Let's take a closer look at how science makes use of the human body's ability for regeneration to generate new therapies.
by Pearly Neo
The area of medicine and medical therapies have come a long way since the dawn of civilisation, going back way further that history can accurately trace and with unlimited potential promise aided by the development of science and technology. Given the limitless number of ailments, diseases and injuries out there, no rate of growth can ever be said to be quick enough, and such has driven the growth of the translational research effort – the specific application of scientific knowledge, e.g. biology and biomedical science, to develop new medical procedures, therapies, diagnostics and other tools to deal with vital medical needs today.1 Within this vast area lies the field of regenerative medicine, where research focuses on the development of ways to repair, regrow, or replace diseases and/or damaged cells, tissues, or even entire organs.2
Although only more recently directly recognised as a branch of medicine, regeneration has roots dating back thousands of years. In particular, ancient Greek mythology has stories depicting this, for example, after the Titan god Prometheus stole fire from Mount Olympus to save mankind, thus offending Zeus, he was chained to a rock and tortured for 30,000 years by having an eagle pick at his liver each night and regenerate each day, only to suffer the same torment again and again. At first glance, this may seem like nothing more than a slightly gruesome story that warns us against stealing, but deeper insight will reveal that the Greeks were not just making these things up out of thin air – the liver is in fact the only organ in the human body with the ability to regenerate itself after injury. In fact, the name ‘hepar’ in concern with the liver also originated from the Greek term ‘to repair oneself’.3
Myths aside, regenerative medicine today still very much builds on this essence of self-reparation and regrowth, and primarily concentrates on three main areas: cellular therapies, tissue engineering, and the use of artificial organ or medical devices.
A large number of regenerative medicine therapies that are most commonly seen today are cellular. Amongst these, one of the most major biomedical approaches used is that of stem cells, which are human cells with the capability to differentiate into other types of more specific tissue cells, then multiplying via cell division to produce large numbers of the specific cells. Under normal circumstances, the human body will naturally employ stem cells as a means of repairing damaged cells or replacing diseases ones. As a therapy, the concept employed is that when adult stem cells are harvested and injected to a damaged or diseased tissue/organ site, and the right environment is provided, the stem cells will be able to specialise, grow and multiply into the specific tissue or organ cells, thus reconstructing the damaged or diseased area.4
Stem cells can be harvested from a variety of areas, from blood to bone marrow, and a particularly well-known form of stem cell therapy is that of cord blood stem cell transplantation therapy, which especially in cases of blood cancers, makes use of stem cells extracted from umbilical cord blood for transplantation, with the objective of restoring the body’s ability to form its own blood and immune cells.5
Cellular-based therapies have come a long way in the past two decades since coming to light in the 1990s, and are able to target a widespread number of specific tissue types as well. A prominent example include knee cartilage therapy Carticel, which builds on the concept of autologous chondrocyte implantation, which involves harvesting chondrocytes or cartilage cells and culturing these into sufficient amounts for implantation back to the defective knee cartilage.6
Where cellular therapies depend on cells to naturally grow and divide into the required tissue after transplantation, tissue engineering uses a much more mechanical approach. It involves the insertion of a biologically-compatible scaffolding at the target site where new tissue is needed, and will generally be formed 1) according to the shape of the desired tissue, and 2) with materials and biochemicals that will attract the desired cells to form the new tissue. This field is relatively younger than that of cellular therapy, and so far most research has focused on soft tissue and the biological scaffolding material.
Due to the nature of the human body, there are numerous challenges to consider when choosing the materials to form the scaffolding. These range from it being able to successfully evade and prevent attack from the body’s own immune system which will activate itself upon the detection of most foreign materials, to the necessity for the scaffolding to have the flexibility to grow and/or move depending on its location.
As such, there is a great deal of ongoing research focused on this area, encompassing materials such as alginate, a polysaccharide found in algae,7 to chitosan, a polymer found in the chitin shells of shrimp and other crustaceans.8 Other, newer methods involve the application of 3D-printing,9 especially in the use of engineering bone tissue.
Artificial organs and/or medical device transplantation
The final arm of regenerative medicine is the area of artificial organs and medical devices. This mostly applies when a particular organ fails, and a significant period of time is required to find and/or grow a replacement, necessitating an interim strategy to ensure that the patient survives the wait by temporarily substituting or supplementing the function of the failing organ with an artificial one. This is especially clear in terms of circulatory or pulmonary support, as the human body would not be able to survive for long without the normal functioning of these organs.
A lot of effort is concentrated on artificial replacements for organs like the lungs10 and heart,11 with many recent examples surfacing in Asia from the nation-first usage of heart pumps in Singapore12 to the usage of rocket technology to develop an artificial heart in China.13 Additionally, when it comes to artificial organs like heart valves, which need to be implanted inside the body, it is also imperative that focus be placed on safety and the possible immunological risks that accompany this.14
The future of regenerative medicine
At its current rate of growth, regenerative medicine shows great promise that it poses a significant challenge to treatments in the current cardiovascular and metabolic disorders (CVMD) space, according to data and analytics company GlobalData. Although a vast majority of treatments and therapies are still in the preclinical stage, with enough time, a significant number of these will make their way to human trials and to the open market, which potentially means that eventually, these therapies would be much more widely available than they are at present.
- Quinlan, E. et. al. (2015). Development of collagen–hydroxyapatite scaffolds incorporating PLGA and alginate microparticles for the controlled delivery of rhBMP-2 for bone tissue engineering. Journal of Controlled Release. 198:71-79. DOI: https://doi.org/10.1016/j.jconrel.2014.11.021
- Rodríguez-Vázquez, M. et. al. (2015). Chitosan and Its Potential Use as a Scaffold for Tissue Engineering in Regenerative Medicine. BioMed Research International. 2015:1-15. DOI: http://dx.doi.org/10.1155/2015/821279
- Sears, N.A. (2016). A Review of Three-Dimensional Printing in Tissue Engineering. Tissue Engineering Part B: Reviews. 22:4. DOI: http://doi.org/10.1089/ten.teb.2015.0464
- Jaffer, I.H. et. al. A mechanical heart valve is the best choice. 2016. A mechanical heart valve is the best choice. Heart Asia. 8: 62-64. DOI:10.1136/heartasia-2015-010660
Pearly Neo is an experienced writer and editor with a particular interest in the food, travel and biomedical science fields.