Stem Cells constitute an intriguing and promising field of medicine because of their ability to regenerate and heal damaged tissue. This article covers the biology of stem cells, the pros and cons, and their promising abilities to further our study of medicine.
Introduction
Stem cells are the raw materials of the body, the cells that give rise to all other cells with specialized roles. Under the appropriate conditions, these unique human cells can develop into a variety of cell types by dividing themselves to generate new cells known as daughter cells in the body or in a laboratory. This can include everything from muscle cells to brain cells. In some situations, they can also repair damaged tissues. These daughter cells can either continue to differentiate into new stem cells or can become specialized cells with a more narrowly defined function, such as bone, brain, heart, or blood cells. No other cell in the body has the capacity to naturally produce different cell types. Because of these distinguishing traits, stem cells have historically been assumed to be everlasting and ageless.
Types of Stem Cells
Every organ and tissue in your body is built on stem cells. There are numerous types of stem cells that originate in various parts of the body or form at various stages throughout our lifetimes. These include embryonic stem cells, which exist only during the early stages of development, as well as other types of tissue-specific (or adult) stem cells, which appear during fetal development and remain in our bodies throughout our lives. All stem cells have the ability to self-renew (produce copies of themselves) and differentiate (develop into more specialized cells). Aside from these two fundamental capacities, stem cells differ greatly in what they can and cannot do, as well as the conditions under which they can and cannot do specific things. To begin with, there are three fundamental types of stem cells: Embryonic Stem Cells, Adult Stem Cells, and Induced Pluripotent Stem Cells.
- Embryonic Stem Cells
Embryonic stem cells are extracted from the blastocyst, a mostly hollow ball of cells that forms three to five days after an egg cell is fertilized by a sperm in humans. The size of a human blastocyst is around the size of the dot above this “i.” During normal development, the cells within the inner cell mass give rise to the more specialized cells that give rise to the complete body—all of our tissues and organs. When scientists extract the inner cell mass and cultivate it in a particular laboratory environment, the cells retain the qualities of embryonic stem cells. Embryonic stem cells are pluripotent, which means they can give rise to every cell type in the fully developed body save the placenta and umbilical cord. These cells are extremely significant because they provide a sustainable supply for researching normal development and disease, as well as evaluating medicines and other therapies. Human embryonic stem cells were predominantly produced from blastocysts developed by in vitro fertilization (IVF) that were no longer required for assisted reproduction. (3) Scientists seek to learn more about how these cells differentiate as they develop. As we learn more about these developmental processes, we may be able to apply them to stem cells produced in a lab and maybe regenerate tissues like the liver, intestines, nerves, and skin for transplantation. (4).
Figure 1: The Journal Of Clinical Investigation
- Adult Stem Cells
Adult stem cells, also known as somatic stem cells, are undifferentiated cells found in nearly all creatures’ bodies, including humans, in a variety of organs. Adult stem cells, which have been found in a variety of tissues including skin, heart, brain, liver, and bone marrow, are normally restricted to becoming any type of cell in the tissue or organ in which they dwell, as opposed to embryonic stem cells, which can become any cell in the body. Adult stem cells are believed to be multipotent, meaning they can differentiate into certain types of body cells exclusively, not into any type of cell. (6). These adult stem cells, which can live in tissue for decades, replace cells that are lost in the tissue as needed, such as the daily generation of new skin in humans. (5). Most adult tissues, including bone marrow and fat, contain a tiny amount of these stem cells. Adult stem cells, in comparison to embryonic stem cells, have a more limited potential to give rise to various bodily cells. Adult stem cells were thought to only be capable of producing comparable types of cells until recently. For example, researchers previously believed that stem cells found in bone marrow could only give rise to blood cells. However, new research reveals that adult stem cells can generate a variety of cell types. For instance, bone marrow stem cells might be able to develop into heart or bone cells. This research has resulted in early-stage clinical trials to assess the usefulness and safety of the product in humans. (1)
