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【Objective】 To study the changes in serum immunoglobulin levels in children with thalassemia who undergo repeated blood transfusions and explore their correlation with delayed hemolytic transfusion reactions(DHTR). 【Methods】 Serum samples from children with thalassemia who received blood transfusion treatment from June 2022 to April 2023 (observation group) and healthy children who underwent physical examination (control group) in our hospital were collected. The levels of serum immunoglobulins (IgG subtype, IgM, IgA, IgE and IgD) were detected using flow cytometry CBA multi-factor quantitative detection technology, and the differences between the two groups were compared. The children were divided into 4 groups according to different transfusion numbers: ≤10 numbers, 11-30 numbers, 31-50 numbers and >50 numbers, and the differences between different blood transfusion numbers and serum immunoglobulin levels in each group were compared using one-way analysis of variance (ANOVA). Children with thalassemia with DHTR were in the hemolysis group, and children with thalassemia who did not experience DHTR were in the non-hemolysis group. The changes in serum immunoglobulins (IgG subtypes, IgM, IgA, IgE and IgD) between the two groups were compared to explore the correlation between serum immunoglobulins in thalassemia children with repeated transfusion and DHTR. 【Results】 The levels of IgG1, IgG3, IgG4 and IgA in the observation group were significantly higher than those in the control group, with the increase of(2.07±2.12), (0.67±2.03), (0.30±0.37)and(6.04±11.40)mg/mL, respectively, while the level of IgD in observation group was significantly lower than that in the control group, with a decrease of(0.03±0.01)mg/mL, P0.05). IgG1 and IgG4 both significantly increased with the number of blood transfusions.The IgG1 in the 4 groups increased sequentially as(0.30±0.62), (0.41±0.51)and(3.60±3.48)mg/mL, and IgG4 increased sequentially as (0.12±0.13), (0.22±0.07) and (0.21±0.38)mg/mL. IgG2, IgM and IgD showed a significant decrease, with IgG 2, IgM, and IgD in four groups decreased as(0.91±1.50), (0.14±0.10)and(0.05±0.05)mg/mL, respectively, showing significant differences with the number of blood transfusions(P0.05). IgG1, IgG3 and IgG4 in the hemolysis group were significantly higher than those in the non-hemolysis group, with an increase of (4.44±3.41), (0.73±1.26)and(0.52±0.40), respectively(P0.05). 【Conclusion】 The serum immunoglobulin levels of children with thalassemia who undergo repeated blood transfusions are abnormal. There are differences in correlation between the number of blood transfusions and serum immunoglobulin levels among children with thalassemia who undergo repeated blood transfusions. The relevant serum immunoglobulins for DHTR in children with thalassemia who undergo repeated blood transfusions are IgG1, IgG3 and IgG4.
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Objective To investigate the influence of different cell structures on the static and dynamic mechanical performance of porous titanium alloy scaffolds,and to provide a theoretical mechanical basis for the application of scaffolds in the repair of mandibular bone defects.Methods Porous titanium alloy scaffolds with diamond,cubic,and cross-sectional cubic cell structures were manufactured using three-dimensional printing technology.Uniaxial compression tests and ratcheting fatigue with compression load tests were conducted to analyze the static and dynamic mechanical performances of scaffolds with different cell structures.Results The elastic moduli of the diamond cell,cross-sectional cubic cell,and cubic cell scaffolds were 1.17,0.566,and 0.322 GPa,respectively,and the yield strengths were 71.8,65.1,and 31.8 MPa,respectively.After reaching the stable stage,the ratcheting strains of the cross-sectional cubic,diamond,and cubic cell scaffolds were 3.3%,4.0%,and 4.5%,respectively.The ratcheting strain increased with increasing average stress,stress amplitude,and peak holding time,and decreased with increasing loading rate.Conclusions The evaluation results of the static mechanical performance showed that the diamond cell scaffold was the best,followed by the cross-sectional cubic cell scaffold and the cubic cell scaffold.The evaluation results of the dynamic mechanical performance showed that the cross-sectional cubic cell scaffold performed the best,followed by the diamond cell scaffold,whereas the cubic cell scaffold performed the worst.The fatigue performance of the scaffold is affected by the loading conditions.These results provide new insights for scaffold construction for the repair of mandibular bone defects and provide an experimental basis for further clinical applications of this scaffold technology.
