A porcine model of phenylketonuria generated by CRISPR/Cas9 genome editing.

Phenylalanine hydroxylase-deficient (PAH-deficient) phenylketonuria (PKU) results in systemic hyperphenylalaninemia, leading to neurotoxicity with severe developmental disabilities. Dietary phenylalanine (Phe) restriction prevents the most deleterious effects of hyperphenylalaninemia, but adherence to diet is poor in adult and adolescent patients, resulting in characteristic neurobehavioral phenotypes. Thus, an urgent need exists for new treatments. Additionally, rodent models of PKU do not adequately reflect neurocognitive phenotypes, and thus there is a need for improved animal models. To this end, we have developed PAH-null pigs. After selection of optimal CRISPR/Cas9 genome-editing reagents by using an in vitro cell model, zygote injection of 2 sgRNAs and Cas9 mRNA demonstrated deletions in preimplantation embryos, with embryo transfer to a surrogate leading to 2 founder animals. One pig was heterozygous for a PAH exon 6 deletion allele, while the other was compound heterozygous for deletions of exon 6 and of exons 6-7. The affected pig exhibited hyperphenylalaninemia (2000-5000 µM) that was treatable by dietary Phe restriction, consistent with classical PKU, along with juvenile growth retardation, hypopigmentation, ventriculomegaly, and decreased brain gray matter volume. In conclusion, we have established a large-animal preclinical model of PKU to investigate pathophysiology and to assess new therapeutic interventions.

Review of Rodent Euthanasia Methods.

The optimal choice of euthanasia method for laboratory rodents depends on a number of factors, including the scientific goals of the study, the need to minimize animal pain and/or distress, applicable guidelines and laws, the training and proficiency of personnel, and the safety and emotional needs of the personnel performing the euthanasia. This manuscript aims to provide guidance to researchers so they may select the method of euthanasia that results in minimal experimental confounds, such as the creation of artifact and alteration of tissues and analytes. Specific situations addressed include euthanasia of large numbers of rodents and euthanasia of neonates. Recent literature supports the notion of significant strain-dependent differences in response to euthanasia methods such as CO2 inhalation. To assist researchers in selecting a strain-appropriate method of euthanasia, the authors present a summary of methodologies for assessing the effectiveness of euthanasia techniques, including elements and parameters for a scoring rubric to assess them.

Compassion Fatigue, Euthanasia Stress, and Their Management in Laboratory Animal Research.

This review is designed to assist both individuals and organizations involved in animal-based research to understand and appreciate the importance and potential risks of compassion fatigue and euthanasia stress. We reviewed current literature regarding compassion fatigue and euthanasia stress as they relate to the laboratory animal science community. Definitions, recognition, and mitigation steps are clarified. We offer educational and mitigation advice and present needs for future research on these topics that is related directly to the laboratory animal science community.

Comparison of Atipamezole with Yohimbine for Antagonism of Xylazine in Mice Anesthetized with Ketamine and Xylazine.

The α2 adrenergic agonist xylazine produces a sedative effect and is typically combined with ketamine and used for anesthesia or chemical restraint of laboratory mice. Xylazine's sedative effect-and its undesirable side effects of bradycardia, hypotension, and poor tissue perfusion-can be reversed by administration of α2 antagonists, such as atipamezole or yohimbine. Although atipamezole and yohimbine dosing guidelines are available for mice, no controlled comparison has been performed to guide the lab animal community in the selection of one over the other. This study is a single-dose crossover comparison of these 2 antagonist drugs, given intraperitoneally at clinically recommended doses, to determine which results in more rapid recovery of mice from xylazine-ketamine anesthesia. Time to return of righting reflex was used as the primary outcome measure. Mice were anesthetized with xylazine (10 mg/kg IP) and ketamine (80 mg/kg IP), followed 15 min later by injection of an α2 antagonist or saline (control). Time to return of righting reflex differed significantly among groups, with mice recovering in an average of 10.3 min after administration of atipamezole (1 mg/kg IP) as compared with 21.3 min after yohimbine (1.5 mg/kg IP) and 38.2 min after saline. When rapid recovery of mice after xylazine-ketamine anesthesia is desirable, administration of an antagonist to reverse the effects of the xylazine is indicated. When injection of the antagonist by the technically simple intraperitoneal route is desirable, our data indicate that (at the doses evaluated) atipamezole is more effective than yohimbine.

