Q: What is the umbilical cord?
A: The umbilical cord is a long tube-like structure that forms even before the fetus (baby) forms (see Figure 1). It has two arteries and one large vein which carry blood back and forth between the placenta and the fetus. The fetus’ (baby’s) heart pumps the blood between his/her body and the placenta. The mother’s blood supplies oxygen and nourishment and takes away waste products to keep the fetus healthy (their blood does not mix—the exchange occurs across a very thin membrane).
Figure 1: Fetal Circulation
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Q: What are stem cells?
A: When we say “stem cells” on this website, we are referring to the stem cells found in large numbers in the blood of fetuses and infants. These are often referred to as “hematopoietic” or blood-making stem cells. Never again in one’s life will there be such a high number of circulating stem cells. We now know that these cells can specialize into multiple types of cells in the body as needed and can help heal the body. (see http://stemcells.nih.gov).
There are several important properties of stem cells. They can “self-renew.” This means that when they divide as all of our cells do, they can make one exact replica of themselves along with a new type of cell. This is important to keep stems cells available in the body for maintenance throughout our lifetime. They can also “differentiate” or make specialized cells such as heart or brain cells. The term for this is “pluripotent” meaning that they can become many different kinds of cells as the body needs.
We are on the edge of what we know about stem cells. The research on stem cells is in its infancy and many scientists and others are very excited about their potential. Every day, there is a new article in the paper about experiments using stem cells to treat everything from cerebral palsy to Alzheimer’s disease. Stem cells are difficult to study. They do not behave in the research laboratory as they do in the human body. In your body, if you have an area of inflammation (swelling, irritation, etc.), the lining of the blood vessels in that area release cytokines (messenger proteins). It is believed that these cytokines signal the stem cells to come to that area to help heal and repair the site. This process is called “homing” – the stem cells are called "home" to the damaged area in the body. The fact that it is hard for scientists to make the exact mixture of cytokines to "home" the stem cells has hampered research.
We think that a newborn should obtain his or her full number of available stem cells at birth. This can be accomplished by delaying the cord clamping or even by milking the cord at birth. If the labor and birth is especially traumatic for the infant, the stem cells are available to help with healing. One recent German experiment using young rats demonstrates this very well.
Meier and colleagues (2006) demonstrated that administration of human cord blood to rats in whom neurological damage had been created was useful in preventing the development of cerebral palsy. They cut the rat pup’s carotid artery on one side creating a progressive inflammatory process. This led to the death of neurons on one side of the rat’s brain and resulted in spastic paresis (cerebral palsy). In one half of the damaged rats, they injected human umbilical cord stem cells into the abdomen within 24 hours after the injury. The rats who were given the human cord blood stem cells did not develop spastic paresis. The rats who were damaged and got no treatment or who got the treatment after 24 hours, developed cerebral palsy. Upon histologic (microscopic) examination of the rat brains at 21 days after the injury, Meier et al. (2006) found that the human umbilical cord blood stem cells had crossed the blood-brain barrier and had surrounded and infiltrated the damaged areas of the injured rats’ brains. These cells appeared to provide scaffolding for repair. The scientists did not find any stem cells in the uninjured side of the brain. This suggests that factors (probably cytokines) from the damage areas signaled the stem cells . Human infants most likely to develop cerebral palsy rarely obtain their full allotment of stem cells at birth—usually the cord is cut right away. We estimate that when the cord is clamped right after birth, infants lose millions stem cells. Might these stem cells play a role in healing our infants’ brains? We believe that this animal study, along with other studies on the healing powers of stem cells, demands that the safety of immediate cord clamping at birth be studied and must include long term follow up of children to the age of at least three years of age.
When an infant receives more blood volume at birth, he/she should also receive a greater allotment of hematopoietic stem cells. When cells are collected for freezing and storing, fewer stem cells are available as the processing reduces the stem cell count by 33%. Male infants have a higher content of stem cells collected even when corrected for birth weight. Thus immediate cord clamping may be more damaging for male infants. In one of our studies, we found a significant advantage of less intraventricular hemorrhage (bleeding in the brain) and less sepsis (infection) in preterm male infants with a brief delay in cord clamping (Mercer 2006).
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(Last updated: 02/07/2009)