Are there advantages in the use of specific pathogen-free baboons in pig organ xenotransplantation models?

Baboons have natural antibodies against pig antigens. We have investigated whether there are differences in anti-non-Gal pig antibody levels between baboons maintained under specific pathogen-free (SPF) conditions and those housed under conventional conditions (non-SPF) that might be associated with improved outcome after pig-to-baboon organ transplantation. Baboons (n = 40) were housed indoors (SPF n = 8) or in indoor/outdoor pens (non-SPF n = 32) in colonies of similar size and structure. Non-SPF colonies harbor a number of pathogens common to non-human primate species, whereas many of these pathogens have been eliminated from the SPF colony. Complete blood cell counts (CBC), blood chemistry, and anti-non-Gal IgM and IgG levels were monitored. There were no significant differences in CBC or blood chemistry between SPF and non-SPF baboons. Anti-non-Gal IgM levels were significantly lower in the SPF baboons than in the non-SPF baboons (MFI 7.1 vs. 8.8, P < 0.05). One SPF and two non-SPF baboons had an MFI >20; if these three baboons are omitted, the mean MFIs were 4.8 (SPF) vs. 7.5 (non-SPF) (P < 0.05). Anti-non-Gal IgG was minimal in both groups (MFI 1.0 vs. 1.0). As their levels of anti-non-Gal IgM are lower, baboons maintained under SPF conditions may be beneficial for xenotransplantation studies as the initial binding of anti-pig IgM to an α1,3-galactosyltransferase gene-knockout pig organ may be less, thus resulting in less complement and/or endothelial cell activation. However, even under identical SPF conditions, an occasional baboon will express a high level of anti-non-Gal IgM, the reason for which remains uncertain.

Auxiliary liver allografting and xenografting in the nonhuman primate.

Auxiliary liver transplantation has been performed in the baboon using allografts (n = 8) and concordant xenografts from donor African green monkeys (n = 8). The native portal vein was ligated in all cases and the native common bile duct was ligated in 5 cases. The immunosuppressive therapy used was identical in both the allografts and xenografts and consisted of triple drug therapy (cyclosporine, cyclophosphamide, and methylprednisolone), all at dosages consistent with clinical use. During the determination of the surgical technique to be applied, there were 5 early failures (3 allografts, 2 xenografts), and 2 deaths at 10 and 20 days from multiorgan failure and sepsis, respectively (xenografts). The remaining 9 baboons (5 allografts, 4 xenografts) were electively euthanized at 16-62 days (allografts) and 35-120 days (xenografts). Hyperacute rejection or antibody-mediated rejection was not seen in the grafted livers. Episodes of acute cellular rejection occurred in the majority of animals within the first 30 days and recurred in the longer-term survivors, but could be controlled by bolus therapy with intravenous methylprednisolone. Satisfactory donor liver function was confirmed using a number of tests, including scintigraphy in 3 cases. We conclude that auxiliary liver transplantation using a closely related donor species is feasible in baboons and might be extended to humans with terminal liver failure. A baboon-to-man auxiliary liver graft may serve as a "bridge" until either a human cadaver donor liver became available or native liver function recovers in patients with fulminant hepatic failure.

The effects of photoperiod on the switching of myometrial contractility patterns of pregnant baboons: relationship to surgery and parturition.

OBJECTIVES: Pregnant baboons were studied to determine the precise time of the switch from myometrial contractures to contractions in relation to photoperiod after laparotomy and at parturition. We compared the patterns recorded in baboons to those we have previously reported in pregnant rhesus monkeys to determine fundamental primate characteristics. METHODS: Seven pregnant baboons (126-160 days' gestation) were instrumented with femoral arterial and venous catheters and electrodes for myometrial electromyogram. All animals were subjected to a 14-hour light:10-hour dark photoperiod. Myometrial activity was monitored using a computer-based data acquisition system. Onset time for all switches was noted and standardized against time of lights off. Animals were studied at three stages of pregnancy (stage 1, first 10 days after laparotomy; stage 2, more than 10 days after laparotomy and more than 10 days before cesarean; and stage 3, 10 days before cesarean section or vaginal delivery). RESULTS: All baboons demonstrated myometrial switches for a variable number of days preceding parturition. Onset of darkness was 0 hours. Average time of stage 1 switch onset was 2.17 +/- 0.60 hours and was not different from stage 3 switch onset, which was -1.00 +/- 0.27 hours. CONCLUSIONS: Myometrial contractile patterns showed clear photoperiodicity in the switch from contractures to contractions in late pregnancy in the baboon. The relationship of the switch from contractures to contractions was not altered by surgical laparotomy. There was a significant difference in the time of switch in relation to photoperiod between pregnant rhesus monkeys and baboons. However, the fact that a significant photoperiod exists in both species indicates a fundamental similarity in the switch from contractures to contractions in primate pregnancy.

