The idea of growing new organs, by way of using other animal’s embryos is no longer a far-off ludicrous idea. In fact on January 26th researchers stated in an article in Cell that “Injecting human stem cells into pig and cattle embryos created embryos that incorporate a small number of human cells.” Although a seemingly small improvement we are one step closer to the momentous yet quite controversial idea of using hybrid, or chimeric, animals to produce human organs for transplant. However, Juan Carlos Izpisua Belmonte, a stem cell biologist at the Salk Institute for Biological Studies in La Jolla, Calif warns that, “Farm animals incubating human organs won’t appear anytime soon.” Even though Belmonte led the team of researchers and they have accomplished a major goal of proving that human cells can indeed integrate into a pig he feels “we’re still far away from that.” It is essential even with such fascinating new findings to remain reasonable and logical. There continues to be much work to do, but this work is a step in the right direction. Due to both ethical and funding hurdles human-animal chimera work is in its infancy and is likely to be slow in future growth. However, hybrids of rats and mice are already hinting that growing an organ from one species in another is a viable strategy for curing some diseases and perhaps enthusiasm for such research will follow. Another team of researchers reported in Nature that they “grew mouse pancreases in rats” which resulted in mouse insulin-producing cells from rat grown organs. These xenograft cells were then transferred from the rats to diabetic mice, curing their diabetes without any use of immunosuppressive drugs to prevent rejection. This finding raises hope that animal-grown organs tailored to individual patients could be transplanted without fear of rejection. Another issue facing organ development from other animals is the effect of a host environment on the respective stem cells. Researchers used the gene-editing tool CRISPR/Cas9 and disabled Pdx-1 and genes involved in heart and eye development so that mice couldn’t grow functioning versions of those organs. Rat stem cells injected into mouse embryos filled in, growing functional organs, including one the researchers didn’t expect. Rats don’t have gallbladders, but “rat stem cells introduced into mice embryos are able to form gallbladders,” the researchers reported. The result indicates that it may not be possible to re-create in lab dishes the mechanical forces, chemical signals and other conditions an organ needs to develop properly. In the context of human-pig chimeras the results were not as promising and many agrees “more work is needed to improve growth of human cells in pig embryos.”
This article and its premise of the development of both successfully accomplished mice-rat chimeras and the more science-fiction human-pig chimeras has an integral role in our society. Stem cells are an important resource and as we learn how to capitalize on their diversity and ease with which they are manipulated, many diseases and disorders may possibly be remedied. It is important to use new CRISPR technology in order to devise ways to cultivate new organs and consequently save lives. These recent studies are transformative to our society as well as to the field of regenerative medicine. Although seemingly inconsequential this research and all succeeding research will transform science for many years to come.
The author of this article, Tina Hesman Saey, overall wrote a wonderful piece. I particularly enjoyed her use of quotes as well as her evident in-depth research about the topic. By including the ideas and point of views of many leading researchers on the topic Saey asserts a sense of authority and intellectual exploration of the complex issue. Additionally, by including previous work in just the past decade readers realize how the current mouse cells in a rat is such a step forward. We realize this is not a new occurrence but a study based on a culmination of other works. However, Saey did err a little with her organization of her article. For example, I felt that defining chimeric animals, although important to do, was done in the wrong place. The definition of chimeric animals are good information located in a bad place. Sequentially it made no sense to go from discussing organ rejection to defining chimeric animals to discussing research by Hiromitsu Nakauchi on mouse pancreases. The information seems random and adds to the confusion. In order to improve this Saey should simply re-read her work and/or enlist an editor and read her piece for overall coherence and logical placement of ideas. Writing, especially about science, can be difficult: where to include data or a definition where etc. Essentially, although well intentioned defining chimeric where she did led to a slightly less effective article by Saey even though everything else is nearly impossible to mess up.
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