A Stem Cells Overview. What Are They and How Do They Work As a Novelty Treatment in Regenerative Medicine?
- Brandon Perez
- Jan 16
- 5 min read
The human body is composed of many different cell types that form tissues and organs, each with specific functions vital to maintaining overall health. It was discovered some time ago that certain differentiated cells, such as those in the skin, intestinal lining, and blood, have a short lifespan and lack the ability to self-renew. (Shern Kwok Lim and Boon Yin Khoo, 2021). Stem cells are a distinct group of cells found throughout all stages of life, characterized by their capacity to self-renew and differentiate into various cell types, you could say that they serve as the origin from which specialized cell types within differentiated tissues and organs are generated. During the neonatal stage, stem cells differentiate and multiply into the various cell types and lineages needed for ongoing development. In adults, however, their main function shifts to regeneration and tissue repair. (Salomon Poliwoda et. al, 2022).
Embryonic, Adult and Induced stem cells. Different types of stem cells, their utility and implications
Stem cells are categorized depending on their potential to differentiate into more types of human body cells. Pluripotent stem cells have a higher potential for differentiation and self-renewal as they proliferate as multiple cell lineages (meaning that they could theoretically turn into any type of cell in the human body), making them a valuable option for disease treatment. However, ethical concerns arise when using these cells, as embryonic stem cells are obtained from embryos at the blastocyst stage, which involves the destruction of the embryo.
A newer and exciting option is induced pluripotent stem cells, which are made by reprogramming regular body cells to act like stem cells. This approach is less invasive than traditional methods. After being reprogrammed, these cells can be directed to become specific cell types by copying the body's natural environment in the lab. (Ria Margiana et. al, 2022). Still, since they require more processing in the laboratory and represent a more expensive option, there are not as many treatments based on induced pluripotent stem cells available in the market.
Due to these limitations, researchers turned their focus to adult stem cells, the multipotent cells found in adult tissues and organs. These stem cells, also labeled mesenchymal stem cells, or mesenchymal stromal cells, are a type of postnatal stem cell capable of self-renewal and can differentiate into various cell types. Mesenchymal stromal cells have several key traits, such as being easy to isolate and cultivate, having the flexibility to adapt to different environments, and an innate ability to move towards areas of injury. They also have anti-inflammatory and anti-cell death properties in damaged tissues and help regulate the immune response through paracrine signaling, as well as antimicrobial effects and the ability to clear bacteria. These cells can activate other stem cells in the body and stimulate the formation of new blood vessels. Thanks to these remarkable properties, mesenchymal stromal cells are seen as a promising option for treating various human diseases. So far, mesenchymal stromal cell therapy has been successfully used to treat a range of conditions, including metabolic, degenerative, and inflammatory diseases, as well as in tissue repair and regeneration, and even in cancer treatments. (Pardis Saeedi, Raheleh Halabian, Abbas Ali Imani Fooladi, 2019).
Where do mesenchymal stem cells come from?
Mesenchymal stem cells can be obtained virtually from every part of the body. Currently, the primary sources of mesenchymal stromal cells (mesenchymal stem cells) are bone marrow and fat tissue. The bone marrow in mammals plays a key role in producing blood cells (a process called hematopoiesis) and maintaining bone health. It contains a mix of different cell types, including both blood-forming stem cells and non-blood-forming stem cells like fibroblast precursors, which are better known as mesenchymal stromal cells (mesenchymal stem cells). (Pardis Saeedi, Raheleh Halabian, Abbas Ali Imani Fooladi, 2019). Obtaining mesenchymal stromal cells from bone marrow suppose practical challenges, such as the difficulty and invasiveness of the procedure, as well as factors related to the donor. For instance, it can cause pain, bleeding, or infection, making it a more complicated process compared to harvesting cells from peripheral blood or leftover tissues from surgeries, like fat or birth-related tissues. (Roberto Berebichez-Fridman and Pablo R. Montero-Olvera. 2018).
