ObjectiveTo explore the feasibility of establishment of a artificial joint aseptic loosening mouse model by cobalt-chromium particles stimulation.MethodsTwenty-four 8-week-old male severe combined immunodeficient (SCID) mice were divided into experimental group (n=12) and control group (n=12). The titanium nail was inserted into the tibial medullary cavity of mouse in the two groups to simulate artificial joint prosthesis replacement. And the cobalt-chromium particles were injected into the tibial medullary cavity of mouse in experimental group. The survival of the mouse was observed after operation; the position of the titanium nail and the bone mineral density of proximal femur were observed by X-ray film, CT, and Micro-CT bone scanning; and the degree of dissolution of the bone tissue around the tibia was detected by biomechanical test and histological staining.ResultsTwo mice in experimental group died, and the rest of the mice survived until the experiment was completed. Postoperative imaging examination showed that there was no obvious displacement of titanium nails in control group, and there were new callus around the titanium nails. In experimental group, there was obvious osteolysis around the titanium nails. The bone mineral density of the proximal tibia was 91.25%±0.67%, and the maximum shear force at the tibial nail-bone interface was (5.93±0.85) N in experimental group, which were significantly lower than those in control group [102.07%±1.87% and (16.76±3.09) N] (t=5.462, P=0.041; t=3.760, P=0.046). Histological observation showed that a large number of inflammatory cells could be seen around the titanium nails in experimental group, while there was no inflammatory cells, and obvious bone tissue formation was observed in control group.ConclusionThe artificial joint aseptic loosening mouse model can be successfully established by cobalt-chromium particles stimulation.
Objective To study the culture and purification of the fetal mouse liver mesenchymal stem cells(MSCs) in vitro and to investigate their differentiation potential and the composite ability with true bone ceramic(TBC). Methods The single cell suspension of MSCs was primarily cultured and passaged, which was prepared from the fetal mouse liver; the flow cytometry was applied to detectCD29, CD34, CD44 and CD45. The osteogenic differentiation was induced in chemical inducing system; the osteogenic induction potency was tested. The purified fetal mouse liver MSCs were compounded with TBC covered with collagen type Ⅰ in vitro and the cell attachment and proliferation to the TBC were observed. Results The primary MSCs of fetal mouse liver were easy to culture in vitro. They proliferated well and were easy to subcultured. The proliferation ability of primary and passaged MSCs was similar. Flow cytometric analysis showed the positive results for CD29, CD44 and the negative results for CD34, CD45. After 7 days of induction, the MSCs expressed collagen type I and alkaline phosphatase(ALP) highly. After 14 days of induction, the fixed quantity of ALP increased significantly. After 28 days of induction, calcium accumulation was observed by Von Kossa’s staining. Many liver MSCs attached to the surface of TBC. Conclusion The MSCs of the fetalmouse liver can be obtained, subcultured and purified easily. After culturing in chemical inducing system, the MSCs of fetal mouse liver can be successfully induced to osteoblast-like cells, attach to the surface of TBC and proliferate well.
Objective To investigate the effect of tranilast on wound healing and the mechanism of inhibiting scar hyperplasia in mice, and to study the relationship between the inhibiting ability of tranilast on scar hyperplasia and administration time. Methods Sixty-six Kunming mice were selected to build deep II degree burn model, and were randomly divided into the control group (18 mice), the early intervention group (18 mice), the medium intervention group (18 mice), and the late intervention group (12 mice). The mice in the early intervention group, the medium-term intervention group, and the late intervention group were given tranilast 200 mg/(kg·d) by gastrogavage at immediate, 7 days, and 14 days after burn respectively, and the mice in the control group were managed with same amount of normal saline every day. The wound healing was observed regularly. At 14, 28, and 42 days in the early and medium intervention groups and at 28 and 42 days in the late intervention group, fresh tissues were taken from 6 mice to observe the shape of mast cells by toluidine blue staining, collagen content by Masson staining; the collagen type I and collagen type III content were measured to calculate the I/III collagen content ratio by immunohistochemistry method, the contents of transforming growth factor β1 (TGF-β1) and histamine were detected by ELISA; and the ultrastructure of fibroblasts was observed under transmission electron microscope. Results There was no significant difference in wound healing time between groups (F=1.105,P=0.371). The mast cells number, collagen content, TGF-β1 content, histamine content, and the I/III collagen content ratio in the early intervention group were significantly less than those in the other groups (P<0.05). Significant difference was found in mast cells number, collagen content, and histamine content between control group and medium or late intervention group at the other time points (P<0.05) except between control group and late intervention group at 42 days (P>0.05). Compared with the control group, the activity of fibroblasts in the early intervention group was obviously inhibited, and the arrangement of the fibers was more regular; the fibroblast activity in the medium and late intervention groups was also inhibited obviously. Conclusion Tranilast has no obvious effect on the wound healing time in mice. Tranilast intervention shows the inhibitory effect on the scar hyperplasia which can significantly reduce the number of mast cells, the content of histamine and TGF-β1, inhibit the ability of fibroblasts synthetic collagen and adjust the proportion of collagen synthesis. The immediate tranilast intervention may have the best inhibitory effect on scar hyperplasia.
