By: Amy Hammett
Introduction
The term tissue engineering itself was presented back in the 1980s. It is a field of research focused on the development and creation of substitutes that could potentially replace or improve damaged tissues or whole organs within humans. This is done through the application of combining scaffolds, cells, and other biological components into tissues that are functional.
Regenerative medicine is another field that encompasses not just tissue engineering but also the incorporation of research regarding “self-healing,” which is where the body restores and/or redevelops is own cells and organs through the process of using its own bodily systems in order to return to normal function. There are multiple forms of treatments included in regenerative medicine, which are stem cell treatments, cartilage regeneration, platelet-rich plasma (PRP), and prolotherapy. Generally, the term is used to refer to clinical therapies that involve biomedical approach of stem cells, and tissue engineering is one of the examples of this approach. Others include cell therapies, which is the injection of stem or progenitor cells, and immunomodulation therapy, which is the reconstruction of active molecules.
Together, the terms are combined to formulate TERM, which is a “multidisciplinary science” that combines “basic sciences such as materials science, biomechanics, cell biology, and medical sciences” to construct or repairs tissues and/or organs that have been damaged in some way to its original function. One of the main hopes for TERM is to lessen the demand for donated organs from donors.
Procedure
The basic unit of life on Earth are cells, and therefore, cells are the basis of tissues which then lead to organs. Groups of cells create structures that act as their support system, which is known as extra-cellular matrix or a scaffold. Along with its important role in support, the extra-cellular matrix also serves as a relay station for signals, or messages, from signaling molecules. Each signal, if strong enough, can begin a signal cascade to trigger a response. By understanding how cells interact with each other and its environment along with organization and roles of tissues and organs, scientists are able to develop methods that can manipulate these processes to rebuild and create organs and tissues that have been damaged.
One way this is done is to create a new scaffold, which can be done through a wide variety of materials such proteins and plastics (National Institute of Biomedical Imaging and Bioengineering). For instance, synthetic scaffolds have been created from “purified extracellular matrix components or algae-derived alginate” or from polymers that designed to be degradable which allows its “gradual replacement” by cells (Mao and Mooney 14453). The scaffold is then used as support for cells seeded in vitro where the cells build a matrix to form a foundation form tissue transplantation. Another method is where the scaffold is used as a growth factor or “drug deliver device” (Howard, Buttery, Shakesheff, and Roberts). With this method, the scaffold is combined with growth factors. By doing this, once it is transplanted into a body, the cells form the body would “recruited to…site and form tissue upon and throughout the matrices” (Howard, Buttery, Shakesheff, and Roberts). It is also important to keep in mind the materials used to create these scaffolds are different materials can create different reactions of cells. Additionally, the building of scaffolds can modify the “response of cells” leading to the tissue formation (Howard, Buttery, Shakesheff, and Roberts).” Another method is by using a pre-existing scaffold to create new tissues. Simply, tissue and organ architecture are “deeply connected with function” (Mao and Mooney 14453). The donated organ is stripped of its original cells and the collagen that is left is used to group the new tissues. This process as already been done to create hearts, livers, and other organs of the body. (National Institute of Biomedical Imaging and Bioengineering).
Applications:
Tissue engineering and regenerative medicine, which is once again known as TERM, has be applied to several different areas, and/or branches, of the medical field. The applications of tissue engineering are once again heavily to its design and choice of materials. Earlier, it was mentioned how a synthetic scaffold was created from synthetic polymers that are degradable and this has been useful in discovering potential solutions regarding heart defeats. Cardiomyocytes, which is also known as cardiac muscle cells lack the ability to replace damages cell due to the inability to divide, which means the heart is cannot repair/heal itself. Instead, scar tissue forms to keep the heart intact, but the heart is unable to contract (Curtis and Russell). With this, the method has been applied to and used in clinical trails for the treatment of congenital heart defeats in children and adult patients (Mao and Mooney 14453).
Another way TERM can be applied is through cellular therapies. As stated earlier, regenerative medicine is where the human body is able to restore its damaged organs and tissues usings its own systems, and this is largely done by the work of cells. One of the basic strategies of regenerative medicine is implanting, or injecting, new healthy cells in order to replace groups of cells that are no longer functioning properly. This can be done by injecting the cells alone or by using a carrier, such as hydrogel. The types of cells used for these processes can be cells that are related cells that were retrieved from a tissue biopsy and then grown in a lab culture, or be stem cells (Olson, Atala, and Yoo). An example would be using cellular therapy to restore or regenerate the cells that produce insulin of the pancreas, which would lead new treatments for diabetes (Olson, Atala, and Yoo).
