Abstract: Objective To assess the feasibility of transferring major histocompatibility complex (MHC) gene into the thymus to mitigate xenograft rejection. Methods By molecular cloning technique, we extracted and proliferated the-H-2K d gene from donor mice (MHC class Ⅰ gene of Balb/c mice) and constructed the expression vector plasmid of pCI-H-2K d. Twenty SD rats were selected as receptors, and by using random number table, they were divided into the experimental group and the control group with equal number of rats in each group. By ultrasoundguided puncture and lipofection method, the pCI-H-2Kd was injected into thymus of SD rats in the experimental group and meanwhile, empty vector plasmid of pCIneo was injected into thymus of SD rats in the control group. Subsequently, we transplanted the donor mice myocardium xenografts into the receptor rats, and observed the xenograft rejection in both the two groups. Results The survival time of the xenotransplanted myocardium in the experimental group was significantly longer than that in the control group (14.61±2.98 d vs. 6.40±1.58 d, t=-7.619,Plt;0.05). Microtome section of transplanted myocardium in the control group showed a relatively large amount of lymphocyte infiltration and necrosis occurred to most part of the transplanted myocardium, while microtome section of experiment group showed no lymphocyte infiltration and most of the cells of the transplanted myocardium were still alive. After mixed lymphocyte culture, the reaction of receptors to donor cells in the experiment group was obviously lower than that in the control group (t=4.758, P=0.000).After the count by flow cytometer, the xenoMHC molecules were expressed in the receptors’ thymus with a transfection efficiency of 60.7%. Conclusion Our findings suggest that xenograft rejection can be mitigated substantially by donor’s MHC gene transferring into receptor’s thymus. This may provide theoretical and experimental evidence for inducing xenotransplantation tolerance.
ObjectiveTo explore the effect of Poria cocos on xenograft tumors of gastric cancer SGC-7901 cell line in mude mice. Method①After establishment of xenograft tumor of gastric cancer SGC-7901 cell line, 10 nude mice were equally divided into normal control group and Poria cocos group. The nude mice of each group were gavaged with normal saline (NS) and Poria cocos (0.5 mL) for 32 days, respectively. Tumor volume were measured to draw tumor growth curves and the tumor weight inhibitory rate was calculated with tumor weight (on the 32-day, nude mice were sacrificed to get the xenograft tumors). The expressions of B cell lymphoma 2 (Bcl-2), Bcl-2 associated X protein (Bax), Caspase-3, Caspase-9, and vascular endothelial growth factor (VEGF) were detected by immunohistochemical staining. ②Preparation of drug serum containing Poria cocos. Gastric cancer SGC-7901 cell line were be divided into 2 groups: normal control group and Poria cocos group. Cells of normal control group were treated with serum containing NS, and cells of Poria cocos group were treated with drug serum containing 10% Poria cocos. After 24 hours and 48 hours, Western-blot was used to detect the expressions of Bcl-2 and Bax. ResultsOn 32-day, the volume and weight of xenograft tumors in normal control group〔(2 652.17±225.01) mm3 and (2.48±0.21) g〕were both higher than those of Poria cocos group〔(1 247.56±277.23) mm3 and (1.28±0.28) g〕, P<0.050. The tumor inhibitory rate in Poria cocos group was 48.39%. The results of immunohistochemical staining showed that, compared with normal control group, Poria cocos could down-regulate the expressions of Bcl-2〔(4.20±1.10）score vs. (8.00±1.20) score〕and VEGF〔(3.80±0.45) score vs. (7.80±1.10) score〕, while up-regulate the expressions of Bax〔(7.40±1.34) score vs. (3.00±0.71) score〕, Caspase-3〔(6.60±1.34) score vs. (2.60±0.55) score〕, and Caspase-9〔(7.20±1.79) score vs. (4.00±1.22) score〕, P<0.050. Compared with normal control group (1.72±0.03), the expression value of Bcl-2 was all higher in 24 h-Poria cocos group (0.96±0.04) and 48 h-Poria cocos group (0.77±0.04), P<0.050, and the expression value was higher in 48 h-Poria cocos group than that of 24 h-Poria cocos group (P<0.050). Compared with normal control group (0.15±0.01), the expression value of Bax was higher in 48 h-Poria cocos group (0.55±0.01), P<0.050, but there was no significant difference between the normal control group and 24 h-Poria cocos group（0.19±0）, P>0.050. ConclusionsPoria cocos can restrain the growth of xenograft tumors for gastric cancer SGC-7901 cell line in mude mice, and the mechanism may be related to mitochondrial apoptosis pathway and the inhibition of expression of VEGF.
