Phenotypic and Molecular Characterization of Domestic Cat (Felis catus) Spermatogonial Stem Cells.

In many mammalian species, surface markers have been used to obtain enriched populations of spermatogonial stem cells (SSCs) for assisted reproduction and other applications; however, little is known about the expression patterns of feline SSCs. In this study, we assessed expression of the SSC surface markers commonly used in other species, KIT, ITGA6, CD9, GFRalpha1, ADGRA3, and THY1, in addition to the less frequently used pluripotent markers TRA-1-60, TRA-1-81, SSEA-1, and SSEA-4 in SSCs of both prepubertal and adult domestic cats (Felis catus). To further characterize cat SSCs, we sorted cells using SSC-specific markers and evaluated the expression of the pluripotent transcription factors NANOG, POU5F1, and SOX2 and the proto-oncogene MYC within these populations. We concluded that SSC surface markers used in other mammalian species were not specific for identifying cat SSCs. However, the pluripotent markers we evaluated were more specific to cat spermatogonia, and the presence of SSEA-1 and SSEA-4 in fewer and primarily individual cells suggests that these two markers may be used for enrichment of cat SSCs. The expression of pluripotent transcription factors at mRNA level by single-stained cells positive for SSEA-4 and by dual-stained cells positive for both GFRalpha1 and SSEA-4 reflects the undifferentiated stage of cat SSCs. The absence of transcription factors in double-stained cells positive for only one marker implies the loss of the stem cell-like identity with the loss of either GFRalpha1 or SSEA-4. Further investigation is warranted to elucidate the biological characteristics of these spermatogonial subpopulations.

Characterization and Multilineage Differentiation of Domestic and Black-Footed Cat Mesenchymal Stromal/Stem Cells from Abdominal and Subcutaneous Adipose Tissue.

Transplantation of mesenchymal stem cells (MSCs) isolated from bone marrow or adipose tissue is emerging as a promising tool for cell replacement therapy and regenerative medicine in domestic and endangered animal species. Defining the differentiation capability of adipose-derived mesenchymal stromal/stem cells (AMSCs) collected from different depot sites of adipose tissue will be essential for developing strategies for cell replacement therapy. In the present study, we compared the biological characteristics of domestic cat AMSCs isolated from visceral fat of the abdominal cavity (AB) with AMSCs from subcutaneous (SQ) tissue, and the functional capability of domestic and black-footed cat (Felis nigripes) AMSCs to differentiate into other cell types. Our results showed that both domestic and black-footed cat adipose-derived stromal vascular fractions contained AMSCs. Both domestic cat AB- and SQ-AMSCs showed important clonogenic ability and the minimal MSC immunophenotype as defined by the International Society for Cellular Therapy in humans. However, domestic cat AB-AMSCs had higher percentages of cells positive for MSCs-associated cluster of differentiation (CD) markers CD90(+) and CD105(+) (92% and 80%, respectively) than those of SQ-AMSCs (77% and 58%, respectively). Although these results may suggest that AB-AMSCs may be more multipotent than SQ-AMSCs, both types of cells showed similar expression of pluripotent genes Oct-4 and Klf4, except for higher expression of Nanog than in AB-AMSCs, and equivalent in vitro multilineage differentiation. Under appropriate stimuli, the black-footed cat and both domestic cat AB- and SQ-AMSCs differentiated not only toward mesoderm cell lineages but also toward ectoderm cell lineage, such as neuron cell-like cells. Black-footed cat AMSCs had more capability to differentiate toward chondrocytes. These results suggest that the defined AMSC population (regardless of site of collection) could potentially be employed as a therapeutic agent for both domestic and endangered diseased or injured felids.

Trichostatin A modified histone covalent pattern and enhanced expression of pluripotent genes in interspecies black-footed cat cloned embryos but did not improve in vitro and in vivo viability.

Abstract The black-footed cat (BFC; Felis nigripes), one of the smallest wild cats, is listed as threatened. Interspecies somatic cell nuclear transfer (Is-SCNT) offers the possibility of preserving endangered species. Development to term of interspecies BFC (Is-BFC) cloned embryos has not been obtained, possibly due to abnormal epigenetic reprogramming. Treatment of intraspecies cloned embryos with TSA improves nuclear reprogramming and in vitro and in vivo viability. In this study, we evaluated (1) whether covalent histone modifications differ between Is-BFC cloned embryos and their IVF counterparts, (2) the optimal TSA concentration and exposure times to modify the covalent histone patterns, (3) if TSA enhances in vitro and in vivo developmental competence of cloned embryos, and (4) expression of pluripotent genes. Results indicated that the covalent histone modifications of Is-BFC cloned embryos aberrantly differ from their DSH-IVF counterpart embryos. Aberrant epigenetic events may be due partially to the inability of the DSH cytoplasm to modify the restrictive epigenetic marks of the BFC nuclei after somatic cell nuclear transfer (SCNT). Incomplete remodeling of the histone H3K9me2 in Is-BFC cloned embryos possibly contributes to abnormal expression of pluripotent genes and low embryonic development. Treatment of Is-BFC cloned embryos with TSA remodeled the covalent pattern in H3K9ac and H3K9me2, resembling epigenetic patterns in IVF counterpart embryos, and resulted in activation of some pluripotent genes. However, genomic reprogramming of Is-BFC cloned blastocysts did not follow the same reprogramming pattern observed in DSH-IVF embryos, and in vitro and in vivo developmental competence was not enhanced.

Global H3K9 dimethylation status is not affected by transcription, translation, or DNA replication in porcine zygotes.

Methylation of the lysine 9 residue of histone H3 (H3K9) is linked to transcriptional repression. The observed structure of chromatin in porcine and murine embryos is different with regard to H3K9 dimethylation status, leading to our hypothesis that the intracellular mechanisms responsible for H3K9 methylation would also differ between these two species. The objectives of this study were: (1) to determine the extent that DNA, mRNA, and protein synthesis serve in maintaining the asymmetrical distribution of dimethylated H3K9 in porcine zygotes, (2) determine the extent to which the intracellular localization of individual pronuclei correlated with H3K9 dimethylation status, and (3) to determine the abundance of transcripts encoding the histone methyltransferases, with H3K9 methylation activity, in porcine oocytes and embryos. Our findings are that (1) H3K9 dimethylation status is not affected by DNA replication, transcription, or protein synthesis, (2) the location of a pronucleus does not significantly affect the H3K9 dimethylation status of the chromatin within that pronucleus, and (3) the histone methyltransferases with activity for H3K9 differ in transcript abundance in porcine oocytes and cleavage stage embyros. These results support our hypothesis that there is a difference in intracellular mechanisms affecting dimethylation status of H3K9 between porcine and murine embryos.