Balancing the welfare: the use of non-human primates in research

“Natural Laboratory Complex” for novel primate neuroscience

We propose novel strategies for primate experimentation that are ethically valuable and pragmatically useful for cognitive neuroscience and neuropsychiatric research. Specifically, we propose Natural Laboratory Complex or Natural Labs, which are a combination of indoor-outdoor structures for studying free moving and socially housed primates in natural or naturalistic environment. We contend that Natural Labs are pivotal to improve primate welfare, and at the same time to implement longitudinal and socio-ecological studies of primate brain and behavior. Currently emerging advanced technologies and social systems (including recent COVID-19 induced “remote” infrastructures) can speed-up cognitive neuroscience approaches in freely behaving animals. Experimental approaches in natural(istic) settings are not in competition with conventional approaches of laboratory investigations, and could establish several benefits at the ethical, experimental, and economic levels.

CRISPR/Cas9 system: a reliable and facile genome editing tool in modern biology

Genome engineering has always been a versatile technique in biological research and medicine, with several applications. In the last several years, the discovery of Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-Cas9 technology has swept the scientific community and revolutionised the speed of modern biology, heralding a new era of disease detection and rapid biotechnology discoveries. It enables successful gene editing by producing targeted double-strand breaks in virtually any organism or cell type. So, this review presents a comprehensive knowledge about the mechanism and structure of Cas9-mediated RNA-guided DNA targeting and cleavage. In addition, genome editing via CRISPR-Cas9 technology in various animals which are being used as models in scientific research including Non-Human Primates Pigs, Dogs, Zebra, fish and Drosophila has been discussed in this review. This review also aims to understand the applications, serious concerns and future perspective of CRISPR/Cas9-mediated genome editing.

Welfare Improvement by Enrichment Programs in Common Marmoset Females Under Social Isolation

Animal welfare is critical to buffer stress in captive animals and to ensure the reliability of data from studies. The most usual environmental enrichment technique (EE) for social non-human primates is the social enrichment. However, some experimental protocols require keeping individuals isolated, thus demanding other types of EE. We tested in six adult Callithrix jacchus females, single housed for experimental purpose, the stress buffering efficacy of a structural enrichment protocol (SEP) and SEP in combination with a foraging enrichment (FSEP) using  fecal cortisol and behaviors to infer stress levels. Both types of EE improved welfare in different ways, while cortisol levels decreased with both EE as compared to the baseline, autogrooming, and piloerection increased after FSEP probably due to the new foods. Therefore, these findings support alternative practices of EE when social animals are living in isolation and reinforce the positive role of structural and food enrichment for decreasing stress markers. It also encourages studies on welfare with females, since its use as an animal model has increased .

Body surface area-based equivalent dose calculation in tree shrew

Tree shrew (Tupaia belangeri) is a promising experimental animal in biomedical research, but the equivalent doses of drugs between tree shrew and human and other animals has not been explored, which hinders its further application in a wider scope. The main objective of this article is to provide a method of equivalent dose conversion between tree shrews and other species based on body surface area (BSA). BSA of tree shrews were measured by Image J software, and then the average Km value of tree shrews was figured out based on the body weights and BSA, then the conversion coefficients of equivalent dose among tree shrew and other species of experimental animals were calculated based known data. The Km value of tree shrews was 0.105 ± 0.001. Through BSA conversion, the equivalent dose for tree shrews (D-ts) relative to rats was obtained by formula: D-ts = 1.36 × D-a (rats weighing 200g as example), and the error was less than 10% when the BW of the tree shrew was 0.09 kg-0.15 kg. The coefficients of equivalent dose transferring from tree shrews to human and other species were calculated in article. These parameters could be used to determine a suitable dosing strategy for tree shrew studies.

Mini-review: Aging of the neuroendocrine system: Insights from nonhuman primate models

The neuroendocrine system (NES) plays a crucial role in synchronizing the physiology and behavior of the whole organism in response to environmental constraints. The NES consists of a hypothalamic-pituitary-target organ axis that acts in coordination to regulate growth, reproduction, stress and basal metabolism. The growth (or somatotropic), hypothalamic-pituitary-gonadal (HPG), hypothalamic-pituitary-adrenal (HPA) and hypothalamic-pituitary-thyroid (HPT) axes are therefore finely tuned by the hypothalamus through the successive release of hypothalamic and pituitary hormones to control the downstream physiological functions. These functions rely on a complex set of mechanisms requiring tight synchronization between peripheral organs and the hypothalamic-pituitary complex, whose functionality can be altered during aging. Here, we review the results of research on the effects of aging on the NES of nonhuman primate (NHP) species in wild and captive conditions. A focus on the age-related dysregulation of the master circadian pacemaker, which, in turn, alters the synchronization of the NES with the organism environment, is proposed. Finally, practical and ethical considerations of using NHP models to test the effects of nutrition-based or hormonal treatments to combat the deterioration of the NES are discussed.

