Objective:To investigate effects of bone-resorptive lesion on stress distribution of femoral head and on progression in patients with osteonecrosis of the femoral head (ONFH).Methods:From April 2014 to September 2018, a total of 155 femoral heads from 94 patients diagnosed with ARCO stage II and III ONFH were retrospectively reviewed, including 77 males and 17 females with aged 39.90±10.45 years old (ranged from 18-64 years). The hips were divided into two groups according to whether there were bone-resorptive lesions. Further, we compared whether there was statistical difference between the two groups in staging. Then, a case of ARCO II hip joint without bone-resorptive lesion was selected from the included patients. Six femoral head with different diameters of spherical bone-resorptive lesion of 5 mm, 7 mm, 10 mm, 14 mm, 18 mm, and 23 mm were simulated. The influence of bone-resorptive lesion on the stress distribution of necrotic area and a spherical shell extending 1 mm radially around the bone-resorptive lesion was investigated by finite element method in slow walking conditions.Results:Of the 155 ONFH hips, 67 hips are complicated by bone-resorptive lesions, of which 17 were ARCO II, 50 were ARCO III. A total of 88 hips did not contain bone-resorptive lesions, of which 58 were ARCO II, ARCO III 30 cases. The proportion of ARCO stage II in the group with bone-resorptive lesions was significantly higher than that in the group without bone-resorptive lesions (χ 2=25.03, P=0.000). The finite element stress distribution cloud diagram showed that there was a stress concentration area around the bone-resorptive lesions. The maximum von Mises stress around bone-resorptive lesions in the models that contained a synthetic bone-resorptive lesions were significantly higher than those reported in the matched, non-synthetic bone-resorptive lesions finite element models ( t=3.139, P=0.026). The values for maximum von Mises stress around bone-resorptive lesions were 6.94±1.78 MPa and 5.01±0.35 MPa for the group with synthetic bone-resorptive lesions and the group non-synthetic bone-resorptive lesions, respectively. There was a positive correlation between the diameter of bone-resorptive lesions and the maximum and mean von Mises stress of necrotic areas as well as the maximum von Mises stress around bone-resorptive lesions. Conclusion:Bone-resorptive lesions can increase the maximum stress and average stress in the necrotic area. The larger the bone-resorptive lesion, the more the stress increases. There is a stress concentration area around the bone-resorptive lesions, which may accelerate the collapse of the femoral head.

BACKGROUND:Transforming growth factor β1 (TGF-β1) and interleukin 1β (IL-1β) have been reported to play an important role in the occurrence and development of primary osteoarthritis. OBJECTIVE:To investigate the association between gene polymorphisms of TGF-β1 and IL-1β and primary knee osteoarthritis. METHODS: Han and Uyghur elderly populations in Xinjiang Uygur Autonomous Region, China were surveyed on the prevalence of osteoarthritis, followed by allotted to osteoarthritis and health groups according the symptoms and radiography. Genotyping TGF-β1-509C/T and -1348C/T and IL-1β-511C/T was performed to analyze the relationship between the gene polymorphisms of TGF-β1 and IL-1β and osteoarthritis. RESULTS AND CONCLUSION:Alleles T and C with genotypes CC, CT and TT were detected in both two groups. In the Uygur population, the genotype frequency of TGF-β1-509C/T and IL-1β-511C/T showed significant difference between osteoarthritis and health groups (P < 0.05). In the Han population, the genotype frequency of TGF-β1-1348C/T showed significant difference between two groups (P < 0.05). These results suggest that the Uygur individuals carrying TT genotype of TGF-β1-509C/T and IL-1β-511C/T, and Han people carrying the TT genotype of TGF-β -1348T are more susceptible to osteoarthritis.

BACKGROUND:Accumulative evidence supports that co-culture technology can be applied to construct the tissue-engineered cartilage with excellent biological characters. OBJECTIVE:To elaborate the co-culture concept and conclude and analyze seed cell sources, cel mixed ratio, spatial y-defined co-culture models and biomaterials in co-culture systems to conclude and analyze the biological characters of tissue-engineered cartilage, and to prospect progression of co-culture systems in cartilage tissue engineering. METHODS:The first author retrieved the databases of PubMed, Web of Science, and CNKI for relative papers published from January 1976 to May 2016 using the keywords ofco-culture, co-culture systems;articular cartilage, chondrocytes, mesenchymal stem cells;tissue engineering, articular cartilage tissue engineeringin English and Chinese, respectively. Finally 60 literatures were included in result analysis, including 1 Chinese and 59 English articles. RESULTS AND CONCLUSION:Co-culture technology emphasizes the role of microenvironment in terms of various physical, chemical and biological factors in the cell processing. In cartilage tissue engineering, co-culture systems contribute to maintain the viability and natural cell phenotype of chondrocytes and induce cartilage differentiation of mesenchymal stem cells. In addition, co-culture technology provides a novel way for cartilage tissue engineering to overcome the shortage of chondrocytes and repair injury to the cartilage-subchondral bone. However, the mechanisms of cell-cell interaction in co-culture systems still need to be explored in depth, so as to optimize the co-culturing conditions and construct perfect tissue-engineered cartilage.

