Body & disease areas
reNEW research covers stem cells from, or able to form, many different organs of the body. Our aim is to help transform the lives of people with stem cell medicine. Click on the different body areas and learn more about the disease focus of the ongoing stem cell research within reNEW.
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What are stem cells?
Stem cells are the building blocks of every tissue within our bodies. During development, stem cells help to form all of our organs. For the rest of our lives, stem cells serve as an internal repair system for each tissue, replacing the cells that are lost each day, such as those in our skin, hair, blood, or the lining of our intestines, as well as replenishing tissues after damage and disease.
Stem cells have two key properties:
- The ability to divide and create an identical copy of themselves. This process is called self-renewal.
- The ability to differentiate into a more specialised cell type to carry out a specific function.
Hence, stem cells generate all the many cells and structures within our bodies from beginning to end.
What are the different types of stem cells?
There are two broad categories of stem cells: multipotent and pluripotent stem cells.
Many adult tissues contain a rare population of adult stem cells or tissue-specific stem cells. These are also known as somatic stem cells. Tissue-specific stem cells are found in organs that constantly need to replenish themselves, like red blood cells in the blood, epidermal cells in the skin, and intestinal cells in the gut. Adult stem cells can give rise to some, or all the mature cell types found in a particular tissue or organ. Hence, adult stem cells are considered as “multipotent.”
The term ‘pluripotent’ means that such cells have an ability to form all tissues of the body. There are two sources of human pluripotent stem cells: embryonic stem cells and induced pluripotent stem cells. They can be grown and expanded in this undifferentiated state to help researchers learn about early human development processes that are otherwise inaccessible. They can also be used to study human disease, screen drugs, and build tissues, all of which have the potential to lead to medical therapies.
During the first 3-5 days of embryonic development, as small number of pluripotent stem cells form from the fertilised egg. These few cells, referred to as embryonic stem cells, give rise to all the cells of the embryo. Isolating these embryonic stem cells provide a source of stem cells from which any other tissue can be made.
Embryonic stem cells can be collected from the blastocyst, a very early stage of human development. Such embryos are available with the consent of the donors from embryos excess to need collected by in vitro fertilization (IVF) clinics. The blastocyst is a hollow ball of approximately 150-200 cells, containing an inner cell mass of embryonic stem cells. This is prior to implantation and prior to the formation of any organs. While embryonic stem cells cannot develop into a viable human embryo outside of the blastocyst, they have an ability to be directed into a myriad of different cell types.
Induced pluripotent stem cells (iPS) have similar properties to embryonic stem cells but are derived from mature and fully differentiated adult cells, such as skin cells. Any adult somatic cell – any body cell, except the reproductive cells, i.e., the egg or sperm – can be reprogrammed back to a pluripotent state. This reprogramming involves transient gene expression – the temporary expression of genes expressed for a short time – of key factors that take the cell back to a state similar to that in the early embryo.
As these can be made from any adult cell type, it is possible to make patient-specific iPS cells. This enables researchers to study the cause of a particular disease by differentiating these stem cells to the affected tissue, such a kidney, heart, or brain. iPS cells are critical for developing accurate models of human disease which can then be used when developing drugs. As a source of human pluripotent cells that does not require the use of a blastocyst, this has fewer ethical implications. However, the reprogramming process itself is inefficient and the use of adult cells can introduce mutations acquired by the donor during life.
For both embryonic and iPS cells, there are now many methods for generating complex tissues models of almost all organs using this starting material.
How are stem cells used?
Although there is a lot of interest in stem cell medicine, the number of stem cell-based treatments currently available remains limited.
The most frequently used stem cell therapy is bone marrow transplant, which essentially involves mobilising from the bone marrow the hematopoietic (blood) stem cells. This process is used to treat patients with certain types of blood cancers or immune disorders. Blood collected from the umbilical cord is another abundant source of blood stem cells and can be used to treat cancer and rare hereditary diseases in children. The capacity of the stem cells of the skin to recover wounds has also long been exploited for the treatment of burns.
More recently, clinical trials have commenced for the use of stem cells in the treatment of diabetes, Parkinson’s disease, and macular degeneration of the eye.
There are also treatments under development for heart failure and intestinal disease. The genetic correction or modification of adult stem cells is also being developed for the treatment of specific cancers, genetic skin disease, muscular dystrophy, and severe combined immune deficiency.
The use of stem cells for other diseases is still in the experimental phase and needs to be fully tested. Until these new treatments have passed the mandatory clinical trials and been approved by the regulatory authorities, their efficacy and safety are not considered proven, and their use is not recommended.
Though there is a lot of interest in stem cell medicine, the number of treatments currently available is limited.
What is stem cell medicine?
Within reNEW, we consider stem cells as providing multiple opportunities to improve health. A direct stem cell therapy would include a treatment that delivers into a patient stem cells or stem cell-derived tissues to replace or repair the patient’s damaged cells or tissue. A gene modified stem cell therapy is one where the patient’s cells are genetically modified to replace or repair an inherited disease and then delivered to that patient. Stem cells can also be used to model a disease state for the purpose of identifying a successful therapy, such as a drug or antisense of RNA therapy.
Together, we regard these three approaches as stem cell medicine.
Currently available stem cell treatments are limited. In addition, a number of unproven stem cell therapies have been made available directly to patients, particularly using fat stem cells. We would recommend that you consult our patient resources if you have specific questions about potential stem cell treatments.
You may also consider consulting your doctor or specialist or contacting local patient advocate and health organizations with expertise in your condition for additional information and assistance.
Below are some valuable patient resources to consider:
International Society for Stem Cell Research
An independent, global non-profit organisation promoting excellence in stem cell science and applications to human health.