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【Objective】 To investigate the changes in cellular immunity (peripheral blood lymphocyte subsets) and humoral immunity (serum immunoglobulin and ferritin) status among children with thalassemia who received repeated transfusions in Yunnan. 【Methods】 Forty-six children with thalassemia who underwent repeated blood transfusions from January 2020 to October 2022 were selected as the observation group. Forty children with thalassemia who did not receive blood transfusion were included in control group 1, and 46 healthy children underwent physical examination were included in control group 2. The differences in lymphocyte subsets, serum immunoglobulin levels and ferritin concentrations were compared among the three groups. 【Results】 For lymphocyte subsets: CD3+, CD4+ and CD4+/CD8+ in the observation group was lower than the control group 1 and 2: 57.60±8.36 vs 64.57±7.56 vs 66.58±5.65, 33.16±5.67 vs 38.62±8.36 vs 38.62±6.41 and 1.49±0.09 vs 2.32±0.15 vs 2.13±0.16, respectively; CD16+ CD56+ in the observation group was lower than the control group 2: 11.21±5.06 vs 16.70±7.92; CD8+ in the observation group was higher than control group 1 and control group 2: 26.63± 1.75 vs 20.60±1.43 vs 18.92±0.84; CD19+ in the observation group was higher than the control group 2: 24.06±6.42 vs 19.67 ±8.42, P<0.05, but no significant difference was noticed between the two control groups(P>0.05). For serum immunoglobulin and ferritin: IgG and ferritin in the observation group were higher than control group 1 and control group 2: 10.59±3.88 vs 7.02±3.88 vs 5.58±1.98 and 2 037.37±1 377.59 vs 72.63±56.71 vs 59.48±33.88. IgA in the observation group was higher than the control group 2: 1.06±0.92 vs 0.39±0.32(P<0.05), but no significant difference was noticed between the two control groups (P>0.05). The difference of IgM and IgE between the three groups was not significant (P > 0. 05). 【Conclusion】 The proportion of lymphocyte subsets in thalassemia children with repeated blood transfusion was imbalanced,and the level of immunoglobulin in humoral immunity was abnormal.
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【Objective】 To share the experience of autologous platelet-rich plasma(PRP) combined therapy in successful treatment of refractory osteomyelitis with fractures in children. 【Methods】 One case of refractory osteomyelitis with fracture in children failed to respond to traditional treatment for more than 14 months. A total of 20 mL of whole blood was collected from the child, and 6 mL of PRP with 4 to 5 times concentration was prepared by secondary centrifugation. To prepare 2 cm×2 cm platelet concentrate gel (PG), 3 mL of PRP was mixed with a 0.3 mL activator which was then covered with an absorbable dressing. A three-way tube sprayed the remaining 3 mL of PRP and 0.3 mL activator into the surrounding tissues. 【Results】 The X-ray film of the patient followed up for 1 week showed that the fracture line was blurred, and the fracture end had obvious callus formation. The X-ray film reexamination at 4 months showed that the fracture end healed well, the fracture surface healed, and the osteomyelitis healed. 【Conclusion】 Autologous PRP has a good effect in the treatment of refractory osteomyelitis combined with fracture in children, which can provide a new method for clinical treatment.
