ERK-independent African Green monkey pluripotent stem cells in a putative chimera-competent state

An expedition in the jungle of pluripotent stem cells of non-human primates

For nearly three decades, more than 80 embryonic stem cell lines and more than 100 induced pluripotent stem cell lines have been derived from New World monkeys, Old World monkeys, and great apes. In this comprehensive review, we examine these cell lines originating from marmoset, cynomolgus macaque, rhesus macaque, pig-tailed macaque, Japanese macaque, African green monkey, baboon, chimpanzee, bonobo, gorilla, and orangutan. We outline the methodologies implemented for their establishment, the culture protocols for their long-term maintenance, and their basic molecular characterization. Further, we spotlight any cell lines that express fluorescent reporters. Additionally, we compare these cell lines with human pluripotent stem cell lines, and we discuss cell lines reprogrammed into a pluripotent naive state, detailing the processes used to attain this. Last, we present the findings from the application of these cell lines in two emerging fields: intra- and interspecies embryonic chimeras and blastoids.

In Vivo Generation of Organs by Blastocyst Complementation: Advances and Challenges

The ultimate goal of regenerative medicine is to replace damaged cells, tissues or whole organs, in order to restore their proper function. Stem cell related technologies promise to generate transplants from the patients' own cells. Novel approaches such as blastocyst complementation combined with genome editing open up new perspectives for organ replacement therapies. This review summarizes recent advances in the field and highlights the challenges that still remain to be addressed.

Generation of donor organs in chimeric animals via blastocyst complementation

The lack of organs for transplantation is an important problem in medicine today. The growth of organs in chimeric animals may be the solution of this. The proposed technology is the interspecific blastocyst complementation method in combination with genomic editing for obtaining “free niches” and pluripotent stem cell production methods. The CRISPR/Cas9 method allows the so-called “free niches” to be obtained for blastocyst complementation. The technologies of producing induced pluripotent stem cells give us the opportunity to obtain human donor cells capable of populating a “free niche”. Taken together, these technologies allow interspecific blastocyst complementation between humans and other animals, which makes it possible in the future to grow human organs for transplantations inside chimeric animals. However, in practice, in order to achieve successful interspecific blastocyst complementation, it is necessary to solve a number of problems: to improve methods for producing “chimeric competent” cells, to overcome specific interspecific barriers, to select compatible cell developmental stages for injection and the corresponding developmental stage of the host embryo, to prevent apoptosis of donor cells and to achieve effective proliferation of the human donor cells in the host animal. Also, it is very important to analyze the ethical aspects related to developing technologies of chimeric organisms with the participation of human cells. Today, many researchers are trying to solve these problems and also to establish new approaches in the creation of interspecific chimeric organisms in order to grow human organs for transplantation. In the present review we described the historical stages of the development of the blastocyst complementation method, examined in detail the technologies that underlie modern blastocyst complementation, and analyzed current progress that gives us the possibility to grow human organs in chimeric animals. We also considered the barriers and issues preventing the successful implementation of interspecific blastocyst complementation in practice, and discussed the further development of this method

Parsing the pluripotency continuum in humans and non-human primates for interspecies chimera generation

Pluripotency refers to the potential of single cells to form all cells and tissues of an organism. The observation that pluripotent stem cells can chimerize the embryos of evolutionarily distant species, albeit at very low efficiencies, could with further modifications, facilitate the production of human-animal interspecies chimeras. The generation of human-animal interspecies chimeras, if achieved, will enable practitioners to recapitulate pathologic human tissue formation in vivo and produce patient-specific organs inside livestock species. However, little is known about the nature of chimera-competent cellular states in primates. Here, I discuss recent advances in our understanding of the pluripotency continuum in humans and non-human primates (NHPs). Although undefined differences between humans and NHPs still justify the utility of studying human cells, the complementary use of NHP PS cells could also allow one to conduct pilot studies testing interspecies chimera generation strategies with reduced ethical concerns associated with human interspecies neurological chimerism. However, the availability of standardized, high-quality and validated NHP PS cell lines covering the spectrum of primate pluripotent states is lacking. Therefore, a clearer understanding of the primate pluripotency continuum will facilitate the complementary use of both human and NHP PS cells for testing interspecies organogenesis strategies, with the hope of one day enabling human organ generation inside livestock species.