Dental stem cells

Stem cells are specialized cells, capable of renewing themselves through cell division and differentiating into cells of multiple lineages, which could become new stem cells or specialized cells with a more specific function. No other cell in our body has this natural ability to generate new cell types. 

There are many types of stem cells in our body. These cells are classified into embryonic stem cells, adult stem cells, induced pluripotent stem cells, and perinatal stem cells. 

Embryonic stem cells come from blastocysts, which are embryos that are 3 to 5 days old. A blastocyst at this stage has approximately 150 cells. These stem cells are pluripotent; that is, they can divide into more stem cells or become any type of cell in the body, a characteristic that is very interesting for their use in the regeneration or repair of diseased tissues or organs. 

Adult stem cells are found in small amounts in most adult tissues, such as bone marrow or fat. They have a more limited capacity than embryonic stem cells to generate different cells in the body. However, emerging evidence suggests that they can indeed create different cell types. Therefore, early clinical trials are currently underway to evaluate the safety and usefulness of adult stem cells in people with other diseases (neurological, cardiac...). 

Induced pluripotent stem cells are adult cells modified to have the properties of embryonic stem cells. This transformation process has been achieved through genetic reprogramming. Changing the genes of adult cells makes it possible to reprogram the cells to act similarly to embryonic stem cells. The advantage of this technique is that immune system rejection of the new stem cells can be prevented. However, it is not yet clear whether using this modified adult cell would cause adverse effects in humans. 

Finally, we call perinatal stem cells the stem cells discovered in amniotic fluid and umbilical cord blood. These cells also can develop into specialized cells. However, more studies on these cells are also needed to better understand their potential. 

Mesenchymal stem cells are adult stem cells that can be isolated from human and animal sources. Human mesenchymal stem cells are non-hematopoietic multipotent stem cells with the ability to differentiate into mesodermal lineages, such as osteocytes, adipocytes, and chondrocytes, as well as ectodermal (neurocytes) and endodermal (hepatocytes) lineages. They were first observed in the bone marrow and have been isolated from various tissues such as adipose tissue, amniotic fluid, endometrium, dental tissues, and the umbilical cord, thanks mainly to increasing clinical trials. 

In addition, mesenchymal stem cells have immunomodulatory characteristics, secreting cytokines and immune receptors that regulate the microenvironment in the host tissue. These characteristics (immunomodulation and secretion of anti-inflammatory molecules) make them an effective tool in treating chronic diseases. 

Thanks to the ability of stem cells to renew themselves and give rise to a differentiated cell, the possibility of using these properties for repairing, improving, and replacing damaged organs has been studied in recent decades. Stem cell transplantation has been successfully tested at the clinical level to treat various diseases, confirming the high hopes for this emerging technique. 

However, there are many scientific and ethical obstacles that prevent rapid progress in research on the use of human stem cells. 

Until a few years ago, the international community was divided on the issue of stem cell research. 

Recently, several countries have enacted regulatory changes to address issues raised by research and scientific advances that have ethical and social implications. 

The International Society for Stem Cell Research (ISSCR), the world's largest professional organization of stem cell scientists, has also recently published updated guidelines for stem cell research and developing new clinical therapies. These guidelines provide an internationally agreed set of principles widely adopted worldwide.  

These guidelines promote appropriate and sustainable stem cell research. They do not replace local laws and regulations. Still, They can assist in the interpretation and development of local laws and provide guidance for research practices not covered by the legislation. 

Some of the following guidelines are standards that apply to any primary research. Others respond to challenges particularly applicable to stem cell research, such as those related to research activities involving the use of human embryos and gametes. 

The new guidance comes when technologies rapidly evolve, and emerging areas of stem cell discovery and applications provide unprecedented opportunities for understanding human biology and disease. Still, they also raise questions that have societal and ethical implications. The guidelines are based on widely shared principles of science that call for rigor, oversight, and transparency in all areas of practice. Adherence to these principles ensures that stem cell research is conducted with scientific and ethical integrity and that new therapies are evidence-based. 

The ISSCR developed earlier sets of guidelines that are also widely followed by researchers and institutions around the world, but this new set of guidelines updates and expands on those topic areas and brings all guidance together under ordinary principles of research integrity, patient welfare, respect for research subjects, transparency, and social justice. 

In response to advances in science, the guidelines encompass a broader and more expansive scope of research and clinical effort than before, impose rigor at all stages of research, address the cost of regenerative medicine products, and highlight the need for accurate and effective public communication. 

Despite the many significant advances made since the discovery of stem cells, central ambiguities still exist in the field regarding the nature, identity, function, mode of isolation, and experimental management of mesenchymal stem cells; which are the focus of intensive efforts worldwide aimed at elucidating their unique nature and properties, and developing cell-based therapies for a wide range of diseases.