Xenogeneic Group Research Articles

Comparıson of the effect of the autogenıc and xenogenıc use of platelet-rıch plasma on rabbıt chondrocutaneous composıte graft survıval

The platelet-rich plasma (PRP) has become popular in the medical world due to its content of growth factors and numerous studies are experimental. In experimental studies, the preparation and application of PRP are problematic and allogenic PRP transfers have been preffered, because of the difficulties in preparation of autogenic PRP in animal experiments. Xenogenic transfers and their effects have not been studied in this topic. This study aimed to investigate the effect of autogenic and xenogenic use of PRP on composite graft viability. Methods: Two composite grafts are prepared for each ear of nine rabbits. Each ear was randomly divided into three groups. After the procedure, the wound edges and base were injected with 1 cc serum physiologic, autogenic PRP or 1 cc human-derived xenogenic PRP. At 3 weeks, samples were taken, photographic and histopathological evaluations were made. Results: The graft viability was better in autogenic and xenogenic group compared to the control group. In comprasion of autogenic and xenogenic groups, although the macroscopic evaluation revealed better graft viability and less necrosis in the group which had been treated with autogenic PRP, the difference was not statistically significant. The three groups did not significantly differ in terms of inflammation. Vascularization examined histopathologically. CD31 staining, which was used to evaluate angiogenesis, was significantly higher in the autogenic PRP group than the remaining two groups. Conclusion: Although autogenic PRP has better results histopathologically, the xenogenic use of PRP may be an alternative for studies, when macroscopic evaluation is necessary.

Sinus Mucosal Damage Triggered by Synthetic or Xenogeneic Bone Substitutes: A Histological Analysis in Rabbits.

Background: It has been shown in rabbit models that the sinus mucosa in contact with graft particles might experience a progressive thinning and perforations. The phenomenon depends on the graft used. Hence, the aim of the present study was to compare the damaging effects of a synthetic of a xenogeneic graft. Methods: Forty New Zealand rabbits received a bilateral sinus elevation. Both sinuses of twenty rabbits were grafted with a biphasic 60% hydroxyapatite and 40% β-tricalcium phosphate while the other twenty received a deproteinized bovine bone mineral graft. Thinned sites (<40 µm) and perforations on the mucosa in contact with graft particles were evaluated after 2 and 10 weeks (ten animals each period). The width of the pseudostratified epithelium was also measured as control. Results: After 2 weeks of healing, 61 thinned sites were detected in the Synthetic group and 49 in the Xenogeneic group. After 10 weeks, the number of thinned mucosae increased to 79 sites in the Synthetic group (p = 0.222 between periods), and to 114 sites in the Xenogeneic group (p = 0.030 between groups; p = 0.001 between periods). Perforations were few in the 2-week period, two in two sinuses out of 20 in the Synthetic group, and four in two sinuses out of 20 in the Xenogeneic group (p = 0.721). In the 10-week period, the perforations increased to eight in the Synthetic group, distributed in six sinuses out of 20, and to sixteen in the Xenogeneic group, distributed in 11 sinuses out of 20 (p = 0.082). The pseudostratified epithelium presented a reduced width at the thinned sites. Conclusions: The contact with synthetic or xenogeneic grafts will induce thinning and possible perforations of the sinus mucosa. This effect will increase over time, and it is stronger at the xenogeneic than the synthetic graft.

