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Medrano J.V.,University of Valencia | Martinez-Arroyo A.M.,University of Valencia | Sukhwani M.,University of Pittsburgh | Noguera I.,University of Valencia | And 6 more authors.
Fertility and sterility | Year: 2014

OBJECTIVE: To illustrate the step-by-step protocol followed to assay germ cell transplantation into the seminiferous epithelium of mouse testes.DESIGN: Video presentation of an animal model for research in reproductive and regenerative medicine.SETTING: Research laboratory.ANIMAL(S): Male nude mice (NU-Foxn1(nu)).INTERVENTION(S): Mice were chemically sterilized with alkylant compounds (busulfan) followed by gonadal microsurgery to inject donor germ cells.MAIN OUTCOME MEASURE(S): Donor cells should be labeled with reporter genes, such as green fluorescent protein (GFP), lactose operon (LacZ), or alternatively design an effective strategy with specific antibodies to track them within the recipient testes. Sperm detection in the ejaculate can also be used as a read out. However, in this case detection of the donor genotype in the sperm is mandatory to elucidate their origin.RESULT(S): In the present study we describe the complete protocol for germ cell transplant by efferent duct injection, including the preparation of recipient mice, surgery for the germ cell transplant, and analysis of recipient testes. The main strength of this technique is that it constitutes the gold standard for a functional test of the germ cell potential as only spermatogonial stem cells are able to properly colonize the seminal lumen. Both fresh and frozen/thawed testicular cells are suitable for this technique as donor germ cells. Also, enrichment of living spermatogonial stem cells, previous to the transplant, seems to improve the efficiency of colonization. For proper colonization of germ cells, the niche should be available and thus mouse strains that lack endogenous spermatogenesis such as W/W(v) mutant mice are usually used. In the case of nonmatched donor cells, seminiferous epithelium of immune-suppressed recipient mice should be germ cell depleted before the transplant. One limitation of this technique is that the procedure can take up to 3 months. Also, in contrast to the full recovery of spermatogenesis in mouse-to-mouse transplants, xenotransplantation of germ cells from phylogenetically distant species, such as humans into mouse recipients, results in colonization of donor cells and spermatogonial expansion, but fail in their spermatogenic progression due to evolutive incompatibilities with the recipient niche. Xenografting of pieces of donor testis tissue under the skin of mouse hosts is an alternative approach that is currently being investigated to try to solve this limitation.CONCLUSION(S): Transplantation of spermatogonial stem cells into the seminal lumen of mouse testes is a functional assay that defines this cellular subpopulation by its ability to colonize it. This technique can be used as a model to elucidate the insights of spermatogonial stem cells, to produce transgenic animals by genetically manipulating donor cells before transplantation, but also it has potential applications in fertility preservation in cattle and humans as it is feasible in large animals, as recent reports have demonstrated with rhesus monkeys, that recovered spermatogenesis after allogenic transplantation, and even from human cadaver testes. Therefore spermatogonial stem cells isolated from prepuberal boys, who are treated with alkylant chemotherapy, could be returned to their testis to regenerate spermatogenesis in the future. Copyright © 2014 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved. Source


Medrano J.V.,University of Valencia | Medrano J.V.,Fundacion Institute Investigacion Sanitaria La Fe | Martinez-Arroyo A.M.,University of Valencia | Sukhwani M.,University of Pittsburgh | And 8 more authors.
Fertility and Sterility | Year: 2014