Identification and Characterization of Novel Rat Polyomavirus 2 in a Colony of X-SCID Rats by P-PIT assay.

Polyomaviruses (PyVs) are known to infect a wide range of vertebrates and invertebrates and are associated with a broad spectrum of diseases, including cancers, particularly in immune-suppressed hosts. A novel polyomavirus, designated rat polyomavirus 2 (RatPyV2), was identified from a breeding colony of rats having X-linked severe combined immunodeficiency. Using a human panpolyomavirus immunohistochemistry test (P-PIT), RatPyV2 was initially detected in the parotid salivary gland of a colony member. Rolling circle amplification using DNA from harderian and parotid glands identified a novel 5.1-kb polyomavirus genome closely related to human Washington University (WU) and Karolinska Institute (KI) and vole polyomaviruses but notably divergent from Rattus norvegicus PyV1 (RnorPyV1; also designated RatPyV1). Further screening showed RatPyV2 inclusion body infection in the lung epithelium and variably in other respiratory, reproductive, and glandular tissues of 12/12 (100%) rats. IMPORTANCE Although P-PIT was developed to detect diseases associated with known human polyomaviruses, the identification of a new polyomavirus in rats suggests that it may have utility as a broad-based screen for new, as well as known polyomaviruses. Our findings suggest that RatPyV2 may be a commensal infection of laboratory rats that can lead to disseminated disease in T cell immune-deficient rats. Infection of the X-SCID rats with RatPyV2 and Pneumocystis carinii is a potential model for coinfection pathogenesis and treatment options during transplant preclinical studies.

Systemic delivery and pre-clinical evaluation of nanoparticles containing antisense oligonucleotides and siRNAs.

By virtue of their potential to selectively silence oncogenic molecules in cancer cells, antisense oligonucleotides (ASO) and small interfering RNAs (siRNAs) are powerful tools for development of tailored anti-cancer drugs. The clinical benefit of ASO/siRNA therapeutic is, however, hampered due to poor pharmacokinetics and biodistribution, and suboptimal suppression of the target in tumor tissues. Raf-1 protein serine/threonine kinase is a druggable signaling molecule in cancer therapy. Our laboratory has developed cationic liposomes for systemic delivery of raf ASO (LErafAON) and raf siRNA (LErafsiRNA) to human tumor xenografts grown in athymic mice. LErafAON is also the first ASO containing liposomal drug tested in humans. In this article, we primarily focus on a modified formulation of systemically delivered cationic liposomes containing raf antisense oligonucleotide (md-LErafAON). The cationic liposomes were prepared using dimyristoyl 1,2-diacyl-3-trimethylammonium-propane (DMTAP), phosphatidylcholine (PC), and cholesterol (CHOL). The toxicology, pharmacokinetics, biodistribution, target selectivity, and anti-tumor efficacy studies of md-LErafAON were conducted in mice. We demonstrate that md-LErafAON is the next generation of systemically delivered and well-tolerated antisense therapeutic suitable for clinical evaluation.

Effects of maternal and infant characteristics on birth weight and gestation length in a colony of rhesus macaques (Macaca mulatta).

A retrospective study using maternal and birth statistics from an open, captive rhesus macaque colony was done to determine the effects of parity, exposure to simian retrovirus (SRV), housing, maternal parity, and maternal birth weight on infant birth weight, viability and gestation length. Retrospective colony statistics for a 23-y period indicated that birth weight, but not gestation length, differed between genders. Adjusted mean birth weights were higher in nonviable infants. Mothers positive for SRV had shorter gestations, but SRV exposure did not affect neonatal birth weights or viability. Infants born in cages had longer gestations than did those born in pens, but neither birth weight nor viability differed between these groups. Maternal birth weight did not correlate with infant birth weight but positively correlated with gestation length. Parity was correlated with birth weight and decreased viability. Increased parity of the mother was associated with higher birth weight of the infant. A transgenerational trend toward increasing birth weight was noted. The birth statistics of this colony were consistent with those of other macaque colonies. Unlike findings for humans, maternal birth weight had little predictive value for infant outcomes in rhesus macaques. Nonviable rhesus infants had higher birth weights, unlike their human counterparts, perhaps due to gestational diabetes occurring in a sedentary caged population. Similar to the situation for humans, multiparity had a protective effect on infant viability in rhesus macaques.