BACKGROUND: How to promote the regeneration after peripheral nerve injury, especially after large defects, is a difficulty to be solved.OBJECTIVE: To review the mechanism of Wallerian degeneration and the development of nerve conduits.METHODS: PubMed database was searched for the literatures addressing the modular mechanism of Wallerian degeneration and nerve repair using the English keywords peripheral nerve regeneration, Wallerian degeneration, nerve guidance conduits. A total of 74 eligible literatures were included based on the exclusion criteria.RESULTS AND CONCLUSION: Rat SARM1 and fruit fly dSARM have been found to be highly implicated in Wallerian degeneration, indicating that the changes of nicotinamide adenine nucleotide/nicotinamide adenine dinucleotide may be related to the activated SARM1. Whether delaying Wallerian degeneration is good or bad is still in dispute. The future study should focus on the early inhibition of Wallerian degeneration and promotion of neuroregeneration following peripheral nerve injury.

BACKGROUND:Cartilage tissue engineering has been widely used to achieve cartilage regeneration in vitro and repair cartilage defects. Tissue-engineered cartilage mainly consists of chondrocytes, cartilage scaffold and in vitro environment. OBJECTIVE:To mimic the environment of articular cartilage development in vivo, in order to increase the bionic features of tissue-engineered cartilage scaffold and effectiveness of cartilage repair. METHODS: Knee joint chondrocytes were isolated from New Zealand white rabbits, 2 months old, and expanded in vitro. The chondrocytes at passage 2 were seeded onto a scaffold of articular cartilage extracelular matrix in the concentration of 1×106/L to prepare cel-scaffold composites. Cel-scaffold composites were cultivated in an Instron bioreactor with mechanical compression (1 Hz, 3 hours per day, 10% compression) as experimental group for 7, 14, 24, 28 days or cultured staticaly for 1 day as control group. RESULTS AND CONCLUSION:Morphological observations demonstrated that the thickness, elastic modulus and maximum load of the composite in the experimental group were significantly higher than those in the control group, which were positively related to time (P < 0.05). Histological staining showed the proliferation of chondrocytes, formation of cartilage lacuna and synthesis of proteoglycan in the experimental group through hematoxylin-eosin staining and safranin-O staining, which were increased gradualy with mechanical stimulation time. These results were consistent with the findings of proteoglycan kit. Real-time quantitative PCR revealed that mRNA expressions of colagen type I and colagen type II were significantly higher in the experimental group than the control group (P < 0.05). The experimental group showed the highest mRNA expression of colagen type I and colagen type II at 21 and 28 days of mechanical stimulation, respectively (P < 0.05). With the mechanical stimulation of bioreactor, the cel-scaffold composite can produce more extracelular matrix, such as colagen and proteoglycan, strengthen the mechanical properties to be more coincident with thein vivo environment of cartilage development, and increase the bionic features. With the progress of tissue engineering, the clinical bioregeneration of damaged cartilage wil be achieved.

