Enhancing the efficiency of xenogenic catfish production by transplanting cultured blue catfish (Ictalurus furcatus) germ line stem cells into channel catfish (I. punctatus) triploid fry

Xenogenesis, an advanced hatchery technology for hybrid catfish (channel catfish, Ictalurus punctatus ♀ × blue catfish, I. furcatus ♂) production, involves transplanting germline stem cells (GSCs) from diploid donors into sterile recipients. Currently, freshly extracted GSCs are used, however cell production depends on age, size, and seasonal cycle of the donor, causing challenges. In vitro propagation could address these issues by providing a year-round GSCs supply. The present study compared effectiveness of fresh vs. cultured oogonial stem cells (OSCs) and spermatogonial stem cells (SSCs) for transplantation. Triploid channel catfish fry were injected at 5 days post-hatch (DPH) with PKH26 labelled fresh or cultured OSCs or SSCs. Growth and survival of recipient fish were assessed at 45 and 90 DPH, while donor cell colonization was quantified using PKH26. PCR and fluorescence images were used to determine percent xenogens. No significant differences in fry growth were observed between fresh and cultured treatments at 45 and 90 DPH. However, fluorescence imaging revealed significantly higher cell, cluster area in cultured treatments compared to fresh treatments. Cell, cluster areas significantly increased from 45 to 90 DPH in both fresh and cultured treatments. Cell area at 45 DPH was significantly higher in cultured treatments than fresh treatments, while no difference was detected at 90 DPH. PCR analyses revealed a higher proportion of xenogens in recipients injected with cultured cells (85.7%) compared to fresh cells (83.3%). Our findings demonstrate that cultured stem cells perform comparably to fresh stem cells, offering a promising approach for future cell transplantation.