Cells are the smallest building block of the human body. All organs and human tissue are made up of billions of specialised cells, such as heart muscle cells, nerve cells, red blood cells and hair cells, among others.
Stem cells, also known as precursor cells, are cells with the ability to give origin to specialised cells that make up the tissues and organs of our body. This specialisation occurs throughout life.
Stem cells have unique characteristics:
Differentiation: the ability to give rise to different types of cells specialised in certain functions.
Self-renewal: the ability to originate new stem cells.
Proliferation: the ability to divide indefinitely.
The characteristics of stem cells allow damaged tissue to be repaired and dying cells to be replaced. As a result, they are important for the treatment of a range of diseases.
Stem cell sources:
Umbilical cord blood
Stem cells from umbilical cord blood are similar to those found in bone marrow. The so-called hematopoietic stem cells are responsible for creating blood and immune system cells.
Over 80 diseases can be treated with umbilical cord blood.
According to publications from the New York Blood Center, umbilical cord blood has already been used to treat over 80 diseases. Most transplants are for treating blood and immune system diseases, but umbilical cord blood cells are also used for the treatment of metabolic diseases.
Umbilical cord tissue
The umbilical cord tissue is enriched in mesenchymal stem cells, with properties different to cord blood cells. These can be differentiated into cartilage, bone and muscle cells, among other tissues.
Research is currently being carried out with mesenchymal stem cells in the field of regenerative medicine, i.e. for the development of organs and tissues based on stem cells. There has already been some success, although there is still much to discover.
In parallel, umbilical cord tissue stem cells are considered valuable, as they have the ability to attenuate the immune response when used with hematopoietic stem cells. This could reduce complications of allogeneic transplants, those where donor and recipient are not the same person.
Stem cells from umbilical cord tissue have already been used to successfully treat acute graft versus host disease (GVHD).
Combined use of umbilical cord blood and umbilical cord tissue stem cells in allogeneic hematopoietic transplants
Pre-clinical studies suggest that the success of hematopoietic transplants is around six times greater1 when mesenchymal cells from umbilical cord tissue are co-transplanted with umbilical cord blood.*
The success of hematopoietic transplantation is based on the reconstitution of the patient’s immune system, specifically measured through the recovery of the leucocyte count (CD45+ cells) in peripheral blood after the transplant. The speed of immune system reconstitution, a factor that is vital to patient survival, depends on a range of factors, specifically the number of cells transplanted, the source of stem cells that is used and the manifestation of graft versus host disease (GVHD).
There is a lower incidence of GVHD when umbilical cord blood is used (compared to bone marrow). However, immune system reconstitution is slower than when bone marrow or peripheral blood is used2. The use of mesenchymal cells from umbilical cord tissue can speed up the immune system reconstitution process (see graph) in the transplant recipient, increasing the likelihood of a successful transplant.
(1) Umbilical Cord Mesenchymal Stem Cells: Adjuvants for Human Cell Transplantation. Friedman et al., Biology of Blood and Marrow transplantation 2007, 13: 1477-1486.
(2) Analysis of Immune Reconstitution in Children Undergoing Cord Blood Transplantation. Moretta et al., Experimental Hematology 2001, 29, 371-379.
Optimizing Engraftment Source and Dose of Stem Cells. Schmitz & Barrett. Seminars in Hematology 2002, Jan; 39(1):3-14.
*NOTE: pre-clinical studies are carried out in animals, and it may not be possible to fully reproduce the results when transposed to clinical practice in human beings
Blood cancer diseases
The aim of an umbilical cord blood transplant is to replace diseased or deficient bone marrow of an individual patient with healthy stem cells, in order to regenerate the patient’s bone marrow.
The transplant is performed after the patient has received chemo- and/or radio-therapy.
On the day of the transplant, the patient receives umbilical cord blood cells administered by a process similar to receiving intravenous blood or medication.
Transplantation refers to the infusion or transfusion of umbilical cord blood cells. These healthy cells will replace the patient’s cells and are responsible for the formation of new, healthy cells in the recipient.
In diseases currently in the phase of clinical trial
In most treatments in the research phase, the way in which stem cells contribute to treatment after infusion is still not fully understood. However, some mechanisms have been described as being responsible for the observed improvements. Emphasis should be placed on the following:
migration of stem cells to the injury site and their differentiation (transformation) into tissue cells, promoting their repair;
the regulatory effect on immune system activity;
the increased release of factors that combat inflammation;
the release of other factors that promote repair.