BACKGROUND:Magnesium can be degraded voluntarily in vivo, so a second surgery is avoided. However, its aloys have not been widely used in the clinical orthopedics because there is a lack of accurate and reliable methods to assess its degradationin vivo.
OBJECTIVE:To explore the degradation of micro-arc-oxidized AZ31 magnesium aloy in the femoral condyle of rabbits based on micro-CT images and relative data.
METHODS:Forty micro-arc-oxidized AZ31 magnesium aloys were implanted into the right femoral condyle of 40 New Zealand rabbits. Then 10 right femoral condyles were removed at 5, 10, 15 and 20 weeks after surgery, respectively, to quantitatively analyze and evaluate the degradation of AZ31 magnesium aloys by micro-CT images and relative data.
RESULTS AND CONCLUSION:The surface of AZ31 aloys was corroded progressively with dark color and distorted appearance at 5-20 weeks post implantation. Micro-CT images showed that in the first 5 weeks, the degradation was inactive, and at the 10th week, it turned active; at the 15th week, the corrosion pits were obviously increased in number, and the corrosion area and corrosion speed were enlarged and fastened, respectively. Up to the 20th week, the aloy surfaces were ful of corrosion pits besides roughness and discontinuity. Relevant data analysis showed that the volume fraction of magnesium aloy was 98.6%, 97.1% and 86.4% at the 5th, 10th and 20th weeks after implantation, respectively, and it had a significant decrease from the 10th to 15th week and from the 15th to 20th week (P < 0.05). Within 15-20 weeks, the volume fraction of magnesium aloy was decreased by 6.5% that was the maximum volume reduction per unit cycle. With the progress of corrosion, the surface continuously became rough and vague, and its surface area was enlarged; the ratio of surface area to volume continuously increased, and there was a significant difference at 15 and 20 weeks (P < 0.05). Because of the increasing number of corrosion pits, the cross-sectional radius decreased, which was reflected by the trabecular thickness decreasing from 1.00 to 0.87 mm. From the view of the slope of curve, the trabecular thickness decreased most rapidly at 10-15 weeks. The mineral density of magnesium aloy continuously decreased from 649.302 to 356.445 mg/cm3 during the whole experiment period (P< 0.05). In addition, the micro-CT image density decreased from 679.710 to 644.947 mg/cm3, but there was no significant difference. To conclude, the degradation speed is peaked at 10-20 weeks after implantation, and the content of magnesium aloys decrease with degradation, but the magnesium density has no significant change.

Objective To determine the effect of NEL-like type 1 gene (NELL-1) transfection in vivo in the repair of traumatic femoral head necrosis.Methods Twenty-four SD rats were randomly divided into three groups (8 rats per group) according to the lottery method,ie,sham group (served as normal control),NELL-1 treatment group (injected NELL-1 gene by recombinant adenovirus vectors around the hip one week after osteonecrosis model induced surgically) and placebo group (given an equal volume of saline solution at the same time after the induction of osteonecrosis).Femurs were taken from the animals 5 weeks after surgery.Gross observation was performed for morphology changes,X-ray assessment for femoral head height and length ratio (H/L),Micro-CT measure for bone parameters of femoral head including total volume (TV),bone volume (BV),total mineralized content (TMC),trabecular thickness (Tb.Th) and trabecular space (Tb.SP),and histological study for osteocytes,osteoblasts and osteoclasts.Results Preserved femoral head shape was noted in NELL-1 treatment group compared to the obvious flattening of the femoral head in placebo group.No heterotopic osteogenesis was observed in any group.Femoral head H/L ratio for 0.753 2 ± 0.040 2 in NELL-1 treatment group was higher than 0.598 4 ± 0.037 0 in placebo group (P ＜ 0.05),but lower than 0.920 2 ± 0.037 0 in sham group (P＜0.05).TV,BV,TMC and BMD between NELL-1 treatment and sham groups did not differ significantly (P ＞ 0.05),but all were increased compared to placebo group (P ＜ 0.05).There was no significant differences in Tb.Th and Tb.SP among three groups (P ＞ 0.05).Most osteocytes were alive in NELL-1 treatment group.More active osteoblasts and osteoclasts were noted in NELL-1 treatment group than those in placebo group.Conclusion NELL-1 gene transfection can preserve femoral head shape and bone content,promote osteoblast activity and neovascularization and hence is an effective treatment for rat traumatic osteonecrosis.However,the activity of osteoclasts is stimulated simultaneously.

