Hyperactivation of PI3K/AKT/mTOR signal pathway impairs TNF-α-induced autophagy in mesenchymal stem cells from patients with ankylosing spondylitis / 南方医科大学学报

OBJECTIVE@#To investigate the changes in autophagy of mesenchymal stem cells (MSCs) from patients with ankylosing spondylitis and explore the mechanism for decreased autophagy in ASMSCs.@*METHODS@#MSCs collected from 14 patients with AS (ASMSCs) and from 15 healthy donors (HDMSCs) were cultured in the absence or presence of 25 ng/mL TNF-α for 6 h. Autophagy of the cells was determined by immunofluorescence staining of GFP-LC3B, and the results were confirmed by detecting the protein expressions of autophagy markers LC3 II/LC3 I and P62. The mRNA expressions of the related genes were detected using qRT-PCR, and the protein expressions of the autophagy markers and signaling pathway-related molecules were determined with Western blotting. TG100713 was used to block the PI3K/AKT/mTOR signal pathway, and its effect on autophagy of ASMSCs was evaluated.@*RESULTS@#ASMSCs showed significantly weaker GFP-LC3B puncta staining and lower protein expression levels of LC3 II/LC3 I but higher levels of P62 protein (P < 0.05), indicating a decreased autophagy capacity as compared with HDMSCs. TNF-α-induced ASMSCs showed significantly higher protein expressions of p-PI3K/ PI3K, p-AKT/AKT and p-mTOR/mTOR than HDMSCs (P < 0.05), suggesting hyperactivation of the PI3K/AKT/mTOR signaling pathway in ASMSCs. Blocking PI3K/AKT/mTOR signaling with TG100713 eliminated the difference in TNF-α-induced autophagy between HDMSCs and ASMSCs.@*CONCLUSION@#In patients with AS, hyperactivation of the PI3K/AKT/mTOR signaling pathway results in decreased autophagy of the MSCs and potentially contributes to chronic inflammation.

FGF-2/PELA/BMP-2 microcapsule scaffold promotes osteogenic differentiation of rat periosteum-derived stem cells in vitro / 南方医科大学学报

<p><b>OBJECTIVE</b>To observe the effect of a microencapsule scaffold capable of sustained release of fibroblast growth factor-2 (FGF-2) and bone morphogenetic protein-2 (BMP-2) in promoting the osteogenic differentiation of rat periosteum-derived stem cells (PDSCs) in vitro.</p><p><b>METHODS</b>PDSCs from 4-week-old SD rats, after identification of the surface markers using flow cytometry, were induced to differentiate into osteoblast, chondroblast, and adipocyte lineages. The differentiated cells were verified by staining with Alizarin red, toluidine blue, alcian blue, oil red O and by immunofluorescence assay. FGF-2/PELA/BMP-2, FGF-2/PELA, PELA/BMP-2 and PELA microcapsules were prepared, examined for surface morphologies using scanning electron microscopy (SEM), and tested for controlled release of FGF-2 and BMP-2 using ELISA. The third passage of PDSCs were cultured in the presence of the aqueous extracts of one of the 4 materials, and alkaline phosphatase (AKP) activity in the culture media was detected at 7 and 14 days of culture; the expression levels of osteogenesis-related genes were quantified with quantitative real-time PCR (qRT-PCR). The osteogenic differentiation ability of the PDSCs cultured with the extracts was compared.</p><p><b>RESULTS</b>The PDSCs, which expressed mesenchymal stem cell surface markers, were shown to have osteogenic, chondrogenic and adipogenic differentiation potentials. The cells cultured with the extract of FGF-2/PELA/BMP-2 microcapsules showed the highest AKP activity at 7 and 14 days of culture, and their expression levels of OCN and RunX-2 mRNA were the highest among the 4 groups; RunX-2 expression reached its peak level on day 14, and OCN mRNA expression level increased progressively as the culture time extended.</p><p><b>CONCLUSION</b>FGF-2/PELA/BMP-2 biomimetic controlled release microcapsules preserve the cytokine activities and are capable of promoting the osteogenic differentiation of rat PDSCs.</p>

