Stem cell therapy factsheet

What are stem cells?

The human body is made up of billions of cells, each one of which is derived from a single fertilised 'egg cell'. However, the body's cells are not all identical. There are at least two hundred distinct cell types, all with different features and functions, such as neurons (nerve cells), liver cells, skin cells, and so on. These specialised cells are the body's mature or fully differentiated, cells, all of which are derived from their common ancestors, stem cells.

Stem cells themselves fall into three categories of potency, or ability to differentiate into other cell types, depending on their stage of development. 'Totipotent' cells are considered the 'master' cells of the body because they contain the genetic information needed to create all of the cell types in the body. Human cells only retain this capacity during the first few divisions of a fertilized egg.

Next come 'pluripotent' cells, which are also highly versatile and can give rise to any cell type except the cells of the placenta. Embryonic stem cells are pluripotent stem cells.

Finally, in the foetus, and in some adult tissues (such as bone marrow), the stem cells found are 'multipotent', meaning that they can give rise to several other cell types, but those types are limited in number and normally specific to the organ system in which they reside. These are also termed somatic, or lineage-restricted, stem cells.

ReNeuron's stem cells fall into this final category, which we believe are the most likely to provide effective cell therapy treatments.

The potential of stem cell therapy

Stem cell therapy has the potential to revolutionise the treatment of a variety of human conditions. Rather than addressing the symptoms of a particular disease or condition, stem cell therapy seeks to address the cause of the condition, to effect repair or reversal of the disease state through the regeneration of the affected tissue. ReNeuron's development programs seek to exploit the potential of stem cell therapy.

The ageing process, the onset of disease and the stresses of modern life all contribute to cell death within major organs of the body, including the brain. Cell degeneration or malfunction is one of the primary causes of serious diseases such as Parkinson's disease, Alzheimer's disease, diabetes, blindness and heart disease. Within the field of regenerative medicine, cell therapy involves replacing these dead or non-functioning cells with healthy, functioning cells of the equivalent or complementary type.

Cell therapy has been in existence for many decades and is a proven curative medicine. The most common example of stem cell therapy is the transplantation of bone marrow cells in leukaemia patients. Less well-known treatments include the transplantation of islet (insulin-producing) cells for the treatment of Type 1 diabetes and the transplantation of bone and cartilage cell grafts for the treatment of severe broken bones or for the rebuilding of joints.

These cell therapy treatments rely for the most part on the transplantation of healthy, mature cells, taken from the patient's own body, from donor relatives or from donated organs. However, mature, or fully differentiated, cells usually lose the ability to regenerate themselves. For this reason, mature cells from the brain or other specialised organs cannot be grown successfully in the laboratory beyond a small number of cell divisions. Consequently, cell therapy treatments using mature cells have not been successfully developed for large-scale clinical applications because of the limitations on the number of suitable cells available.

Stem cells offer the potential to overcome the technical difficulties associated with existing cell therapy treatments. Stem cells are the primitive undifferentiated cells that have the ability to give rise to the many different specialised types of cells (differentiated cells) that make up the organs and tissues in the human body. They can be made to grow in the laboratory and retain the ability to differentiate into the particular specialised cell type required. In animal studies, stem cells have also been shown to migrate from the point of implant and home into areas of disease or damage, sometimes over considerable distances.

In most cases, stem cell transplantation treatments involve relatively straightforward surgical procedures. Cells can and have been transplanted into the human brain, for example, in procedures that are performed under local anaesthetic and require at most a short hospital stay. Similar approaches would apply where other organs are being treated.

Stem cell therapy offers particular potential in areas of significant unmet, or poorly met, medical need. Diseases of the brain, such as stroke and Parkinson's disease, can dramatically reduce quality of life. They consequently represent major healthcare costs, particularly in terms of long-term care. There are no treatments that effectively address the causes of these diseases. Stem cell transplantation therapy offers the potential to alleviate the symptoms of, or cure, these diseases and many others.

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