Objective To investigate the effect of M2 microglia (M2-MG) transplantation on spinal cord injury (SCI) repair in mice. Methods Primary MG were obtained from the cerebral cortex of 15 C57BL/6 mice born 2-3 days old by pancreatic enzyme digestion and identified by immunofluorescence staining of Iba1. Then the primary MG were co-cultured with interleukin 4 for 48 hours (experimental group) to induce into M2 phenotype and identified by immunofluorescence staining of Arginase 1 (Arg-1) and Iba1. The normal MG were harvested as control (control group). The dorsal root ganglion (DRG) of 5 C57BL/6 mice born 1 week old were co-cultured with M2-MG for 5 days to observe the axon length, the DRG alone was used as control. Forty-two 6-week-old female C57BL/6 mice were randomly divided into sham group (n=6), SCI group (n=18), and SCI+M2-MG group (n=18). In sham group, only the laminae of T10 level were removed; SCI group and SCI+M2-MG group underwent SCI modeling, and SCI+M2-MG group was simultaneously injected with M2-MG. The survival of mice in each group was observed after operation. At immediate (0), 3, 7, 14, 21, and 28 days after operation, the motor function of mice was evaluated by Basso Mouse Scale (BMS) score, and the gait was evaluated by footprint experiment at 28 days. The spinal cord tissue was taken after operation for immunofluorescence staining, in which glial fibrillary acidic protein (GFAP) staining at 7, 14, and 28 days was used to observe the injured area of the spinal cord, neuronal nuclei antigen staining at 28 days was used to observe the survival of neurons, and GFAP/C3 double staining at 7 and 14 days was used to observe the changes in the number of A1 astrocytes. Results The purity of MG in vitro reached 90%, and the most of the cells were polarized into M2 phenotype identified by Arg-1 immunofluorescence staining. M2-MG promoted the axon growth when co-cultured with DRGs in vitro (P<0.05). All groups of mice survived until the experiment was completed. The hind limb motor function of SCI group and SCI+M2-MG group gradually recovered over time. Among them, the SCI+M2-MG group had significantly higher BMS scores than the SCI group at 21 and 28 days (P<0.05), and the dragging gait significantly improved at 28 days, but it did not reach the level of the sham group. Immunofluorescence staining showed that compared with the SCI group, the SCI+M2-MG group had a smaller injury area at 7, 14, and 28 days, an increase in neuronal survival at 28 days, and a decrease in the number of A1 astrocytes at 7 and 14 days, with significant differences (P<0.05). ConclusionM2-MG transplantation improves the motor function of the hind limbs of SCI mice by promoting neuron survival and axon regeneration. This neuroprotective effect is related to the inhibition of A1 astrocytes polarization.
