Design and testing of a humanized porcine donor for xenotransplantation

Recent human decedent model studies1,2 and compassionate xenograft use3 have explored the promise of porcine organs for human transplantation. To proceed to human studies, a clinically ready porcine donor must be engineered and its xenograft successfully tested in nonhuman primates. Here we describe the design, creation and long-term life-supporting function of kidney grafts from a genetically engineered porcine donor transplanted into a cynomolgus monkey model. The porcine donor was engineered to carry 69 genomic edits, eliminating glycan antigens, overexpressing human transgenes and inactivating porcine endogenous retroviruses. In vitro functional analyses showed that the edited kidney endothelial cells modulated inflammation to an extent that was indistinguishable from that of human endothelial cells, suggesting that these edited cells acquired a high level of human immune compatibility. When transplanted into cynomolgus monkeys, the kidneys with three glycan antigen knockouts alone experienced poor graft survival, whereas those with glycan antigen knockouts and human transgene expression demonstrated significantly longer survival time, suggesting the benefit of human transgene expression in vivo. These results show that preclinical studies of renal xenotransplantation could be successfully conducted in nonhuman primates and bring us closer to clinical trials of genetically engineered porcine renal grafts.

Effects of activity on avian gastrocnemius tendon

Physical activity and its relationship to animal health is a continuous concern of the food animal industry. This study investigated the relationship between broiler (meat-type chicken) activity to the structural integrity of the gastrocnemius tendon. Birds were exposed to treadmill pacing to determine if increased mobilization would increase tendon strength and improve its resistance to soft tissue injury. One hundred eighty broilers raised under normal commercial housing conditions were forced to walk on a treadmill 30 min/d, 5 d/wk for 3 wk, beginning at 3 wk of age. The treadmill treatment did affect the growth rate of the broilers. At the end of the study, the average body mass of the treatment birds was 9% less than the average body mass of the control birds, and the average length of the treatment shanks was 5% less than those from the control birds. Biomechanical parameters were measured and used to determine changes in the structural and material integrity of the tendons. The treadmill treatment did not affect tendon toughness, stiffness, relaxation behavior, and failure strength, but treatment did appear to affect tendon geometry, in which 33% of the treadmill treatment tendons had an increased amount of tissue near the bifurcation. The treadmill treatment did not affect the amount of procollagen within the tendon, and no cellular anomalies were found.

Semiquantitative measurement of cytokine messenger RNA in endomyocardium and peripheral blood mononuclear cells from human heart transplant recipients

BACKGROUND

Cytokines play a central role in inflammatory responses and in specific immune responses directed toward alloantigens. The pattern and quantity of cytokines produced in graft rejection can yield valuable information regarding the cellular and molecular mechanisms of the antigraft response.

METHODS

We used the polymerase chain reaction to semiquantitatively measure changes in the amount of messenger RNA from the interleukin-1 beta, interleukin-2, interleukin-4, interleukin-6, interleukin-10, tumor necrosis factor-alpha, interferon-gamma, interleukin-1 receptor antagonist, and the interleukin-2 receptor genes in the peripheral blood and endomyocardium of cardiac allograft recipients during the first 8 weeks after transplantation. A total of 328 samples of resting (n = 251) and stimulated (n = 77, stimulated with phytohemagglutinin and lipopolysaccharide for 18 hours) peripheral blood mononuclear cells collected from 16 patients were measured. To measure intragraft cytokine levels, we analyzed 150 endomyocardial biopsy specimens from 19 patients.

RESULTS

No elevation in expression was seen before injection, but, after the onset of rejection and concomitant with treatment, there was a decrease in detectable mRNA (p < 0.05) for the pro-inflammatory monokines interleukin-1 beta, interleukin-6, and tumor necrosis factor-alpha in resting peripheral blood mononuclear cells, and a decrease for the T-cell derived cytokines interleukin-4 and interleukin-10 in stimulated peripheral blood mononuclear cells. These changes in mRNA expression occurred coincidentally with decreases in the percentage of lymphocytes and monocytes in the peripheral blood after administration of rejection therapy. In endomyocardial biopsy specimens, there were no detectable changes in the quantities of cytokine mRNA specimens for the interferon-gamma, interleukin-6, interleukin-10, interleukin-1ra, and interleukin-1 beta genes before rejection. In general, the levels of these cytokines were near the lower limits of detection by our assay in endomyocardial biopsies, mRNA from the interleukin-2, interleukin-4, tumor necrosis factor-alpha, and interleukin-2R genes were undetectable.

CONCLUSIONS

We conclude that changes in the expression of cytokine mRNA in both peripheral blood mononuclear cells and endomyocardial biopsy specimens as measured by the semiquantitative polymerase chain reaction method used in this study does not effectively predict rejection. The decline in peripheral blood mononuclear cell cytokine mRNA after rejection treatment is likely due to changes in the proportion of lymphocytes and monocytes in the peripheral blood in concert with a steroid-induced downregulation by cytokine gene transcription.

Treatment of respiratory infections in horses with ceftiofur sodium

Ceftiofur sodium was evaluated as a therapy for respiratory infections in horses. This cephalosporin antimicrobial was administered intramuscularly every 24 h and at a dose of 2.2 mg/kg (1.0 mg/lb) of body weight. The efficacy of ceftiofur sodium was compared with that of a positive control drug, ampicillin sodium (recommended dose of 6.6 mg/kg [3 mg/lb], given every 12 h). Both treatments were continued for 48 h after clinical symptoms were no longer evident (maximum of 10 days). Fifty-five (55) horses with naturally acquired respiratory infections were included in the study; 28 were treated with ceftiofur and 27 with ampicillin. Clinical improvement was recorded for 92.9% of the patients treated with ceftiofur and 92.6% of the animals receiving ampicillin. Both therapies reduced body temperatures to an afebrile level after 2 days of treatment. Complete recovery/cure was noted for 78.6% of the ceftiofur patients and 59.3% of the horses treated with ampicillin. Supporting variables (depression/malaise, respiration/dyspnoea, nasal discharge) were assessed and these also substantiated the effectiveness of the treatments. Both antibiotics were well tolerated. Neither pain nor swelling were noted at the ceftiofur injection site(s). None of the animals developed diarrhoea. Data from this study indicated that ceftiofur sodium is an effective and safe treatment for respiratory infections in horses.