University of Navarra CIMA-University of Navarra, Spain
Abstract: Blastocyst complementation is a promising strategy to generate transplantable organs. However, the low efficiency of the complementation process and the limited ability of human cells to generate interspecies chimeras significantly constrain the potential of this technology. In this study, we tested the effect of modulating cell competition mechanisms through c-Myc levels, first in a mouse-rat interspecies model and then in human-mouse settings. As a starting point we have microinjected rat embryonic stem cells (ESCs) in mouse host embryos expressing Myc at varying levels, according to their genotype. We found that reduction of Myc expression in the host increases both the frequency of chimera generation and the contribution of rat cells to the chimera embryo at E9.5, in a dose-dependent manner. Applying this approach to an interspecies heart complementation model, it boosted the efficiency of heart complementation by rat cells three folds, by embryonic day E10.5. Finally, we have extended this approximation to human-mouse chimera generation. Reducing Myc levels in host mouse embryos or artificially enhancing them in human naïve cells significantly improves the colonization of mouse embryos by human iPSCs 72 hours post-injection in vitro. However, following embryo transfer into pseudopregnant mouse recipients, human cell contribution is minimal as analyzed at E6.5, highlighting the need for innovative strategies to enhance human cell survival and integration in xenogeneic embryos
Funding Source: This work was supported by PID2021-122589OB-I00 funded by MCIN/AEI/10.13039/501100011033 and FEDER a way to make Europe, UE; Gob. Navarra Bioheart 0011-1411-2022-000092; “La Caixa” Foundation LCF/PR/HR24/00152