Objective To investigate the mechanism of vascular stromal fraction (SVF) at the early stage after aspirated fat transplantation. Methods Fat was harvested from 5 cases of women undergoing abdominal liposuction operation, and SVF was isolated. Aspirated fat with (group B) or without (group A) SVF was injected subcutaneously into the back of nude mice, and the grafts were harvested at 1, 3, 5, and 7 days. Graft wet weight was measured; and immunohistochemical method (CD31) was performed and the secretion of vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF) were qnantified by Western blot assay. Results The wet weight of transplanted adipose tissue showed an increasing tendency in groups A and B with time, and no significant difference was found between groups A and B (P gt; 0.05). At 1 and 3 days after transplantation, no CD31 positive cells was seen in 2 groups; the CD31 positive cells of group B were significantly more than those of group A at 5 and 7 days (P lt; 0.05), and the CD31 positive cells at 7 days were significantly more than those at 5 days in 2 groups (P lt; 0.05). Western blot test showed that VEGF expression reached peak at 3 days , then decreased gradually; the expression of VEGF protein in group B was significantly higher than that in group A at 1, 3, and 5 days (P lt; 0.05). The expression of HGF protein in groups A and B remained at a high level within 5 days, but it tended to decrease at 7 days, which was significantly higher in group B than that in group A (P lt; 0.05). Conclusion SVF can enhance angiogenesis by secretion of growth factors at the early stage after aspirated fat transplantation.
ObjectiveTo study the effect and mechanism of lipopolysaccharide (LPS) on osteoclasts formation and its bone resorption function.MethodsBone marrow-derived macrophages (BMMs) were extracted from the marrow of femur and tibia of 4-week-old male C57BL/6 mice. Flow cytometry was used to detect BMMs. The effect of different concentrations of LPS (0, 100, 200, 500, 1 000, 2 000 ng/mL) on BMMs activity was examined by cell counting kit 8 (CCK-8) activity test. In order to investigate the effect of LPS on osteoclastogenesis, BMMs were divided into macrophage colony-stimulating factor (M-CSF) group, M-CSF+receptor activator of nuclear factor κB ligand (RANKL) group, M-CSF+RANKL+50 ng/mL LPS group, M-CSF+RANKL+100 ng/mL LPS group. After the completion of culture, tartrate resistant acid phosphatase (TRAP) staining was used to observe the formation of osteoclasts. In order to investigate the effect of LPS on the expression of Connexin43, BMMs were divided into the control group (M-CSF+RANKL) and the LPS group (M-CSF+RANKL+100 ng/mL LPS); and the control group (M-CSF+RANKL), 50 ng/mL LPS group (M-CSF+RANKL+50 ng/mL LPS), and 100 ng/mL LPS group (M-CSF+RANKL+100 ng/mL LPS). The expressions of Connexin43 mRNA and protein were detected by Western blot and real-time fluorescent quantitative PCR, respectively. In order to investigate the effect of LPS on osteoclast bone resorption, BMMs were divided into M-CSF group, M-CSF+RANKL group, M-CSF+RANKL+50 ng/mL LPS group, and M-CSF+RANKL+100 ng/mL LPS group. Bone absorption test was used to detect the ratio of bone resorption area.ResultsThe flow cytometry test confirmed that the cultured cells were BMMs, and CCK-8 activity test proved that the 100 ng/mL LPS could promote the proliferation of BMMs, showing significant differences when compared with the 0, 200, 500, 1 000, and 2 000 ng/mL LPS (P<0.05). TRAP staining showed no osteoclast formation in M-CSF group. Compared with M-CSF+RANKL group, the osteoclasts in M-CSF+RANKL+50 ng/mL LPS group and M-CSF+RANKL+100 ng/mL LPS group were larger with more nuclei, while the osteoclasts in M-CSF+RANKL+100 ng/mL LPS group were more obvious, and the differences in the ratio of osteoclast area between groups were statistically significant (P<0.05). Western blot result showed that the relative expression of Connexin43 protein in LPS group was significantly higher than that in control group (P<0.05). Real-time fluorescent quantitative PCR showed that the relative expression of Connexin43 mRNA in control group, 50 ng/mL LPS group, and 100 ng/mL LPS group increased gradually, and the differences between groups were statistically significant (P<0.05). Bone resorption test showed that osteoclast bone resorption did not form in M-CSF group, but the ratio of bone resorption area increased gradually in M-CSF+RANKL group, M-CSF+RANKL+50 ng/mL LPS group, and M-CSF+RANKL+100 ng/mL LPS group, and the differences between groups were statistically significant (P<0.05).ConclusionLPS at concentration of 100 ng/mL can promote the expression of Connexin43, resulting in increased osteoclastogenesis and enhanced osteoclastic bone resorption.
