Stem cell therapy has gained significant attention in recent years. Advertisements that claim such therapies could cure cancer, reverse organ failure, or even slow down aging are all over the internet and in newspapers. Yet, due to the fact that stem cell therapy is such a new concept, it has become subject to ill-intentioned organizations trying to scam people who are unfamiliar with the mechanisms of stem cell therapy. This article will explore what stem cell therapy is, its underlying mechanisms, and the prospect of this rising field of biology. 

Stem cells are unique types of cells with the remarkable ability to develop into various specialized cell types in the body. A primary feature of stem cells is their pluripotency or multipotency, i.e., pluripotent and multipotent, meaning they can differentiate into many or all types of cells depending on the signals they receive. Upon being exposed to certain differentiation factors, stem cells can regulate the expression of certain genes accordingly, which requires changing their morphology, function, and even location. In other words, the aforementioned stem cells are now transformed into another cell type entirely 

There are several different types of stem cells. Based on their origins, stem cells can be divided into three types. The first is embryonic stem cells (ESCs) that originate from embryos, capable of differentiating into almost every type of human cell except those of the placenta. Another includes adult stem cells that originate from an adult individual, for example, bone marrow cells, with reduced differentiation capabilities compared to ESCs. The final option is induced pluripotent stem cells, and changing into these cells is a process that can reverse differentiated cells when they encounter certain signals, discovered by Shinya Yamanaka in 2006. 

The fascinating ability of stem cells to turn into functioning human cells suggests that they can be utilized to treat a variety of diseases. One big branch of the medical utilization of stem cells is regenerative medicine. As suggested by its name, regeneration medicine uses stem cells to regenerate or replace dysfunctional organs and tissues. One widely studied method of utilizing stem cells is by engineering purified and characterized stem cells into tissues ex vivo (Latin for “outside the organism”) and transplanting them into the recipient. For example, ongoing research seeds stem cells into a 3D-printed porous scaffold and induces them into bone cells. The bone cells form a calcium-rich, mineralized extracellular matrix (ECM) around themselves while living in the scaffold. This 3D structure can then be transplanted into a patient with a bone injury to assist bone regeneration. Another method to utilize stem cells is by direct injection into the recipient. Stem cells demonstrate a fascinating behavior called homing, in which they, in response to damage at another location, migrate to the “crime scene” and become the local source of cells to aid repair. It is also observed that stem cells themselves can stimulate the regeneration of damaged tissue by mobilizing neighboring cells. 

The first, and to this day only, FDA-approved stem cell therapy is hematopoietic stem cell (HSC) transplantation, otherwise known as bone marrow transplantation. Hematopoietic (hema, Greek for “blood”, plus poietic, Greek for “formation”) stem cells are stem cells that are capable of differentiating into blood cells. As its name suggests, this therapy is used to treat deficiencies in blood cell production, either due to leukemia or chemotherapy side effects. Hematopoietic stem cells are first harvested from the donor’s bone marrow. They are then evaluated and allowed to proliferate in vitro. The cells are then transfused into the recipient through a process known as engraftment, before these exogenous cells find their way to the recipient’s bone marrow and start making blood cells. 

Beyond HSC transplantation, there are no other approved stem cell therapies in the US. This raises the question: if stem cell therapy has such great potential, why is it not practiced on a bigger scale in hospitals? Firstly, despite decades of research, stem cell biology is still a very young subject. Research scientists are still struggling to understand the specific mechanisms and pathways of stem cell activity, while the results of clinical trials sometimes differ and even contradict each other. As a result, government health agencies such as the FDA are slow in approving such therapies. In addition, researchers face many obstacles when attempting to have the exogenous stem cells live happily in their new host. Recipients of grafts are often subject to rejection or infection in cases of infected or incompatible transplants. In 2021, stem cell injections in the US caused grave infections in at least 20 patients who received umbilical cord blood-derived products marketed as "stem cell treatment". Some recipients of HSC transplantations experience a condition known as graft versus host effect, where some of the newly injected cells, now differentiated into white blood cells, start attacking the host. 

With so much being said, is stem cell therapy, after all, to be trusted? Concerning this article is not patient-specific, I can only suggest that patients consult doctors before deciding whether or not to receive stem cell therapy. However, stem cells, with their fascinating abilities, are well before their prime.