[Controlled release of siRNA nanoparticles loaded in a novel external stent prepared by emulsion electrospinning attenuates neointima hyperplasia in vein grafts].

OBJECTIVE: To evaluate a strategy of using TF siRNA loaded in a novel external stent prepared by hybrid ultrafine fibrous membrane consisting of PLGA/Chitosan nanoparticles as a therapy for vein graft disease. METHODS: Hybrid ultrafine fibrous membranes consisting of PLGA/Chitosan nanoparticles were fabricated via a specially designed electrospinning setup. After soaking in chloroform to dissolve PLGA, the amount of chitosan in the hybrid membranes was determined. The water uptake of the hybrid ultrafine fibrous membranes was investigated by incubation in phosphate buffer solution. Right jugular vein-carotid artery interposition grafting models in Sprague-Dawley rats were randomly divided into five groups:Group A (external stent consisting of PLGA/CS-TFsiRNA nanoparticles), Group B (external stent consisting of PLGA/CS-Stealth(TM) RNAi negative control nanoparticles), Group C (external stent consisting of PLGA/CS blank nanoparticles), Group D (external stent consisting of PLGA), Group E (without perivenous external stent). BLOCK-iT(TM) Fluorescent Oligo was used to confirm its stability and successful transfer into the vein graft wall. The vein grafts were harvested at 1, 3, 7, 14, 28 d after operation, respectively. The TF protein expression of vein grafts was analyzed by Western blot and immunochemistry at 1, 3, 7 d after operation, respectively. The expression of proliferating cell nuclear antigen (PCNA) was identified by immunochemistry methods. The thickness of neointima at 28 d was calculated by computer imaging analysis system. RESULTS: The PLGA and CS amount in PLGA/Chitosan nanoparticles membranes could be well controlled by adjusting the flow rate for electrospinning of PLGA and chitosan nanoparticles, respectively. Because of the introduction of chitosan, which is a naturally hydrophilic polymer, the hybrid membranes exhibited good water absorption properties. BLOCK-iT(TM) Fluorescent Oligo could be detected in the graft wall even 12 days after operation. The expression of TF protein in Group A was significantly less than that in control groups at 3 d after operation (P < 0.05, 0.40 +/- 0.03 vs 0.75 +/- 0.01, 0.75 +/- 0.05, 0.77 +/- 0.07) and at 7 d after operation (P < 0.05, 0.30 +/- 0.03 vs 0.84 +/- 0.05, 0.86 +/- 0.06, 0.85 +/- 0.06). The expression of PCNA in Group A decreased significantly in comparison with control groups at 14 d after operation (P < 0.01, 13.0% +/- 2.6% vs 25.0% +/- 2.8%, 24.2% +/- 3.9%, 24.0% +/- 4.1%, 44.8% +/- 3.7%). The thickness of neointima at 28 d after grafting in Group A was significantly less than the untreated group (P < 0.01, 18.8 microm +/- 2.9 microm vs 38.7 microm +/- 5.0 microm, 37.3 microm +/- 3.6 microm, 37.2 microm +/- 2.6 microm, 67.5 microm +/- 4.8 microm). CONCLUSION: The novel external stent prepared by hybrid ultrafine fibrous membrane consisting of PLGA/Chitosan nanoparticles inhibits early neointima formation in rat vein grafts. This strategy may be a practicable and promising form of gene delivery against vein graft failure.

[Atelocollagen-mediated small interfering RNA delivery for effective gene silencing in rat vein grafts].

