Scientists from the Institute Salce (founded by Jonas Salk, Creator of polio vaccine) in La JOLLA, California has long worked to create in the laboratory the first in the history of embryos, including human cells, and swine. That, finally, they succeeded, according to the prestigious journal “Cell”.
Previous attempts to grow human-pig chimeras
Scientists promise what they want because of this more accurately identify the earliest stages of life zarodkowego: how is the development of a human embryo, and what is happening at this stage for certain defects and diseases. Also plan to use this technique for obtaining cells and tissues, which can be verified in the future new medicines.
it is, however, in General the Chimera?
From a biological point of view, chimeras are organisms composed of cells that differ genetically. Sometimes it happens that the chimeras occur in nature. Sometimes they are created by scientists. In 1984, they created a Chimera called a “geep”. It originated from the compound at the embryonic stage of development of cells of the goat (from the English. goat) and sheep (sheep). Chimeryzm is also daily bread for transplantologów perceiving tissues and organs between humans. However transplantolodzy interested in chimeras for another reason.
the Woman who emerged from the fusion of two embryos.
so, I would like to use a Chimera for growing bodies that will solve the constant shortage of organs for transplant, which are sick.
it is estimated that only in USA are dying every day 22 people who did not wait for transplant.
so, the goal is to grow human organs in the body – most likely – a pig, because biologically our fabrics are very similar to each other.
- we focused on this road, the first important step, says Professor Juan Carlos Izpisua Belmonte, the main author of the work.
Przeskoczone 18 million years
At the beginning of Belmonte with his team created Chimera mysio-szczurzą: introduced in mysiego cells of rats and allowed them to Mature. Researchers have, however, to try in advance to the cells of the rat could find a niche and well in the “float” and gave rise to new tissue or narządowi. For this we used the method called CRISPR, which is considered a breakthrough in changing the genome.
Crime with dual DNA
CRISPR is a mechanism by which, for example, bacteria protect themselves from attack by viruses. Genetic material of the virus after penetration into the bacteria is cut into fragments and wbudowywany in their own genome. Scientists have learned to use this system to perform genetic modifications.
if you were removed from mouse embryos, genes, for example, development of heart, pancreas or eyes.
Then entered cells rats that had their own (szczurzą) copy of this gene, which was previously deleted.
we Wanted a way to check if you can fill in the blank genetic “niche”. In developing organisms, cells mice, rats gave rise to the heart, pancreas and eyes, says Dr. Jun Wu, co-author of the work
- moreover, the rat cells gave rise to bubble moczowemu, though, because rats do not normally produce this body, from about 18 million years, when the evolutionary paths of mice and rats diverged – adds Jun Wu.
Chimera human, but not very
After testing the techniques on rodents, scientists from California started to create chimeras with human cells.
Decided to use as “owner” of the embryos of cows and pigs. “The main question was – what human cells are able to survive in the embryo of the animal,” write the authors in “Cell”. Experiments with equal cow was much more difficult and expensive. The researchers focused on zarodkach why pigs are attracted to their 1.5 million (from American farmers). Easy, however, was not.
- From an evolutionary point of view, the people from the pigs absent five times more than a rat from a mouse. Moreover, pregnancy in pigs lasts about a third of that in humans. We were so perfect copy “timeing”, that is to enter a human cell in such a moment in the development of swine embryo that they were able to “disrupt” with this development, explains Jun Wu
- Can you compare it with cars wjeżdżającymi on the highway. If they go at the same pace, it is well; if they have a completely different speed, easy on the case – adds the researcher.
Scientists they have given to swine embryos dozen different types of human cells to test, which will cope better there. Won the so-called induced pluripotent stem cells that have the ability to differentiate into almost any cell type of an adult organism.
- Brought to the creation of embryos świńsko-human chimeras. Wszczepiliśmy their maciorom, and we have allowed for further development of the stage when it was 3-4 weeks. This time enabled us to check progress. We avoided thus the ethical issues associated with the further development of chimeras in the adult organism, says Professor Belmonte.
Simply won’t
the Researcher stresses that the pace of development of differentiation of human cells in the pig embryo was not at all too large. And that’s good news. Does not want we created the Chimera was “too human” (just one human cell had 100 thousand. pork). We didn’t want to cause a situation to human cells started, for example, to develop the brain. While the human cells in the Chimera have evolved rather in the direction of the muscle, heart, liver or kidneys – added Belmont.
“we just Wanted to prove that something like that was even possible. In the subsequent steps we want to learn how to manage the process so that the end result was to breed in the body of pigs are healthy and fully functional human body," summed up.
but this is Not so simple. As in the online edition of the journal “Science” draws the attention of Professor Joe Zhou from the Institute of stem cell Research at Harvard University, although the current results are optimistic, however, is the growing of organs suitable for transplantation continues to present enormous technical difficulties.
For this, as always, come questions of ethics. Some experts fear, for instance, that adult animal-a Chimera, aimed, for example, human nerve cells, it would be more intelligent than “nature”. Probably no one imagines that human cells in a pig Chimera begin to differentiate into sperm or eggs.
With such problems, scientists from California they will have to deal with.
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