Direct in vitro propagation of avian germ cells from an embryonic gonad biorepository

Authors: HU, TUANJUN - Roslin Institute; Purdy, Phil; BLANK, MARCEL - Universidade De Sao Paulo; MUHONJA, CHRISTINE - International Livestock Research Institute (ILRI) - Kenya; PEREIRA, RICARDO - Universidade De Sao Paulo; TIAMBO, CHRISTIAN - International Livestock Research Institute (ILRI) - Kenya; MCGREW, MIKE - Roslin Institute

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/20/2024
Publication Date: 8/26/2024
Citation: Hu, T., Purdy, P.H., Blank, M.H., Muhonja, C.K., Pereira, R.J., Tiambo, C.K., McGrew, M.J. 2024. Direct in vitro propagation of avian germ cells from an embryonic gonad biorepository. Poultry Science. Article e104260. https://doi.org/10.1016/j.psj.2024.104260.
DOI: https://doi.org/10.1016/j.psj.2024.104260

Interpretive Summary: Direct introduction of cryopreserved embryonic gonadal germ cells into a sterile chicken host to reconstitute a chicken breed has been demonstrated as a feasible approach for preserving and utilizing chicken genetic resources. However, this method requires a large quantity of frozen germplasm to provide sufficient gonadal germ cells (GGCs) for generation of fertile surrogate female hosts. Applying this method to indigenous chicken breeds, research lines, and other bird species is difficult due to small flock numbers and poor egg production. Propagating germ cells from the frozen gonadal tissues may be a solution for preservation of the genetic resources of these breeds and lines. Here, we describe a simplified method for culture of GGCs from frozen embryonic gonads. At this developmental stage, the germ cells are autonomously shed into medium during culture, yielding hundreds to thousands of high quality cells. The resulting cultures are highly enriched with GGCs and can be used to re-colonize recipient’s gonads. Entire chicken embryos can also be frozen and used as a source of GGCs as well, but the results are not as high compared to when gonads are isolated prior to freezing. These storage methods offer a primary and supplementary approach to safeguard chicken breeds bearing valuable genetic traits and should be applicable for the preservation of genetic resources of many avian species.

Technical Abstract: Direct introduction of cryopreserved embryonic gonadal germ cells into a sterile chicken surrogate host to reconstitute a chicken breed has been demonstrated as a feasible approach for preserving and utilizing chicken genetic resources. However, this method requires a large quantity of frozen germplasm to provide sufficient gonadal germ cells (GGCs) for generation of fertile surrogate female hosts. Applying this method to indigenous chicken breeds and other bird species is difficult due to small flock numbers and poor egg production in each egg laying cycle. Propagating germ cells from the frozen gonadal tissues may be a solution for the biobanking of these birds. Here, we describe a simplified method for culture of GGC from frozen embryonic 9.5 day gonads. At this developmental stage, the germ cells are autonomously shed into medium, yielding hundreds to thousands of mitosis-competent germ cells. The resulting cultures of GGCs have over 90% purity, uniformly express SSEA-1 and DAZL antigens and can re-colonize recipient’s gonads. The GGC recovery rate from frozen gonads are 42 – 100%, depending on length of cryopreservation and breed of chicken. Entire chicken embryos can also be directly cryopreserved for later gonadal isolation and culture. This storage method is a supplementary approach to safeguard local indigenous chicken breeds bearing valuable genetic traits and should be applicable to the biobanking of many bird species.