Derivation of rhesus monkey parthenogenetic embryonic stem cells and its microRNA signature

An expedition in the jungle of pluripotent stem cells of non-human primates

For nearly three decades, more than 80 embryonic stem cell lines and more than 100 induced pluripotent stem cell lines have been derived from New World monkeys, Old World monkeys, and great apes. In this comprehensive review, we examine these cell lines originating from marmoset, cynomolgus macaque, rhesus macaque, pig-tailed macaque, Japanese macaque, African green monkey, baboon, chimpanzee, bonobo, gorilla, and orangutan. We outline the methodologies implemented for their establishment, the culture protocols for their long-term maintenance, and their basic molecular characterization. Further, we spotlight any cell lines that express fluorescent reporters. Additionally, we compare these cell lines with human pluripotent stem cell lines, and we discuss cell lines reprogrammed into a pluripotent naive state, detailing the processes used to attain this. Last, we present the findings from the application of these cell lines in two emerging fields: intra- and interspecies embryonic chimeras and blastoids.

Analysis of developmental imprinting dynamics in primates using SNP-free methods to identify imprinting defects in cloned placenta

Our knowledge of genomic imprinting in primates is lagging behind that of mice largely because of the difficulties of allelic analyses in outbred animals. To understand imprinting dynamics in primates, we profiled transcriptomes, DNA methylomes, and H3K27me3 in uniparental monkey embryos. We further developed single-nucleotide-polymorphism (SNP)-free methods, TARSII and CARSII, to identify germline differentially methylated regions (DMRs) in somatic tissues. Our comprehensive analyses showed that allelic DNA methylation, but not H3K27me3, is a major mark that correlates with paternal-biasedly expressed genes (PEGs) in uniparental monkey embryos. Interestingly, primate germline DMRs are different from PEG-associated DMRs in early embryos and are enriched in placenta. Strikingly, most placenta-specific germline DMRs are lost in placenta of cloned monkeys. Collectively, our study establishes SNP-free germline DMR identification methods, defines developmental imprinting dynamics in primates, and demonstrates imprinting defects in cloned monkey placenta, which provides important clues for improving primate cloning.

CPPED1-targeting microRNA-371a-5p expression in human placenta associates with spontaneous delivery

MicroRNAs (miRNAs) are important regulators of gene expression, and their expression is associated with many physiological conditions. Here, we investigated potential associations between expression levels of miRNAs in human placenta and the onset of spontaneous term birth. Using RNA sequencing, we identified 54 miRNAs differentially expressed during spontaneous term labor compared to elective term births. Expression levels of 23 miRNAs were upregulated, whereas 31 were downregulated at least 1.5-fold. The upregulated miRNA miR-371a-5p putatively targets CPPED1, expression of which decreases during spontaneous birth. We used a luciferase reporter–based assay to test whether a miR-371a-5p mimic affected translation when it bound to the 3′ untranslated region of CPPED1. In this setting, the miR-371a-5p mimic resulted in lower luciferase activity, which suggests that miR-371a-5p regulates levels of CPPED1. In conclusion, inversely correlated levels of miR-371a-5p and CPPED1 suggest a role for both in spontaneous delivery.

Non-coding RNAs: emerging regulatory factors in the derivation and differentiation of mammalian parthenogenetic embryonic stem cells

Parthenogenetic embryonic stem cells (PESCs) are ESCs derived from early parthenogenetic embryos. Haploid PESCs, containing haploid DNA, originate from a single sperm or occyte, while, diploid PESCs originate from two fused occytes. Most PESC lines used so far are diploid. PESCs exhibit representative pluripotent stem cell features, such as the capacity for self-renewal and the pariticular molecular signatures. Whereas, PESCs display distinctive properties, such as differential regulation of X-chromosome inactivation (XCI) and divergent monitor of genes involved in multiple biological processes. PESCs are considered promising in the regeneration medicine and developmental biology. Non-coding RNAs (ncRNAs), especially miRNAs and lncRNAs, have garnered increasing attention over the past 2 decades. They are now known to be involved in almost all cellular processes due to their full-range regulation of gene expression. Numerous studies have indicated that embryonic stem cells (ESCs) displayed distinct signatures of ncRNA genes, which play key roles in the pluripotency and self renewal of ESCs. However, the expression pattern of ncRNAs in PESCs and their roles in the derivation and differentiation of PESCs were rarely reported. In this paper, we reviewed recent research on the derivation and differentiation of PESCs and describe the emerging role of ncRNAs in these processes.