Establishing a new alveolar cleft model in rats to investigate the influence of jaw reconstructions on orthodontic tooth movement

BackgroundThe aim of the present investigation was to develop a new cleft model in rats that allows alveolar cleft repair and subsequent tooth movement. MethodsA complete continuity-interrupting alveolar cleft was performed on the left-side maxillae of 33 rats through ultrasonic surgery. The clefts were filled with bone wax, and microCT scans were done to analyze the cleft size. After four weeks, the cleft repair was completed using autologous, xenogeneic (human), or synthetic bone substitute. After an additional four weeks, the orthodontic tooth movement was initiated. ResultsFourteen rats died during the research, and the study design was constantly adapted accordingly. The main reasons for death included breathing problems during or immediately after the experimental activities (eight animals), followed by two deaths due to circulatory failures. In the remaining 19 animals, the average cleft size was about 2.70 ± 0.46 × 2.01 ± 0.25 × 1.18 ± 0.20 mm, and the mean velocity of orthodontic tooth movement after seven days was between 0.21 ± 0.08 mm in the autologous group and 0.50 ± 0.54 mm in the xenogeneic group. After 56 days, the mean values ranged between 0.67 ± 0.27 mm in the autologous group and 0.82 ± 0.72 mm in the synthetic group. ConclusionsSurgical interventions in the oral cavity of rats requires a stronger anesthesia and lead to increased risk of coolant and coagulated blood aspiration. The new alveolar cleft model in rats allows for subsequent orthodontic tooth movement after cleft repair, but only in the mesial root of the first molar.

Physical characterization of biphasic bioceramic materials with different granulation sizes and their influence on bone repair and inflammation in rat calvaria

Biphasic calcium phosphate bioceramics (BCP) consist of a mixture of hydroxyapatite (HA) and beta-tricalcium phosphate (β-TCP) within the same particle. Due to their osteoconductive properties, biocompatibility and resemblance to natural bone, these materials have become a promising and suitable alternative to autologous bone grafting. First, the topography characteristics, specific surface area, and total pore volume of BCP were evaluated using scanning electron microscopy and the BET and BJH methods. Next, this study aimed to evaluate the intensity of the inflammatory process and the bone neoformation capacity of various particle sizes of BCP in the repair of critical defects in the calvaria of rats. A xenogeneic biomaterial was used in the control group. After 30, 60, and 90 days, the animals were euthanized, followed by the processing of the samples to measure the intensity of inflammatory infiltrates and the areas of bone neoformation. Our results indicate that no considerable differences were observed in the inflammatory scores in sites treated with distinct BCP grain sizes. A greater area of bone neoformation was measured in the xenogeneic group at all analysis times, with no substantial differences in bone formation between the BCP particle size in the range of 250–500 µm and 500–1000 µm.

Endochondral Bone Regeneration by Non-autologous Mesenchymal Stem Cells.

Mimicking endochondral bone formation is a promising strategy for bone regeneration. To become a successful therapy, the cell source is a crucial translational aspect. Typically, autologous cells are used. The use of non-autologous mesenchymal stromal cells (MSCs) represents an interesting alternative. Nevertheless, non-autologous, differentiated MSCs may trigger an undesired immune response, hampering bone regeneration. The aim of this study was to unravel the influence of the immune response on endochondral bone regeneration, when using xenogeneic (human) or allogeneic (Dark Agouti) MSCs. To this end, chondrogenically differentiated MSCs embedded in a collagen carrier were implanted in critical size femoral defects of immunocompetent Brown Norway rats. Control groups were included with syngeneic/autologous (Brown Norway) MSCs or a cell-free carrier. The amount of neo-bone formation was proportional to the degree of host-donor relatedness, as no full bridging of the defect was observed in the xenogeneic group whereas 2/8 and 7/7 bridges occurred in the allogeneic and the syngeneic group, respectively. One week post-implantation, the xenogeneic grafts were invaded by pro-inflammatory macrophages, T lymphocytes, which persisted after 12 weeks, and anti-human antibodies were developed. The immune response toward the allogeneic graft was comparable to the one evoked by the syngeneic implants, aside from an increased production of alloantibodies, which might be responsible for the more heterogeneous bone formation. Our results demonstrate for the first time the feasibility of using non-autologous MSC-derived chondrocytes to elicit endochondral bone regeneration in vivo. Nevertheless, the pronounced immune response and the limited bone formation observed in the xenogeneic group undermine the clinical relevance of this group. On the contrary, although further research on how to achieve robust bone formation with allogeneic cells is needed, they may represent an alternative to autologous transplantation.

