Stem cell transplantation

A stem cell transplantation (SCT) is a procedure in which a patient receives healthy stem cells to replace damaged or diseased stem cells. To perform a stem cell transplantation, stem cells that have the ability to form new blood-forming stem cells are used. Cord blood is one of three sources of blood-forming cells used in transplantation. The other two sources are bone marrow and peripheral blood stem cells.

Autologous stem cell transplantation

Blood-forming stem cells can be used for various types of transplantation. An autologous bone marrow transplant can be used for malignant lymphomas, myelomas and other tumours. In an autologous transplant, the patient is both donor and recipient of the stem cells, i.e. the patient’s own stem cells are used. The use of umbilical cord blood began in the 2000s, which is why only children have been treated with autologous stem cells to date. The need for a stem cell transplant increases with age, so the number of autologous stem cell transplants using umbilical cord blood is therefore expected to increase over time.

Allogeneic stem cell transplantation

SCT is also used in various hereditary or malignant blood diseases that affect the cells in the blood, bone marrow or immune system. Then an allogeneic stem cell transplantation is usually performed, which means that it is a close relative or unrelated individual who is the donor. A stem cell transplantation is also an approved treatment for certain types of multiple sclerosis, MS in Sweden.


One of the advantages of cord blood stem cells is that the cord blood can be collected in advance, tested and frozen, ready to use. When a patient comes in with a diagnosis such as acute leukemia it is urgent. Then the stem cells from cord blood can easily be thawed in 37° C water bath. Analysis is performed to see how viable the cells are after freezing and after this the stem cells can be given intravenously to a patient. In the body, the cord blood stem cells migrate to the center of the bone. In the bone marrow, these stem cells start to produce new, non-diseased blood and immune system cells.

Prognosis after stem cell transplantation:

A stem cell transplantation is an established treatment for both children and adults in several different diseases and diagnoses. The results have been continuously improved. Improved diagnostics, better diagnostics, better diagnostic markers, and better supportive treatment results in clearly improved survival rates. However, relapse of the underlying disease remains a risk, as for most treatments.

Improvements in stem cell transplantations with cord blood:

Doctors and scientists are constantly working to find new ways to improve the transplant process, whether using cord blood, bone marrow or peripheral blood. The main limitation with cord blood is the number of cells available, as the amount of blood remaining in the umbilical cord and placenta is limited. Researchers are now well advanced in developing methods to multiply blood-forming stem cells in the laboratory. Recently a team has published encouraging results from clinical trials on the efficacy of Omidubicel vs standard umbilical cord blood transplantation[2].

Omidubicel is a stem cell product manufactured from cord blood cultured together with an active component, Nicotinamide.

The mechanism is that nicotinamide inhibits cell differentiation and improves the functionality of the cultured cord blood stem cells[2],[3]. 125 patients ages 13 to 65 years with hematologic malignancies were randomly assigned to treatment with, Omidubicel or standard umbilical cord blood. In summary, Omidubicel transplants had similar short-term advantages as transplantation with stem cells from bone marrow.

The engraftment of Omidubicel was a few days faster than the median for standard bone marrow transplants[3].

Engraftment is when the blood-forming cells you received on transplant day start to grow and make healthy blood cells. And in addition Omidubicel1 also had the long-term advantages of cord blood transplantations,   lower risk of Graft versus Host Disease, GvHD [8] and presumably Graft versus Leukaemia, GvL effect [5]. GvHD means that the white blood cells of the new immune system, which are formed by the transplanted blood stem cells, recognize the body they have been transplanted into as foreign and attack it. GvL means that the immunocompetent donor cells attack any remaining leukaemia cells and kill them. Also, transplantation with Omidubicel resulted in fewer early bacterial and viral infections and less time in hospital[2].

Long-term benefits in the first-year post-transplant, for the patients with hematologic malignancies have been seen with Omidubicel, compared to umbilical cord blood transplantation.[3]

This is according to follow-up results of the trial performed by Horwitz, et al., presented at the 2022 Tandem Meeting, in Salt Lake City, Utah[6].  Hopefully the product will be approved by the FDA, Food and Drug Administration and this will offer new options to physicians and patients.