Cord Blood vs Marrow

Cord blood transplant is a treatment option to bone marrow transplant.
Since the clinical application of cord blood is a relatively recent phenomenon, there is no conclusive agreement yet on the comparative benefits of cord blood over bone marrow in HSC transplants.  However, a number of observations, outlined in the table below, are generally accepted by the medical community.

Bone Marrow/Peripheral Blood Cord Blood
Donation requires surgery. Matched donors are hard to find, and even if they are found, only 1/3 can avail themselves to the hospital for the donation [1]. Collection of cord blood is painless and risk free, independent of the transplant operation. Once processed and HLA typing completed, the cord blood unit is ready for matching
Requires a perfect match of HLA for successful grafting. Partial donor-recipient matching is possible in cord blood transplant although patients generally benefit from a higher matched cord blood unit.  Because partial matching is viable, transplants to adults using multiple cord blood units were reported.
A higher chance of inducing graft-versus-host diseases (GvHD) [2] since stem cells harvested from bone marrow are more matured. Less likely to induce a GvHD complication because the cord blood stem cells appear to be immunologically naïve [3].
More prone to virus infection, particularly those viruses which were dormant in the donor's body might become active and attack the patient when his/her immunity system is most vulnerable. Cord blood stem cell is less likely to be exposed to virus infection.
Provides a large dose of stem cells and thus enables rapid engraftment. Limited dose of stem cells and thus slower engraftment.

In Hong Kong, in a retrospective study aimed at reviewing the outcome of unrelated umbilical cord blood transplantation in children using cord blood from the Hong Kong Red Cross, doctors had confirmed that “the outcome of which (umbilical cord blood transplantation) was comparable to that of bone marrow transplantation.”[4]   Depending on the disease and the patient's condition, cord blood transplant and bone marrow transplant may each have its own merits specific to the situation.

[1] “Cord Blood: A Solution for Bone Marrow Transplantation”, http://www.nationalcordbloodprogram.org, (accessed 10 May 2007).  
[2] GvHD stands for graft vs host disease which is a condition whereby the white blood cells from a donor attack the tissues of the recipient after a transplant.
[3] Laughlin, M.J. (2001). “Umbilical cord blood for allogeneic transplantation in children and adults”, Bone Marrow Transplant. 27, 1–6.