A Novel, Efficient Method to Isolate Chicken Primordial Germ Cells from Embryonic Blood Using Cell Culture Inserts

Primordial germ cells (PGCs) play a crucial role in preserving poultry genetic resources and conducting transgenic research. A system for the rapid isolation of PGCs from single chicken embryonic blood was established in this paper. We found that PGCs can migrate to the lower layer of chicken embryonic fibroblasts (CEFs) through pores smaller than their diameter, while blood cells cannot, when co-cultured with CEFs of passages two to three. Based on the characteristics of PGCs, we developed a new PGC isolation method (cell culture insert/CEF adhesion method) that utilizes a 3 μm cell culture insert and CEFs of passages two to three. Using this method, approximately 700 PGCs can be isolated from the blood of a single chicken embryo at Hamburger and Hamilton (H&H) stage 17 of development. The separation rate achieved was 87.5%, with a separation purity of 95%. The separation rate of this method was 41.4% higher than the common Percoll density gradient centrifugation method and 33.6% higher than lysis with ACK buffer. PGCs isolated from embryonic blood could proliferate 37-fold within 2 weeks when cultured in a feeder-free culture system. They also continued to express the SSEA-1 and DAZL proteins and retained the ability to migrate in vivo. Overall, PGCs separated using cell culture inserts/CEF adhesion method retain their stem cell characteristics and migration ability. PGCs also exhibit good proliferation efficiency, making them suitable for subsequent transgenic experiments or genetic resource preservation.

Poultry genetic heritage cryopreservation and reconstruction: advancement and future challenges

Poultry genetics resources, including commercial selected lines, indigenous breeds, and experimental lines, are now being irreversibly lost at an alarming rate due to multiple reasons, which further threats the future livelihood and academic purpose. Collections of germplasm may reduce the risk of catastrophic loss of genetic diversity by guaranteeing that a pool of genetic variability is available to ensure the reintroduction and replenishment of the genetic stocks. The setting up of biobanks for poultry is challenging because the high sensitiveness of spermatozoa to freezing–thawing process, inability to cryopreserve the egg or embryo, coupled with the females being heterogametic sex. The progress in cryobiology and biotechnologies have made possible the extension of the range of germplasm for poultry species available in cryobanks, including semen, primordial germ cells, somatic cells and gonads. In this review, we introduce the state-of-the-art technologies for avian genetic resource conservation and breed reconstruction, and discuss the potential challenges for future study and further extending of these technologies to ongoing and future conservation efforts.

Successful cryopreservation and regeneration of a partridge colored Hungarian native chicken breed using primordial germ cells

Primordial germ cells (PGCs) are the precursors of germline cells that generate sperm and ova in adults. Thus, they are promising tools for gene editing and genetic preservation, especially in avian species. In this study, we established stable male and female PGC lines from 6Hungarian indigenous chicken breeds with derivation rates ranging from 37.5 to 50 percent. We characterized the PGCs for expression of the germ cell-specific markers during prolonged culture in vitro. An in vivo colonization test was performed on PGCs from four Hungarian chicken breeds and the colonization rates were between 76 and 100%. Cryopreserved PGCs of the donor breed (Partridge color Hungarian) were injected into Black Transylvanian Naked Neck host embryos to form chimeric progeny that, after backcrossing, would permit reconstitution of the donor breed. For 24 presumptive chimeras 13 were male and 11 were female. In the course of backcrossing, 340 chicks were hatched and 17 of them (5%) were pure Partridge colored. Based on the backcrossing 1 hen and 3 roosters of the 24 presumptive chimeras (16.6%) have proven to be germline chimeras. Therefore, it was proven that the original breed can be recovered from primordial germ cells which are stored in the gene bank. To our knowledge, our study is a first that applied feeder free culturing conditions for both male and female cell lines successfully and used multiple indigenous chicken breeds to create a gene bank representing a region (Carpathian Basin).

Avian Satellite Cell Plasticity

Simple Summary

Adult muscle regeneration and reconstruction is dependent on a population of adult stem cells, known as satellite cells. These cells were suggested to exhibit a certain degree of plasticity, being able to differentiate into lineages unassociated with muscle cells. In this study, we have used a range of visualization methods, as well as PCR, to identify a population of satellite cells obtained from samples of chicken muscles. Then, the cells, expressing a previously introduced detectable transgene, were introduced into chicken embryos and detected after three and eighteen days of their development. The traces of cell populations derived from the introduced satellite cells were detected in a range of embryonic tissues in both of the studied timeframes. The results of this study give further proof of the plasticity of muscle satellite cells, showing the potential locations of their migration during embryonic development.

Abstract

Adult myogenesis is dependent on a population of precursor cells, located between the sarcolemma and the basal lamina of the muscle fiber. These satellite cells, usually present in a quiescent state, become activated in response to mechanical muscle strain, differentiating and fusing to add new nuclei to enlarging muscles. As their myogenic lineage commitment is induced on demand, muscle satellite cells exhibit a certain amount of plasticity, possibly being able to be directed to differentiate into non-myogenic fates. In this study, myosatellite cells were isolated from chicken muscle samples, characterized in vitro and introduced into developing blastoderms. They were further investigated using fluorescence microscopy, immunohistochemistry and PCR, to determine their location in embryos after three and eighteen days. The results of the in vitro analysis confirmed that the cells obtained from the Pectoralis thoracicus are highly myogenic, based on the expression of Pax7, Myogenin, MyoD, Desmin and the myotube assay. Furthermore, the investigation of satellite cells within the embryo showed their migration to the regions of Pectoralis thoracicus, heart, liver, gizzard, proventriculus, intestine and brain. Overall, the results of the study proved the high myogenicity of chicken Pectoralis thoracicus cell isolates, as well as provided new information about their migration pathways following introduction into the blastocyst. The presence of the introduced LacZ or eGFP transgenes across the embryo, even 20 days after myosatellite cell injection, further supports the notion that satellite cells exhibit significant plasticity, potentially transdifferentiating into non-muscle lineages.