Surgical and Immunohistochemical Outcomes of Scleral Reconstruction with Autogenic, Allogenic and Xenogenic Grafts: An Experimental Rabbit Model

ABSTRACT Purpose: Choukroun’s platelet-rich fibrin (PRF), a second-generation platelet concentrate, has unique morphological and chemical features and may be considered as a scaffold for scleral reinforcement and regeneration. The purpose of this study was to compare the use of xenogenic human-derived amniotic membrane (HAM), allogenic sclera, and autogenic PRF in rabbit lamellar scleral defect model with respect to both anatomical and immunohistochemical improvement. Methods: A total of 45 adult New Zealand rabbits were randomized into five groups: normal control; without surgical procedure, negative control; scleral defect model (SDM), xenogenic HAM; SDM+HAM graft, allogenic sclera; SDM+allogenic sclera graft, autogenic PRF; SDM+autogenic PRF graft. Clinical findings, Hematoxylin&Eozin (HE), Masson Trichrome, Verhoeff Acid Fuchsin, Transforming Growth Factor β Receptor 1, Fibroblast Growth Factor, Bone Morphogenetic Protein 2, collagen type 1, aggrecan, and Matrix Metalloproteinase 2 were evaluated. Results: Ocular surface inflammation was significantly lower in normal control and autogenic PRF groups (p < .001). Graft was avascular and not integrated to scleral wound area in 25% rabbits of allogenic sclera group (p = .02), was out of the scleral wound in 33.3% rabbits of xenogenic HAM group (p > .05), all the grafts were at the normal location and viable in autogenic PRF group. The inflammation and vascularization in autogenic PRF group was significantly lower than negative control and xenogenic HAM groups in HE (p < .001). The collagen score of negative control and xenogenic HAM groups were significantly lower than normal control (p < .001) and autogenic PRF (p < .001) groups. There were insignificant differences between allogenic sclera and autogenic PRF groups (p > .05). For immunohistochemistry, the closest values to normal control group were detected in autogenic PRF group for all immunomarkers. Conclusion: Autogenic PRF showed superior features via its excellent anatomical and chemical composition for scleral regeneration when compared to single-layered xenogenic HAM and allogenic sclera grafts.

Comparison of The Therapeutic Effect of Syngeneic, Allogeneic, and Xenogeneic Adipose Tissue-Derived Mesenchymal Stem Cells on Abortion Rates in A Mouse Model.

Objective Mesenchymal stem cells (MSCs), due to their immunomodulatory functions, are an ideal candidate for the treatment of immune-related diseases. Recurrent spontaneous abortion (RSA) is one of the most common complications of pregnancy which in many cases is related to the immune system disorders. Our previous study has shown that the abortion rate was decreased following the syngeneic MSCs therapy in abortion-prone mice. In this study, the therapeutic effect of syngeneic, allogeneic, and xenogeneic MSCs was compared in a mouse model of RSA. Materials and Methods In this experimental study, MSCs were isolated from adipose tissue (ASCs) of CBA/J and BALB/c mice and human. After characterization, ASCs were injected (IP) at day 4 of gestation to female CBA/J mice following their mating with DBA/2 male mice. In the control group, phosphate-buffered saline (PBS) was injected and CBA/J×BALB/c mating was also used as the normal pregnancy control. On day 14.5 of pregnancy, embryo resorption rate was determined. Results The abortion rate significantly decreased following the ASCs therapy from syngeneic (6.31%), allogeneic (6.54%), and xenogeneic group (12.36%) compared to ASCs non-treated group (34.4%). There was no statistical difference between ASCs treated groups, however syngeneic and allogeneic ASCs reduced the abortion rate more efficiently than xenogeneic ASC. ConclusionThe abortion rate was significantly decreased following the intraperitoneal administration of ASCs from various donated sources in abortion-prone mice. These results indicated that the immunogenicity of allogeneic and xenogeneic ASCs is not a contradictory problem for their therapeutic effects on RSA.