OBJECTIVE: To evaluate the efficacy of using small interfering RNA targeting TF as a therapy for vein graft failure. METHODS: External jugular vein to carotid artery interposition vein grafts, which were applied to a low flow condition, were made in 120 Sprague-Dawley rats weighing 260 to 300 g. These rats were randomly divided into 4 groups, 30 rats each group. Group A was atelocollagen-TF Stealth Select RNAi group. Group B was atelocollagen-TF Stealth RNAi group. Group C was atelocollagen group. Group D was control group. Small interfering RNA mixed with atelocollagen was administrated to the external wall of grafted veins. The TF protein expression of vein grafts was analyzed by Western blot at 1, 3, 7, 14, and 28 d postoperatively, and by immunochemistry at 3 d postoperatively. The proliferation index was determined at 14 d postoperatively. Neointimal hyperplasia was evaluated at 28 d postoperatively. BLOCK-iT fluorescent oligo was used to confirm its stability and successful transfer into the vein graft wall at 3 and 7 d postoperatively for another group (n=12). RESULTS: Fluorescence of BLOCK-iT fluorescent oligo could be detected in the graft wall even at 7 d postoperatively. Knockdown of the TF expression was achieved by perivascular application of siRNA using atelocollagen. Compared with control group, the intima thickness at 28 d after grafting was significantly reduced (P < 0.05). This phenomenon was preceded by significant reduction of cell proliferation in siRNA-treated grafts at 14 d postoperatively (P < 0.05). CONCLUSION: The expression of TF in vein grafts can be effectively inhibited by specific siRNAs using a atelocollagen-based nonviral delivery approach in vivo, so that the neointimal thickening can be prevented. Transplants;

[Local shRNA modulation of phosphatidylinositol 3-kinase signaling pathway reduces intimal hyperplasia in vein grafts: experiment with rats].

OBJECTIVE: To investigate whether knockdown Pik3cb p110beta subunit by shRNA in autologous vein grafts can reduce intimal hyperplasia. METHODS: 180 adult SD rats underwent carotid artery bypass graft surgery by using the autologous branch of jugular vein, and they were randomly divided into 6 equal groups: Group A (with the jugular vein grafts treated with 25% Pluronic F-127 only), Group B (with the graft treated with the plasmid encoding shRNA targeting Pik3cb p110beta subunit, pU6-Pik3cb-shRNA-1), Group C (with the graft treated with the plasmid encoding shRNA targeting Pik3cb p110beta subunit, pU6-Pik3cb-shRNA-2), Group D (with the graft treated with the half pU6-Pik3cb-shRNA-1 and pU6-Pik3cb-shRNA-2), and Group E (with the graft treated with the pGenesil-1 scramble shRNA), and Group F (with the jugular vein grafts treated with wortmannin). Specimens of jugular vein graft were harvested 1, 3, 7, 14, and 28 days after surgery to assess the neointimal hyperplasia. Another 18 rats were randomly divided into 6 equal groups as mentioned above to be used in a parallel experiment: 72 h after surgery specimens of jugular vein graft were harvested to undergo fluorescence quantitative real-time PCR and Western blotting to detect the mRNA expression of P13K p110beta subunit and the protein expression of phosphorylated Akt - phospho-Akt (Thr 308) and phospho-Akt (Ser473)-, and mTOR (Ser 2448). And another 9 rats received jugular vein grafts treated with the pGenesil-1 scramble shRNA, and on the postoperative days 1, 2, and 3 respectively 3 rats were killed to undergo fluorescence staining to detect the transfection efficacy. RESULTS: The transfection rate of the plasmid pGenesil-1 was 60% in the vascular smooth muscle cells and 90% in the endothelial cells. The thickness of tunica intima 28 days after the surgery of the pU6-Pik3cb-shRNA-1, pU6-Pik3cb-shRNA-2, 1/2 (shRNA1 + shRNA2), and wortmannin groups were (34.6 +/- 2.7) microm, (39.4 +/- 2.5) microm, (36.7 +/- 2.9) microm, and (40.6 +/- 3.1) microm respectively, all significantly lower than that of the control group (61.8 +/- 4.3 microm, P < 0.05). The expression levels of phospho-Akt (Thr 308), phospho-Akt (Ser 473), and mTOR of the shRNA intervention and wortmannin groups were all down-regulated. CONCLUSION: Knockdown of Pik3cb in interposition carotid artery branch of jugular vein grafts reduces intimal hyperplasia with the possible mechanism of downregulation of phosphatidylinositol 3-kinase signaling through Akt, with resultant decreases in VASC growth and survival. Modulation of the phosphatidylinositol 3-kinase pathway through knockdown Pik3cb may represent a novel therapy to prevent vein graft intimal hyperplasia after bypass grafting.