BACKGROUND:Cartilage extracelular matrix with a large number of signaling molecule proteins and factors is likely to be an ideal material for tissue engineering cartilage.
OBJECTIVE: To investigate the possibility of calcium alginate and cartilage extracelular matrix combined with microencapsulated stem cels derived from human umbilical cord Wharton’s jely to construct ectopic tissue-engineered cartilage in nude mice.
METHODS: Microfilament suspension of the cartilage extracelular matrix was prepared. Human stem cels derived from Wharton’s jely of the umbilical cord were inoculated in to calcium alginate and cartilage extracelular matrix gel microspheres as experimental group. Stem cels derived from human umbilical cord Wharton’s jely were incubated in simple alginate gel microspheres as control group. After in vitro culture, the microspheres wereimplanted into the dorsal subcutaneous tissue of nude mice. Samples were taken after 4 weeks, respectively, for gross and histological observation.
RESULTS AND CONCLUSION:The stem cels exhibited paralel-chondrocyte morphology in microspheres, which grew and proliferated quite wel during in vitro culture. A new paralel-cartilaginous tissue was found in the subcutaneous tissue 4 weeks after surgery in the experimental group, and the tissue was positive for hematoxylin-eosin, safranine O, toluidine blue and colagen II. A large number of paralel-chondrocytes and cartilage lacuna-like structures were observed under a microscope with no obvious inflammatory reaction around the microspheres. The control group showed the partial degradation of microspheres, surrounded by only a smal number of inflammatory cels and lymphocytes. Calcium alginate and cartilage extracelular matrix microspheres have a rather good histocompatibility which can be used to construct paralel-cartilaginous tissues by implanting stem cel-microspheric compound into the subcutaneous tissue of nude mice.

Objective To compare the bone microstructure and osteoblast and osteoclast activity in different regions of osteonecrosis of the femoral head.Methods The osteonecrosis femoral heads were collected from 10 patients (Ficat Ⅳ) who had undergone total hip arthroplasty from March 2011 to May 2013.There were 6 males and 4 females.Their average age was 47.7 years old (range,40-57 years).The samples were divided into subchondral bone region,necrotic region,sclerosis region and healthy region according to radiographic results,then the bone microstructure,micro mechanism and osteoblasts/osteoclasts activity were analyzed byMicro-CT,RT-PCR,Nanoindentation,immunohistochemistry and Trap staining.Results According to the micro-CT results,the continuity of trabecular bone in necrotic region was damaged.The number of trabecular was increased and the gap was narrowed in sclerosis region.The shape and number of trabecular bone were normal in the healthy region.The elasticity moduli in different regions were:subchondral bone region 13.808±4.22 GPa,necrotic region 13.999±3.816 GPa,sclerosis region 17.266±3.533 GPa and healthy region 11.927±1.743 GPa.The hardness were subchondral bone region 0.425±0.173 GPa,necrotic region 0.331±0.173 GPa,sclerosis region 0.661±0.208 GPa,and healthy region 0.423±0.088 GPa.The trap staining of subchondral bone in healthy region and necrotic region were positive while other regions were negative.Immunohistochemistry staining showed that compared with necrotic region,the RANK and RANKL staining level increased significantly in subchondral bone and necrotic region,while Runx2 and BMP2 staining level increased significantly in sclerosis region.Conclusion The mechanical properties of trabecular have no significant difference between necrotic region and healthy region in the progress of the osteonecrosis,while the bone structure has obvious changes.An active bone resorption is observed in subchondral bone and necrotic region,while a higher bone formation activity is found in sclerosis region.

Objective To probe the immunological traits of mesenchymal stem cells derived from umbilical cord Wharton's jelly (WJMSCs). Methods The diced Wharton's jelly which was from healthy fullterm birth human umbilical cord was cultured. The mesenchymal stem cells were identified with mesenchymal stem cells markers expression by flow cytometry and multiple differentiation ability. The expression of MHC- Ⅰ / Ⅱ, costimulatory molecules (CD40, CD80 and CD86) was detected with flow cytomctry, immunocytochemistry, and RT-PCR. The expression of immune inhibitors like HLA-G, IDO, and PGE2 was detected by immunocytochemistry and RT-PCR. The expression of immune-related molecules as IL-10, TGF-β, FGF and VEGF was detected with antibody microarray and western blot. Further more, to clarify the in vivo immune reaction of hWJMSCs, we fabricated the hWJMSC-scaffold constructs and implanted them into the rabbit backs. The lymphocyte infiltration and implanted cell survival observed with immunofluorescence. Results After culturinge of diced Wharton's jelly tissue, we obtained spindle-shaped cells. With differentiation medium, the cells can differentiate into osteoblasts, chongdrocytes, adipose cells and schwann cells. Expression of MHC, costimulatory molecules, and a series of immune suppressive-related molecules was found. Immune inhibitors as HLA-G, 1DO, PGE2, and immune suppressive related molecules as HGF, VEGF, TGFand IL-10 were positively expressed. But the cells did not express MHC-Ⅱ. No immune rejection was observed in vivo after implantation of hWJMSC-scaffold constructs. Conclusion It can be concluded that hWJMSCs have very low immunogenicity, which means the cells have potential to induce immune tolerance.The hWJMSCs do not provoke immune rejection in vivo.