ABSTRACT
Enrichment and propagation of gonocytes or spermatogonial stem cells (SSCs) from cryopreserved testicular tissue is essential to apply SSCs-related techniques in large domestic animals. We previously reported the cryopreservation of adult bovine testicular tissue. Here, we conducted the enrichment and culture of putative gonocytes from cryopreserved testicular tissues of post-natal 1-day-old bulls. The testicular structure was well maintained after freezing and thawing. Higher mRNA levels of gonocyte/SSCs markers (PLZF, GFRα1, and UCHL-1) than those of pluripotency genes (Oct4, Sox2, and Nanog) were detected in the frozen-thawed sex cords. GFRα1 was specifically detected in the membrane and cytoplasm of gonocytes by immunostaining. Differential plating provided 40-50% enrichment of putative gonocytes. They were single, paired-, aligned-cells, or grape cluster-like colonies in minimum essential medium (MEM) containing 2.5% FBS + 2 mM glutamine + 100 IU/mL penicillin-streptomycin + 40 µg/mL gentamycin + 15 mM HEPES + 10 mM ß-mercaptoethanol + 0.1 mM non-essential amino acids + 1 mM sodium pyruvate. On day 3, gonocyte progeny increased and the contaminated somatic cells spread and concurrently divided slowly. On day 5, gonocyte progeny proliferated continuously and typical intercellular bridges formed by incomplete cytokinesis in paired-cells or aligned-cysts were observed. Immunochemically, they were still GFRα1 and PLZF positive. These cells expressed significantly higher gonocyte/SSCs marker mRNAs than pluripotency gene mRNAs, concomitant with a higher level of differentiated spermatogonia marker c-kit. With time, gonocyte progeny colonies appeared in varied sizes and expanded dramatically on day 7. After cultured for 9-10 days, however, large colonies collapsed and dispersed as some single cells and small syncytial cysts. Together, MEM containing 10% dimethyl sulfoxide + 2.5% newborn calf serum provides efficient cryoprotection for the testicular tissue from 1-day-old neonatal bulls. Putative gonocytes enriched from these nascent tissues present robust proliferation capacity, conserved gonocyte/SSCs markers, and SSCs-like in vitro features.
Subject(s)
Adult Germline Stem Cells/metabolism , Cell Differentiation/physiology , Spermatogonia/metabolism , Testis/metabolism , Adult Germline Stem Cells/cytology , Animals , Animals, Newborn , Cattle , Cell Proliferation/physiology , Cells, Cultured , Cryopreservation , Glial Cell Line-Derived Neurotrophic Factor Receptors/genetics , Glial Cell Line-Derived Neurotrophic Factor Receptors/metabolism , Kruppel-Like Transcription Factors/genetics , Kruppel-Like Transcription Factors/metabolism , Male , Nanog Homeobox Protein/genetics , Nanog Homeobox Protein/metabolism , Octamer Transcription Factor-3/genetics , Octamer Transcription Factor-3/metabolism , SOXB1 Transcription Factors/genetics , SOXB1 Transcription Factors/metabolism , Spermatogonia/cytology , Testis/cytology , Ubiquitin Thiolesterase/genetics , Ubiquitin Thiolesterase/metabolismABSTRACT
Miniature pigs have been recognized as valuable experimental animals in medical research. However, porcine models related to gene knockout of human diseases are not widely available. The objective of this study was to establish Mx1-Cre pigs using somatic cell nuclear transfer. In this study, we created transgenic pigs using somatic cell nuclear transfer (SCNT). Transfer of 210, 230, 250 and 215 zygotes to four surrogates produced 10 piglets. The Cre recombinase expression in transgenic pigs was studied using reverse transcriptase (RT)-PCR and immunohistochemistry. Mx1-Cre swine were shown to harbor the Cre gene in their genomic DNA using the PCR. In conclusion, Mx1-Cre transgenic piglets were successfully produced by SCNT. These transgenic swine, in conjunction with inducible systems for controlling Cre expression and function, are likely to have a profound impact on the study of human diseases.
ABSTRACT
The most established methods for development of transgenic animals are the microinjection of DNA into the fertilized eggs, but it is still a procedure of certain complexity and high cost. Therefore, the idea of using sperm as a vehicle to carry exogenous DNA into eggs is very attractive, and there have been some successful reports. Though the methods are rather simple they sometimes have low reproducibility. To improve the technique we transinfected the spermatozoa in testicular duct, not in vitro, to produce mice which expressed human tissue plasminogen activator (tPA) in mammary gland. The results demonstrated that: (1) 5 transinfected mice mated 10 female mice in 10 days after operation, (2) 79 founders were developed and 42 survived, (3) using PCR to detect foreign DNA integrated into the genome of founders, 7 out of 42 founders were positive (16.67%), (4) The expression level of tPA was 48-80 ng/ml in the milk of 5 PCR positive founders and (5) the foreign DNA integrated into the genome was detected in 2 out of 4 1st offspring by PCR technique.