Objective To investigate the correlation between down-regulation of miR-381-3p and inhibition of osteogenic differentiation of mouse embryonic palatal mesenchymal (MEPM) cells in 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD)-induced cleft palate of fetal mice. Methods Thirty-two pregnant mice were randomly divided into TCDD group and control group, 16 in each group. On embryonic day 10.5 (E10.5), the pregnant mice in TCDD group were orally administrated with TCDD at dosage of 28 μg/kg, while the pregnant mice in control group received equivalent corn oil. The pregnant mice in each group were sacrificed on E13.5 and E14.5, fetal palates were collected for analysis. The expression of miR-381-3p was detected by real-time fluorescent quantitative PCR and the protein expressions of runt- related transcription factor 2 (RUNX2) and osteopontin (OPN) were detected by Western blot. MEPM cells were extracted from fetal palates on E14.5 in control group and passaged. The 3rd passage cells were cultured with TCDD at dosage of 10 nmol/L for 0, 0.5, 1, 2, and 3 days. The expression of miR-381-3p was detected after 0, 0.5, 1, 2, and 3 days and the protein expressions of RUNX2 and OPN were detected after 0, 1, 2, and 3 days. Then, the 3rd passage cells were divided into 4 groups. The MEPM cells were transfected with miR-381-3p inhibitor (inhibitor group), NC inhibitor (NC inhibitor group) and miR-381-3p mimics (mimics group), NC mimics (NC mimics group) for 48 hours, respectively. And the expressions of miR-381-3p and the protein expressions of RUNX2 and OPN were detected. Results On E13.5 and E14.5, 96 fetal mice in control group and 92 in TCDD group were obtained. The bilateral palates contacted in control group on E14.5, and a gap between the bilateral palates existed in TCDD group. On E13.5 and E14.5, the relative expressions of miR-381-3p and RUNX2 and OPN proteins were significant lower in TCDD group than in control group (P<0.05). The relative expression of miR-381-3p at 0.5 and 1 day after TCDD treatment of MEPM cells were significantly lower than that at 0 day (P<0.05); then, the relative expressions at 2 and 3 days significantly increased, showing no significant difference when compared with that at 0 day (P>0.05). The relative expressions of RUNX2 and OPN proteins at 1, 2, and 3 days were significantly lower than that at 0 day (P<0.05). The relative expressions of miR-381-3p and RUNX2 and OPN proteins significantly lower in inhibitor group than in NC inhibitor group (P<0.05) and higher in mimics group than in NC mimics group (P<0.05). Conclusion Down-regulation of miR-381-3p expression may be associated with inhibition of osteogenic differentiation of MEPM cells in TCDD-induced cleft palate of fetal mice.
Objective Tissue engineered bone (TEB) lacks of an effective and feasible method of storage and transportation. To evaluate the activity of osteogenesis and capabil ity of ectopic osteogenesis for TEB after freeze-dried treatment in vitro and in vivo and to explore a new method of preserving and transporting TEB. Methods Human bone marrow mesenchymal stem cells (hBMSCs) and decalcified bone matrix (DBM) were harvested from bone marrow and bone tissue of the healthy donators. TEB was fabricated with the 3rd passage hBMSCs and DBM, and they were frozen and dried at extremely low temperatures after 3, 5, 7, 9, 12, and 15 days of culture in vitro to obtain freeze-dried tissue engineered bone (FTEB). TEB and FTEB were observed by gross view and scanning electron microscope (SEM). Western blot was used to detect the changes of relative osteogenic cytokines, including bone morphogenetic protein 2 (BMP-2), transforming growth factor β1 (TGF-β1), and insul in-l ike growth factor 1 (IGF-1) between TEB and FTEB. The ectopic osteogenesis was evaluated by the methods of X-ray, CT score, and HE staining after TEB and FTEB were transplanted into hypodermatic space in athymic mouse. Results SEM showed that the cells had normal shape in TEB, and secretion of extracellular matrix increased with culture time; in FTEB, seeding cells were killed by the freeze-dried process, and considerable extracellular matrix were formed in the pore of DBM scaffold. The osteogenic cytokines (BMP-2, TGF-β1, and IGF-1) in TEB were not decreased after freeze-dried procedure, showing no significant difference between TEB and FTEB (P gt; 0.05) except TGF-β1 15 days after culture (P lt; 0.05). The ectopic osteogenesis was observed in TEB and FTEB groups 8 and 12 weeks after transplantation, there was no significant difference in the calcified level of grafts between TEB and FTEB groups by the analysis of X-ray and CT score. On the contrary, there was no ectopic osteogenesis in group DBM 12 weeks after operation. HE staining showed that DBM scaffold degraded and disappeared 12 weeks after operation. Conclusion The osteogenic activity of TEB and FTEB is similar, which provides a new strategy to preserve and transport TEB.