Real-time in vivo loading in the lumbar spine: part 1. Interbody implant: load cell design and preliminary results.

STUDY DESIGN: Instrumented interbody implants were placed into the disc space of a motion segment in two baboons. During the animal's activities, implants directly measured in vivo loads in the lumbar spine by telemetry transmitter. OBJECTIVES: Develop and test an interbody implant-load cell and use the implant to measure directly loads imposed on the lumbar spine of the baboon, a semiupright animal. SUMMARY OF BACKGROUND DATA: In vivo forces in the lumbar spine have been estimated using body weight calculations, moment arm models, dynamic chain models, electromyogram measurements, and intervertebral disc pressure measurements. METHODS: An analytical model was used to determine the force-strain relation in a customized interbody implant. After validation by finite element modeling, strain gauges were mounted onto the implant and connected to a telemetry transmitter. Implants were placed surgically into the L4-L5 disc space of skeletally mature baboons and the transmitter in the flank. After surgery, load data were collected from the animals during activities. Radiographs were taken monthly to assess fusion. RESULTS: The implant-load cell is sufficiently sensitive to monitor dynamic changes in strain and load. During extreme activity, highest measurable strain values were indicative of loads in excess of 2.8 times body weight. CONCLUSIONS: The study technique and technology are efficacious for measuring real-time in vivo loads in the spine. Measuring load on an intradiscal implant over the course of healing provides key information about the mechanics of this process. Loads may be used to indicate performance demands on the intervertebral disc and interbody implants for subsequent implant design.

Serial laparoscopic biopsies of liver and spleen from Schistosoma-infected baboons (Papio spp.).

PURPOSE: To obtain large, serial biopsy samples from the liver and spleen by using laparoscopy. Large samples were needed for measurement of inflammatory mediators during various stages of schistosomiasis. METHODS: Each of the seven female baboons (Papio sp.) underwent as many as three laparoscopies, for a total of 19 laparoscopic procedures. This process permitted sampling of the liver, spleen, and mesenteric lymph nodes before and at 6 and 9 weeks after infection with Schistosoma mansoni. All surgery was performed through three trocar sites. Postoperative care included preemptive analgesia. After surgery, we monitored the animals' appetite and measured the core body temperature and activity by using implanted radiofrequency transmitters. RESULTS: We obtained samples of the liver and splenic biopsies during all 19 laparoscopic procedures. The mean weight of the liver biopsies was 3.7 g and that of the spleen samples was 5.3 g. We encountered small adhesions during 5 of the 12 reoperations. Eating and activity rapidly returned after surgery. CONCLUSIONS: Laparoscopy permitted collection of large, serial biopsies with apparently limited stress to the animals. Laparoscopy can be used for biopsies in studies to characterize disease response, confirm normal organ histology prior to drug toxicity studies, determine target-organ drug concentrations in pharmacokinetic studies, and measure drug residues. This refinement likely will reduce required animal numbers by decreasing the effect of surgery compared to that of the experimental conditions, enhance animal well-being, and permit repeated measurements in an animal that serves as its own control.

Continuous infusion anaesthesia in baboons with alphaxolone-alphadolone.

39 experiments were carried out in baboons using continuous intravenous infusion of alphaxalone-alphadolone as an anaesthetic for periods of up to 6 h. This steroid anaesthetic was found to be safe and reliable, with smooth, rapid induction, uneventful recovery, and no evidence of cumulative effect.

Method for transilial bone biopsy in baboons.

A surgical method for obtaining transilial bone biopsy specimens in baboons that provides adequate amounts of trabecular and cortical bone for histomorphometric analysis was developed. Biopsy specimens were removed from a site on the craniodorsal portion of the ilium by use of an 8-mm trephine.

Anaesthetic management of baboons undergoing heterotopic porcine cardiac xenotransplantation.