Chromosomal Abnormalities in Embryonic and Somatic Stem Cells

The potential use of stem cells (SCs) for tissue engineering, regenerative medicine, disease modeling, toxicological studies, drug delivery, and as in vitro model for the study of basic developmental processes implies large-scale in vitro culture. Here, after a brief description of the main techniques used for karyotype analysis, we will give a detailed overview of the chromosome abnormalities described in pluripotent (embryonic and induced pluripotent SCs) and somatic SCs, and the possible causes of their origin during culture.

Generation of parthenogenetic goat blastocysts: effects of different activation methods and culture media

The present study was carried out to investigate the effects of different activation methods and culture media on the in vitro development of parthenogenetic goat blastocysts. Calcium (Ca2+) ionophore, ethanol or a combination of the two, used as activating reagents, and embryo development medium (EDM), modified Charles Rosenkrans (mCR2a) medium and research vitro cleave (RVCL) medium were used to evaluate the developmental competence of goat blastocysts. Quantitative expression of apoptosis, stress and developmental competence-related genes were analysed in different stages of embryos. In RVCL medium, the cleavage rate of Ca2+ ionophore-treated oocytes (79.61 ± 0.86) was significantly (P < 0.05) higher than in ethanol (74.90 ± 1.51) or in the combination of both Ca2+ ionophore and ethanol. In mCR2a or EDM, hatched blastocyst production rate of Ca2+ ionophore-treated oocytes (8.33 ± 1.44) was significantly higher than in ethanol (6.46 ± 0.11) or in the combined treatment (6.70 ± 0.24). In ethanol, the cleavage, blastocyst and hatched blastocyst production rates in RVCL medium (74.90 ± 1.51, 18.30 ± 1.52 and 8.24 ± 0.15, respectively) were significantly higher than in EDM (67.81 ± 3.21, 14.59 ± 0.27 and 5.59 ± 0.42) or mCR2a medium (65.09 ± 1.57, 15.36 ± 0.52 and 6.46 ± 0.11). The expression of BAX, Oct-4 and GlUT1 transcripts increased gradually from 2-cell stage to blastocyst-stage embryos, whereas the transcript levels of Bcl-2 and MnSOD were significantly lower in blastocysts. In addition, different activation methods and culture media had little effect on the pattern of variation and relative abundance of the above genes in different stages of parthenogenetic activated goat embryos. In conclusion, Ca2+ ionophore as the activating agent, and RVCL as the culture medium are better than other tested options for development of parthenogenetic activated goat blastocysts.

Full-length novel MHC class I allele discovery by next-generation sequencing: two platforms are better than one

Deep sequencing has revolutionized major histocompatibility complex (MHC) class I analysis of nonhuman primates by enabling high-throughput, economical, and comprehensive genotyping. Full-length MHC class I cDNA sequences, which are required to generate reagents such as MHC-peptide tetramers, cannot be directly obtained by short read deep sequencing. We combined data from two next-generation sequencing platforms to discover novel full-length MHC class I mRNA/cDNA transcripts in Chinese rhesus macaques. We first genotyped macaques by Roche/454 pyrosequencing using a 530-bp amplicon spanning the densely polymorphic exons 2 through 4 of the MHC class I loci that encode the peptide-binding region. We then mapped short paired-end 250 bp Illumina sequence reads spanning the full-length transcript to each 530-bp amplicon at high stringency and used paired-end information to reconstruct full-length allele sequences. We characterized 65 full-length sequences from six Chinese rhesus macaques. Overall, approximately 70 % of the alleles distinguished in these six animals contained new sequence information, including 29 novel transcripts. The flexibility of this approach should make full-length MHC class I allele genotyping accessible for any nonhuman primate population of interest. We are currently optimizing this method for full-length characterization of other highly polymorphic, duplicated loci such as the MHC class II DRB and killer immunoglobulin-like receptors. We anticipate that this method will facilitate rapid expansion and near completion of sequence libraries of polymorphic loci, such as MHC class I, within a few years.