Analysis of clinical factors correlating with osteoporosis in patients with type 2 diabetes mellitus / 南方医科大学学报

<p><b>OBJECTIVE</b>To analyze the clinical factors that contribute to lowered bone mineral density (BMD) of the lumbar vertebrae in type 2 diabetic patients.</p><p><b>METHODS</b>Forty type 2 diabetic patients with osteoporosis and 40 age- and gender-matched healthy individuals, selected using propensity score method, were examined for BMD of the L1 to L4 vertebrae and the left femur. Age, gender, course of the disease, body mass index (BMI), fasting blood glucose, serum calcium, serum phosphate, urinary calcium, and urinary phosphate were compared between the two groups.</p><p><b>RESULTS</b>BMD of the L1 to L4 vertebras was significantly lower in the diabetic group than in the healthy individuals (P<0.05). In the diabetic patients, BMD showed an obvious difference between male and female patients and was negatively correlated with the course of the disease but positively with BMI, fasting blood glucose, urinary calcium and urinary phosphate; BMD was not correlated with age, serum calcium or serum phosphate in these patients.</p><p><b>CONCLUSION</b>Osteoporosis in type 2 diabetic patients is closely related with gender, BMI, course of the disease and poorly controlled glucose level.</p>

Pullout test in expansive unilateral open-door laminoplasty of the cervical spine with OsteoMed M3 plate and screws: the screw orientation matters / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the impact of screw orientation on the pullout strength of OsteoMed M3 titanium screws in expansive unilateral open-door laminoplasty of the cervical spine.</p><p><b>METHODS</b>Six fresh human cervical spine specimens were randomly numbered and OsteoMed M3 plate and screws were used for an expansive unilateral open-door laminoplasty. The screws were inserted in the lateral mass at different extraversion angles (0°, 30° and 45°). The maximum pullout strength was tested on the ElectroForce material testing machine.</p><p><b>RESULTS</b>The maximum pullout strength was 81.60∓7.33 N, 150.05∓15.57 N, and 160.08∓17.77 N in extraversion angle 0°, 30°, and 45° groups, respectively. The maximum pullout strength was significantly less in extraversion angle 0° group than in 30° and 45° groups (P<0.05), but similar in the latter two groups.</p><p><b>CONCLUSION</b>The pullout strength of the screws inserted at an extraversion angle over 30° provides stronger fixation than an angle of 0° in the unilateral open-door laminoplasty using OsteoMed M3 titanium plate and screws.</p>

Placement of short iliac screw using Galveston technique in lumbosacral fusion / 南方医科大学学报

<p><b>OBJECTIVE</b>To evaluate the effect of placement of short iliac screw using Galveston technique in lumbosacral fusion.</p><p><b>METHODS</b>From October 2003 to August 2007, 18 consecutive patients (mean age 46 years ranging from 25 to 62 years) received placement of short iliac screw in lumbosacral fusion. The patients were followed up for a mean of 18 months (12-23 months), and the effect of lumbosacral fusion was evaluated according to standing anterior-posterior and lateral plain films taken before and after the operation and at the follow-up and also on the basis of symptom relief.</p><p><b>RESULTS</b>The mean time of surgery was 210 min (180-290 min). No complications occurred during and after the operation. According to the evaluation criteria of surgical treatment of low back pain formulated by the spine group of Chinese Orthopedic Association, excellent clinical outcome was achieved in 12 cases, good outcome in 3 cases, and tolerable outcome in 2 cases, with the excellent and good outcome rate of 83%.</p><p><b>CONCLUSION</b>The Galveston technique for short iliac screw placement can obtain satisfactory outcome in the lumbosacral fusion.</p>