A detailed anaesthetic technique for baboons (Papio anubis) undergoing heterotopic abdominal cardiac xenotransplantation is described. Twenty-two baboons served as transplant recipients. Donors were either crossbred farm pigs (Sus scrofa) (n = 4) or transgenic pigs (Sus scroefa) (n = 18) expressing human complement regulatory proteins on the endothelium. Intra-operative management was complicated by the physiological consequences of infrarenal. abdominal aortic cross-clamping, in addition to the immunological sequelae related to cross-species transplantation. In choosing anaesthetics for this procedure, we considered the need for maximal cardiac stability throughout a long surgical procedure that required abdominal aortic cross-clamping to facilitate the implantation of an oversized porcine cardiac graft. Baboons received a balanced anaesthetic consisting of inhaled isoflurane in oxygen, intravenous fentanyl and intravenous pancuronium. The pharmacological techniques employed were found to be safe and reliable and were well tolerated by our recipients without any significant side-effects.

Generation of monocyte-derived insulin-producing cells from non-human primates according to an optimized protocol for the generation of PCMO-derived insulin-producing cells.

OBJECTIVE: The vision of potential autologous cell therapy for the cure of diabetes encourages ongoing research. According to a previously published protocol for the generation of insulin-producing cells from human monocytes, we analyzed whether the addition of growth factors could increase insulin production. This protocol was then transferred to a non-human primate model by using either blood- or spleen-derived monocytes. METHODS: Human monocytes were treated to dedifferentiate into programmable cells of monocytic origin (PCMO). In addition to the published protocol, PCMOs were then treated with either activin A, betacellulin, exendin 3 or 4. Cells were characterized by protein expression of insulin, Pdx-1, C-peptide and Glut-2. After identifying the optimal protocol, monocytes from baboon blood were isolated and the procedure was repeated. Spleen monocytes following splenectomy of a live baboon were differentiated and analyzed in the same manner and calculated in number and volume. RESULTS: Insulin content of human cells was highest when cells were treated with activin A and their insulin content was 13,000 µU/1 million cells. Insulin-producing cells form primate monocytes could successfully be generated despite using human growth factors and serum. Expression of insulin, Pdx-1, C-peptide and Glut-2 was comparable to that of human neo-islets. Total insulin content of activin A-treated baboon monocytes was 16,000 µU/1 million cells. CONCLUSION: We were able to show that insulin-producing cells can be generated from baboon monocytes with human growth factors. The amount generated from one spleen could be enough to cure a baboon from experimentally induced diabetes in an autologous cell transplant setting.

Waiting time to radiotherapy as a prognostic factor for glioblastoma patients in a scenario of medical disparities / Tempo de espera para a radioterapia como um fator prognóstico em pacientes com glioblastoma em um cenário de disparidades médicas

Objective To evaluate the effect of waiting time (WT) to radiotherapy (RT) on overall survival (OS) of glioblastoma (GBM) patients as a reliable prognostic variable in Brazil, a scenario of medical disparities. Method Retrospective study of 115 GBM patients from two different health-care institutions (one public and one private) in Brazil who underwent post-operative RT. Results Median WT to RT was 6 weeks (range, 1.3-17.6). The median OS for WT ≤ 6 weeks was 13.5 months (95%CI , 9.1-17.9) and for WT > 6 weeks was 14.2 months (95%CI, 11.2-17.2) (HR 1.165, 95%CI 0.770-1.762; p = 0.470). In the multivariate analysis, the variables associated with survival were KPS (p < 0.001), extent of resection (p = 0.009) and the adjuvant treatment (p = 0.001). The KPS interacted with WT to RT (HR 0.128, 95%CI 0.034-0.476; p = 0.002), showing that the benefit of KPS on OS depends on the WT to RT. Conclusion No prognostic impact of WT to RT could be detected on the OS. Although there are no data to ensure that delays to RT are tolerable, we may reassure patients that the time-length to initiate treatment does not seem to influence the control of the disease, particularly in face of other prognostic factors. .

Objetivo Avaliar o efeito do tempo de espera (TE) até radioterapia na sobrevida global de pacientes com glioblastoma como um fator prognóstico confiável. Método Estudo retrospectivo de 115 pacientes com glioblastoma, que foram submetidos à radioterapia pós-operatória, em dois serviços diferentes no Brasil (um público e outro privado). Resultados Mediana de TE para radioterapia foi de 6 semanas (variação, 1,3-17,6). A mediana de sobrevida para TE ≤ 6 semanas foi de 13,5 meses (IC95%, 9,1-17,9) e para TE > 6 semanas foi de 14,2 meses (IC95%, 11,2-17,2) (HR 1,165, 0,770-1,762; p = 0,470). Na análise multivariada, as variáveis associadas à sobrevida foram perfomance status (p < 0,001), extensão da ressecção (p = 0,009) e tratamento adjuvante (p = 0,001). Conclusão Não se observou impacto prognóstico para TE até a radioterapia na sobrevida. Diante de outros fatores prognósticos, é possível assegurar de que o espaço de tempo até a radioterapia não parece influenciar o controle da doença. .

