Tracheal stents are often used to maintain the patency of the trachea and bronchia in patients suffering from central airway lesions. Metallic tracheal stents are now widely used in the clinical setting, but these types of stents can cause many intractable material-related complications. Biodegradable tracheal stents are made of biodegradable polymer materials with good mechanical strength for maintaining the patency of the lesion segment during a certain period of time, and then they can be gradually degraded into harmless products in human body. Compared with conventional metallic tracheal stent, biodegradable tracheal stents have a good prospect in clinic. In this article, we review the choice of biodegradable tracheal stent materials, experimental progress in biodegradable tracheal stent as well as the challenges we are facing.
Objective To study the effects and mechanisms of major immune nutrients and to introduce the progresses of clinical applications about enteral immunonutrition. Methods The related literatures about the effects and clinical applications of enteral immunonutrition were reviewed. Results Infection rate can be reduced and the hospitalization can be shortened as a result of the improved nutritional status and immune competence of patients which can be enhanced by reasonable enteral immune nutrition. Most of the patients suffering from serious diseases can benefit from enteral immunonutrition, such as gastrointestinal cancers, post-transplantation complications, chronic liver disorders, acute pancreatitis and so on. However, as a new nutrition therapy, the clinical use of enteral immunonutrition in critically ill patients is still controversial. Conclusions Enteral immunonutrition plays an important role in the nutritional support of patients with serious diseases, such as gastrointestinal cancers, organ failures. However, much work remains to be done.
Objective To summarize the advancement of immune tolerance in pancreas transplantation.Methods Relevant literatures about immune tolerance in pancreas transplantation, which were published recently domestic and abroad were collected and reviewed. Results The main methods to induce immune tolerance are peripheral tolerance and central tolerance. The induction of chimerism by infusion of donor-specific bone marrow cells is the research hot spot recently. Conclusion The infusion of donor-specific bone marrow cells in combination with one or more peripheral tolerance maybe can induce immune tolerance successfully. However, it should be researched further.
Objective To study the feasibility of transplanting autologous venous endothelial cells, as the liner, to the allogenic vein and to investigate the patency rate after such transplantation. Methods Autologous endothelial cells were gained after the administration of 0.2% collagenase and the centrifugalization of the enzyme liquid. The cells were not cultivated in a 60 ml plastic culture until the presence of the second generation. The cultivated cells were confirmed as endothelial cells by factor Ⅷ related antigen. The multiplied cells were lined in vitro onto the luminal surface of allogenic vein that was disposed by freeze-drying and radiation. The orthotopic transplantation of autologous venous endothelial cells was performed after the 9-day incubation. Results (9.47±0.35)×106 endothelial cells were obtained after the cultivation. Three hours after cell seeding, the luminal surface of allogenic vein was covered with vast endothelial cells but still had not formed an intact endomembrane. On day 9, the luminal surface was covered with a continuous endothelial monolayer and the arrangement and the shape of the cells all showed the perfect condition of endothelial cells. Eight weeks later, all the transplanted veins kept unobstructed. Conclusion The approach of lining allogenic vein with autologous endothelial cells in vitro may keep the vein unobstructed in the long term.
ObjectiveTo study the cell apoptosis and the dynamic expression and significance of apoptosis-related genes in graft veins. MethodsA rat experimental model of autogenous graft vein was established by transplanting the right external jugular vein to infrarenal abdominal aorta in 100 Wistar rats. TUNEL and immunohistochemistry were used to detect the apoptosis, the expression of apoptosis-related genes bcl-2 and bax in vascular smooth muscle cells (VSMCs) of graft veins. ResultsWithin the 8 weeks after transplantation, the apoptotic VSMCs in the graft veins were much more than those in the control group with the apoptotic rate reaching the peak〔（28.5±16.6）%〕 on the 2nd week and dropping to （8.1±2.8）% during the 4th to 8th week. There was statistical difference compared to the control group 〔(0.5±0.2)%, P＜0.01〕. From 1 to 2 weeks, the positive rate of bcl-2 was (22.1±5.4)% which was higher than that of the control group and the 4-8 week group (P＜0.01); from 1 to 6 weeks, the expression of bax was higher than that of the control group 〔(5.5±2.3)%〕 and the postoperative 8th week group 〔(8.2±2.9)%, P＜0.01〕.Conclusionbcl-2 and bax protein may be involved in the regulation of apoptosis of VSMCs. Apoptosis of VSMCs may be an important factor in graft remodeling and graft vein stenosis.
【Abstract】Objective To study the influence of transplantation of cultured parathyroid cells on the survival of the allografts in rats. Methods Parathyroid cells digested with collagenase and trypsin were cultured and transplanted under the left renal capsule. The survival time of the allografts was recorded and the allografts were examined by transmission electron microscopy.Results In fresh parathyroid cells group, the mean survival time was (9.25±3.45) days. While in cultured parathyroid cells group, the survival time was (46.25±7.44) days (P＜0.01). During the 50 days of observation, serum calcium and PTH remained normal in 6 of 8 rats. There were intact parathyroid cells in the allografts which had abundant rough endoplasmic reticula,mitochondria and secretory granules. Conclusion Transplantation of cultured parathyroid cells in rats can prolong the survival time of allografts and is a potent way to cure hypoparathyroidism.