[Separation of gastrothoracopagus conjoined twins: 2 cases report].

OBJECTIVE: To investigate reasonable surgical therapy for conjoined twins. METHODS: Two pairs of gastrothoracopagus were admitted in July 2004 and April 2005 respectively. The first pair was separated by emergency surgery for the rupture of umbilical hernia resulting in the exposure of intestines. The thoracic and abdominal wall was repaired with local skin flaps, and the secondary wound was covered with artificial skin. Skin expanders were embedded in thoracic and abdominal wall 2 months after birth in the second pair. The surgical separation was performed one month after. The deficiencies of pericardium, sternum and abdominal wall were reconstructed by allogenic grafting of pericardium, porous polyethylene implant and monofilament polypropylene patch respectively. The thoracic and abdominal wall was repaired with expanded rotation skin flap. RESULTS: The first twins died of respiratory failure and circulatory and respiratory failure 2 hours and 39 hours after the separation respectively. Both of the second pair survived and were discharge after healing. CONCLUSIONS: The separation of gastrothoracopagus should be performed after skin expansion in the interest of the closure of wound. It's better to use porous polyethylene implant and monofilament polypropylene patch to reconstruct the sternum and abdominal wall respectively.

[Experimental study on mechanical properties of decellularized porcine aortic valve and effects of precoating methods of biological scaffold on histocompatibility].

OBJECTIVE: To observe the mechanical properties of decellularized porcine aortic valve, and to explore the effects of precoating methods of biological scaffold on histocompatibility. METHODS: Fresh porcine aortic valves were decellularized using trypsin, TritonX-100 and nuclease. Treated valves were evaluated by light microscopy, scanning electron microscopy (SEM) and mechanical test. Three groups of scaffold were precoated with phosphate buffered saline (PBS), poly-L-lysine (PLL) and fetal bovine serum (FBS) respectively. Myofibroblasts were seeded onto each scaffold. Light and electron microscopic observation was performed and MTT test was used to examine efficiency of cell attachment. RESULTS: HE stain and SEM showed that cells were almost absent in the treated leaflet. The wave-like collagen together with the whole three-dimensional structure was maintained. Compared with normal valves, the Max-load, Max-stress and elastic modulus decreased while the Max-strain increased (P<0.05). The result of MTT test showed more cells were attached on the valves treated with FBS compared to the other two groups. Histological investigations also confirm that the high degree of cell attachment on the valves precoated with FBS (F=129.26, P=0.000). CONCLUSIONS: Enzyme combined with detergent and nucleases can remove cells from porcine aortic valves. Meanwhile the mechanical properties of these valves may be altered. Precoating porcine aortic valve with FBS is an effective method to improve cell attachment, growth and increasing.

[Origin of neointimal cells in autologous vein graft in rat model].

OBJECTIVE: To investigate the potential cell sources of neointimal cells in autologous vein graft in rat model. METHODS: Vein graft neointimal cell origins were investigated using a model of vein-to-artery interposition modal. Slides were stained with hematoxylin and eosin, immunohistochemical staining was also performed with primary antibodies alpha-smooth actin or CD34. RESULTS: Neointimal thickening was greater at the proximal ends (65.2 +/- 4.6) microm and, to a lesser extent, distal ends (64.7 +/- 5.3) microm, in comparison to the middle of the graft (63.5 +/- 5.6) microm. Vein-originating cells survived and make a contribution to neointimal formation within the vein graft, mostly adjacent to the lumen, suggesting an intimate association with endothelial cells, donor arterial smooth muscle cells or circulating progenitor cells. CONCLUSIONS: Vein graft neointimal cells arise predominantly from vein-derived endothelial cells, donor arteria smooth muscle cells or circulating progenitor cells. It suggests clinical relevance of stenosis-inhibiting therapies directed at the vein graft or early system pharmacologic administration.

[Heat-shock protein 70 may be a putative endogenous ligand of Toll-like receptor-4 of human monocytes].