Ethical and Scientific Pitfalls Concerning Laboratory Research with Non-Human Primates, and Possible Solutions

Basic and applied laboratory research, whenever intrusive or invasive, presents substantial ethical challenges for ethical committees, be it with human beings or with non-human animals. In this paper we discuss the use of non-human primates (NHPs), mostly as animal models, in laboratory based research. We examine the two ethical frameworks that support current legislation and guidelines: deontology and utilitarianism. While human based research is regulated under deontological principles, guidelines for laboratory animal research rely on utilitarianism. We argue that the utilitarian framework is inadequate for this purpose: on the one hand, it is almost impossible to accurately predict the benefits of a study for all potential stakeholders; and on the other hand, harm inflicted on NHPs (and other animals) used in laboratory research is extensive despite the increasing efforts of ethics committees and the research community to address this. Although deontology and utilitarianism are both valid ethical frameworks, we advocate that a deontological approach is more suitable, since we arguably have moral duties to NHPs. We provide suggestions on how to ensure that research currently conducted in laboratory settings shifts towards approaches that abide by deontological principles. We assert that this would not impede reasonable scientific research.

Population genomics of wild Chinese rhesus macaques reveals a dynamic demographic history and local adaptation, with implications for biomedical research

Background

The rhesus macaque (RM, Macaca mulatta) is the most important nonhuman primate model in biomedical research. We present the first genomic survey of wild RMs, sequencing 81 geo-referenced individuals of five subspecies from 17 locations in China, a large fraction of the species’ natural distribution.

Results

Populations were structured into five genetic lineages on the mainland and Hainan Island, recapitulating current subspecies designations. These subspecies are estimated to have diverged 125.8 to 51.3 thousand years ago, but feature recent gene flow. Consistent with the expectation of a larger body size in colder climates and smaller body size in warmer climates (Bergman's rule), the northernmost RM lineage (M. m. tcheliensis), possessing the largest body size of all Chinese RMs, and the southernmost lineage (M. m. brevicaudus), with the smallest body size of all Chinese RMs, feature positively selected genes responsible for skeletal development. Further, two candidate selected genes (Fbp1, Fbp2) found in M. m. tcheliensis are involved in gluconeogenesis, potentially maintaining stable blood glucose levels during starvation when food resources are scarce in winter. The tropical subspecies M. m. brevicaudus showed positively selected genes related to cardiovascular function and response to temperature stimuli, potentially involved in tropical adaptation. We found 118 single-nucleotide polymorphisms matching human disease-causing variants with 82 being subspecies specific.

Conclusions

These data provide a resource for selection of RMs in biomedical experiments. The demographic history of Chinese RMs and their history of local adaption offer new insights into their evolution and provide valuable baseline information for biomedical investigation.

Successful production of genome-edited rats by the rGONAD method

BACKGROUND

Recent progress in development of the CRISPR/Cas9 system has been shown to be an efficient gene-editing technology in various organisms. We recently developed a novel method called Genome-editing via Oviductal Nucleic Acids Delivery (GONAD) in mice; a novel in vivo genome editing system that does not require ex vivo handling of embryos, and this technology is newly developed and renamed as "improved GONAD" (i-GONAD). However, this technology has been limited only to mice. Therefore in this study, we challenge to apply this technology to rats.

RESULTS

Here, we determine the most suitable condition for in vivo gene delivery towards rat preimplantation embryos using tetramethylrhodamine-labelled dextran, termed as Rat improved GONAD (rGONAD). Then, to investigate whether this method is feasible to generate genome-edited rats by delivery of CRISPR/Cas9 components, the tyrosinase (Tyr) gene was used as a target. Some pups showed albino-colored coat, indicating disruption of wild-type Tyr gene allele. Furthermore, we confirm that rGONAD method can be used to introduce genetic changes in rat genome by the ssODN-based knock-in.

CONCLUSIONS

We first establish the rGONAD method for generating genome-edited rats. We demonstrate high efficiency of the rGONAD method to produce knock-out and knock-in rats, which will facilitate the production of rat genome engineering experiment. The rGONAD method can also be readily applicable in mammals such as guinea pig, hamster, cow, pig, and other mammals.

Of Men and Mice: Modeling the Fragile X Syndrome

The Fragile X Syndrome (FXS) is one of the most common forms of inherited intellectual disability in all human societies. Caused by the transcriptional silencing of a single gene, the fragile x mental retardation gene FMR1, FXS is characterized by a variety of symptoms, which range from mental disabilities to autism and epilepsy. More than 20 years ago, a first animal model was described, the Fmr1 knock-out mouse. Several other models have been developed since then, including conditional knock-out mice, knock-out rats, a zebrafish and a drosophila model. Using these model systems, various targets for potential pharmaceutical treatments have been identified and many treatments have been shown to be efficient in preclinical studies. However, all attempts to turn these findings into a therapy for patients have failed thus far. In this review, I will discuss underlying difficulties and address potential alternatives for our future research.

