【摘要】 目的 分析重力因素对二维探测器阵列验证静态调强计划的影响，判断机架角度归为0°的测量方法是否安全可靠。 方法 在0°机架角和实际治疗机架角分别测量静态调强计划的剂量分布，以3 mm范围内偏差lt;3%(3% 3 mm)标准进行γ分析，获得相对于参考剂量分布的通过率，分析通过率变化规律。分析两种方法测量的等中心点绝对剂量的差异。 结果 通过率的变化呈随机分布，96.9%的照射野偏差lt;2.5%。所有计划的85.7%绝对剂量偏差lt;2%，最大偏差为4.75%。 结论 使用二维探测器阵列在0°角进行调强计划的日常验证是安全可靠的。【Abstract】 Objective To analyze impacts of gravity on the verification of IMRT plans with 2-Dimensional detector arrays and to evaluate the reliability of the measurements in vertical direction (gantry angle=0). Methods The dose distributions for each beam in IMRT plans were measured with 0 degree gantry angle and actual gantry angle respectively. The γ percentage pass rate (according to 3% 3 mm) for each beam under each angle condition was obtained by the comparison between the measured dose distribution and the calculated dose map from the treatment planning system which was treated as the reference distribution. Then the absolute dose at the isocenter for each plan was measured at each angle condition and was analyzed. Results The variations of γ percentage pass rates between the two types of measurements were randomly distributed, and the deviations for 96.9% beams were less than±2.5%. The differences between absolute doses for 85.7% beams were less than±2% and the biggest deviation was -4.75%. Conclusion Verification of IMRT plans for the radiotherapy quality assurance using 2-Dimensional detector arrays in 0 degree gantry angle is safe and reliable.
Objective To study three-dimensional culturing methods of neonatal rat cardiac myocytes in simulated microgravity. Methods Neonatal rat primary cardiac myocytes were separated and seeded into polylactic acid scaffolds, stirredin spinner flasks for 24 hours, and then moved into rotary cell culture system for three-dimensional culture. The growth of cardiac myocytes was observed underinverted phase contrast microscope, scanning electron microscope and transmission electron microscope, and metabolic assay was assessed by MTT assay. Results Cardiac myocytes with sustained metabolic activity attached to the polylactic acid scaffolds, extended and confluenced. Pulsations of PLAcardiac myocytes was found in some areas. Conclusion The rotary cell culture system is suitable to develop neonatal rat cardiac myocytes culturing for three-dimensional modeling.
ObjectiveTo investigate the effect of overexpressing the Indianhedgehog (IHH) gene on the chondrogenic differentiation of rabbit bone marrow mesenchymal stem cells (BMSCs) in a simulated microgravity environment. MethodsThe 2nd generation BMSCs from rabbit were divided into 2 groups: the rotary cell culture system (RCCS) group and conventional group. Each group was further divided into the IHH gene transfection group (RCCS 1 group and conventional 1 group), green fluorescent protein transfection group (RCCS 2 group and conventional 2 group), and blank control group (RCCS 3 group and conventional 3 group). RCCS group cells were induced to differentiate into chondrocytes under simulated microgravity environment; the conventional group cells were given routine culture and chondrogenic induction in 6 well plates. During differentiation induction, the ELISA method was used to detect IHH protein expression and alkaline phosphatase (ALP) activity, and quantitative real-time PCR to detect cartilage and cartilage hypertrophy related gene expressions, and Western blot to detect collagen typeⅡ, agreecan (ANCN) protein expression; and methylene blue staining and Annexin V-cy3 immunofluorescence staining were used to observe cell slide. ResultsAfter transfection, obvious green fluorescence was observed in BMSCs under fluorescence microscopy in RCCS groups 1 and 2, the transfection efficiency was about 95%. The IHH protein levels of RCCS 1 group and conventional 1 group were significantly higher than those of RCCS 2, 3 groups and conventional 2, 3 groups (P < 0.05); at each time point, ALP activity of conventional 1 group was significantly higher than that of conventional 2, 3 groups (P < 0.05); ALP activity of RCCS 1 group was significantly higher than that of RCCS 2 and 3 groups only at 3 and 7 days (P < 0.05). Conventional 1 group expressed high levels of cartilage-related genes, such as collagen typeⅡand ANCN at the early stage of differentiation induction, and expressed high levels of cartilage hypertrophy-related genes, such as collagen type X, ALP, and Annexin V at the late stage (P < 0.05). RCCS 1 group expressed high levels of cartilage-related genes and low levels of cartilage hypertrophy-related genes at all stages. The expression of collagen typeⅡprotein in conventional 1 group was significantly lower than that of conventional 2 and 3 groups at 21 days after induction (P < 0.05); RCCS 1 group expressed high levels of collagen typeⅡand ANCN proteins at all stages (P < 0.05). Methylene blue staining indicated conventional 1 group was stained lighter than conventional 2 and 3 groups at 21 days after induction; while at each time point RCCS 1 group was significantly deeper than RCCS 2 and 3 groups. Annexin V-cy3 immunofluorescence staining indicated the red fluorescence of conventional 1 group was stronger than that of conventional 2 and 3 groups at each time point. The expression of red fluorescence in each RCCS subgroup was weak and there was no significant difference between the subgroups. ConclusionUnder the simulated microgravity environment, transfection of IHH gene into BMSCs can effectively promote the generation of cartilage and inhibit cartilage aging and osteogenesis. Therefore, this technique is suitable for cartilage tissue engineering.
