Scientists in Spain and the United Kingdom managed to inject tiny sensors thinner than the coronavirus and shaped like solar panels on the International Space Station into live eggs. The way these chips bend allows us to measure the force generated from the moment the sperm enters until the embryo divides into two cells.
Researchers from Barcelona Institute of Microelectronics (IMB-CNM) CSIC with University of Bath (UK) has made chips and inserted them into living cells to detect mechanical changes that occur in the early stages of embryonic development.Details will be published in the magazine this week Natural materials.
The chip acts as a mechanical sensor and is very small: it is almost impossible to measure 22 x 10.5 microns, with 25nm thick. This means that its length is three times the diameter of a human hair and three times the length of viruses such as SARS-CoV-2.
The equipment has been manufactured in the clean room of IMB-CNM under the supervision of scientists. Jose Antonio Plaza.Then, in the laboratory at the University of Bath, another Anthony CF Perry The chip and sperm have been injected together Mouse egg Analyze the early stages of fertilization. In humans, this initial process occurs in a similar way.
Using this device, they have been able to measure the force inside the recombinant egg (ie its cytoplasm) from the introduction of sperm to the division into two cells.
The choreography of embryonic development
Square commented: “By similar to dance, the embryo arranges movements during development, we not only see the importance of movements, but also the intensity.” Microscopic examination, We can see how the chip bends inside the battery”.
He added: “Given that we have modeled, we know exactly what force must be applied in some way to make the chip bend. By visualizing the curvature, we can infer what mechanical force is happening inside the battery.”
According to the authors, one of the novelties of the study is the ability to directly detect these forces, that is, from inside the embryo and throughout the initial fertilization process.
He pointed out: “So far, almost all the work is to use external tools to obtain indirect measurement results. If they are done from the inside, they are very local and do not describe the reorganization of the cytoplasm.” Marta Duch IMB-CNM researchers and the first author of this article.
Therefore, scientists have initially measured the forces obtained in the pipeline. Reprogramming sperm DNA, Is what happened after the sperm injection. Plaza said: “Although it is difficult to compare, we found that these forces are greater than those measured by other groups in muscle cells.”
They also observed Embryonic membraneThe reason why it is harder than the inside is Pronuclear (Cell nuclei carrying female and male genetic material) converge to fuse in the center of the embryo. According to scientists, they did not detect force during the fusion process, perhaps because this promoted chromosomal recombination.
The next stage is Division of the first unit Into two halves. Here, the authors saw the change in the stiffness of the cytoplasm: “At this time, our chip shows that the cytoplasm has become more rigid, which will facilitate the transmission of force in the embryo and make it longer.”
This elongation is necessary for the subsequent division into two units. Later, when the cell divides into two parts, the rigidity of the cytoplasm is reduced, which may help the division.
This basic research is Conceptual work (Proof of concept(English) to prove the viability of the mechanical sensor inside the cell. As we all know, cell mechanical force has important biological significance, but until now, mechanical force cannot be accurately measured during the entire initial fertilization process.
Application in assisted reproduction
The author also emphasizes that this work can help to better understand the first stage of the fertilization process. In this sense, it has been found that the mechanics of the mouse embryo in its initial stage is similar to that of the human embryo.
Therefore, this research may be of interest in the future Fertilization MedicineAnd this is also true when analyzing diseases related to certain deformities in the early stages of embryonic formation.
In addition to the Spanish-British team mentioned, scientists from the University of Granada and the Polytechnic University of Catalonia also participated in the study.
Marta Duch, Núria Torras, Maki Asami, Toru Suzuki, María Isabel Arjona, Rodrigo Gómez-Martínez, Matthew D. VerMilye, Robert Castilla, José Antonio Plaza and Anthony CF Perry. “Tracking changes in intracellular force and mechanical properties in mouse single-cell embryo development.” Natural materials, May 25, 2020. (This research was conducted under the public funding of the National R + D + i Program).