Refinement of vascular access port placement in nonhuman primates: complication rates and outcomes.

Chronic vascular access is often needed in experimental animal studies, and vascular access ports (VAP) have been proposed as an alternative to conventional venipuncture. We previously reported on VAP implantation by using femoral venous cutdown (FVC) and tunneling. In an attempt to decrease the moderate complications associated with the FVC method, we developed the single-incision, peripheral-insertion (SIPI) method. In a retrospective evaluation, 92 FVC procedures were compared with 113 SIPI procedures in cynomolgus and rhesus macaques and baboons with as much as 2.5 y of follow-up. The rate of complications was significantly lower for the SIPI method than for the FVC method (19.4% versus 33.7%), particularly in regard to infectious complications (8.0% versus 27.3%, respectively). In addition, VAP patency for blood sampling and fluid infusion was significantly better for the SIPI method than for the FVC method, with 1-y patency rate of 83% and 46%, respectively, and 2-y patency rate of 74% and 36%, respectively. Additional advantages of the SIPI method include the simplified implantation of the VAP and access in the homecage without any sedation or restraint after appropriate training of animals to cooperate. We conclude that the SIPI method presents an opportunity for refinement and is superior to the FVC method for chronic vascular access.

Requirements for the welfare of baboons and pigs used in animal-to-animal xenotransplantation experiments.

OBJECTIVE: Review the welfare requirements of pigs and baboons used for xenotransplantation in research laboratories. Because of the requirements to maintain optimum health status, these animals are often kept in barren enclosures with little or no enrichment. They may also be exposed to procedures causing stress and discomfort. Although animal-to-human xenotransplantation is, at the present time, not approved in Australia, research is currently being performed to develop laboratory procedures, using the pig-to-baboon model. RESULTS AND CONCLUSION: We make recommendations for the husbandry of baboons and pigs used for xenotransplantation, to increase their welfare and minimise stress during experimental procedures, while attempting to preserve the health status required. It is proposed that novel standards should be devised and implemented for baboons, whereas existing pig welfare appraisal schemes could, with minor changes, be suitable for assessing the welfare of pigs used for xenotransplantation.

Pathology of renal xenograft rejection in pig to non-human primate transplantation.

Xenotransplantation has the potential to alleviate the critical shortage of organs for transplantation in humans. Miniature swine are a promising donor species for xenotransplantation. However, when swine organs are transplanted into primates, hyperacute rejection (HAR), acute humoral xenograft rejection (AHXR), acute cellular xenograft rejection (ACXR), and chronic xenograft rejection prevent successful engraftment. Developing a suitable regimen for preventing xenograft rejection requires the ability to accurately diagnosis the severity and type of rejection in the graft. For this purpose, histopathology remains the most definitive and reliable tool. We discuss here the characteristic features of xenograft rejection in a preclinical pig-to-non-human primate transplantation model. In miniature swine to baboon xenotransplantation, marked interstitial hemorrhage develops in HAR, and renal microvascular injury develops with multiple platelet-fibrin microthrombi in both HAR and AHXR. T-cell-mediated cellular immunity plays an important role in ACXR. Chronic humoral and cellular rejection may induce chronic xenograft rejection, and will be a major cause of graft loss in discordant xenotransplantation.

Oesophagojejunal anastomosis after total gastrectomy.

Techniques of oesophagojejunal anastomosis were studied in chacma baboons (Papio ursinus ursinus). End-to-end anastomosis utilizing a Roux-en-Y loop and interrupted silk sutures gave the best results. End-to-end anastomosis performed in 3 animals resulted in jejunal volvulus.

Transplantation of the heart and both lungs. Experimental and clinical experience and review of the literature.