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As a kind of elastic load-bearing connective tissues on bone surface in dynamic joints, articular cartilage can provide low wear lubrication, shock absorption, load transfer and other supporting functions, and has hierarchical fiber composite structures and excellent mechanical properties. As an avascular and aneural tissue,the degenerated articular cartilage lacks the capability of self-healing after damage. The high incidence of arthritisis still a hot spot in basic and clinical researches. Articular cartilage is a mechanical sensitive tissue, andmechanical environment will affect the development of tissues in different directions. Extensive researches onbiomechanics and mechanobiology of articular cartilage were conducted in 2022. Many studies on morphology, function and mechanical state of cartilage,as well as mechanical state of cartilage under different conditions were reported. Some cartilage-related loading devices were designed at animal, tissue and cell levels. Researches onthe repair of cartilage degeneration and injury under mechanical loads were carried out in vitro and in vivo, andsome important repair method and means were obtained. The biomechanical and mechanobiology research on articular cartilage is the basis of arthritis, cartilage defect and repair. The influence of quantitative mechanical under 4 conditions on the repair of articular cartilage injury needs further study in vivo and in vitro
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Objective To study stress relaxation behaviors of cartilage scaffolds under different degradation cycles by using finite element analysis combined with theoretical models. Methods Based on the established degradation theoretical model, the elastic modulus of the scaffold was calculated under different degradation cycles. The finite element model of cartilage scaffolds was established and stress relaxation simulation was performed to analyze the variation of scaffold relaxation stress with time. The stress relaxation constitutive model was established to predict mechanical properties of the scaffold. Results The elastic modulus of cartilage scaffolds at 14 th, 28th, 42nd, 56th day after degradation was 32. 35, 31. 12, 29. 91, 28. 74 kPa, respectively. The upper layer for cartilage scaffolds was the largest. The overall relaxation stress of the scaffold decreased rapidly with time and then tended to be stable. At 8th week after degradation, the stress which the scaffold couldwithstand was still within the physiological load range of the cartilage. The predicted results of the stress relaxation constitutive model were in good agreement with the finite element simulation results. Conclusions The elastic modulus of the scaffold gradually decreases with the increase of degradation time. The longer the degradation period is, the less stress the scaffold can withstand. At the same degradation period, the larger the applied compressive strain, the larger the stress on the scaffold. Both the finite element simulation and stress relaxation constitutive model can effectively predict stress variations of cartilage scaffolds under degradation
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Objective To study the effect of irrigation mechanical stimulation on scaffold degradation by numerical simulation, so as to predict its degradation degree. MethodsBased on perfusion experimental data, the fluid-solid coupling model was established by Comsol. The finite element model of scaffold was established by ABAQUS. Based on the models, the degradation performance of scaffold was simulated and predicted. Results The fluid-solid coupling simulation showed that the initial pressure at the speed of 15.79 mL/min was two-fold of that at 7.89 mL/min. Along the thickness of scaffold from the surface to the bottom, the pressures between the two velocities were decreased and gradually close to each other. The degradation of scaffold structure could be simulated dynamically by combining the degradation constitutive model with the finite element model. The obtained degradation data were consistent with the experimental data, and the residual molecular weight reached 0.643 on the 56th day. Compared with the experimental data, the simulation accuracy was higher than 98%. Conclusions The larger the perfusion velocity is, the greater the pressure on scaffold will be. Under the same perfusion velocity, the maximum force occurs on the surface of scaffold. The degradation pattern of scaffold can be predicted by applying the degradation constitutive model and the finite element model.
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The small molecule nutrients and cell growth factors required for the normal metabolism of chondrocyte mainly transport into the cartilage through free diffusion. However, the specific mass transfer law in the cartilage remains to be studied. In this study, using small molecule rhodamine B as tracer, the mass transfer models of cartilage were built under different pathways including surface pathway, lateral pathway and composite pathway. Sections of cartilage at different mass transfer times were observed by using laser confocal microscopy and the transport law of small molecules within different layers of cartilage was studied. The results showed that rhodamine B diffused into the whole cartilage layer through surface pathway within 2 h. The fluorescence intensity in the whole cartilage layer increased with the increase of mass transfer time. Compared to mass transfer of 2 h, the mean fluorescence intensity in the superficial, middle, and deep layers of cartilage increased by 1.83, 1.95, and 3.64 times, respectively, after 24 h of mass transfer. Under lateral path condition, rhodamine B was transported along the cartilage width, and the molecular transport distance increased with increasing mass transfer time. It is noted that rhodamine B could be transported to 2 mm away from cartilage side after 24 h of mass transfer. The effect of mass transfer under the composite path was better than those under the surface path and the lateral path, and especially the mass transfer in the deep layer of cartilage was improved. This study may provide a reference for the treatment and repair of cartilage injury.