Biological corneal inlay for presbyopia derived from small incision lenticule extraction (SMILE)

Corneal inlays are a relatively new treatment option for presbyopia. Using biological inlays, derived from lenticules extracted from small incision lenticule extraction, may offer advantages over commercialized synthetic inlays in the aspect of biocompatibility. We conducted a non-human primate study to evaluate the safety, predictability, efficacy and tissue response after autogeneic, decellularized xenogeneic and xenogeneic lenticule implantation. The lenticule implantation effectively resulted in central corneal steepening (simulated keratometric values increased by 1.8–2.3 diopters), central hyper-prolate changes (asphericity Q values changed by −0.26 to −0.36), corneal anterior surface elevation (7.7–9.3 μm) and reasonable effective zone (1.5–1.8 times of the lenticule physical diameter), with no differences among the three groups. Slit lamp microscopy, transmission electron microscopy, confocal microscopy, histology and immunohistochemistry analyses confirmed the biocompatibility of the autogeneic and decellularized lenticules, whereas one eye in the xenogeneic group developed corneal stromal rejection during the study period. Our results showed that lenticule implantation has the potential for the management of presbyopia, and provide the basis for future clinical studies. The decellularization process may increase the potential utilization of lenticules without changing the efficacy.

Repeated transplantation of allogeneic cardiosphere-derived cells boosts therapeutic benefits without immune sensitization in a rat model of myocardial infarction

A single dose of allogeneic cardiosphere-derived cells (CDCs) improves cardiac function and reduces scarring, and increases viable myocardium in the infarcted rat and pig heart without eliciting a detrimental immune response. Clinical trials using single doses of allogeneic human CDCs are underway. It is unknown whether repeat dosing confers additional benefit or if it elicits an immune response. Wistar-Kyoto rats underwent coronary artery ligation and intramyocardial injection of CDCs, with a second thoracotomy and repeat CDC injection 3 weeks later. Treatment permutations included 2 doses of allogeneic Brown-Norway CDCs (n = 24), syngeneic Wistar-Kyoto CDCs (n = 24), xenogeneic human CDCs (n = 24) or saline (n = 8). Cardiac function was assessed by transthoracic echocardiography, infarct size and inflammatory infiltration by histology, and cellular and humoral immune responses by lymphocyte proliferation and alloantibody assays. Repeat dosing of allogeneic and syngeneic CDCs improved ejection fraction by 5.2% (95% CI 2.1 to 8.3) and 6.8% (95% CI 3.8 to 9.8) after the first dose, and by 3.4% (95% CI 0.1% to 6.8%) and 6.4% (95% CI 4.2% to 8.6%) after the second dose. Infarct size was equally reduced with repeat dosing of syngeneic and allogeneic CDCs relative to xenogeneic and control treatments (p < 0.0001). Significant rejection-like infiltrates were present only in the xenogeneic group; likewise, lymphocyte proliferation and antibody assays were positive in the xenogeneic and negative in syngeneic and allogeneic groups. Repeat dosing of allogeneic CDCs in immunocompetent rats is safe and effective, consistent with the known immunomodulatory and anti-inflammatory properties of CDCs. These findings motivate clinical testing of repeatedly dosed CDCs for chronic heart disease.