【Abstract】 Objective To produce a new bone tissue engineered carrier through combination of xenograft bone (X)and sodium alginate (A) and to investigate the biological character of the cells in the carrier and the abil ity of bone-forming in vivo, so as to provide experimental evidence for a more effective carrier. Methods BMSCs were extracted from 2-week-old New Zealand rabbits and the BMSCs were induced by rhBMP-2 (1 × 10-8mol/L). The second generation of the induced BMSCs was combined with 1% (V/W) A by final concentration of 1 × 105/mL. After 4-day culture, cells in gel were investigated by HE staining. The second generation of the induced BMSCs was divided into the DMEM gel group and the DMEM containing 1% A group. They were seeded into 48 well-cultivated cell clusters by final concentration of 1 × 105/mL. Seven days later, the BMP-2 expressions of BMSCs in A and in commonly-cultivated cells were compared. The second generation of the induced BMSCs was mixed with 2% A DMEM at a final concentration of 1 × 1010/mL. Then it was compounded with the no antigen X under negativepressure. After 4 days, cells growth was observed under SEM. Twenty-four nude mice were randomly divided into 2 group s (n=12).The compound of BMSCs-A-X (experimental group) and BMSCs-X (control group) with BMSCs whose final concentrat ion was 1 × 1010/mL was implanted in muscles of nude mice. Bone formation of the compound was histologically evaluated by Image Analysis System 2 and 4 weeks after the operation, respectively. Results Cells suspended in A and grew plump. Cell division and nuclear fission were found. Under the microscope, normal prol iferation, many forming processes, larger nucleus, clear nucleolus and more nuclear fission could be seen. BMP-2 expression in the DMEM gel group was 44.10% ± 3.02% and in the DMEM containing 1% A group was 42.40% ± 4.83%. There was no statistically significant difference between the two groups (P gt; 0.05). A was compounded evenly in the micropore of X and cells suspended in A 3-dimensionally with matrix secretion. At 2 weeks after the implantation, according to Image Analysis System, the compound of BMSCs-A-X was 5.26% ± 0.24% of the totalarea and the cartilage-l ike tissue was 7.31% ± 0.32% in the experimental group; the compound of BMSCs-X was 2.16% ± 0.22% of the total area and the cartilage-l ike tissue was 2.31% ± 0.21% in the control group. There was statistically significant difference between the two groups (P lt; 0.05). At 4 weeks after the operation, the compound of BMSCs-A-X was 7.26% ± 0.26% of the total area and the cartilage-l ike tissue was 9.31% ± 0.31% in the experimental group; the compound of BMSCs-X was 2.26% ± 0.28% of the total area and the cartilage-l ike tissue was 3.31% ± 0.26% in the control group. There was statistically significant difference between the two groups (P lt; 0.05). Conclusion The new carrier compounding A and no antigen X conforms to the superstructural principle of tissue engineering, with maximum cells load. BMSCs behave well in the compound carrier with efficient bone formation in vivo.
Objective To observe the systemic and local immune response after repair of nerve defect with acellular nerve xenograft laden with allogenic adipose-derived stem cells (ADSCs) in rhesus monkey so as to evaluate the safety of the proposed material for nerve reconstruction. Methods Bilateral tibial nerves were taken from a healthy adult male landrace (weighing 48 kg) to prepare acellular nerve xenograft by chemical extraction. ADSCs were isolated from a healthy adult male rhesus monkey (weighing 4.5 kg), and were seeded into the acellular nerve grafts. The radial nerve defect models with 25 mm in length were established in 10 healthy adult female rhesus monkeys (weighing 3-5 kg), and they were divided into cell-laden group (n=5) and non-cell-laden group (n=5) randomly. Defect was repaired with acellular nerve xenograft laden with allogenic ADSCs in cell-laden group, with acellular nerve xenograft only in non-cell-laden group. The blood samples were taken from peripheral vein preoperatively and at 14, 60, and 90 days after operation for lymphocyte analysis; at 5 months after operation, the grafts were harvested to perform histological examination for local immune response and nerve regeneration. The nerve autograft in rhesus monkey was used as control. Results In cell-laden group and non-cell-laden group, no significant difference was found in the count of lymphocytes and T lymphocytes, the percentage of T lymphocytes, CD8+ T lymphocytes, as well as the ratio of CD4+ T lymphocytes to CD8+ T lymphocytes between pre- and post-operation (P gt; 0.05); in cell-laden group, the percentage of CD4+ T lymphocytes at 14 days was significantly lower than that at 60 and 90 days postoperatively (P lt; 0.05). The percentage of CD4+ T lymphocytes in cell-laden group was significantly lower than that in non-cell-laden group at 14 days (P lt; 0.05), but no significant difference was found in the other indexes at the other time between 2 groups (P gt; 0.05). At 5 months after operation, mild adhesion was found on the surface of nerve xenografts; the epineurium of nerve xenografts was thicker than that of nerve autografts; and neither necrosis nor fibrosis was found. CD3+, CD4+, CD8+, CD68+, and CD163+ T lymphocytes were scattered within the grafts, in which regenerative axons were revealed. CD3+, CD4+, CD8+, CD68+, and CD163+ T lymphocytes were comparable in cell-laden group, non-cell-laden group, and autograft group. Conclusion Repair of nerve defect with acellular nerve xenograft elicits neither systemic nor local immune response in rhesus monkeys. Implantation of allogenic ADSCs might result in transient depression of CD4+ T lymphocytes proliferation early after surgery, no immune response can be found.