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Author: Mia
Introduction : A common feature of animals with regeneration abilities is the presence of pluripotent stem cells in adults. When animals are injured, these cells are responsible for recreating missing body parts.
stem cells is an biology miracle that can repair, restore, replace and regenerate cells . In most animals and humans, these cells are limited to regenerating the cell types they are allocated. For example, hair follicle stem cells will only regenerate hair, and intestinal stem cells will only replenish the intestine.
However, many distant invertebrate stem cell populations are pluripotent in adult animals, meaning they can regenerate nearly any missing cells, a process known as systemic regeneration. Although these adult pluripotent stem cells (aPSCs) are present in many different types of animals (such as sponges, hydroglycols, planarians, flatworms, and some sea squirts, the mechanism of their regeneration remains unclear.
Recently, in a study published in the journal Cell in Harvard University, researchers determined the cellular mechanisms and molecular trajectories of the three-spotted black panther worm (Hofstenia miamia) forming adult pluripotent stem cells.
DOI:https://doi.org/10.1016/j.cell.2022.11.008
Whole body chopped can regenerate
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Three-spotted black panther worm is an marine animal , the academic name is Hofstenia miamia. It is one of the animals with the strongest whole body regeneration ability ever. Cut off the head of the three-spotted black panther worm and the other head will replace it; cut off its tail and it will grow another one. Cut the worm into three pieces, whether diagonally beveled or transversely, within eight weeks, there will be three fully formed worms.
researchers said that a common feature of animals with regeneration is the presence of pluripotent stem cells in adults. When animals are injured, these cells are responsible for recreating missing body parts. By understanding how animals like the Three-Spotted Black Panther Worm make these stem cells, it is possible to better understand what gives some animals the ability to regenerate. Professor Mansi Srivastava, a senior author of the
study, collected three-spotted black panther worms in the wild many years ago. After returning to the lab, he began to make many embryos that were easy to study. Srivastava and postdoctoral researcher Lorenzo Ricci developed a transgenic protocol in H. miami in a previous study, which allowed lead author Julian O. Kimura to continue to study the question of how these stem cells form.
tracks the embryonic development process
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researchers deduced that the adult pluripotent stem cells contained in worm larvae must be produced during embryonic development. Ricci used transgenic technology to create a cell line that fluorescent green by introducing Kaede protein into cells. Kaede is light convertible, which means that it can be illuminated with a laser beam of a specific wavelength to convert it to red. Therefore, these cells can be irradiated with laser light, turning individual green cells of the embryo into red.
images show how single cells of the embryos are specifically and systematically converted into red
. Then, Kimura tracks the development process of the embryos from single cells to multicellular. Early division of these cells is marked by stereotypic division, which suggests that embryonic cells divide in exactly the same pattern, so that cells can be consistently named and studied. This also raises the possibility that perhaps every cell has a unique purpose. For example, in the eight-cell phase, the cells in the upper left corner may produce some kind of tissue, while the cells in the lower right corner may produce another.
8 single cells of embryos in cell stage transform into red
To determine the function of each cell, Kimura performed a systematic light conversion on each cell in early embryos, creating a complete fate map in the eight-cell stage. In the embryo at the 16-cell stage, he found a pair of very special cells that produced cells that looked like neoblasts (i.e., adult undifferentiated cells).
To prove that they produce neoblasts, Kimura tested this special set of cells, named 3a/3b. He found that only the offspring of these cells produced new tissues during regeneration. Furthermore, another decisive feature is the level of gene expression in stem cells, which must express hundreds of genes. To determine whether 3a/3b meets this characteristic, Kimura selected the offspring of 3a/3b luminescent red cells and all other luminescent green cells and separated the red and green cells using sorter . Then, he used single-cell sequencing technology to study which genes are expressed in red and green cells respectively. This data confirms that at the molecular level, only the progeny of 3a/3b cells matches the stem cells.
locks on a set of genes
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Kimura says: "This ultimately confirms that we found the cell source of stem cell populations in our system. But it is important that understands the cell source of stem cells to allow us to capture them when cells mature and determine which genes are involved in making them ." Kimura generated a huge embryonic development dataset at the single-cell level, detailing which genes are expressed in all cells in the embryo from the beginning to the end of embryonic development.
researchers eventually locked in a group of genes, including the transcription factors Hes, FoxO and Tbx, which may be very important controllers of pluripotent stem cell formation, and homologs of these genes play an important role in human stem cells. The researchers plan to continue to dig deeper into the mechanisms of how these genes work in the three-spotted black panther worm stem cells to reveal how nature evolved ways to make and maintain pluripotent stem cells. In summary, understanding the molecular regulators of aPSCs will allow researchers to compare these mechanisms among species, revealing how pluripotent stem cells evolved across animals.
Reference:
https://www.eurekalert.org/news-releases/973580
https://www.cell.com/cell/fulltext/S0092-8674(22)01420-9#%20
Note: This article aims to introduce the progress of medical research and cannot be used as a reference for treatment plans. If you need health guidance, please go to a regular hospital for treatment.
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