Elianna has a rare inherited blood disorder called alpha thalassemia major, which prevents her red blood cells from forming properly. The disease, which has no cure, is usually fatal for a developing fetus.
But while still in her mother’s womb, Elianna received a highly daring treatment. Doctors isolated healthy blood stem cells from her mother and injected them through a blood vessel that runs down the umbilical cord. Four months later, Elianna was born with a loud cry and a glistening head of hair, defying all medical odds.
Elianna is the first in a pioneering clinical trial that pushes the boundaries of stem cell transplants.
The idea that you can treat a fetus while inside a mother’s womb is pretty radical. Doctors have long thought that fetuses are encased in an impermeable protected barrier, which helps protect the developing human from outside insults.
Early experiments with fetal stem cell transplants seemed to support the dogma. Most trials using the father’s stem cells failed, leading doctors to believe that the procedure couldn’t be done.
But subsequent research in animals discovered a crucial tidbit of information: the mother’s immune system, not the fetus, was rejecting the father’s stem cells.
There’s more: rather than being quarantined, fetuses continuously exchange cells with their mothers, so much so that fetal cells can actually be isolated from a mother’s bloodstream.
The reason for this is to quiet both parties’ immune systems. Because the fetus has part of the father’s DNA, it makes a portion of their cells foreign to the mother. This back-and-forth trafficking of cells “teaches” both the mom’s and the fetal immune system to calm down: even though the cells aren’t a complete genetic match, the fetuses’ cells will tolerate their mother’s cells, and vice-versa. In this way, during pregnancy the fetal immune system is on hold against the mother.
This harmonious truce changes once the baby is born. The child’s immune system grinds into action, attacking any cells that are foreign to its body. Once born, a bone marrow transplant requires drugs to kill off the infant’s own bone marrow cells and make room for healthy ones. It also requires high doses of immunosuppressant drugs to keep the infant’s immune system at bay while the new, healthy cells do their job.