![]() ![]() In addition to prevention of the accumulation of mutations, ESCs exhibit superior capabilities to repair DNA lesions and elude the reproduction of mutations in daughter cells 2. Thus, ESCs employ specific processes that minimize the accumulation of DNA mutations to maintain their genomic integrity. In early embryonic development, the accrued mutations need to be precisely repaired to prevent chromosomal defects, infertility, or death 1. Here, we review the fundamental links between the stem cell-specific HR process and DNA damage response as well as the different strategies employed by ESCs to maintain genomic integrity.Įmbryonic stem cells (ESCs), derived from inner cell mass (ICM), are capable of both self-renewal as well as pluripotency, which is the ability to differentiate into diverse cell types. The maintenance of genome integrity is key to preserving the functions of ESCs and reducing the risks of cancer development, cell cycle arrest, and abnormal replication. In addition, abundant HR proteins in the prolonged S phase can efficiently protect ESCs from external damages and protect against genomic instability caused by DNA breaks, facilitating rapid and accurate DNA break repair following chromosome duplication. Thus, HR is essential for the maintenance of genomic integrity and prevents cellular dysregulation and lethal events. For instance, HR repairs impaired chromosomes and prevents the collapse of DNA replication forks during cell proliferation. HR is involved in several aspects of chromosome maintenance. Compared to differentiated cells, ESCs harbor an elevated level of homologous recombination (HR)-related proteins and exhibit exceptional cell cycle control, characterized by a high proliferation rate and a prolonged S phase. After years of research scientists seem to be on the brink of success with a number of stem cell treatments which could change medicine forever.Embryonic stem cells (ESCs) possess specific gene expression patterns that confer the ability to proliferate indefinitely and enable pluripotency, which allows ESCs to differentiate into diverse cell types in response to developmental signals. Scientists have been using them for years in bone marrow transplants, and they are now investigating different types of adult stem cells, and how they might control the way they develop. It's ethically tricky too, because the stem cells come from human embryos.Īdult stem cells offer another possible route. ![]() The clinical challenge is to encourage the embryonic stem cells to develop into the type of cells we need, without them growing into we don't want. Scientists have found ways to grow embryonic stem cells in the lab, and are trying to use them to cure conditions such as diabetes (by replacing the insulin-producing cells in the pancreas), or enable people paralysed by spinal injuries to walk again by re-growing spinal nerves. Using human stem cells in medicine is quite another. That's massively useful for lots of things, like producing orchids and other house plants quickly and cheaply, conserving endangered species, or making clones of plants that have been genetically modified to deal with environmental stresses. Plant stem cells can be used to make clones, identical copies of the parent plant. Each one has the potential to form a whole new plant! Unsurprisingly, people want to make use of these amazing cells. The big difference is that the stem cells in adult plants can still make every type of plant cell. They're found at the meristems, the growing tips of the roots and the shoots. For example bone marrow stem cells only form different types of blood cells. But the adult stem cells are more limited in the types of cell they can make. They also start to differentiate, to become specialised for different purposes.įor example, red blood cells look very different from nerve cells, but they both start out as embryonic stem cells.Īdults don't have any embryonic stem cells, but they do still have stem cells - they're essential for replacing or repairing normal cells which become damaged, or worn out. The stem cells continue to divide by mitosis, and so the embryo grows. ![]() ![]() The cells on the inside layer of this very early embryo can make all of the cell types needed in your body. This then divides by mitosis to form two identical cells, and they just keep on dividing to form a hollow ball of 200-300 tiny cells. We're all very complex organisms, made up of lots of different types of cells carrying out different jobs in our bodies such as nerve cells, blood cells, fat cells and muscle cells.Įach one of us starts off as a single cell when an egg and a sperm join together. ![]()
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