Stem cells are foundational cells with the ability to develop into many different, specialized cell types required by the body. They can also self-renew, making more cells like themselves. Pregnancy is a period of intense biological activity driven by stem cells, which are not only building a new individual but also creating unique opportunities for medical science. This article explores their functions, the sources they provide, and their collection, storage, and medical applications.
The Natural Role of Stem Cells During Pregnancy
During pregnancy, stem cells are the principal drivers of fetal growth and development. In the earliest stages, pluripotent embryonic stem cells give rise to every cell type and organ in the developing fetus. This process of differentiation is a complex event that builds the body’s intricate systems, from heart muscle to neurons. The placenta, a temporary organ connecting the fetus to the uterine wall, is also a hub of stem cell activity that supports the pregnancy, facilitates nutrient exchange, and manages the unique immunological environment between mother and fetus.
A fascinating aspect of pregnancy is microchimerism, the two-way exchange of cells between the mother and fetus. Fetal stem cells cross the placenta and enter the mother’s circulation, where they can persist for decades. Research suggests these cells may travel to sites of maternal injury and participate in tissue repair, highlighting a deep biological connection.
Valuable Stem Cell Sources from Pregnancy
Pregnancy provides several sources of stem cells that can be collected at birth. The most well-known source is umbilical cord blood, which is rich in hematopoietic stem cells (HSCs). These cells are responsible for generating all the cells of the blood and immune system, and their established ability to treat blood-related disorders makes them valuable.
The umbilical cord tissue itself, specifically the gelatinous substance known as Wharton’s jelly, is another significant source. This tissue is abundant in mesenchymal stem cells (MSCs), which are multipotent and can develop into bone, cartilage, and fat cells. They also modulate the immune system and reduce inflammation, making them a focus of regenerative medicine research.
The placenta is now recognized as a rich reservoir of both HSCs and MSCs, and its large volume can provide a greater quantity of stem cells. Additionally, amniotic fluid, the protective liquid surrounding the fetus, contains a mix of fetal stem cells with potential for therapeutic use.
Collecting and Storing Pregnancy-Derived Stem Cells
The collection of stem cells from the umbilical cord and placenta is a safe procedure performed immediately after birth, posing no risk to the mother or child. A medical professional drains the blood from the clamped umbilical cord into a sterile bag. To collect cord tissue, a segment of the cord is cleaned and placed in a transport container.
After collection, parents have two options for storage: public or private banking. Public banking is an altruistic donation where the unit is processed, typed, and listed on a registry for any matching patient, at no cost to the parents.
Private banking involves fees for processing and long-term storage, reserving the unit exclusively for the child or family members. The cells are processed to isolate the stem cells, then cryopreserved in liquid nitrogen to maintain their viability for decades.
Medical Uses of Stem Cells from Pregnancy
Stem cells from pregnancy, particularly hematopoietic stem cells (HSCs) from umbilical cord blood, are used in transplants to treat over 80 different diseases. These include various forms of leukemia, lymphoma, and inherited blood disorders like sickle cell anemia and thalassemia. These transplants can be autologous, using the patient’s own cells, or allogeneic, using cells from a donor.
The use of mesenchymal stem cells (MSCs) from cord tissue and the placenta is largely in the clinical trial phase for regenerative medicine. Scientists are investigating their potential to repair damaged tissues and modulate immune responses in conditions like cerebral palsy, type 1 diabetes, and in cardiac repair after a heart attack.
Using pregnancy-derived stem cells offers several advantages. The cells are younger and more adaptable than adult stem cells from other sources. In allogeneic transplants, cord blood stem cells have a lower risk of causing graft-versus-host disease. Their collection is also ethically straightforward, avoiding the controversies associated with embryonic stem cells.
Ethical Considerations and Regulations
Stem cell banking brings forth several ethical considerations, particularly regarding the choice between public and private options. A primary debate centers on equitable access, contrasting the shared resource model of public banking with the exclusive nature of private banking. Informed consent is another area of focus, ensuring parents receive clear, unbiased information about the likelihood of using the cells and the differences between banking models.
Governmental bodies regulate the collection, processing, and therapeutic use of these stem cells to ensure safety and efficacy. In the United States, the Food and Drug Administration (FDA) oversees this field, setting standards for cell processing facilities and approving new stem cell therapies. Accreditation from organizations like the AABB (Association for the Advancement of Blood & Biotherapies) is an indicator of a bank’s adherence to high-quality standards.
These regulations help distinguish between established, proven treatments and those that are still experimental. This oversight protects patients from unproven therapies while providing a framework for legitimate research to advance the field.