Using genetic reprogramming, scientists successfully turned ordinary adult cells into stem cells. Researchers can reprogram adult cells to behave like embryonic stem cells by modifying their DNA. This new technology may allow for the use of reprogrammed cells rather than embryonic stem cells, as well as the prevention of immune system rejection of the new stem cells. However, scientists are unsure whether employing changed adult cells will have a negative impact on humans. Researchers were able to transform ordinary connective tissue cells to become functioning heart cells. In experiments, animals with heart failure who were injected with fresh heart cells had better heart function and survival time.(1)
Types of Adult Stem Cells
- Hematopoietic Stem Cells (Blood Stem Cells)
- Mesenchymal Stem Cells
- Neural Stem Cells
- Epithelial Stem Cells
- Skin Stem Cells
Figure 2: Sciencedirect
- Induced Pluripotent Stem Cells
Induced pluripotent stem (iPS) cells are lab-engineered cells that have been transformed from tissue-specific cells, such as skin cells, into cells that act like embryonic stem cells. They are a happy medium between adult stem cells and embryonic stem cells. iPSCs are generated by inserting embryonic genes into a somatic cell (such as a skin cell) and causing it to return to a “stem cell like” state. IPS cells are important tools for scientists to understand more about normal development, illness start and progression, and for creating and testing new medications and therapies. While iPS cells share many of the same properties as embryonic stem cells, such as the potential to give rise to all cell types in the body, they are not identical. Scientists are trying to figure out what these distinctions are and what they represent. For starters, the first iPS cells were created by inserting extra copies of genes into tissue-specific cells using viruses. Researchers are exploring a variety of methods for creating iPS cells, with the goal of eventually using them as a source of cells or tissues for medical therapies. One example is that the first iPS cells were created by inserting extra copies of genes into tissue-specific cells using viruses. (3). These cells, like ESCs, are thought to be pluripotent. This method of genetic reprogramming to make embryonic-like cells, discovered in 2007, is unique and requires several more years of research before it can be used in clinical therapy. (4).
The Importance Of Stem Cells
Stem cells may benefit your health in a variety of ways and through a variety of novel treatments in the future. Stem cells, according to researchers, will be used to help build new tissue. For example, healthcare providers may one day be able to treat patients with persistent heart disease. They can accomplish this by cultivating healthy heart muscle cells in the lab and transferring them into damaged hearts. Other medicines could target type 1 diabetes, spinal cord injury, Alzheimer’s disease, and rheumatoid arthritis. New treatments could potentially be evaluated on pluripotent stem cell-derived cells.
Stem cells, with their unique regeneration powers, hold fresh promise for treating diseases such as diabetes and heart disease. However, substantial work in the laboratory and clinic remains to be done to understand how to employ these cells for cell-based therapies to cure disease, often known as regenerative or reparative medicine. Laboratory studies of stem cells allow scientists to understand about the cells’ basic features and what distinguishes them from other types of cells. Scientists are already employing stem cells in the lab to test novel medications and create model systems for studying normal growth and determining the reasons of birth abnormalities. Stem cell research continues to enhance understanding of how an organism grows from a single cell and how healthy cells replace damaged cells in mature creatures. Stem cell research is one of the most exciting areas of modern biology, yet, like with many burgeoning domains of scientific endeavor, it raises scientific concerns as quickly as it generates new discoveries. (4)
Although adult stem cell research is encouraging, adult stem cells might not be as adaptable and resilient as embryonic stem cells. The potential for using adult stem cells to cure diseases is constrained by the fact that not all cell types can be produced from adult stem cells. Adult stem cells are also more likely to have abnormalities because of chemicals or other environmental dangers, or because the cells made mistakes during replication. Adult stem cells, on the other hand, have been discovered to be more versatile than previously imagined. (1).
Stem Cell Line
A stem cell line is a collection of in vitro-grown cells that all descended from a single initial stem cell. A stem cell line’s cells continue to multiply without differentiating into other types of cells. Ideally, they continue to produce more stem cells and are genetically flawless. From a stem cell line, groups of cells can be extracted and shared with other researchers or frozen for future use.