Major histocompatibility complex class I haplotype diversity in Chinese rhesus macaques

The use of Chinese-origin rhesus macaques (Macaca mulatta) for infectious disease immunity research is increasing despite the relative lack of major histocompatibility complex (MHC) class I immunogenetics information available for this population. We determined transcript-based MHC class I haplotypes for 385 Chinese rhesus macaques from five different experimental cohorts, providing a concise representation of the full complement of MHC class I major alleles expressed by each animal. In total, 123 Mamu-A and Mamu-B haplotypes were defined in the full Chinese rhesus macaque cohort. We then performed an analysis of haplotype frequencies across the experimental cohorts of Chinese rhesus macaques, as well as a comparison against a group of 96 Indian rhesus macaques. Notably, 35 of the 51 Mamu-A and Mamu-B haplotypes observed in Indian rhesus macaques were also detected in the Chinese population, with 85% of the 385 Chinese-origin rhesus macaques expressing at least one of these class I haplotypes. This unexpected conservation of Indian rhesus macaque MHC class I haplotypes in the Chinese rhesus macaque population suggests that immunologic insights originally gleaned from studies using Indian rhesus macaques may be more applicable to Chinese rhesus macaques than previously appreciated and may provide an opportunity for studies of CD8(+) T-cell responses between populations. It may also be possible to extend these studies across multiple species of macaques, as we found evidence of shared ancestral haplotypes between Chinese rhesus and Mauritian cynomolgus macaques.

Research with parthenogenetic stem cells will help decide whether a safer clinical use is possible

The derivation and use of parthenogenetic stem cells (pESCs) are envisaged as a reliable alternative to conventional embryonic stem cells. Similar to embryonic stem cells in their proliferation, expression of pluripotency markers and capacity to multilineage differentiation, pESCs are at a lower risk of immune rejection within stem cell-based therapeutics. Moreover, pESCs represent an important model system to study the effect of paternally imprinted genes on cell differentiation. However, currently available information about the genetic and epigenetic behaviour of pESCs is limited. Thus, a detailed look at the biology of parthenogenetic (PG) embryos and PG-derived cell lines would allow gaining insight into the full potential of pESC in biotechnology. In this commentary article we review some features related to the biology of PG embryos and pESCs. In addition, novel traits on bovine pESCs (bpESCs) are discussed.

MicroRNAs miR-371-3 in serum as diagnostic tools in the management of testicular germ cell tumours

BACKGROUND

miRNAs are small noncoding RNA molecules that can be released into body fluids. Germ cell tumours (GCTs) overexpress miRNAs of the miR-371-3 cluster. Thus, serum levels of these miRNAs may correlate with tumour load.

METHODS

miRNAs of the miR-371-3 cluster were quantified in cubital vein blood samples of 20 GCT patients with clinical stage 1, and of 4 patients with advanced stages before and after treatment. In six patients testicular vein blood (TVB) was examined additionally. Seventeen healthy males served as controls. Likewise, expression of miRNAs in 15 matching tumour specimens was measured.

RESULTS

In all patients, serum levels of miRNAs 371-3 were much higher than in controls. In stage 1, levels decreased postoperatively 336.7-fold, 7.4-fold, and 7.7-fold for miRNAs 371a-3p, 372, and 373-3p, respectively (P<0.01). Also, in those cases with advanced disease levels dropped to the normal range after completion of treatment. miR-371-3 levels in TVB exceeded those in peripheral blood in all cases. Expression of miR-371a-3p was also documented in tumour tissue. However, no correlation was found regarding the extent of miRNA expression in tissue and the values measured in matching serum.

CONCLUSION

Thus, miR-371a-3p serum level appears to be a useful biomarker in GCTs.