Subject(s)
Cartilage, Articular , Rhodamines/pharmacology , ChondrocytesABSTRACT
Objective To design a novel strain loading device for studying the mechanical biology of adherent cells. Methods Based on the technology of substrate deformation loading, the device adopted controllable stepper to cause deformation of the silastic chamber, so as to realize cell loading with multiple units and large strain. The device was developed to test its loading functions. The three-dimensional (3D) models of the silastic chamber were established to simulate the loaded chamber by the finite element technology, and uniformity of the strain field was analyzed. The device applied 5% strain to bone marrow stromal cells (BMSCs) with 0.5 Hz stretch frequency at 2 hours per day for 5 days, and an inverted phase contrast microscope was used to observe the morphology of BMSCs. Results The developed strain loading device for adherent cells in vitro could provide mechanical unidirectional strain up to 50% with three groups of cell loading substrates; within the 10% stain range, the area of uniform strain filed on the silastic chamber remained above 50%, which ensured that the cells were loaded evenly; the morphology of BMSCs was obviously altered, and the direction of arrangement tended to be perpendicular to the loading direction of principal strain. Conclusions The device shows the advantages of reliable operation, wide strain range, adjustable frequency and convenient operation. It can be used to load multiple cell culture substrates at the same time, which provides convenient conditions for the study of cell mechanobiology.
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Natural degeneration or trauma of articular cartilage all can lead to its structural and functional damage. Without blood supply and nerve innervation, chondrocytes in the matrix lacunae obtain essential nutrients and excrete metabolites mainly through osmosis, finally leads to its low metabolic activity and difficulty in self-repair after injury. At present, drug conservative treatment and surgical operation are the main clinical treatment, but both of them can't meet the clinical needs well. The development of cartilage tissue engineering provides a new direction for the repair of articular cartilage injury, in which growth factors plays a very important role. Growth factors, together with seed cells and cell scaffolds, constitute the three elements for the construction of tissue-engineered cartilage. Among them, Growth factors can significantly promote cell proliferation and differentiation and induce their functions. Various growth factors synergistically mediate the differentiation of seed cells into chondrocytes. In recent years, stem cell cartilage tissue engineering developed rapidly, which has opened a new way for repair of articular cartilage damage due to its abundant cell resources, small damage to body itself, strong ability of proliferation and directional differentiation, biological repair and other prominent advantages. Different types of hydrogels and stem cells show different abilities to support chondrogenesis and require different growth factors to induce chondrocyte differentiation. Traditional growth factors for tissue engineering include transcription growth factor β, insulin-like growth factors, bone morphogenetic proteins, fibroblast growth factors and cartilage derived morphogenetic protein. Recently, some scholars found that platelet-rich plasma, platelet-rich fibrin, Kartogenin and Mechano-growth factor can also effectively induce chondrogenic differentiation of stem cells and maintain chondrocyte phenotype. In addition, some synthetic compounds such as dexamethasone and inorganic particles can also promote the differentiation of stem cells into cartilage. This article systematically summarized the new progress of the traditional growth factors, emphatically introduced the new discovered growth factors and some synthetic compounds and inorganic particles, which can induce stem cells into cartilage. Finally classified the different sources of stem cells and its suitable growth factors, and gave an outlook of the next research direction of growth factors.
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As the main organ of the body, the load-bearing ability of bone is closely connected to its biomechanical properties. Bone is a complex hierarchical biomaterial, whose biomechanical properties are determined by its own structure and biological characteristics. Because of its mechanical adaptability, bone tissues represent different biomechanical properties under different mechanical loading. To quantify the complicated properties of bone and provide an accurate theoretical basis for clinical research, it is necessary to give insight into the biomechanical properties of bone at different levels and the constitutive relationships of bone tissues. In this review, relative researches on constitutive relationships in recent years were summarized based on its hierarchical biomechanical properties.
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As the main organ of the body, the load-bearing ability of bone is closely connected to its biomechanical properties. Bone is a complex hierarchical biomaterial, whose biomechanical properties are determined by its own structure and biological characteristics. Because of its mechanical adaptability, bone tissues represent different biomechanical properties under different mechanical loading. To quantify the complicated properties of bone and provide an accurate theoretical basis for clinical research, it is necessary to give insight into the biomechanical properties of bone at different levels and the constitutive relationships of bone tissues. In this review, relative researches on constitutive relationships in recent years were summarized based on its hierarchical biomechanical properties.