Transplantation of the heart and both lungs is the only therapy that can be offered to certain patients with end-stage pulmonary vascular disease. Our experimental experience with the baboon is presented. Fourteen allotransplants were performed, 12 recipients (inadequately immunosuppressed with cyclosporin A and azathioprine) surviving between 4 and 29 days. In 11 cases death resulted from acute rejection which predominantly involved the lungs, the heart being spared in 10 cases; the remaining death was from bronchopneumonia. Two autotransplanted baboons survived until sacrificed at 6 months. Indications for the operation, selection of both the recipient and the donor, and recent results at other centres are briefly reviewed. It would seem that this operation is recommended in selected patients with idiopathic pulmonary hypertension or Eisenmenger's syndrome whose condition is deteriorating and in whom no other form of therapy is applicable.

Technique for primate heterotopic cardiac xenotransplantation.

Heterotopic cardiac transplantation in the primate is a valuable method for the evaluation of immuno-suppressive regimens. This report describes our technique for heterotopic transplantation of cardiac grafts into the neck of baboons. Preliminary experience with cross-genus cardiac transplantation in the nonhuman primate is discussed.

Is preoperative fasting necessary?

The effects of fasting and of histamine (H2) antagonists on gastric volume and acidity were studied in 56 baboons undergoing various surgical procedures under general anesthesia and randomly allocated into 4 groups; group A--fasted for 14 hours; group B--given 100-120 ml of water 3 hours before surgery; groups C and D--also given 100-120 ml of water 3 hours before surgery; in addition, the former received cimetidine 10 mg/kg IM and the latter ranitidine 1.5 mg/kg IM 30-40 minutes before anesthesia. There were no significant differences between groups A and B with respect to the gastric volume and pH. Both ranitidine and cimetidine significantly (P < 0.02) reduced gastric volume and increased gastric pH. Thus, prolonged withholding of oral fluids does not reduce the gastric volume or increase gastric pH. H2-antagonists are effective in reducing both gastric residual volume and pH.

The effect of pregnancy on endometriosis in baboons (Papio anubis, Papio cynocephalus).

BACKGROUND: This study was performed to test the hypothesis that endometriosis undergoes regression during pregnancy. METHODS: This study was performed on 11 baboons with histologically proven endometriosis, housed at the Institute of Primate Research, Nairobi, Kenya. In each individual baboon paired laparoscopies were performed prior to and during pregnancy (6 during first and 5 during second trimester of gestation) with an interval of 5 +/- 3 months. During each laparoscopy the number, size and type of endometriosis implants were noted in detail on a pelvic map; the endometriosis score and stage were calculated according to the revised American Fertility Society (AFS) classification. In each baboon the observations prior to and during pregnancy were compared and analysed by Wilcoxon signed rank test (two-tailed). RESULTS: No significant change was observed in the AFS score or stage of endometriosis, or in the number, size and type of endometriotic lesions in baboons during gestation when compared to the nonpregnant state. CONCLUSION: In baboons pregnancy had no significant effect on endometriosis during the first or second trimester of gestation.

The implantation of natural tooth form bioglasses in baboons. A preliminary report.

This report describes a 6-month screening study comparing the tissue responses of several bioglass natural tooth implants in adult female baboons. The dental implants were designed to elicit osteogenesis at the interface of the implant and the oral tissues. This is in contrast to those types of implant materials that are merely biologically acceptable. Incisor teeth were extracted, dupplicated in bioglass, returned to the natural sockets, and splinted to the adjacent natural tooth, where they remained splinted for 3 months and then free standing for an additional 3 months. Microscopic evaluation revealed distinct histopathologic characteristics with certain bioglass formulas, such as ankylosis, a pseudofibrous capsule with fibers running parallel to the root surface, or an apparently true periodontal membrane with properly oriented Sharpey's fibers. True cementogenesis was not found.

Arthroplasty by osteocartilaginous graft in primates.

Joint surface grafting has evolved from use of cadaveric materials preserved chemically and physically, to viable allogeneic and autogenic grafts in nearly a century of surgical history. Technical problems arising at the interface between foreign substances and living tissues has limited engineering arthroplasty such that a biological grafting process is eagerly sought. If successful with long periods of joint functioning, the scope of application to human victims of trauma, disease, and tumors of joints is wide. Whereas rabbits and dogs have been extensively used as models, primates have not. Whereas osteochondral allografts in Papio ursinus (the South African baboon) have been quite successful in hip, knee and shoulder joints, but the follow-up has been no more than a few years. Human autografts have been successful with periods of 10 and 15 years, but the present series is inadequate for statistical assessment. Further investigations of allografts and autografts in human joints are warranted.