Since the first report in 1989, umbilical cord blood stem cells have been used successfully for hematopoietic stem cell transplants (HSCT). Ever since, umbilical cord blood transplants have been carried out for more than 40,000 different malignant and non-malignant (cancerous and non-cancerous) conditions worldwide.1
The Basics Of Bone Marrow Transplants
What Is Bone Marrow?
The spongy tissue known as bone marrow is found inside the bones. Bone marrow is generally collected from the hip bone & sternum. It contains stem cells that further produce white blood cells (leukocytes), red blood cells (erythrocytes), and platelets. The donor's bone marrow is extracted under general anesthesia. It is then filtered, treated, and either immediately transplanted into the recipient, or is examined, frozen, and kept for later use.
In a bone marrow transplant, bone marrow is transplanted into the recipient to produce new stem cells. The bone marrow used for transplant could either be one’s own bone marrow or that sourced from the donor. One must note here that the bone marrow donor need not be related to the recipient, and even unrelated donors can be a good match.
Cord Blood Transplant At A Glance
Umbilical cord blood is an alternative source of hematopoietic stem cells (multipotent primitive stem cells that can develop into all types of blood cells). Patients suffering from blood disorders, blood cancers, immune disorders, and metabolic disorders can find a treatment with allogeneic (where the donor’s stem cells are used for the transplant) and autologous (where own stem cells are used for the transplant) hematopoietic stem cell transplants.2
Initially, this method of treatment was limited to children only because of the low cell dose. And it has shown high rates of success for both related and unrelated cord blood transplants in the pediatric setting. With greater emphasis on HLA (Human Leukocyte Antigen) match & cord blood units of sufficient cell dose, the results for cord blood transplantation in adults have also significantly improved.
Let’s now gain further insights on how a cord blood transplant is better than a bone marrow transplant with the help of the following two studies.
Study 1: Cord Blood For Stem Cell Transplant May Outperform Matched Sibling Donor3
This study was done at the University of Colorado Anschutz Medical Campus.
For a cancer patient needing a bone marrow transplant, there are mainly two options - transplant with their own stem cells or from that of a donor. Donor stem cells are usually sourced from 4 common donor sources: A matched related donor (sibling), a matched unrelated donor (from a donor database), a half-matched donor, or umbilical cord blood.
Each of these sources has its pros and cons but a matched sibling is usually ranked first - given the 25% chance of inheriting the same HLA haplotype.4 Then comes the matched unrelated donor. Patients who don’t have either of these two options are eventually left with the option to proceed with unrelated cord blood and half-matched donors.
This study is based on a decade of research and treatment. The overall survival rate of a cord blood transplant is no different than when a matched related donor is used as a source for a stem cell transplant.
In This Study:
The comparison was done between 190 patients receiving cord-blood transplants and 123 patients receiving transplants from the matched sibling donors.
Some of the key findings of this study are listed as follows:
- The chances of developing graft-versus-host disease were lower with cord blood transplants as compared to bone marrow.
- Relapse rates were lower in patients who underwent a cord blood transplant.
- Patients who received a cord blood transplant showed better recovery rates.
Jonathan Gutman, MD, CU Cancer Center investigator and director of the allogeneic stem cell transplantation program at the UCHealth University of Colorado Hospital, says - It is not just lower graft-versus-host disease rates that make cord blood transplants more preferable, but also lower relapse rates and faster recovery rates contribute to their popularity. Hence, we can come down to the conclusion that cord blood transplants may outperform bone marrow transplants.
Study 2: Umbilical Cord Blood Treats Rare Genetic Diseases5
A trial was done on 44 children at UPMC Children’s Hospital of Pittsburgh. These children had conditions like sickle cell, thalassemia, Hunter syndrome, Krabbe disease, metachromatic leukodystrophy (MLD), and various types of immune deficiencies.
During this trial, they infused donated unrelated umbilical cord blood into these children and safely treated them. The study participants also received a low dose of chemotherapy and immunosuppressant drugs to prevent any chances for rejection of donor stem cells. These drugs were gradually tapered off as the cells got integrated into the patients’ bodies. A small fraction of the cord blood was reserved for infusion into the participants a few weeks after the initial infusion to turn on the immune system.
One must note here that this procedure allows for easier matching of immune profiles between the donor and the recipient. This is good news for ethnic minorities where the probability of finding a perfect match is very low.
- The overall post-infusion complications were relatively mild as none of the participants experienced severe chronic graft-versus-host disease.
- The mortality rate from viral infection due to immune suppression was 5%, and as researchers state, it is much lower when compared to other studies.6
- This trial showed high levels of safety & efficacy, in addition to covering a broad range of conditions.
A rapidly available stem cell source, umbilical cord blood units (UCB) also facilitate flexibility in HLA matching and provide nearly uniform access to hematopoietic stem cell transplant (HSCT).
Further, to conclude, Paul Szabolcs, M.D, Division Director of Bone Marrow Transplantation and Cellular Therapies at UPMC Children’s Hospital says, “the team was able to design an efficacious approach with the help of this method which is proven to be effective for at least 20 diseases. And umbilical cord blood can treat many rare genetic disorders, however, we have just begun our exploration, I am sure many diseases can be successfully treated with this method, there’s more to find out! We have a long way to go!”
A Parting Note
We hope this blog helped you understand why cord blood transplant is superior to bone marrow transplant. There’s definitely a lot more to cord blood stem cells than what meets the eye! And we believe the same is ought to unfold with the multiple ongoing clinical trials.