I stumbled across this very cool article today and just had to share. It’s called Artificial Jellyfish Built From Rat Cells, and as the title suggests, it describes a “jellyfish”, or medusoid, that Harvard University and Caltech bioengineers have built using a silicone “body” and the muscle cells from the heart of a rat. When placed in a tank and exposed to an electrical field, the medusoid contracts and expands, convincingly mimicking the swimming motion of a real live jellyfish medusa. Check out the video from the article:
Now, I think this is really interesting. The article points out that the artificial “creature” has important implications for drug testing. That is of course very important, and is an awesome advance for the study of physiology and medicine. It gives scientists a much greater understanding of the biomechanics of muscle cells, which makes them that much easier to build with and manipulate. The article states that their next step will be to build a medusoid with human heart cells (the heart cells are actually grown directly on the sheet of patterned silicone, in order to get them to spread and form an effective network). Then, of course, they will be able to test new drugs on these medusoids and study how the pumping movements are affected.
But what interests me most about this is simply the idea that scientists might be able to build an organism from scratch in the lab. That day is of course still a long way off. A medusoid built from silicone and muscle cells is innovative, but still a far cry from being an actual organism. In order to be considered a true life form, there are many different criteria that must be met: it must be made up of cells (can be unicellular or multicellular), able to respond to external stimuli, be able to reproduce on its own, be able to grow and metabolize, and be homeostatic (able to regulate its own internal environment. By this definition, bacteria are alive but viruses are not (bacteria are cells, viruses are simply particles made of genetic material with a protein coat, incapable of reproducing without a host organism).
When you think about it, even the simplest life forms are breathtakingly complex. In order for bioengineers to truly build an artificial jellyfish, they would need to be able to assemble hundreds or even thousands of different cell types into tissues and then organs. Jellyfish, or cnidarians (Phylum Cnidaria) are some of the simplest animals on Earth, aside from sponges, which do not even have any true tissue layers, just loose aggregations of cells that perform different functions. Cnidarians are diploblastic, meaning they have two different tissue layers, the ectoderm and the endoderm, between which is sandwiched a jelly-like substance called mesoglea. In contrast, all of the more complex animals including vertebrates are triploblastic, with three tissue layers: endoderm and ectoderm as well as mesoderm. The mesoderm is the tissue layer that gives rise to muscle cells, and because cnidarians lack that layer they rely on tissue called myoepithelium, which are similar to muscle cells in that they allow movement, but are actually derived from the ectoderm layer, which gives rise to the epithelium (i.e. skin). So you can see that compared to vertebrates, or even complex invertebrates such as arthropods, jellyfish and their ilk are incredibly simple creatures. And yet they are still extremely complex compared to what scientists are able to build in a lab. Let’s just take a moment to appreciate how amazing all organisms are, how incredible life is and how impossible to emulate.
That was just a very very basic overview of organisms and the complexity of life, but I imagine that most of you who are reading this are already familiar with the concept. If not, please feel free to ask me any questions you may have. I get very geekily excited over stuff like this. And as always, I am hoping that this article will spark some discussion. Do you believe that scientists will ever actually be able to build a true organism from scratch? Would it be extremely simple, like a sponge, or could it perhaps be more complex, like a cnidarian or even something else? Would there be ethical implications? Or do you think this is such a cool concept that it should be attempted just to see if it is possible? Discuss!