Objective: To illustrate the step-by-step protocol followed to assay germ cell transplantation into the seminiferous epithelium of mouse testes. Design: Video presentation of an animal model for research in reproductive and regenerative medicine. Setting: Research laboratory. Animal(s): Male nude mice (NU-Foxn1nu). Intervention(s): Mice were chemically sterilized with alkylant compounds (busulfan) followed by gonadal microsurgery to inject donor germ cells. Main Outcome Measure(s): Donor cells should be labeled with reporter genes, such as green fluorescent protein (GFP), lactose operon (LacZ), or alternatively design an effective strategy with specific antibodies to track them within the recipient testes. Sperm detection in the ejaculate can also be used as a read out. However, in this case detection of the donor genotype in the sperm is mandatory to elucidate their origin. Result(s): In the present study we describe the complete protocol for germ cell transplant by efferent duct injection, including the preparation of recipient mice, surgery for the germ cell transplant, and analysis of recipient testes. The main strength of this technique is that it constitutes the gold standard for a functional test of the germ cell potential as only spermatogonial stem cells are able to properly colonize the seminal lumen. Both fresh and frozen/thawed testicular cells are suitable for this technique as donor germ cells. Also, enrichment of living spermatogonial stem cells, previous to the transplant, seems to improve the efficiency of colonization. For proper colonization of germ cells, the niche should be available and thus mouse strains that lack endogenous spermatogenesis such as W/Wv mutant mice are usually used. In the case of nonmatched donor cells, seminiferous epithelium of immune-suppressed recipient mice should be germ cell depleted before the transplant. One limitation of this technique is that the procedure can take up to 3 months. Also, in contrast to the full recovery of spermatogenesis in mouse-to-mouse transplants, xenotransplantation of germ cells from phylogenetically distant species, such as humans into mouse recipients, results in colonization of donor cells and spermatogonial expansion, but fail in their spermatogenic progression due to evolutive incompatibilities with the recipient niche. Xenografting of pieces of donor testis tissue under the skin of mouse hosts is an alternative approach that is currently being investigated to try to solve this limitation. Conclusion(s): Transplantation of spermatogonial stem cells into the seminal lumen of mouse testes is a functional assay that defines this cellular subpopulation by its ability to colonize it. This technique can be used as a model to elucidate the insights of spermatogonial stem cells, to produce transgenic animals by genetically manipulating donor cells before transplantation, but also it has potential applications in fertility preservation in cattle and humans as it is feasible in large animals, as recent reports have demonstrated with rhesus monkeys, that recovered spermatogenesis after allogenic transplantation, and even from human cadaver testes. Therefore spermatogonial stem cells isolated from prepuberal boys, who are treated with alkylant chemotherapy, could be returned to their testis to regenerate spermatogenesis in the future. © 2014 American Society for Reproductive Medicine. Source


Martinez-Arroyo A.M.,University of Valencia | Martinez-Arroyo A.M.,INCLIVA Biomedical Research Institute | Medrano J.V.,University of Valencia | Medrano J.V.,Fundacion Institute Investigacion Sanitaria La Fe | And 5 more authors.
Current Opinion in Genetics and Development | Year: 2014

Current knowledge about mammalian germ line development is mainly based on the mouse model and little is known about how this fundamental process occurs in humans. This review summarizes our current knowledge of genetic and epigenetic germ line development in mammals, mainly focusing on primordial germ cell (PGC) specification events, comparing the differences between mouse and human models. We also emphasize the knowledge derived from the most successful strategies used to generate germ cell-like cells in vitro in both models and major obstacles to obtaining bona fide in vitro-derived gametes are considered. © 2014 Elsevier Ltd. Source


Martinez-Arroyo A.M.,University of Valencia | Miguez-Forjan J.M.,University of Valencia | Remohi J.,University of Valencia | Pellicer A.,Fundacion Institute Investigacion Sanitaria La Fe | And 2 more authors.
Stem Cells and Development | Year: 2015

Germ line development is crucial in organisms with sexual reproduction to complete their life cycle. In mammals, knowledge about germ line development is based mainly on the mouse model, in which genetic and epigenetic events are well described. However, little is known about how germ line development is orchestrated in humans, especially in the earliest stages. New findings derived from human in vitro models to obtain germ cells can shed light on these questions. This comprehensive review summarizes the current knowledge about mammalian germ line development, emphasizing the state of the art obtained from in vitro models for germ cell-like cell derivation. Current knowledge of the pluripotency cycle and germ cell specification has allowed different in vitro strategies to obtain germ cells with proven functionality in mouse models. Several reports during the last 10 years show that in vitro germ cell derivation with proven functionality to generate a healthy offspring is possible in mice. However, differences in the embryo development and pluripotency potential between human and mouse make it difficult to extrapolate these results. Further efforts on both human and mouse in vitro models to obtain germ cells from pluripotent stem cells may help to elucidate how human physiological events take place; therefore, therapeutic strategies can also be considered. © Copyright 2015, Mary Ann Liebert, Inc. 2015. Source

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