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BACKGROUND: The silk fibroin/type II collagen composite scaffold has been prepared by low-temperature bio-3D printing technology in the previous study and the scaffold has good mechanical properties. Studies have shown that mechanical stimulation is beneficial to bone remodeling, and gradient loading strain is beneficial to the activation of osteoblasts and osteoclasts. OBJECTIVE: To co-culture silk fibroin/type II collagen composite scaffolds with chondrocytes under compression loading, to observe the proliferation of cells, and to observe the preliminary repair effect of silk fibroin/type II collagen composite scaffold on cartilage defects. METHODS: The silk fibroin/type II collagen composite scaffold was prepared by low-temperature 3D printing to detect the porosity of the scaffold. The passage 3 mouse chondrocytes ADTC-5 were inoculated on the silk fibroin/type II collagen composite scaffold and cultured under static culture and mechanical load respectively. (1) Static culture: blank scaffold was set as control, and cell proliferation was detected by MTT assay at 1, 3, 5, 7, 10, 14 days of inoculation. (2) Culture under mechanical load: blank scaffold was set as control. At 1 day after inoculation, 0％, 1％, 5％, 10％, 15％, 20％ compressive strains were applied to the cell-scaffold complex, and continued to load for 3 days. Cell proliferation was detected by MTT assay, and the distribution, adhesion and morphology of the cells on the scaffold were observed by scanning electron microscopy and hematoxylin-eosin staining. A cartilage defect of 3.5 mm in diameter was made in the bilateral knee joint of New Zealand rabbits. The silk fibroin/type II collagen composite scaffold was implanted onto the left side, and no material was implanted onto the right side. The repair site was observed at 8 weeks after surgery. RESULTS AND CONCLUSION: (1) The porosity of the scaffold was (89.3±3.26)％, which was conducive to cell attachment. (2) After 5 days of static culture, the chondrocytes proliferated well on the surface of the composite scaffold. Under 0％, 1％, 5％, 10％, 15％, 20％ compressive strains, the cell proliferation on the scaffold first increased and then decreased, wherein the cell proliferation was highest under 10％ compressive strain, and lowest under 20％ compressive strain. (4) Under the scanning electron microscopy, the chondrocytes in the 0％ load group were distributed in the surface of the scaffold with irregularities, the cell morphology was obvious, and the cell protrusions were fully extended. There were few or no chondrocytes on the contact surface of the 10％ load group, and more cells distributed on the lateral and internal surfaces of the first layer, but the cell morphology was flat with obvious protrusions. (5) Hematoxylin-eosin staining showed that the chondrocytes in the 0％ load group were concentrated on the surface of the scaffold, and there were almost no cells in the pores, while the chondrocytes in the 10％ load group were distributed in the scaffold pores. (6) There was still a circular defect model with no scaffold implantation, and no obvious repair appeared; similar hyaline cartilage appeared in the defect after scaffold implantation, but there was no adhesion to the surrounding defected cartilage, and the new hyaline cartilage was independent. Overall, the adsorption, proliferation and growth of chondrocytes on the silk fibroin-type II collagen scaffolds is better when the compressive strain is 10％, and the composite scaffold can be used as a repair material for cartilage defects.
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Natural degeneration or trauma of articular cartilage all can lead to its structural and functional damage.Without blood supply and nerve innervation,chondrocytes in the matrix lacunae obtain essential nutrients and excrete metabolites mainly through osmosis,finally leads to its low metabolic activity and difficulty in self-repair after injury.At present,drug conservative treatment and surgical operation are the main clinical treatment,but both of them can't meet the clinical needs well.The development of cartilage tissue engineering provides a new direction for the repair of articular cartilage injury,in which growth factors plays a very important role.Growth factors,together with seed cells and cell scaffolds,constitute the three elements for the construction of tissue-engineered cartilage.Among them,Growth factors can significantly promote cell proliferation and differentiation and induce their functions.Various growth factors synergistically mediate the differentiation of seed cells into chondrocytes.In recent years,stem cell cartilage tissue engineering developed rapidly,which has opened a new way for repair of articular cartilage damage due to its abundant cell resources,small damage to body itself,strong ability of proliferation and directional differentiation,biological repair and other prominent advantages.Different types of hydrogels and stem cells show different abilities to support chondrogenesis and require different growth factors to induce chondrocyte differentiation.Traditional growth factors for tissue engineering include transcription growth factor β,insulin-like growth factors,bone morphogenetic proteins,fibroblast growth factors and cartilage derived morphogenetic protein.Recently,some scholars found that platelet-rich plasma,platelet-rich fibrin,Kartogenin and Mechano-growth factor can also effectively induce chondrogenic differentiation of stem cells and maintain chondrocyte phenotype.In addition,some synthetic compounds such as dexamethasone and inorganic particles can also promote the differentiation of stem cells into cartilage.This article systematically summarized the new progress of the traditional growth factors,emphatically introduced the new discovered growth factors and some synthetic compounds and inorganic particles,which can induce stem cells into cartilage.Finally classified the different sources of stem cells and its suitable growth factors,and gave an outlook of the next research direction of growth factors.