Investigation of the immune response to autologous, allogeneic, and xenogeneic mesenchymal stem cells after intra-articular injection in horses

Mesenchymal stem cells have demonstrated immunomodulatory capabilities as well as modest efficacy in animal models of joint injury, warranting further study as a potential treatment of joint disease. The goal of the study was to investigate the blood and synovial immune and histologic response to intra-articular injection of autologous, allogeneic, and xenogeneic bone marrow-derived mesenchymal stem cells (MSC) in horses. The study group consisted of 6 five-year-old Thoroughbred mares that had been injected previously with 15 million, genetically modified autologous, allogeneic, or xenogeneic MSC into the fetlock joints. One group of autologous cells was genetically modified to permit MSC biolocalization in the synovium. To assess response to the injection, synovial biopsies were obtained via arthroscopy 60 days after MSC injection for gross, histologic and molecular analyses. Peripheral blood mononuclear cells were isolated from each horse 120 days after MSC injection and co-cultured with a monolayer of each MSC group to permit quantification of activated CD4+ lymphocytes and cytokine release (ELISA) upon re-exposure to MSC.Arthroscopic examination revealed normal synovium with no grossly detrimental effect to the synovium or cartilage. Intra-articular MSC produced a persistent mononuclear infiltrate for at least 60 days, mostly perivascular, identified as CD3+ lymphocytes. An immune response (significant increase in CD4+ lymphocytes) was detected upon re-exposure to xenogeneic but not to allogeneic or autologous MSC. An inflammatory cytokine release from peripheral blood mononuclear cell/MSC co-cultures was present in all MSC groups but was significantly greater in the xenogeneic group. In conclusion, intra-articular injection of MSC, regardless of cell origin, incited a persistent mononuclear synovitis demonstrating a sustained biologic influence of these cells. Allogeneic cells did not elicit a detectable immune response upon re-exposure using our methods.

Quantification of Islet Loss and Graft Functionality During Immune Rejection by 3-Tesla MRI in a Rat Model

Because metabolic markers are not suitable for early diagnosis of islet graft dysfunction, magnetic resonance imaging (MRI) has been used to study islets that were labeled pretransplantation with superparamagnetic iron oxide nanoparticles. However, the relation between graft functionality assessed by glycemia, and MRI signal remains unclear. We transplanted hyperglycemic rats intraportally with 2500 ferucarbotran-labeled syngeneic (n=10) or allogeneic (n=12) islet equivalents or normoglycemic rats with 5000 xenogeneic human islet equivalents. Images were acquired on a clinical 3-Tesla MRI scanner. When rejection occurred on days 4 and 8 in xenogeneic and allogeneic recipients, 60% (57-68) and 55% (46-73) of the initial signal remained compared to 93% (71-104) and 82% (59-90) in syngeneic controls (P=0.006 and 0.03). With a cutoff value of 84% on day 4 for the diagnosis of allogeneic rejection, sensitivity of 91% and specificity of 70% were obtained. Based on MRI signal on day 4, treatment with antilymphocytic serum from day 4 allowed graft rescue in 75% of recipients. In this model, MRI of pretransplantation superparamagnetic iron oxide nanoparticle-labeled islet grafts allows timely diagnosis of immune rejection.

Graft survival and cytokine production profile after limbal transplantation in the experimental mouse model

AbstractPurpose To evaluate the immune response in the experimental model of orthotopic limbal allo‐ and xenotransplantation in the mouse.Methods Allogeneic (C57BL/6 to BALB/c mouse), xenogeneic (Lewis rat to BALB/c mouse) and syngeneic (BALB/c to BALB/c mouse) limbal transplantations were performed. The rejection of limbal graft was scored according to the corneal opacity. The expression of IL‐2, IFN‐gamma, IL‐4, IL‐10 and inducible nitric oxide synthase (iNOS) were detected by Real‐time PCR in the graft. The donor cell survival was determined by Real‐time PCR after transplantation. The recipients were treated with systemic monoclonal antibodies (mAb) anti‐CD4 and anti‐CD8 and with saline in the control group.Results The allografts were rejected in 9.0 ± 1.8 days and xenografts in 6.5 ± 1.1 days after transplantation, syngeneic limbal grafts survived permanently. Distinct pattern of Th1 and Th2 cytokine production and intragraft expression of the iNOS gene were detected during rejection. Limbal grafts were promptly rejected by Th1 (allogeneic group) or by Th2 (xenogeneic group) type of immune response involving CD4+ cells and iNOS expression. The mean survival time of allogeneic and xenogeneic grafts was prolonged by systemic treatment of mAb anti‐CD4. Treatment with mAb anti‐CD8 did not extend the graft survival.Conclusion The experimental model of limbal transplantation is useful for testing various immunosuppressive approaches to treat rejection after transplantation. The anti‐CD4 mAb treatment presents promising immunosuppressive treatment after limbal transplantation.