Recent research on mesenchymal stromal cell therapy has centered on their distinctive biological characteristics and functions, which may enhance their potential for clinical use. Some of their properties that make them so unique are the following ones:
1. Regenerative potential
Mesenchymal stromal cells (MSCs) are known for their ability to renew themselves and develop into different cell types, like bone, fat, cartilage, and muscle cells. Some research suggests that MSCs might also turn into other types of cells, like liver, nerve, and heart cells, though this is less common (Nayoun Kim and Seok-Goo Cho, 2013)
2. Inmune system regulation
They also play a role in both the body's natural defense system (innate immunity) and its more targeted immune response (adaptive immunity). They regulate immune activity mainly by interacting with immune cells directly or by releasing signaling molecules. These interactions involve various immune cells, including T cells, B cells, natural killer cells, macrophages, monocytes, dendritic cells, and neutrophils. (Na Song, Martijn Scholtemeijer, Khalid Shah, 2020).
3. Migratory capacity
Several studies indicate that mesenchymal stromal cells can move to areas of inflammation and tumors in the body. While the exact reasons for how mesenchymal stem cells migrate are not fully understood yet, research has found that their movement relies on different chemical signals and interactions with specific receptors. (Nayoun Kim and Seok-Goo Cho, 2013)
4. Angiogenic properties
Due to their remarkable ability to differentiate into various cell types, mesenchymal stem cells are considered a valuable alternative for treating ischemic diseases. Additionally, mesenchymal stem cells show significant potential for regenerating tissues and restoring blood flow by promoting the release of different cytokines that support new blood vessel formation and prevent cell death. (Hongyan Tao et. al, 2016)
Conclusion
At the moment, mesenchymal stem cells are the most used stem cells type in regenerative medicine due to their relative simple harvesting method, their lack of ethical issues, their therapeutic properties and their scientifically proved safety profile. They posses a plethora of regenerative properties, such as the ability to create new blood vessels, lower inflammation on several tissues and the attribute to proliferate as skin, bone, fat and muscle cells as well as many other adult cell types. It seems that their uses and applications only continue to grow as researchers explore new possibilities and options.
References:
1. Angelo S. Maoa and David J. Mooneya. (2015) Regenerative medicine: Current therapies and future directions 14452–14459, vol. 112, no. 47
2. Chongtao Zhu, Wei Wu, Xiaowen Qu. (2021). Mesenchymal stem cells in osteoarthritis therapy: a review. Am J Transl Res 13(2):448-461
3. David E. Rodríguez-Fuentes et. al. (2021). Mesenchymal Stem Cells Current Clinical Applications: A Systematic Review.Archives of Medical Research, Volume 52, Issue 1, January 2021, Pages 93-101.
4. Hongyan Tao et al. (2016). Proangiogenic Features of Mesenchymal Stem Cells and Their Therapeutic Applications. Hindawi Publishing Corporation, Stem Cells International, Volume 2016, Article ID 1314709, 11 pages.
5. Margiana et al. (2021) Clinical application of mesenchymal stem cell in regenerative medicine: a narrative review. Stem Cell Research & Therapy. 13:366
6. Nayoun Kim and Seok-Goo Cho (2013). Clinical Applications of Mesenchymal Stem Cells. Korean Journal of Internal Medicine, 2013; 28: 387-402. http://dx.doi.org/10.3904/kjim.2013.28.4.387
7. Na Song, Martijn Scholtemeijer, Khalid Shah1 Mesenchymal (2020) Stem Cell Immunomodulation: Mechanisms and Therapeutic potential. Trends Pharmacol Sci. 41(9): 653–664.
8. Pardis Saeedi, Raheleh Halabian, Abbas Ali Imani Fooladi. (2019). A revealing review of mesenchymal stem cells therapy, clinicalperspectives and Modification strategies. Stem Cell Investig 6:34
9. Salomon Poliwoda et al. (2021) Stem cells: a comprehensive review of origins and emerging clinical roles in medical practice. Orthopedic Reviews. 14(3).
10. Shern Kwok Lim and Boon Yin Khoo. (2021) An overview of mesenchymal stem cells and their potential therapeutic benefits in cancer therapy (Review). Oncology letters 22: 785
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