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BACKGROUND: It is of great significance to study the resilience of articular cartilage for human daily routine and their match quality. OBJECTIVE: To analyze the micromechanical properties of articular cartilage resilience under different loads and at time points. METHODS: The swine cartilage samples coated with tracers were compressed using the MTF-100 tensile machine, and the cartilage compression and resilience were recorded by CCD. Images were processed using digital image correlation technology.RESULTS AND CONCLUSION: During resilience, the strain value on the superficial surface of the cartilage was decreased most, successively followed by the middle layer and the deep layer, while the time of a decrease from 20%, 10% and 6% to 3% was similar. The longer the resilience time was, the more slowly the strain changed in different layers of the cartilage, but the ultimate strain was less than 1%. On the same layer under different compressive stress, the larger load caused faster strain change firstly, and then the smaller load brought about faster strain change. The effect of different continuous compressive time on the same layer of cartilage was similar with the load. These results showed that 90% resilience of the articular cartilage occurred within the first 15 minutes. The mechanical resilience of different layers of the articular cartilage has a close relationship with the loading and the loading time, and both compressive time and loading do harm to the resilience of articular cartilage. Besides, the cartilage will rebound to the state before compression.
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Objective To obtain the ratcheting strain of articular cartilage under different loading conditions,and construct the theoretical model so as to predict the ratcheting strain of cartilage.Methods The fresh articular cartilage obtained from the trochlear of distal femur was used as experimental subject.The ratcheting strain of articular cartilage was tested under cyclic compressive loads by applying the non-contact digital image correlation technique.The theoretical model was constructed to predict the ratcheting strain of articular cartilage with different stress amplitudes and stress rates.The results from predictions were compared with the experimental results.Results The ratcheting strain of cartilage increased rapidly at initial stage and then showed the slower increase with cycles increasing.The ratcheting strain increased with stress amplitude increasing when the stress rate was constant.However,the ratcheting strain decreased with stress rate increasing when the stress amplitude was constant.When the stress rate increased,the ratcheting stain decreased.The prediction results of the established theoretical model were in good agreement with experimental results.Conclusions The ratcheting strain of articular cartilage is proportional to the stress amplitude,and inversely proportional to the stress rate.The established theoretical model can predict the ratcheting strain of articular cartilage and provide guidance for the construction of tissue engineered artificial cartilage.
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BACKGROUND:With the development of science and technology and modern aerospace, the effects of mechanobiology in extreme mechanical environment—high acceleration are becoming an issue of concern. Studies have shown that high acceleration has certain effects on the cels. OBJECTIVE:Based on a centrifuge, to design a cel loading centrifuge used for exploration of cel mechanobiology under high acceleration. METHODS:For the cel loading centrifuge, a culture plate or/and culture bottle ful of culture fluid was/were loaded with constant acceleration or variable velocity to explore the experimental feasibility. Besides, a finite element model was built by ANSYS software according to structure and properties of the rotor. The rotor system was calculated under equilibrium and dangerous working conditions, respectively, to analyze the stress and deformation distribution. Moreover, the strength of the main shaft was checked under the dangerous working conditions. Then the analysis results of ANSYS were compared with the results of strength check. RESULTS AND CONCLUSION:Experimental findings showed that the culture plate or/and the culture bottle could be used for (0-40)×g highly constant acceleration or variable acceleration loading. Through the simulation and comparison analysis, we confirmed the reliability of the cel loading centrifuge. This cel loading centrifuge can be used to implement the study of cel mechanobiology under high acceleration in the general biology laboratory. It also provides a basis for wide application of cel loading centrifuge in the future.