Objective To provide experimental evidence for the clinical application of ischemia therapy to treating pancreatic cancer. Methods After the model of pancreatic transplanted cancer was established in nude mice with orthotransplantation of human pancreatic cancer cell line into the pancreas, the ischemia of the right lobe of the pancreas was induced with ligation of the gastroduodenal, inferior pancreaticoduodenal and dorsal pancreatic arteries. Effects of regional ischemia on the growth of transplanted cancer and the pathomorphology of the transplanted cancer and pericancerous tissue were investigated. Results The transplanted cancer grew slower and its doubling time was longer in the ischemic group than in the control. On the 3rd, 7th and 14th day after operation, the size of transplanted cancer, the proliferative index and protein content of the cancer cells were significantly lower in the ischemic group than in the control (Ｐ＜0.01). Optical microscopy revealed large areas of coagulation necrosis, necrobiotic cells and the infiltration of inflammatory cells. The atrophy of acini, fibrosis and the infiltration of lymphocyte cells were found in pericancerous tissue. Conclusion Regional ischemia can destroy and inhibit the pancreatic transplanted cancer in nude mice effectively. The ischemia changes of pericancerous tissue may be unfavourable for the growth of the pancreatic transplanted cancer.
ObjectiveTo observe the effect of using tungsten drills to prepare mouse knee osteochondral injury model by comparing with the needle modeling method, in order to provide an appropriate animal modeling method for osteochondral injury research.MethodsA total of 75 two-month-old male C57BL/6 mice were randomly divided into 3 groups (n=25). Mice in groups A and B were used to prepare the right knee osteochondral injury models by using needles and tungsten drills, respectively; group C was sham-operation group. The general condition of the mice was observed after operation. The samples were taken at 1 day and 1, 2, 4, and 8 weeks after modeling, and HE staining was performed. The depth, width, and cross-sectional area of the injury site at 1 day in groups A and B were measured, and the percentage of the injury depth to the thickness of the articular cartilage (depth/thickness) was calculated. Toluidine blue staining and immunohistochemical staining for collagen type Ⅱ were performed at 8 weeks, and the International Cartilage Research Society (ICRS) score was used to evaluate the osteochondral healing in groups A and B.ResultsAll mice survived to the completion of the experiment. HE staining showed that group C had normal cartilage morphology. At 1 day after modeling, the injury in group A only broke through the cartilage layer and reached the subchondral bone without entering the bone marrow cavity; the injury in group B reached the bone marrow cavity. The depth, width, cross-sectional area, and depth/thickness of the injury in group A were significantly lower than those in group B (P<0.05). At 1, 2, 4, and 8 weeks after modeling, there was no obvious tissue filling in the injured part of group A, and no toluidine blue staining and expression of collagen type Ⅱ were observed at 8 weeks; while the injured part of group B was gradually filled with tissue, the toluidine blue staining and the expression of collagen type Ⅱ were seen at 8 weeks. At 8 weeks, the ICRS score of group A was 8.2±1.3, which was lower than that of group B (13.6±0.9), showing significant difference (t=?7.637, P=0.000).ConclusionThe tungsten drills can break through the subchondral bone layer and enter the bone marrow cavity, and the injury can heal spontaneously. Compared with the needle modeling method, it is a better method for modeling knee osteochondral injury in mice.