By Nikhil Kumar, Fall 2020.
The idea of regeneration has consistently been portrayed in popular media and entertainment as a kind of superhuman or extraordinary ability. We are often amazed at superheroes’, such as Wolverine and Deadpool, incredible resistance to injury and extremely quick healing. These characters are able to lose entire limbs and completely repair them in a matter of hours. While we wonder if these kinds of abilities could be replicated in everyone in the future, the rapidly growing field of regenerative medicine seems poised to bring us a step closer in that direction and has the potential to give a new lease on life to those suffering serious injuries.
Regenerative medicine is a medical field which focuses on replacing tissues or organs that have been damaged by disease, trauma, or birth defects. This is contrary to the widely accepted clinical approach, where medicine is focused on treating solely the symptoms. In most cases, regenerative medicine aims to amplify the body’s own ability to heal or even entirely take over the functions of damaged organs. As of 2020, regenerative medicine focuses on three major techniques for research into treatment: cellular therapies, tissue engineering, and medical devices/artificial organs [1]. All three of these methods have shown at least some level of success in a clinical setting, with cellular therapy and tissue engineering at the forefront of research in the field.
Possibly the most well-known form of regenerative medicine is cellular therapy. Cellular therapy, in most cases, involves the transplantation of special cells called stem cells to replace or repair damaged tissue and cells [2]. Stem cells are the body’s raw materials for producing specialized tissues and organs. What makes them unique is their undifferentiated nature, which means they are in a versatile state with no special characteristics or organelles. These cells have the potential to divide into daughter cells which either become new stem cells, or specialized cells for a specific tissue. The capabilities of stem cells to multiply quickly and become differentiated to repair damaged tissue give them incredible regenerative qualities. It is important to note that most cells in the adult body are already specialized and are unable to return to an undifferentiated state [3]. While some stem cells exist in the adult body, such as in bone marrow, their numbers are insignificant compared to the number of cells within the adult body that are incapable of any regenerative abilities (such as most neurons and lung tissue) making cellular therapy an attractive medical procedure.
Stem cell therapy involves amplifying the natural healing response to diseased or injured tissues/cells using stem cells and has been a major research focus in regenerative medicine. The process is similar to organ transplantation, where stem cells from a host, or from another part of the body, are cultured to specialize into the cells of interest and are placed in the damaged tissue to speed up the regenerative process. Clinically, stem cell therapy has already found multiple successes and is currently being used to treat a variety of blood cancers. This treatment process involves the replacement of stem cells found in the bone marrow, being damaged by disease or chemotherapy, by other stem cells in a still partially versatile state in order to bolster the immune system and facilitate regeneration [3]. Aside from clinical usage, research in stem cells is actively growing.
Cellular therapy research has seen major success in regenerating major physiological tissues. Type 1 diabetes is a disease in which the body’s immune system attacks its own insulin-producing cells. Stem cells seem to be promising in this regard, as therapies involving replacement of these damaged insulin-producing cells with healthy versions produced by stem cells have reached the clinical trial phase. However, there are still complications since in most cases, immunosuppressant drugs are required to prevent these new cells from being destroyed [4]. Furthermore, stem cells have been observed to have the potential to regenerate the myelin sheath–a lipid nerve covering which improves conductance–and even nerves themselves. While this particular application is promising, with certain adult stem cells being able to produce growth of the axon, the primary conductive region of the neuron–the exact mechanism–and its performance in simulated body microenvironments is not fully understood [5]. Cellular therapies, however, are currently being outpaced in regenerative medicine as technological innovation and ethical issues related to the extraction of stem cells from embryos have shifted them out of the spotlight [6].
In recent years, 3D printing is a technological innovation that has gained a large degree of popularity, paving the way for tissue engineering to take center stage in regenerative medicine research. Tissue engineering is a strategy in which biologically compatible scaffolds are implanted in the body at the site where new tissue is to be formed. These scaffolds are created using biopolymers and are set up so that the regeneration of the tissue creates a specific shape or pattern [2]. The production of biological scaffolds is primarily conducted through 3D printing. Cutting edge research is being carried out to use this technology to create scaffolding within the body. Since current clinical tissue engineering procedures are prone to many surgical complications in implanting the scaffolds, including increased recovery time and risk of infection, this technique could possibly counter these problems while also producing seamless tissue structures and a more effective regeneration procedure. Despite this research being in its very early stages, with a suitable bio-ink polymer being only recently discovered, it is testament to the potential for research in this field and its implications for future medicine [7].
While regenerative medicine is still far from reaching the limits set by popular media and superheroes, its potential is nearly limitless. Creation of biopolymers, clinical applications in cancer treatment, and success with regeneration of human tissues using cellular therapy shows how regenerative medicine has taken great strides toward becoming a dominant form of treatment in the near future. Despite the ethical concerns raised by the larger scientific community, regenerative medicine has adapted and evolved with new technologies, showing a large amount of promise, both in research and its future clinical usage.
[1] “What Is Regenerative Medicine?” Regenerative Medicine at the McGowan Institute, https://mirm-pitt.net/about-us/what-is-regenerative-medicine/.
[2] “Facts About Cellular Therapies.” Site Title, www.aabb.org/aabbcct/therapyfacts/Pages/default.aspx.
[3] “Frequently Asked Questions about Stem Cell Research.” Mayo Clinic, Mayo Foundation for Medical Education and Research, 8 June 2019, www.mayoclinic.org/tests-procedures/bone-marrow-transplant/in-depth/stem-cells/art-20048117.
[4] “Diabetes and Stem Cell Research.” Diabetes.co.uk, 11 Mar. 2020, www.diabetes.co.uk/Diabetes-And-Stem-Cell-Research.html.
[5] Petrova, E. S. “Injured nerve regeneration using cell-based therapies: current challenges.” Acta Naturae (англоязычная версия) 7.3 (26) (2015).
[6] Lo, Bernard, and Lindsay Parham. “Ethical issues in stem cell research.” Endocrine reviews 30.3 (2009): 204-213.
[7] “Tissue Engineering Moves Closer to 3D Printing inside the Body.” Physics World, 18 June 2020, https://physicsworld.com/a/tissue-engineering-moves-closer-to-3d-printing-inside-the-body/.
[8] Forbes, S. J. “Recent advances in stem cells and regenerative medicine.” QJM: An International Journal of Medicine 107.4 (2014): 251-252.
[9] Mao, Angelo S., and David J. Mooney. “Regenerative medicine: current therapies and future directions.” Proceedings of the National Academy of Sciences 112.47 (2015): 14452-14459.
[10] Reisman, Miriam, and Katherine T. Adams. “Stem cell therapy: a look at current research, regulations, and remaining hurdles.” Pharmacy and Therapeutics 39.12 (2014): 846.