Objective To culture primary parathyroid cells by mean of simulated microgravity, observe their basic morphological characteristics, study survival rate and secretory function of parathyroid cells, and explore more excellent culture mean of parathyroid cells. Methods There were 37 male Wistar rats, the body weight was 150–200 g. The rat was intraperitoneally injected with 1% pentobarbital sodium (50 mg/kg). The parathyroid glands were surgically excised and identified pathologically. The parathyroid gland cells were got and digested them with collagenase Ⅱ, which were divided into three groups: conventional culture group (simple parathyroid cells were cultured), polyglycolic acid (PGA) scaffold culture group (the parathyroid cells were cultured on the PGA scaffold), and simulated microgravity culture group (the parathyroid cells and PGA scaffolds were cultured in simulated microgravity environment). The parathyroid cells were cultured for 1, 3, 5 or 7 days in different culture conditions, then the parathyroid hormone (PTH) was measured, morphological characteristics of the parathyroid cell was observed under phase contrast microscope, survival rate of the parathyroid cells was calculated by acridine orange/propidium iodide staining. Results The parathyroid cell morphologies of most cells were well and center of part of cell mass was necrosis on day 7 in the conventional culture group. The most parathyroid cells were spreading toward the poles along the PGA cell scaffold in the longitudinal direction and the adjacent stents were connected by extracellular matrix on day 7 in the PGA scaffold culture group. The parathyroid cells cultured under the simulated microgravity were got round and formed clusters on day 7 in the simulated microgravity culture group. Compared with the other two groups on day 7, the PTH and the survival rate of the parathyroid cells were significantly higher in the simulated microgravity culture group (P<0.05). Conclusions Parathyroid cells cultured in simulated microgravity environment could maintain better morphology, survival rate is higher, and secretory function is better. Therefore, parathyroid cells cultured in simulated microgravity could be used as good donor cell for treatment of hypoparathyroidism. PGA scaffold could be used as a good carrier for culture of parathyroid cell.
To study the effect of microgravity on peripheral oxygen saturation (SpO2) in rats, tail-suspended rats were applied to simulate microgravity environment. SpO2 and arterial oxygen saturation (SaO2) were measured by pulse oximeter and arterial blood gas analyzer (ABGA) respectively on the 14th day, 21st day and 28th day in tail-suspended group and control group. Paired t-test shows that SpO2 was significantly lower than SaO2 in tail-suspended group on the 14th day (P < 0.05), the 21st day ( P < 0.05) and the 28th day ( P < 0.01). The ANOVA results shows that modeling time had significant effect on SpO 2 value but no effect on SaO2 value in tail-suspended group. These results indicate that pulse oximeter may be not suitable for oxygen saturation test in microgravity environment.