SPECIFICITY OF SERUM ANTI-Adi IgG ANTIBODIES FROM PATIENTS WITH GASTROINTESTINAL CANCER

Changes in the glycosylation in cancer may lead to an aberrant expression of A, B incompatible or xenogeneic blood group related antigens. To characterize the specificity of IgG antibodies to A, B, and related glycans in sera of gastrointestinal cancer patients, serum probes and affinity-isolated antibodies were analyzed in the indirect and competitive ELISA using a set of homogenous polyacrylamide (PAA) glycoconjugates. Monoreactive antibodies recognizing Adi (I) and cross-reactive antibodies to Adi/Bdi/Btri (II) or Adi/Atri/Fsdi/Core5 (III) were affinity-isolated on Adi-PAA-Sepharose. The population I showed a higher affinity to Adi-PAA than cross-reactive antibodies. The antibodies II were more specific to Bdi and may belong to the core alpha-Gal reactive antibodies but are also capable of recognizing Adi. The antibodies III were more specific to Atri; they agglutinated A-erythrocytes and belong to anti-A isoantibodies reactive to xenogeneic oligosaccharides. The purified antibody samples were non- or faintly reactive to Tn. The IC50 values of PAA glycoconjugates ranged from 6 × 10−8 to 7 × 10−6 M. No or weak binding of antibodies to the unrelated antigens used in the detection of polyreactivity (ferritin, casein, and DNA) was observed.

Graft rejection in the xenogeneic transplantation of mice: diagnosis with in vivo MR imaging using the homing trait of macrophages

To evaluate the feasibility of magnetic resonance (MR) imaging to depict the in vivo recruitment of superparamagnetic iron oxide (SPIO)-labeled macrophages and to diagnose graft rejection in xenogeneic transplantation. We transplanted the trachea of SD rat (xenogeneic) or C3H/HeN mouse (syngeneic) into the left thighs of six male C3H/HeN mice. The SPIO-labeled macrophage was administered through the tail vein 2 days (acute) or 14 days (chronic) after transplantation in each group. The left thighs of the mice were imaged on a 4.7-T MR scanner 24 h after macrophage administration. We evaluated the extent and pattern of the susceptibility effect (macrophage distribution) and compared them in the two groups. The MR findings were then correlated with the histopathologic results. We also measured in both groups the monocyte chemoattractant protein (MCP)-1 level before and 2 days, 2 weeks, and 4 weeks after transplantation. The band-shaped lower signal intensity (SI) zone was noted around the graft in the acute and chronic phases of xenogeneic group and in the acute phase of syngeneic group, but it was not noted in the chronic phase of syngeneic transplantation. The lower SI zone corresponded to the distribution of SPIO-labeled macrophages on histopathological analyses. On histologic examination, the severe inflammation developed around the xenogeneic graft, but only slightly around the syngeneic graft. MCP-1 was elevated 2 days after transplantation in both groups, but then gradually decreased in the syngeneic group; in xenogenic group, the MCP-1 value decreased by week 2 but then increased by week 4. This study demonstrates that the homing of intravenously administered SPIO-labeled macrophages can be monitored on MR imaging and is correlated with the MCP-1 level and the histopathologic findings of the xenograft rejection.

