For the first time, scientists have been able to synthesize how the cellular structures that give rise to our spinal column form in sequence. Understanding this process can open avenues for future treatments. The results of the discovery were published on Thursday (28), in the journal Nature Communications.
The spinal column has 33 vertebrae, which form from pairs of precursor structures called somites. These parts give rise to our vertebrae, ribs and skeletal muscles.
This structure is essential in all vertebrates, as it is what supports the skeleton. It not only serves as a place for muscle attachment, but also protects the spinal cord and nerve roots.
In order for the spine to form correctly, the development of somites is finely regulated and each pair of somites arises at a specific sequential time point in development.
The segmentation clock, a set of genes that generates oscillatory waves, controls this process, with each wave giving rise to a new pair of somites.
In the new discovery, researchers from the Ebisuya Group at the European Molecular Biology Laboratory (EMBL) in Barcelona created a 3D model in vitro that mimics how the precursor structures that give rise to the spinal column form during human embryonic development.
“For the first time, we were able to create periodic pairs of mature human somites linked to the segmentation clock in the laboratory,” Marina Sanaki-Matsumiya, lead author of the study, said in a statement.
Using this approach, the researchers developed a 3D model in vitro of the formation of human somites, also known as ‘somitogenesis’.
Process of creating somitogenesis
To make reproduction possible, the team of researchers cultured human-induced pluripotent stem cells (hiPSC) in the presence of a cocktail of signaling molecules that induce cell differentiation. Three days later, the cells began to elongate and create anterior (top) and posterior (bottom) axes.
In a second step, the scientists added Matrigel (protein mixture) to the culture mixture. This process formed somitoids – equivalents in vitro of precursor structures of human somites.
Once the somites were formed, the team needed to monitor the segmentation clock, which regulates somitogenesis in these somitoids. For this, they monitored the expression patterns of the HES7 gene, a central part involved in the process.
The research revealed some oscillations in the process, especially when somitogenesis was about to begin. The somites that formed also had clear markers of epithelialization – an important step in their maturation.
Sanaki-Matsumiya explained that there is a link between the size of somites and the segmentation clock. “The generated somites were of constant size, regardless of the number of cells used for the initial somitoid. Somite size did not increase even though the initial number of cells increased,” she said.
This means that somites have a preferred species-specific size, which may be determined by local cell-to-cell interactions, segmentation clock, or other mechanisms.
Source: CNN Brasil