Proactive compliance-the team program approach to revitalizing primate enrichment.

The Division of Laboratory Animal Resources (DLAR) at the University of Pittsburgh proactively instituted a nonhuman enrichment plan that is founded on the United States Department of Agriculture (USDA) Final Report on the Environmental Enhancement to Promote the Psychological Well-being of Nonhuman Primates (July 1999). This document is a draft policy of the USDA that has not yet been enacted. In anticipation of the these standards becoming policy, the DLAR, and our Institutional Animal Care and Use Committee (IACUC), primate user groups, and Enrichment Specialist compared these new standards to our previous IACUC-approved plan. Our goal was to be "proactively compliant" to anticipated policy changes described in The Final Report. We established a program that was consistent with the five "critical" elements of The Final Report and our goal to have a revitalized enrichment plan that applied internal evaluation for continued improvement. A task force was implemented to review current literature and regulations on enrichment. Then a subcommittee consisting of veterinarians, investigators whose research would be affected by the anticipated policy changes, and IACUC members was formed. They established criteria for dispensation from plan elements, brought current protocols into compliance, shared enrichment and documentation techniques, and considered research methods in decision-making. In addition, a primate Enrichment Specialist position was developed and recruited. The Enrichment Specialist worked with investigators to evaluate enrichment and documentation needs and organized and implemented plan structure. The DLAR staff provided animal care and veterinary insight and reported to the IACUC. Investigators discussed how research and enrichment affected each other. The IACUC considered these issues before approving the plan. Our revitalized plan is running smoothly. The Enrichment Specialist oversees plan implementation and documentation. The DLAR assists enrichment and animal assessment. Investigators assist with assessment, provide enhanced enrichment, and document their progress. The IACUC addresses dispensation requests through designated review on the large-animal subcommittee.

Pharmacokinetics, toxicity, and efficacy of ends-modified raf antisense oligodeoxyribonucleotide encapsulated in a novel cationic liposome.

Raf-1 protein serine threonine kinase plays an important role in cell survival and proliferation. Antisense inhibition of Raf-1 expression has been shown to enhance the cytotoxic effects of radiation and anticancer drugs. Here we have evaluated the toxicity, pharmacokinetics, and antitumor efficacy of a novel formulation of liposome-entrapped raf antisense oligodeoxyribonucleotide (LErafAON). The LErafAON preparation showed high liposome entrapment efficiency of rafAON (>85%) and stability at room temperature. In CD2F1 mice, administration of LErafAON produced no morbidity/mortality (5-35 mg/kg/dose, i.v., x12). Dose-related elevations in liver enzymes (alanine aminotransferase and aspartate aminotransferase) and histopathological changes in liver were noted in LErafAON and blank liposome groups. No morbidity/mortality and changes in clinical chemistry or histopathology were observed in New Zealand white rabbits (3.75 mg/kg/dose, i.v., x8; 6.5 mg/kg/dose, i.v., x6) or in cynomolgous monkeys (3.75 or 6.25 mg/kg/dose, i.v., x9). Transient decrease in total hemolytic complement activity (approximately 62-74%) and increases in C3a (approximately 3-fold) and Bb levels (approximately 5-12-fold) were observed in LErafAON and blank liposome groups of monkeys. A 30 mg/kg i.v. dose of LErafAON in human prostate tumor (PC-3)-bearing BALB/c athymic mice gave a terminal plasma half-life of 27 h, and intact rafAON could be detected in plasma and in normal and tumor tissues for up to at least 48 h. In monkeys, the terminal plasma half-life of 30.36 +/- 23.87 h was observed at an i.v. dose of 6.25 mg/kg. LErafAON (25 mg/kg/dose, i.v., x10) or ionizing radiation (3.8 Gy/day, x5) treatment of PC-3 tumor-bearing athymic mice led to tumor growth arrest, whereas a combination of LErafAON and ionizing radiation treatments resulted in tumor regression. LErafAON treatment caused inhibition of Raf-1 protein expression in normal and tumor tissues in these mice (>50%, versus controls). These data have formed a basis of the clinical Phase I studies of LErafAON for cancer treatment.