Effect of continuous passive motion on basic fibroblast growth factor expression during tendon-bone repair after surgical repair of acute rupture of the supraspinatus tendon in rabbits / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the effect of continuous passive motion (CPM) on basic fibroblast growth factor (b-FGF) expression during tendon-bone repair in rabbits and explore the role of stress in the postoperative repair after acute rotator cuff injury.</p><p><b>METHODS</b>Sixteen rabbits randomized into CPM group (n=8) and non-CPM group (n=8) were subjected to surgically induced acute rupture of the supraspinatus tendon and subsequent surgical repair, with another two rabbits serving as the control. Two weeks after the operation, the rabbits in CPM group underwent CPM training, and those in non-CPM group were normally fed only. At 2, 4, 6, and 8 weeks after the operation, 2 rabbits from each group were sacrificed and the tissue samples were obtained for detecting the changes in b-FGF expression.</p><p><b>RESULTS</b>Two weeks after the operation, b-FGF expression was detected in both groups, and the CPM group showed slightly higher and more diffusive expression. At 4 weeks, b-FGF expression was significantly higher and distributed over a greater area in CPM group and in the non-CPM group. A large number of fibroblasts positive for b-FGF expression were identified in CPM group, aligning in parallel with the tendon membrane. At 6 weeks, b-FGF in the CPM group showed no obvious changes but that in the non-CPM group became lightened. At 8 weeks, b-FGF expression was reduced in both groups, which was more obvious in the non-CPM group.</p><p><b>CONCLUSION</b>CPM can promote b-FGF expression to enhance type III collagen synthesis at the tendon-bone interface in early stage of tendon-bone repair following acute rupture of supraspinatus tendon in rabbits, thereby contributing to tendon-bone recovery after rotator cuff injury.</p>

Indication of fusion for degenerative lumbar spinal stenosis treated by "windows technique" laminoforaminotomy / 中华外科杂志

<p><b>OBJECTIVE</b>To explore the indications of fusion for degenerative lumbar spinal stenosis treated by "windows technique".</p><p><b>METHODS</b>From December 1999 to December 2005, 145 consecutive patients who were treated by primary decompression with "windows technique" laminoforaminotomy for degenerative lumbar spinal stenosis, a retrospective study, were divided into 3 groups (A and B and C) by preoperative lumbar conditions and surgical methods. In group A, 39 patients with spinal instability or degenerative lumbar spondylolisthesis or scoliosis underwent decompression and fusion; in group B, 31 patients with spinal instability or degenerative lumbar spondylolisthesis or scoliosis underwent decompression alone; In group C, 75 patients without spinal instability or degenerative lumbar spondylolisthesis or scoliosis were treated by decompression without fusion. On hospital medical records to review, they were followed up by telephone and out-patient referral. Statistics the duration of hospitalization, operative time, estimated blood loss; Observed recrudescence and reoperation and complication; and using Oswestry Disability Index and Visual Analog Scale and satisfaction rate for efficacy assessment, application SPSS 13.0 software.</p><p><b>RESULTS</b>All 145 patients had at least a 3-year follow-up (ranging 37 to 108 months). In the group C, the duration of hospitalization less than in the group A or B (P < 0.05); In the group A, the operative time and estimated blood loss greater than in the group B or C (P < 0.05); The group B treated by decompression alone in the presence of instability or spondylolisthesis or scoliosis showed the worst results by the Oswestry Disability Index or Visual Analog Scale or ate of satisfaction (P < 0.05). The same good results can be obtained in the group A and C. There were not different about recrudescence or reoperation or complication in the three groups.</p><p><b>CONCLUSIONS</b>Fusion should be performed on patients with instability or degenerative lumbar spondylolisthesis or scoliosis after primary decompression with "windows technique" laminoforaminotomy. The patient with simple lumbar spinal stenosis undergone primary surgery does not require fusion.</p>

Biomechanical evaluation of asymmetrical posterior internal fixation for transforaminal lumbar interbody fusion with transfacetopedicular screws / 南方医科大学学报