OBJECTIVE: To explore the relation between human heat shock protein 70 (HSP70) and Toll-like receptor-4 (TLR4) in human monocytes. METHODS: Periphery blood mononuclear cells were isolated from the samples of healthy blood donors' whole blood and monocytes were prepared and cultured. HSP70 of the final concentrations of 2.5 microg/ml, 5.0 microg/ml, 7.5 microg/ml, and 10 microg/ml respectively was added; 6 hours later the concentration of TNF-alpha in the supernatant was detected. Another monocytes were cultured and HSP70 of the final concentration of 5.0 microg/ml was added and the concentrations of NF-kappaB were detected 0, 30, 60, and 120 minutes later respectively. TLR4 blocker of the final concentrations of 5 microg/ml, 20 microg/ml, and 30 microg/ml respectively was added into another culture for 30 minutes and 5.0 microg/ml HSP70 was added, then immunochemistry was used to detect the concentration of NF-kappaB 120 minutes after ELISA was used to detect the concentration of and TNF-alpha 8 hours later. In order to examine the influence of HSP70 on the TLR4 in the cytomembrane of monocytes, HSP70 of the final concentration of 5.0 microg/ml was added into the culture of monocytes for 0, 30, 60, and 120 minutes respectively then flow cytometry was used to detect the mean fluorescence intensity (MFI) of TLR4. RESULTS: HSP70 stimulation increased the TNF-a concentration in the supernatant dose-dependently. The percentages of NF-kappaB positive monocytes were 38 +/- 6, 67 +/- 12, and 54 +/- 12 30 min, 60 min, 120 min after HSP70 stimulation, all significantly higher than that at the beginning of experiment (17 +/- 6, P < 0.05, P < 0.01, and P < 0.01). The percentages of NF-kappaB positive monocytes were 39% +/- 4%, 32% +/- 6%, and 28% +/- 6% 120 minutes after anti-TLR4 mAb stimulation, all significantly lower than that of the control group (67% +/- 12%, all P < 0.05). TLR4 blocker of different concentrations significantly inhibited the TNF-alpha secretion by the monocytes (all P < 0.05). The MFI of TLR4 in the cytomembrane of monocyte was significantly down-regulated 60 minutes, especially 120 minutes, after the HSP70 stimulation in comparison with that before the stimulation (P < 0.05 and P < 0.01). CONCLUSION: TLR4 appears to be involved in HSP70-mediated activation of innate immunity.

[Effects of hydrocortisone sodium succinate on sodium current in human and guinea pig cardiac myocytes].

AIM: To study the effects of hydrocortisone sodium succinate on sodium current in human atrial myocytes and in guinea pig ventricular myocytes. METHODS: Single cardiac myocytes were isolated by enzyme. The effects of hydrocortisone sodium succinate on sodium current (INa) were assessed by applying whole-cell patch clamp techniques. RESULTS: Hydrocortisone sodium succinate (1, 3, 10 micromol x L(-1)) was shown to inhibit INa of both human atrial myocytes and guinea pig ventricular myocytes in concentration dependent manner and the IC50 were 6.97 and 8.74 micromol x L(-1), respectively. The inhibition effects acted quickly (1-3 min) and the maximal activating voltage of INa was not changed in both human and guinea pig cardiac myocytes. CONCLUSION: Hydrocortisone sodium succinate can exhibit inhibitory effects on INa in both human and guinea pig cardiac myocytes, and its inhibitory effects act rapidly, which are not consistent with genomic effects, so there may be nongenomic effects.

Clinical experience in the use of marginal donor hearts.

