PBS control. To investigate these results further, we performed a CHI3L1 knock‐down by lentivirus‐mediated RNA interference in mice. Micro‐computed tomography of infected femurs revealed that S. aureus triggers profound alterations in bone turnover, and femurs of CHI3L1 short hairpin RNA (shRNA‐CHI3L1)‐injected mice infected with S. aureus have significantly less cortical bone destruction when compared with control mice infected with S. aureus. Inhibition of CHI3L1 also decreased inflammation by reducing levels of proinflammatory cytokines and promoted the process of osteogenesis. The Notch signaling pathway has been shown to play an important role in modulating the differentiation of osteoblasts and osteoclasts. Our study showed that Notch1, Jagged1 and Hes1 expression significantly decreased in mice infected with S. aureus compared with the control, and shRNA‐CHI3L1 could increase their level in S. aureus‐infected mice. This research indicates that inhibition of CHI3L1 can reduce the debilitating effects of S. aureus in a murine model of osteomyelitis.

Reconstruction of Moderate-Sized Hand Defects Using a Superficial Lateral Sural Artery Perforator Flap

Background The skin on the lower leg has abundant perforators and, thus, is an excellent donor site for transplant tissue flaps. However, due to vascular variations and body positions, tissue flaps at the posterolateral proximal portion of the lower leg are rarely used for transplantation. This study reports our experience with the use of superficial lateral sural artery perforator (SLSAP) flaps in the repair of moderate-sized hand wounds. Methods From March 2012 to April 2015, the hand wounds of 15 patients were planned for repair using a superficial sural artery perforator flap. In total, 6 patients had a defect in the palm of the hand, 5 in the dorsum of the hand, and 3 in the finger; 1 patient sustained a contracture of the first web space. Results In 12 of the 15 cases, an SLSAP flap was successfully harvested. In the remaining 3 cases, the planned harvest of an SLSAP flap was converted to the harvest of a superficial medial sural artery perforator flap during the operation. The flaps ranged in area from 1.8 × 3.8 cm to 5.5 × 6.5 cm. Primary suture of the donor site was performed in all cases. Dissection of the muscular tissue was avoided. After the operation, venous crisis occurred in 1 case, and a partial area of necrosis developed at the distal end in 1 case. The flap survived in all other cases. Conclusions Our experience showed that the SLSAP flap is suitable for reconstruction of moderate-sized hand defects.

Absorbable scaphoid screw development: a comparative study on biomechanics

Background The scaphoid is critical for maintaining the stability and movement of the wrist joints. This study aimed to develop a new internal fixator absorbable scaphoid screw (ASS) for fixation of the scaphoid waist after fracture and to test the biomechanical characteristics of ASS. Materials and methods An ASS was prepared using polylactic acids and designed based on scaphoid measurements and anatomic features. Twenty fractured scaphoid waist specimens were randomly divided into experimental and control groups (n=10/group). Reduction and internal fixation of the scaphoid were achieved with either Kirschner wires (K-wires) or ASS. A moving target simulator was used to test palmar flexion and dorsal extension, with the range of testing (waist movement) set from 5° of palmar flexion to 25° of dorsal extension. Flexion and extension were repeated 2,000 times for each specimen. Fracture gap displacements were measured with a computerized tomography scanning. Scaphoid tensile and bending strengths were measured by using a hydraulic pressure biomechanical system. Results Prior to biomechanical fatigue testing, fracture gap displacements were 0.16±0.02 mm and 0.22±0.02 mm in the ASS and K-wire groups, respectively. After fatigue testing, fracture gap displacements in the ASS and the K-wire groups were 0.21±0.03 mm and 1.52±0.07 mm, respectively. The tensile strengths for the ASS and K-wire groups were 0.95±0.02 MPa and 0.63±0.02 MPa, respectively. Conclusion Fixation using an ASS provided sufficient mechanical support for the scaphoid after fracture.