Photo of stem cell differentiation from Wikimedia Commons
Every biology student at some point has heard of the term “cell differentiation.” At the most basic level, cell differentiation is how cells become specialized in organisms to perform unique functions. This differentiation or specialization is directed by genetic expression and activation as well as cell needs (as we specifically learned about a few chapters back). Differentiation can drastically alter a cell’s structure, function, and resources needed for survival. Also, specialized cells can be redirected or transformed into a pluripotent cell after specialization if directed by its surroundings and gene expression. And speaking of pluripotency, modern technology has allowed us to artificially create cells that can differentiate called stem cells.
Stem cells are special human cells that are able to develop into many different cell types. Also, all cells are thought to be descended from stem cells, including somatic cells that are not specialized. Based on separate gene expression and unique functions, all differentiated cells contain nearly the same genomic sequences. These specialized cells as they mature and become adult cells can produce fully specialized daughter cells as they divide and reproduce. Despite this, there are exceptions as certain cell types undergo a special type of differentiation called terminal differentiation. This is a much more complex process than this post will delve into, but the basis of terminal differentiation is when a specialized cell leaves the cell cycle through repressors of the cell cycle genes (where the cell can still continue to differentiate). With a basic understanding of cell differentiation and the relative function of stem cells, we can dive deeper into the specifics of stem cells, their functions, and future possibilities. There are two basic types of stem cells: embryonic and adult. Embryonic stem cells come from unused embryos. These cells in research are able to turn into multiple cell types. One type of adult stem cells come from fully matured cell types such as brain cells that can only generate a certain type of cell. Another type of adult stem cells are pluripotent cells that are adult stem cells that have been changed artificially to behave like embryonic stem cells. These cells are thus very similar although these adult cells are still unable to develop into every type of cell or tissue that is needed.
Although the concepts surrounding stem cells are still relatively novel, stem cells are being used and developed to treat different conditions and diseases. For example, hematopoietic cells are used to treat certain bone marrow conditions. These stem cells are immature and thus able to create other functioning blood cells. These cells also help alleviate the effects of radiation and other invasive treatments for those with cancer. In the future, these applications and potential for stem cell treatment can be expanded even further. It might be able to treat even hereditary conditions or serious illnesses that have yet to be cured such as Parkinson’s disease. And if these possibilities become a reality, a connection may develop between allele frequencies and hereditary diseases. With new treatments for hereditary illnesses, certain alleles will be able to stay within a certain population and its gene pool for longer. This expands on content we have covered in class, but this could also potentially add onto the ethical and moral questions that arise in the stem cell field. This post will not mention much of these ethical aspects as to maintain the objectivity of this and as the line between “right” and “wrong” is blurred when the lives of humans are involved. But to be brief and complete, stem cells come from embryos which may raise some moral questions surrounding the use of stem cells and its proceeding research. The use of these cells are not universal as of today and their development and use can be difficult depending on the cell type and patient in question.
Overall, the use of stem cells can greatly impact the field of medicine and science in the future. Diseases such as Alzheimer’s and cancer can be better remedied with advanced technology and greater use of stem cells. Even as of now, these stem cells are able to replicate the functions of both terminal differentiated cells and other specialized cells due to their pluripotent nature. With a better understanding of the development and differentiation of varying types of cells in the body, we can eventually create better and more effective treatments for the complex and novel diseases that affect humans in the future.