<p><b>OBJECTIVE</b>To assess the biomechanical stability of asymmetrical posterior internal fixation for transforaminal lumbar interbody fusion (TLIF) with transfacetopedicular screws (TFPS).</p><p><b>METHODS</b>Range of motion (ROM) testing was performed in 7 fresh-frozen human cadaveric lumbar spine motion segments in flexion/extension, lateral bending, and axial rotation using 10.0 Nm torques at the L3-4 motion segment. The sequential test configurations included intact motion segment, TLIF and ipsilateral pedicle screw (PS), TLIF and ipsilateral PS plus contralateral TFPS according to Boucher technique, and TLIF and bilateral PS. The ROM was determined to assess the construct stability.</p><p><b>RESULTS</b>In flexion/extension, lateral bending, and axial rotation, no measureable difference was found in the ROM between the standard bilateral pedicle screw and the novel asymmetric posterior internal fixation after TLIF. After TLIF, the ipsilateral PS construct provided less segment stability than the novel asymmetric construct with TFPS in flexion, left bending and left rotation. In rotation, the novel asymmetric construct allowed for significant off-axial rotation motions detrimental to the stability and fusion.</p><p><b>CONCLUSION</b>Ipsilateral PS placement plus contralateral TFPS provides stability comparable to that of TLIF with bilateral PS, and can be an alternative in minimal invasive surgery.</p>

A digital model for lumbar motion segment reconstruction and three-dimensional visualization / 南方医科大学学报

<p><b>OBJECTIVE</b>To establish a digital model for reconstruction and three-dimensional visualization of lumbar motion segment from CT images.</p><p><b>METHODS</b>Based on 64 row spiral CT continuous 2-dimensional images of L4-L5 segments, the lumbar structure and various soft tissues were reconstructed with the Mimics software, followed by validation of this model using finite element analysis software.</p><p><b>RESULTS</b>The established three-dimensional digital model of lumbar motion segment included two vertebral bodies, cortical bone, cancellous bone, endplate, annulus fibrosus, nucleus pulposus and 6 types of ligaments. The output result of the digital model can be used to for research of computer aided design, rapid rototyping and finite element analysis.</p><p><b>CONCLUSION</b>The application of thin-layer CT and Dicom standard ensures more accurate digital model establishment, and Mimics software allows more convenient reconstruction of the human skeleton and various soft tissues to facilitate further research.</p>

Surgery simulation with a percutaneous and transpedical interbody bone grafting apparatus / 南方医科大学学报

<p><b>OBJECTIVE</b>To develop a percutaneous and transpedical interbody bone grafting apparatus for vertebral bone defect reconstruction in thoracolumbar fracture correction via minimally invasive operation.</p><p><b>METHODS</b>The percutaneous and transpedical interbody bone grafting apparatus was designed with CAD software, and the reduction effect, range of bone grafting and surgical complications of the apparatus were investigated in adult cadaveric thoracolumbar body and with computerized surgical simulation.</p><p><b>RESULTS</b>The self-designed apparatus was convenient for percutaneous and transpedical interbody bone grafting that did not give rise to complications. CT showed large bone grafting area with increased density in the vertebral body corrected with this apparatus.</p><p><b>CONCLUSION</b>The designed apparatus allows easy manipulation and efficient bone grafting and repositioning. Minimally invasive interbody bone grafting in thoracolumbar fracture can be easily performed with proper application of the apparatus.</p>

Development of an anti-infection nano-hydroxypatite drug delivery microsphere and its drug-release in vitro / 南方医科大学学报

<p><b>OBJECTIVE</b>To develop an anti-infection nano-hydroxypatite (nano-HA) microsphere for local drug delivery for treating osteomyelitis.</p><p><b>METHODS</b>The nano-HA was used as the core carrier to load gentamicin (GM) and coated with poly(-hydroxybutyrate-co- hydroxyvalerate)/polyethylene glycol (PHBV/PEG), which was degradable and biocompatible, to prepare nano-HA-PHBV/PEG-GM microsphere. The surface structure and in vitro drug-release of the microsphere were studied.</p><p><b>RESULTS</b>The microsphere had good drug delivery capability. The samples weighing 90 mg each were soaked in PBS and gentamicin release within the first day was 165.2 microg/ml, which maintained a low release rate in the following days. After 28 days, gentamicin release declined to 8.5 microg/ml, which was higher than the minimal inhibitory concentration of gentamicin (2 microg/ml).</p><p><b>CONCLUSION</b>The local drug delivery system has good drug-release performance in vitro and may possess potential value in clinical management of osteomyelitis.</p>