THE FUTURE OF HUMAN REGENERATION

DENTAL PULP STEM CELLS

THE FUTURE OF HUMAN REGENERATION

By Ayman Lone Helen Wei

Stem cell therapy has long been regarded as the apex of regenerative medicine, more so than organ transplants or synthetic body parts. Because they start as unspecialized cells, stem cells have the ability to either differentiate into various cell types or to self-renew and become new stem cells. These functions allow them to heal – or sometimes regrow – damaged tissue and organs in humans. One of the most commonly used stem cells, called mesenchymal stem cells (MSCs), are derived from specific areas in the body such as bone marrow, umbilical cords, and embryos (which is often the topic of many ethical debates). A new alternative to MSCs are dental pulp stem cells (DPSCs). Even though the use of DPSCs is a recent development, research has uncovered unique traits and increased applicability to treating diseases compared to MSCs.

As the name implies, DPCSs reside under the third molar pulp where they are then extracted for use in stem cell therapy. Compared to MSCs, which are extracted from various organs as mentioned previously, and induced pluripotent stem cells (iPSCs) that are created from scratch from somatic cells, DPSCs present a less invasive, complex, and ethically challenging option for treatment. For example, DPSCs may be extracted during a wisdom tooth surgery or another similar simple dental operation, whereas accessing the bone marrow would require surgery. Another concern regarding MSCs is that contemporary research suggests that stem cells from bone marrow may only be able to differentiate into a few types of cells, namely osteoblasts (bone cells), which are only useful in musculoskeletal regeneration. On the other hand, DPSCs, in addition to the properties of MSCs, can form into osteoblasts, odontoblasts (a type of tooth cell), neurons, and fat cells. This ability to differentiate into various kinds of cells is referred to as multipotency. Although embryonic stem cells (ESCs) are also multipotent, their use brings up many ethical concerns and controversy. ESC extraction involves the destruction of human embryos, sparking debates over whether this extraction would be classified as murder. Many believe that embryos are humans with rights, while others view embryos as groups of cells with which it is permissible to conduct research. Even though the NIH created specific guidelines on stem cell use and research – with emphasis on ESCs – the issue remains a polarizing one in the US, similar to the “pro-choice” vs. “pro-life” debate. The use of DPSCs completely side-steps this debate and avoids these ethical hurdles, highlighting its practicality in research. Similarly, iPSCs – MSCs “reverse engineered” to resemble stem cells – have the flexibility of ESCs without the ethical baggage. As with MSCs, however, the procedure to obtain DPSCs is much simpler than the procedure to produce iPSCs. Overall, DPSCs represent a balance between simplicity and versatility, and have thus been the subject of many applications to specific diseases and fields of medicine.

Three of the main applications of DPSC therapy include dentistry, neurology, and angiogenesis (the generating of new blood vessels).

In terms of dentistry, DPSCs can differentiate into each of the four main components of teeth: enamel, pulp, dentin, and cementum. In fact, one of the earlier studies involving DPSCs showed how the cells could regenerate a dentin-pulp complex for immunocompromised mice, suggesting that perhaps human compatible lab grown teeth are on the horizon. This wouldn’t be too surprising, considering that a species of stem cells originating in dental pulp should be expected to differentiate into teeth-related organs. However, the ability of DPSCs to treat neurological diseases is unexpected. Due to how they express a variety of neurological growth factors, DPSCs have a surprisingly high rate of neurocyte differentiation. This would allow them to combat diseases such as dementia or schizophrenia. In 2019, a team at the University of Warwick conducted a study in which they concluded that DPSCs can effectively treat ischemic stroke. Another surprising trait of DPSCs is their angiogenic properties. Along with the numerous neurological growth factors, DPSCs produce several pro-angiogenic factors that – combined with DPSCs’ high proliferation rate – stimulate the rapid growth of new blood vessels. These applications only touch the surface of what DPSCs are capable of. DPSC research has only just begun, and studies have shown differentiation into liver cells and beta cells (insulin makers), pointing towards potential diabetes and hepatitis treatments.

Many of the possible setbacks of stem cell therapy – ethical questions, difficulty of cell extraction, differentiation versatility, etc. – are addressed and alleviated by DPSCs in some way. These cells are paving the way for a new wave of treatments for all kinds of diseases. After all, the study of DPSCs – and the field of regenerative medicine and tissue engineering in general – is only at its dawn, and the extent of their potential is yet to be fully discovered.

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