Potential Therapies using Stem Cells
Regenerative medicine, often known as stem cell therapy, uses stem cells or their metabolites to stimulate the body’s natural healing process in diseased, dysfunctional, or injured tissue. It is the next step in organ transplantation and employs cells rather than donor organs, which are in short supply. In a lab, researchers cultivate stem cells. Through manipulation, these stem cells can be made to specialize into particular cell types, such as heart muscle cells, blood cells, or nerve cells. The specialised cells can then be injected into the patient. If the patient has cardiac issues, the cells might be injected into the heart muscle, for example. The transplanted, healthy heart muscle cells could then help the injured heart muscle repair.
Embryonic Stem Cell (ESC) Therapies
ESCs have the potential to treat some diseases in the future. Scientists are still learning how ESCs differentiate, and once this process is more understood, the objective is to apply what they’ve learned to get ESCs to develop into the cell of choice that is required for patient therapy. Diabetes, spinal cord injury, muscular dystrophy, heart illness, and vision/hearing loss are among the diseases being treated by ESC therapy. (4)
Adult Stem Cell Therapies
For more than 40 years, bone marrow and peripheral blood stem cell transplants have been used to treat blood illnesses such as leukemia and lymphoma, among others. Scientists have also discovered that stem cells may be found in nearly all parts of the body, and research is ongoing to learn how to identify, remove, and multiply these cells for future application in therapy. Scientists want to develop treatments for ailments such as type 1 diabetes and cardiac muscle restoration after a heart attack. Scientists have also demonstrated the potential for reprogramming ASCs to cause them to transdifferentiate (revert to a cell type other from the one it was replenishing in the local tissue). (4)
Induced Pluripotent Stem Cell Therapies
Therapies based on iPSCs are intriguing because recipient somatic cells can be reprogrammed to a “ESC like” state. The necessary cells could then be produced by using processes to differentiate these cells. This appeals to physicians because it avoids the issue of histocompatibility and lifelong immunosuppression, which is required when donor stem cells are used in transplants. iPS cells are pluripotent cells that mirror most ESC traits, but they do not currently carry the ethical baggage of ESC study and use because iPS cells have not been induced to grow the outer layer of an embryonic cell essential for the cell’s growth into a human individual. (4)
Pros and Cons of Stem Cells
Figure 2: University of Nebraska Medical Center: Types of Stem Cells
Potential Problems in using Stem Cells
Stem cells require considerably more research before their use may be increased. Scientists must first discover more about how embryonic stem cells develop. They will learn how to manage the kind of cells that are produced from them thanks to this. Using adult pluripotent stem cells presents difficulties for scientists as well. Researchers are trying to find a better approach to cultivate these cells because they are challenging to do so in a lab. The body also contains trace amounts of these cells. There is a bigger possibility that they will have DNA issues.
Another issue is that the embryonic stem cells that are now available are likely to be rejected by the body. Additionally, some people believe that using stem cells derived from embryos violates moral principles. For embryonic stem cells to be effective, researchers must be confident that they will develop into the required cell types. Researchers have identified ways to control stem cells to become specific types of cells, such as directing embryonic stem cells to become heart cells. In this field, research is underway. Additionally, embryonic stem cells have the capacity to develop erratically or innately specialize in certain cell types. Researchers are investigating how to control the proliferation and differentiation of embryonic stem cells. Embryonic stem cells could possibly set off an immunological reaction in which the body of the receiver assaults the stem cells as foreign invaders, or they could simply stop working as they should, with unknown repercussions. Researchers are still investigating how to prevent these potential complications. (1).
Akshaya Ganji, Youth Medical Journal 2022
References
- MayoClinic: Stem cells: What they are and what they do-https://www.mayoclinic.org/tests-procedures/bone-marrow-transplant/in-depth/stem-cells/art-20048117
- Standard Medicine: What Are Stem Cells?-https://www.stanfordchildrens.org/en/topic/default?id=what-are-stem-cells-160-38
- A Closer Look at Stem Cells: Types of Stem Cells-https://www.closerlookatstemcells.org/learn-about-stem-cells/types-of-stem-cells/
- University of Nebraska Medical Center: Types of Stem Cell-https://www.unmc.edu/stemcells/educational-resources/types.html
- University of Notre Dame: Adult Stem Cells-https://stemcell.nd.edu/research/alternative-stem-cell-sources/adult-stem-cells/
- Yo Topics: What is a stem cell?- https://www.yourgenome.org/facts/what-is-a-stem-cell/
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