Glutaraldehyde-Fixed Bioprosthetic Heart Valve Conduits Calcify and Fail From Xenograft Rejection

Glutaraldehyde fixation (G-F) decreases but likely does not eliminate the antigenicity of bioprosthetic heart valves. Rejection (with secondary dystrophic calcification) may be why G-F xenograft valves fail, especially in young patients, who are more immunocompetent than the elderly. Therefore, we sought to determine whether rejection of G-F xenograft occurs and to correlate this with graft calcification. Ascending aortas/valves (from rats [syngeneic] or guinea pigs [xenogeneic]) were transplanted (fresh or after 48 hour of G-F) into the infrarenal aortas of young rat recipients for 20 days. A xenogeneic group was also treated with steroids until graft harvest. The valves and media/adventitia were scored blindly for inflammation (0 to 4). Percent graft infiltration by T cells/macrophages was determined (immunohistochemistry), and rat IgG ELISAs were performed. There was >3 times more valve inflammation, >10 times more valve T-cell/macrophage infiltrate, and >3 times antibody rise in the G-F xenogeneic groups compared with the fresh syngeneic or the G-F syngeneic groups (P<0.05). There was >2 times more adventitial inflammation and T-cell/macrophage infiltrate in the xenogeneic groups (P<0.05). Steroid treatment decreased inflammation and antibody rise in the xenogeneic groups (P<0.05). Correlation analysis revealed media/adventitia inflammation (P=0.02) and percent macrophage (P=0.01) infiltration to be predictors of calcification. G-F xenografts have cellular/humoral rejection and calcify secondarily.

Remitting effects of xenogeneic hepatocyte transplantation on acute liver failure and immune rejection in rats

目的 探讨异种肝细胞移植对大鼠急性肝功能衰竭防治效果及其免疫排斥反应.方法将异种豚鼠肝细胞,90%肝除术前1 d植入大鼠脾脏内.观察受试大鼠存活时间,及切肝术后24 h血生化改变.另外观察植入肝细胞被排斥情况及受体CH50、异种抗体IgG、IgM水平变化.结果 (1)中位存活时间,对照组为21 h,同种组为56 h,异种组为40 h.同种组存活时间较对照组延长(P<0.01),异种组亦延长(P<0.05).(2)异种组血糖和凝血酶原时间改善较明显(P<0.05),同种组谷丙转氨酶、总胆红素、血糖、凝血酶原时间都有明显改善(P<0.05或P<0.01).(3)受体CH50和异种抗体IgM水平下降与植入异种肝细胞排斥过程同步.结论异种肝细胞移植对大鼠急性肝功能衰竭有防治作用,补体和异种抗体IgM与排斥反应关系密切。

Evaluation of osteogenic/chondrogenic cellular proliferation and differentiation in the xenogeneic periosteal graft.

To determine whether grafted young periosteum can induce new bone formation in elderly patients, this preliminary study evaluated cell proliferation and differentiation in xenogeneic periosteal grafts in old rats radiographically, histologically, and immunohistochemically. Periosteum harvested from the tibia of young Japanese white rabbits were grafted into old Sprague-Dawley rats with or without administration of 1.0 mg per kilogram per day immunosuppressant FK506. Autogenous old periosteal tissue grafts were also evaluated as a control. Grafted tissue was extirpated after 7, 14, 21, and 45 days. In the xenogeneic group, proliferative cell nuclear antigen-positive cells were observed 7 days after surgery, which differentiated into chondroblasts with bone morphogenetic protein-2 expression and finally formed cartilage by 14 days. Endochondral ossification was observed at 21 days, and bone replacement was completed by 45 days. No osteogenic cell activity was observed in the two other groups. Xenogeneic young periosteum thus maintained its osteogenic/chondrogenic potentiality in older rats.

Intravital microscopic investigation of xenogeneic microcirculation and impact of complement depletion by cobra venom factor.