ObjectiveTo study the protective effect of hepatocyte growth factor(HGF) on grafted mucous membrane of transplanted small bowel.MethodsTotal small bowel transplantation was made in inbred Wistar (RT1k) rats heterotopically,either total parenteral nutrition (control group,n=10) or hepatocyte growth factor supplemented TPN (HGF group,n=10) was given to the recipients from the 2nd day to the 10th day postoperatively. Morphological parameters of the transplanted intestinal mucosa, such as mucosal villous height, villous width, crypt depth, mucosal thickness and villous surface area were observed. Variation of ultrastructure of transplanted epithelial cells was observed. Composition of mucosal protein and DNA content were tested. ResultsComparison between HGF group and the control group were as follows. Mucosal villous height (298.79±22.31） μm vs （176.45±14.62） μm, P=0.001, villous width (107.46±12.34） μm vs （74.20±16.85） μm, P=0.004, crypt depth (104.56±11.17） μm vs （74.45±8.34） μm, P=0.000 5, mucosal thickness (409.53±35.83） μm vs （259.38±24.65） μm, P=0.003, and villous surface area (0.101±0.011) mm2 vs (0.041±0.005) mm2, P=0.001 were found significantly increased in HGF group compared with control group, there were no obvious difference decrease as compared to pretransplant parameters.Mucosal protein composition was higher in HGF group than that in control group （89.65±9.28) mg/g wet wt vs (53.73±11.45) mg/g wet wt, P=0.012, baseline (92.64±10.52) mg/g wet wt, nearly equal to baseline; DNA composition was also high in HGF group （0.89±0.09) mg/g wet wt vs (0.51±0.06) mg/g wet wt, P=0.008, baseline (0.91±0.09) mg/g wet wt. Nearly normal ultrastructure of the graft was maintained in HGF group, atrophied microvilli and broken mitochondrial crista were observed in control group.ConclusionHepatocyte growth factor can improve mucosal structure, preserve enterocyte ultrastructure of isograft after small bowel transplantation in rat.
The model of transplanted colonic SW480 cell line carcinoma in gymnomouse body was set up to observe the effect of octapeptide somatostatin (SMS 201-995,SMS) on the transplanted carcinoma and elucidate its mechanism. Results: the volume, weight, DNA and protein content in carcinoma cell, cell amount and proliferation index of S and G2M phase in SMS group and SMS+PG (pentagastrin) group were markedly lower than those in PG group and control group, those of PG group were markedly higher than those in control group.The cell amount of G0/G1 phase in SMS group and SMS+PG group was markedly higher than that in PG group and control group, and that of PG group was markedly lower than that in control group.All these suggested that somatostatin could not only inhibit the growth of transplanted human colonic SW480 cell line carcinoma directly but also inhibit the growthpromoting effect of gastrin on the transplanted carcinoma.The mechanism might be that somatostatin inhibit the synthesis of cAMP, DNA and protein in carcinoma cells, then inhibit the cell growing from G0/G1 phase to S and G2M phases.Our study might provide experimental basis for the homonotherapy with analogue of somatostatin in patients with large intestine carcinoma.
To verify the role of mAbCD28 in allograft transplantation. The biological action of mAbCD28 had been tested in mixed-lymphocyte-reaction and parathyroid gland allotranplantation in rats. Results: mAbCD28 could significantly suppress the proliferation of T cells in vitro and prolong the survival time of allograft in vivo. The results showed that mAbCD28 could block the costimulatory signals transmitted by CD28 molecules, and played an immunosuppressive role in parathyroid gland transplantation in rats.
Objective To explore the treatment effect of bone marrow mesenchymal stem cells( BMSCs)transplantation in ratmodel of bleomycin-induced pulmonary fibrosis. Methods BMSCs fromten-day-old SDmale rat were cultured and marked with 4, 6-diamidino-2-phenylindole( DAPI) . Seventy female SD rats were randomly divided into four groups. Group A( n = 21) was intratracheally injected with saline as control. Group B( n = 21)were intratracheally injected with BLMA5 to establish pulmonary fibrosis. Group C( n = 21) was injected with BLMA5 intratracheally and BMSCs intravenously via tail vein simultaneously. Group D( n = 7) was injected with BMSCs 14 days after BLMA5 injection. The rats were sacrificed on 7th, 14th and 28th day respectively( rats of group D were on28th) . HE and Masson stainings were performed to observe lung pathological changes. Fluorocyte marked with DAPI was analyzed by fluorescent microscope. Sex determining region Y( SRY) gene were detected by PCR. The lung levels of HYP, tumor necrosis factor-α( TNF-α) and transforming growth factor-β1 ( TGF-β1 ) were measured by ELISA. Results ( 1) In group C and D, BMSCs marked with DAPI were detected in lung frozen section on 7th, 14th and 28th day, and SRY gene of male rats were detected by PCR. ( 2) Alveolitis was most obvious on 7th day and pulmonary fibrosis was most severe on 28th day in group B compared to other three groups( P lt;0. 05 or 0. 01) . Alveolitis and pulmonary fibrosis in group C and D were significantly alleviated compared to group B( P lt; 0. 05) , but still more severe than group A( P lt; 0. 05 or 0. 01) , which in group D was more severe compared to group C( P lt;0. 05) . ( 3) HYP level in group B, coincided with fibrosis, began to increase on7th day and reached the peak on 28th day, significantly higher than other three groups( P lt;0.05 or 0. 01) . TNF-αlevel in group B was highest on 7th day, then descended, which was significantly higher than group A and C on 14th day and not obviously different from other three groups on 28th day. TGF-β1 level in group B was highest on 28th day which was different significantly fromother three groups. Conclusion BMSCs can colonize in the recipient lung tissue and effectively prevent the development of pulmonary fibrosis of rats induced by BLMA5, especially in the early stage.