BACKGROUND: Although heart transplantation has become a standard therapy for end-stage heart disease, there are few published studies regarding the use of transplant organs from marginal donors. Here we describe the clinical outcome we have obtained using marginal donor hearts. METHODS: We analyzed 21 cases of orthotopic heart transplantation for end-stage heart disease performed in our department between September 2008 and July 2010. Of these patients, six received hearts from marginal donors and the remainder received standard-donor hearts. The two groups were compared in terms of both mortality and the incidence of perioperative complications such as infection, acute rejection, and right heart insufficiency. RESULTS: The 1-year survival rate of both groups was 100%. Only one death was recorded in standard-donor group during follow-up. Patients who received marginal donor hearts (83%) experienced more early complications than did the standard-donor-heart group (13%), but the mortality of the two groups was the same. The duration of post-ICU stay was greater in the marginal donor group than in the standard-donor group, (35.5 ± 17.4) days and (21.7 ± 2.6) days, respectively (P < 0.05). CONCLUSIONS: The use of marginal donor hearts increases the number of patients who can receive and benefit from transplants. However, it may introduce an increased risk of early complications, thus care should be taken both in the choice of patients who will receive marginal donor hearts and in the perioperative treatment of those for whom the procedure is performed.

[Pretreatment of donor dendritic cells with NBD-peptide prolongs mouse cardiac allograft survival].

OBJECTIVE: To observe the effects of NBD-peptide pretreatment of the donor dendritic cells in immune tolerance induction in mouse allograft recipients and investigate the mechanisms. METHODS: BALB/c mouse DCs pretreated with NBD-peptide (NBD-Peptide-DC) were injected into the recipient C57BL/6 mice 7 days before transplantation. Cervical heterotopic heart transplantation model was established using the cuff technique and the cardiac allograft survival time was observed. Pathological analysis were performed to examine the graft injection and the responsiveness of the recipient spleen T cell to the donor alloantigen was determined by mixed lymphocyte reaction (MLR). The serum levels of cytokines were determined using ELISA. RESULTS: The cardiac allograft survival time in the NBD-Peptide-DC-treated group (21.83-/+3.54 days) was significantly longer than that in the Day9-DC group (13.33-/+2.58 days) and PBS-treated group (6.66-/+1.21 days) (P<0.01), with also significantly lower pathological grade for graft rejection (P<0.01). The donor-derived NBD-Peptide-DCs induced alloantigen-specific T-cell hyporesponsiveness. In the NBD-Peptide-DC-treated group, the serum levels of IL-12 and IFN-gamma decreased significantly (P<0.01), but the levels of IL-4 and IL-10 increased significantly (P<0.01). CONCLUSION: Injection of donor-derived NBD-Peptide-DCs can leads to donor-specific tolerance in the transplant recipients, and the induction of recipient T-cell hyporesponsiveness and polarization of Th2 response may play important roles in immune tolerance to cardiac allografts.

[Inhibitory effects of RNA interference on MyD88 expression and biological activity in murine myeloid dendritic cells].

AIM: To investigate inhibitory effects of RNA interference on MyD88 expression in murine myeloid dendritic cells(DCs) and detect the biological activity of DCs. METHODS: Three pairs of myeloid differentiation factor 88(MyD88) siRNA were synthesized and transfected into DCs by RNAi-mate. The mRNA and protein expression of MyD88 were analyzed by semi-quantified RT-PCR and Western blot. Mouse DCs were divided into control group and RNA interference group. One of the highest effective siRNA was transfected into RNA interference group. 12 hours later, LPS of the final concentrations of 1.0 mg/L was added in two groups and continued to culture for 3 days. The phenotype and functional properties of DCs were detected by flow cytometry and mixed lymphocyte reaction (MLR). The concentration of TNF-alpha, IFN-gamma and IL-12 in the supernatant was detected by ELISA, and the concentration of NF-kappaB was detected by immunochemistry. RESULTS: mRNA and protein expression were reduced 90% and 85% in sequence2 siRNA, 92% and 88% in sequence3 siRNA respectively but no change was found in other groups. LPS stimulation increased the expression of CD80, CD86 and MHC-II in the cytomembrane of DCs, the concentration of TNF-alpha, IFN-gamma and IL-12 in the supernatant in control group. Besides, LPS stimulation promoted the shift of NF-kappaB to karyon and the proliferation of allogeneic T cells in control group. RNA interference inhibited these effects induced by LPS. CONCLUSION: RNA interference can reduce MyD88 expression in murine myeloid dendritic cells and inhibit the maturation of DCs, which may provide a new strategy of gene therapy for related diseases.