Discordant xenografts are hyperacutely rejected within minutes. Disturbances in the microcirculation are considered to be the central mechanisms of hyperacute xenogeneic rejection (HXR). In this study intravital fluorescence microscopy was applied to investigate the dynamics of microcirculatory alterations in a setting in which HXR was inhibited by complement (C) depletion. Blood flow was measured as rat livers were perfused with isogeneic rat or xenogeneic human blood to assess the pattern of either physiological isogeneic hemoperfusion or in the course of HXR. Next, the complement system of the perfusate was inactivated by cobra venom factor (CVF) in order to inhibit HXR. Liver sinusoids of the isogeneic group were homogeneously perfused (sinusoidal perfusion rate 93.6+/-0.3%), whereas in the xenogeneic group the sinusoidal perfusion rate dropped to 67.1+/-3%. The perfusion in the periportal zone of an acinus was significantly lower ( 59.0+/-3.3%) than in the pericentral zone (76.2+/-3.1%). Treatment with CVF improved the sinusoidal perfusion to a value of 85.6+/-2.3%, physiological perfusion, however could not be reached. In contrast to the isogeneic group, massive white blood cell (WBC) and platelet accumulation was found in the xenogeneic group, especially in the terminal portal vessels and in the periportal zone of liver acini. WBC and platelet counts show that the adherence of these cells appears rapidly in the first 5 min after reperfusion as firm adherence. CVF was not able to inhibit WBC and platelet accumulation, indicating that WBC endothelial interactions do not require an intact complement system. Bile flow, a parameter of liver function, decreased only slightly during isogeneic perfusion. The addition of CVF to the rat blood reduced the bile flow to one half of the untreated isogeneic flow, indicating a hepatotoxic side-effect of CVF. In xenogeneic perfusion the bile flow dropped to 62.6% and with the addition of CVF to 37.5% in the first 15 min after reperfusion. The bile flow of the CVF treated groups recovered during the perfusion but could not reach isogeneic values.

Quantitative analysis of the microcirculation of xenogeneic haemoperfused rat livers by intravital microscopy

Abstract Livers from male Spra-gue-Dawley rats were perfused with heparinised, unmodified isogeneic rat blood (n= 6) or xenogeneic human blood. The microcirculation of these livers, as the primary manifestation of hyperacute xenogeneic rejection, was directly observed and quantified by using fluorescence videomicroscopy. Bile flow and enzyme release of the isogeneic perfused livers were in the physiological range, whereas bile flow was significantly reduced and enzyme release increased during xenogeneic perfu-sion. In contrast to an almost physiological acinar (90.4 %) and sinusoi dal (93.6 %) perfusion rate in the isogeneic group, a rapid breakdown of microcirculation with an acinar perfusion index of 47.5 % and a sinusoidal perfusion rate of 67.1 % were found in the xenogeneic group. This direct quantification of micro-circulatory parameters is a step forward towards sensitive and early characterisation of the severity of the xenogeneic rejection of the liver.

Quantitative analysis of the microcirculation of xenogeneic haemoperfused rat livers by intravital microscopy.

Livers from male Sprague-Dawley rats were perfused with heparinised, unmodified isogeneic rat blood (n = 6) or xenogeneic human blood. The microcirculation of these livers, as the primary manifestation of hyperacute xenogeneic rejection, was directly observed and quantified by using fluorescence videomicroscopy. Bile flow and enzyme release of the isogeneic perfused livers were in the physiological range, whereas bile flow was significantly reduced and enzyme release increased during xenogeneic perfusion. In contrast to an almost physiological acinar (90.4%) and sinusoidal (93.6%) perfusion rate in the isogeneic group, a rapid breakdown of microcirculation with an acinar perfusion index of 47.5% and a sinusoidal perfusion rate of 67.1% were found in the xenogeneic group. This direct quantification of microcirculatory parameters is a step forward towards sensitive and early characterisation of the severity of the xenogeneic rejection of the liver.