Cord blood is the blood left in the umbilical cord and placenta after the birth of the child and is collected after the cord has been cut off. The umbilical cord is routinely discarded with the placenta after a child is born. It is also called placental blood. Cord blood has lots of blood producing stem cells which can be frozen and later used for transplants. Cord blood is genetically unique to the child and the family. Now researchers have found that it can be used to treat many diseases.

Cord blood is now used as an alternative to bone marrow transplant when in future if the child or his family is diagnosed with cancers such as leukemia, lymphoma and other disorders of the blood-making system, such as sickle-cell anemia; severe immune-system disorders; and genetic defects affecting the blood-making system. Researchers are further studying the use of cord blood for the treatment of different types of diseases like arthritis, spinal cord damage, stroke diabetes and Alzheimer's disease, Purkinje cell degeneration, Duchenne's muscular dystrophy, heart disease, and vision and hearing loss, Parkinson's disease, burns osteoarthritis, and rheumatoid arthritis.

All stem cells'regardless of their source?have three general properties: they are capable of dividing and renewing themselves for long periods; they are unspecialized; and they can give rise to specialized cell types. The cord blood contains blood-producing hematopoietic stem cells as well as mesenchymal stem cells. Hematopoietic stem cells have the ability to generate: three major types of brain cells (neurons, oligodendrocytes, and astrocytes); skeletal muscle cells; cardiac muscle cells; and liver cells. Mesenchymal stem cells can create various tissues in the body such as cartilage, bone, muscle, tendon, ligament and fat.

Cord blood transplants have become a strong alternative to bone marrow transplants. Cord blood is easier to collect than traditional bone marrow donation and it is not painful to extract, doesn't require invasive surgery. It is extremely difficult to find a suitable donor for a marrow transplant because six HLAs, or human lymphocyte antigens, a group of proteins in bone marrow cells that can provoke an immune response, need to match or a perfect match is required. In cord blood transplant only three HLAs loci need to match. So in cord blood there is more opportunity for transplant to siblings, parents and grandparents. Cord blood has 10 times more blood-making cells concentrated in it than bone marrow.

Worldwide thousands of successful cord blood stem cell transplants have been performed in the past decade.