An additional method of application involves tissue engineering itself. The process includes modified cells or stem cells that are “seeded onto a biomaterial scaffold,” which is then allowed to grow in vitro before it transplanted in vivo (Olson, Atala, and Yoo). Over the years, there have been successes in engineering organs, such as the urethra and blood vessels within the. Tissue engineering has also been used to create cartilage-like tissue that is fairly similar to the authentic cartilage where multiple of animals models have been utilized (Narayan).
Issues:
Despite the prominent and significant impact that tissue engineering has in the medical field, there are several concerns surrounding this subject. Overall, the research and methodologies that encompass tissue engineering and regenerative medicine are quite complex, which means the means to regulate this research is also beyond simple. One of the main ethical concerns encircling tissue engineering is the use of “animal models at preclinical stages.” (Baker, McQuilling, and King). It is highly common to perform experiments on animals, such as pigs and rats, to better understands the effects of the experiment. However, this brings the question of when the use of animals in these experiments have gone too far, and what are some ways to minimize the usage of them.
Another topic of debate is moving into clinical trials where humans now have become the tests subjects instead of animals. The goal of these test trials is to produce results to help guide and advance researchers in their study and further studies. Therefore, the question of how informed the participants are of the potential benefits as well as the potential harm arises. Trials must be designed and conducted to protect is subjects by clearly addressing risks and minimizing them to its fullest extent. This includes “defining success and failure, and examining what can be done for patient-subjects if/when…experimental intervention fails” (Baker, McQuilling, and King). Along with this brings additional questions of who should participate in these clinical trials and the informed consent. Since this research is focused on repairing damaged tissues and organs, the selection would include patients who have such injuries. Therefore, during their participation, the “standard treatment would remain available,” and if standard treatment is in some way delayed, it would not be fatal or by “minimally disadvantages” (Baker, McQuilling, and King). Furthermore, the patient-subject should be entirely informed of the conditions and have a complete understanding of the process, such as who is performing the trails, what is being done, and the purpose of the research, which again, brings even more questions of ethicalness.
Opinion
The significant impact that tissue engineering can have on the medical field is quite astonishing. With this tool, injuries and defects of the human body would be treated differently as well as seen differently. For instance, birth defects of the heart that were once viewed as untreatable and incurable, could be restored to their original form and function. Since this topic of research is still very new and remains the majority in its working, how to perform clinical trials properly and successfully is indeed a major concern. However, there are many ways to lessen these concerns, some of which have been addressed above. I believe with proper regulation and effective set of rules along with viable collected data, would lessen the objective concerns towards TERM.
Works Cited
Baker, Hannah B et al. “Ethical considerations in tissue engineering research: Case studies in translation.” Methods (San Diego, Calif.) vol. 99 (2016): 135-44. doi:10.1016/j.ymeth.2015.08.010
Curtis, Matthew W, and Brenda Russell. “Cardiac tissue engineering.” The Journal of cardiovascular nursing vol. 24,2 (2009): 87-92. doi:10.1097/01.JCN.0000343562.06614.49
Encyclopædia Britannica, inc. (n.d.). Tissue engineering. Encyclopædia Britannica. https://www.britannica.com/science/tissue-engineering
Howard, Daniel et al. “Tissue engineering: strategies, stem cells and scaffolds.” Journal of anatomy vol. 213,1 (2008): 66-72. doi:10.1111/j.1469-7580.2008.00878.x
Mao, Angelo S., and David J. Mooney. “Regenerative Medicine: Current Therapies and Future Directions.” Proceedings of the National Academy of Sciences of the United States of America, vol. 112, no. 47, 2015, pp. 14452–59. JSTOR, https://www.jstor.org/stable/26465839. Accessed 22 Nov. 2023.
Narayan, R. (2017). Monitoring and evaluation of biomaterials and their performance in vivo. Woodhead Publishing.
Olson, Jennifer L et al. “Tissue engineering: current strategies and future directions.” Chonnam medical journal vol. 47,1 (2011): 1-13. doi:10.4068/cmj.2011.47.1.1
Regenerative medicine. http://www.aabb.org. (n.d.). https://www.aabb.org/news-resources/resources/cellular-therapies/facts-about-cellular-therapies/regenerative-medicine#:~:text=Examples%20include%20cell%20therapies%20(the,laboratory%20grown%20organs%20and%20tissues).
Tissue engineering and regenerative medicine: Achievements, future, and Sustainability in Asia. ReadCube Literature Management Solutions. (n.d.). https://www.readcube.com/articles/10.3389/fbioe.2020.00083
Tissue engineering: The future is here. Johns Hopkins Biomedical Engineering. (n.d.). https://www.bme.jhu.edu/news-events/news/tissue-engineering-the-future-is-here/
4 types of regenerative therapy treatments. Dr. Nael Shanti. (2020, March 16). https://www.shantispinesurgery.com/types-of-regenerative-therapy-treatments/
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