In this study, we aim to investigat the effect of microgravity on osteoblast differentiation in osteoblast-like cells (MC3T3-E1). In addition, we explored the response mechanism of nuclear factor-kappa B (NF-κB) signaling pathway to " zero-g” in MC3T3-E1 cells under the simulated microgravity conditions. MC3T3-E1 were cultured in conventional (CON) and simulated microgravity (SMG), respectively. Then, the expression of the related osteoblastic genes and the specific molecules in NF-κB signaling pathway were measured. The results showed that the mRNA and protein levels of alkaline phosphatase (ALP), osteocalcin (OCN) and type Ⅰ collagen (CoL-Ⅰ) were dramatically decreased under the simulated microgravity. Meanwhile, the NF-κB inhibitor α (IκB-α) protein level was decreased and the expressions of phosphorylation of IκB-α (p-IκB-α), p65 and phosphorylation of p65 (p-p65) were significantly up-regulated in SMG group. In addition, the IL-6 content in SMG group was increased compared to CON. These results indicated that simulated microgravity could activate the NF-κB pathway to regulate MC3T3-E1 cells differentiation.
Objective To prepare the silk fibroin microcarrier loaded with clematis total saponins (CTS) (CTS-silk fibroin microcarrier), and to investigate the effect of microcarrier combined with chondrocytes on promoting rabbit knee articular cartilage defects repair. Methods CTS-silk fibroin microcarrier was prepared by high voltage electrostatic combined with freeze drying method using the mixture of 5% silk fibroin solution, 10 mg/mL CTS solution, and glycerin. The samples were characterized by scanning electron microscope and the cumulative release amount of CTS was detected. Meanwhile, unloaded silk fibroin microcarrier was also prepared. Chondrocytes were isolated from knee cartilage of 4-week-old New Zealand rabbits and cultured. The 3rd generation of chondrocytes were co-cultured with the two microcarriers respectively for 7 days in microgravity environment. During this period, the adhesion of chondrocytes to microcarriers was observed by inverted phase contrast microscope and scanning electron microscope, and the proliferation activity of cells was detected by cell counting kit 8 (CCK-8), and compared with normal cells. Thirty 3-month-old New Zealand rabbits were selected to make bilateral knee cartilage defects models and randomly divided into 3 groups (n=20). Knee cartilage defects in group A were not treated, and in groups B and C were filled with the unloaded silk fibroin microcarrier-chondrocyte complexes and CTS-silk fibroin microcarrier-chondrocyte complexes, respectively. At 12 weeks after operation, the levels of matrix metalloproteinase 9 (MMP-9), MMP-13, and tissue inhibitor of MMP 1 (TIMP-1) in articular fluid were detected by ELISA. The cartilage defects were collected for gross observation and histological observation (HE staining and toluidine blue staining). Western blot was used to detect the expressions of collagen type Ⅱ and proteoglycan. The inflammatory of joint synovium was observed by histological staining and inducible nitric oxide synthase (iNOS) immunohistochemical staining. Results The CTS-silk fibroin microcarrier was spherical, with a diameter between 300 and 500 μm, a porous surface, and a porosity of 35.63%±3.51%. CTS could be released slowly in microcarrier for a long time. Under microgravity, the chondrocytes attached to the surface of the two microcarriers increased gradually with the extension of culture time, and the proliferation activity of chondrocytes at 24 hours after co-culture was significantly higher than that of normal chondrocytes (P<0.05). There was no significant difference in proliferation activity of chondrocytes between the two microcarriers (P>0.05). In vivo experiment in animals showed that the levels of MMP-9 and MMP-13 in group C were significantly lower than those in groups A and B (P<0.05), and the level of TIMP-1 in group C was significantly higher (P<0.05). Compared with group A, the cartilage defects in groups B and C were filled with repaired tissue, and the repaired surface of group C was more complete and better combined with the surrounding cartilage. Histological observation and Western blot analysis showed that the International Cartilage Repair Scoring (ICRS) and the relative expression levels of collagen type Ⅱ and proteoglycan in groups B and C were significantly better than those in group A, and group C was significantly better than group B (P<0.05). The histological observation showed that the infiltration of synovial inflammatory cells and hyperplasia of small vessels significantly reduced in group C compared with groups A and B. iNOS immunohistochemical staining showed that the expression of iNOS in group C was significantly lower than that in groups A and B (P<0.05).Conclusion CTS-silk fibroin microcarrier has good CTS sustained release effect and biocompatibility, and can promote the repair of rabbit cartilage defect by carrying chondrocyte proliferation in microgravity environment.