By: Khushi Sheth
Researchers from the National Cancer Institute have been comparing the fundamental biological differences between cancer cells and normal cells such as cell signaling pathways in order to find a common molecular component among different types of cancer, which can be used towards developing effective treatment options.
One certain strategy is using stem cell technology for multiple types of cancers. Stem cells are capable of repairing, replacing, and regenerating cells regardless of their stage. They are unspecialized cells able to differentiate into any type of cell and are present in both adult cells and embryonic cells. Because there are multiple steps for a cell to become specialized and because developmental potency decreases with each step, a unipotent cell is not capable of changing into as many cells as a pluripotent cell. The signals that cause the stem cell specialization process can come from physical contact between cells or chemical secretion of surrounding tissue, signals from genes in DNA.
The proliferation time of somatic stem cells is longer than Embryonic Stem Cells (ESCs), meaning it is possible to reprogram adult stem cells back to their pluripotent state by transferring the nucleus into the cytoplasm of an oocyte or by fusing it with a pluripotent cell. In order for the stem cell treatment to be successful, recognizing undifferentiated cells through phenotypic pluripotency assays is crucial. Stem cells most commonly have a high nucleus to cytoplasm ratio. Differentiating groups have more spread out cells. Histone modification and DNA methylation are also important in silencing the pluripotency genes that reduce the differentiation potential. hESCs(heterogeneous ESCs) are able to differentiate into embryonic cells which can be thoroughly studied in place of embryos or other organisms Traditional culture methods for hESCs are mouse embryonic fibroblasts.
Researchers made a breakthrough with stem cell technology when the possibility of changing multipotent adult stem cells in mice to the pluripotent state without risking the life of the fetus was discovered. The transcription factors Oct-3/4, Sox2, KLF4, and c-Myc had the ability to induce fibroblasts in embryonic stem cells, thus becoming pluripotent. This retrovirus-mediated transduction produced pluripotent stem cells called iPSCs, which later proved effective for human cells. The pluripotency of iPSCs has a large range of cells from ESCs to unipotent cells.
It was also discovered that a normal somatic cell could acquire pluripotency through fibroblast DNA subtraction in which one gene Myod1 converted fibroblasts into myoblasts, proving the possibility of reprogramming and transferring cells. Enhancement of the development of iPSCs is made possible through downregulation of genes such as p53, which promotes genome stability. Because this process involves histone alteration, there are possible mutation risks. Although there were single mutations in non-genetic regions, iPSCs were made without severe alteration. When somatic cells are being reprogrammed with transcription factors, the epigenetic structure needs to be reconditioned for iPSCs with pluripotency. In order to be useful in therapy, the stem cells must be converted into the desired cell types with this method.
Q: What are the dangers of stem cell technology treatment on the human body?
A: The cells could move from its placement site and change to other cell types and multiply, the cells could fail to work altogether, or the tumor could grow.
Q: What is the difference between the stem cells in adult cells versus embryos?
A: Pluripotency can only occur naturally in embryonic stem cells but it is possible to program somatic cells iPSCs and can form all cell types in an organism.
Q: What is the difference between stem cells and somatic cells?
A: Stem cells are unspecialized and have the capability to divide into new cells and differentiate into different types of cells in the body while regular somatic cells are specialized such as neurons, blood cells, and gametes.