Stem cell toxicology: a powerful tool to assess pollution effects on human health

Environmental pollution is a global problem; the lack of comprehensive toxicological assessments may lead to increased health risks. To fully understand the health effects of pollution, it is paramount to implement fast, efficient and specific toxicity screening that relies on human models rather than on time-consuming, expensive and often inaccurate tests involving live animals. Human stem cell toxicology represents a valid alternative to traditional toxicity assays because it takes advantage of the ability of stem cells to differentiate into multiple cell types and tissues of the human body. Thus, this branch of toxicology provides a possibility to assess cellular, embryonic, developmental, reproductive and functional toxicity in vitro within a single system highly relevant to human physiology. In this review, we describe the development, performance and future perspectives of stem cell toxicology, with an emphasis on how it can meet the increasing challenges posed by environmental pollution in the modern world.

Biologic Data of Cynomolgus Monkeys Maintained under Laboratory Conditions

The cynomolgus monkey (Macaca fascicularis) is a well-known non-human primate species commonly used in non-clinical research. It is important to know basal clinical pathology parameters in order to have a reference for evaluating any potential treatment-induced effects, maintaining health status among animals and, if needed, evaluating correct substantiative therapies. In this study, data from 238 untreated cynomolgus monkeys (119 males and 119 females of juvenile age, 2.5 to 3.5 years) kept under laboratory conditions were used to build up a reference database of clinical pathology parameters. Twenty-two hematology markers, 24 clinical chemistry markers and two blood coagulation parameters were analyzed. Gender-related differences were evaluated using statistical analyses. To assess the possible effects of stress induced by housing or handling involved in treatment procedures, 78 animals (35 males and 35 females out of 238 juvenile monkeys and four adult males and four adult females) were used to evaluate cortisol, corticosterone and behavioral assessment over time. Data were analyzed using a non-parametric statistical test and machine learning approaches. Reference clinical pathology data obtained from untreated animals may be extremely useful for investigators employing cynomolgus monkeys as a test system for non-clinical safety studies.

Functional analysis and transcriptional output of the Göttingen minipig genome

BACKGROUND

In the past decade the Göttingen minipig has gained increasing recognition as animal model in pharmaceutical and safety research because it recapitulates many aspects of human physiology and metabolism. Genome-based comparison of drug targets together with quantitative tissue expression analysis allows rational prediction of pharmacology and cross-reactivity of human drugs in animal models thereby improving drug attrition which is an important challenge in the process of drug development.

RESULTS

Here we present a new chromosome level based version of the Göttingen minipig genome together with a comparative transcriptional analysis of tissues with pharmaceutical relevance as basis for translational research. We relied on mapping and assembly of WGS (whole-genome-shotgun sequencing) derived reads to the reference genome of the Duroc pig and predict 19,228 human orthologous protein-coding genes. Genome-based prediction of the sequence of human drug targets enables the prediction of drug cross-reactivity based on conservation of binding sites. We further support the finding that the genome of Sus scrofa contains about ten-times less pseudogenized genes compared to other vertebrates. Among the functional human orthologs of these minipig pseudogenes we found HEPN1, a putative tumor suppressor gene. The genomes of Sus scrofa, the Tibetan boar, the African Bushpig, and the Warthog show sequence conservation of all inactivating HEPN1 mutations suggesting disruption before the evolutionary split of these pig species. We identify 133 Sus scrofa specific, conserved long non-coding RNAs (lncRNAs) in the minipig genome and show that these transcripts are highly conserved in the African pigs and the Tibetan boar suggesting functional significance. Using a new minipig specific microarray we show high conservation of gene expression signatures in 13 tissues with biomedical relevance between humans and adult minipigs. We underline this relationship for minipig and human liver where we could demonstrate similar expression levels for most phase I drug-metabolizing enzymes. Higher expression levels and metabolic activities were found for FMO1, AKR/CRs and for phase II drug metabolizing enzymes in minipig as compared to human. The variability of gene expression in equivalent human and minipig tissues is considerably higher in minipig organs, which is important for study design in case a human target belongs to this variable category in the minipig. The first analysis of gene expression in multiple tissues during development from young to adult shows that the majority of transcriptional programs are concluded four weeks after birth. This finding is in line with the advanced state of human postnatal organ development at comparative age categories and further supports the minipig as model for pediatric drug safety studies.

CONCLUSIONS

Genome based assessment of sequence conservation combined with gene expression data in several tissues improves the translational value of the minipig for human drug development. The genome and gene expression data presented here are important resources for researchers using the minipig as model for biomedical research or commercial breeding. Potential impact of our data for comparative genomics, translational research, and experimental medicine are discussed.