Cord blood is the blood left in the umbilical cord after a baby is born. The umbilical cord connects a mother to her unborn baby during pregnancy. It contains blood vessels that bring nourishment to the baby and remove waste products.

After a baby is born, the cord is clamped shut and cut. The blood that remains in the cord may be collected and used in two ways:

Cord blood testing. This means doing a variety of tests on cord blood to check the baby's health. Tests may also be done on cord blood if a health care provider is concerned that the baby may have a health condition, such as an infection or an acid-base (pH) imbalance. Some hospitals may routinely collect cord blood samples to do tests to check a baby's general health.

Cord blood banking. This means saving blood from the baby's umbilical cord in a special facility called a cord blood bank. The blood is saved so it can be used to treat certain diseases. Umbilical cord blood is full of special cells called stem cells. Stem cells can develop into many different types of cells found in the body, such as blood, brain, muscle, and organ cells.

Stem cells from cord blood can be used to treat certain blood disorders, including leukemia, Hodgkin disease, and some types of anemia. They can also be used to treat certain inherited metabolic and immune system disorders. Researchers are studying whether stem cell treatment can also help treat other types of diseases.

If you choose to save your baby's cord blood, you have two main options:

• You can donate the blood to a public cord blood bank. Cord blood in public banks may be used by anyone who needs a cord blood transplant. This treatment replaces diseased blood cells with healthy cells from cord blood. In certain cases, donated cord blood may be used for research. If you donate your baby's cord blood, there's no cost to you. But only certain hospitals can collect cord blood for storage in public cord blood banks.
• You can save the blood in a family (private) cord blood bank. This allows you to use the blood for a family member who may benefit from treatment with cord blood. You may be interested in this option if you have a family history of health conditions that can be treated with stem cells from cord blood. You will usually have to pay a fee for the blood collection and storage at a private cord blood bank. But if you or a close family member already has a disease that needs treatment with cord blood, you may qualify for free or low-cost cord blood banking.

What is cord blood testing used for?

Cord blood tests may be done after your baby is born to:

• Measure blood gases. This helps to see if a baby's blood has a healthy level of oxygen and acid-base (pH) balance.
• Measure bilirubin levels. Bilirubin is a waste product made by the liver. High bilirubin levels can cause jaundice, a condition that causes the skin and eyes to turn yellow. Jaundice is common in healthy newborns, and it usually clears up in a few weeks. But it can sometimes be a sign of liver disease, a blood disorder, or another type of condition.
• Do a blood culture test. This test may be done if a provider thinks a baby may have an infection.
• Do a complete blood count (CBC). This test measures many different parts of the blood. It may be done to check for an infection.
• Check blood glucose (sugar) levels. Blood glucose may be high if the mother has diabetes.
• Check to see if a baby was exposed to illegal drugs or certain prescription drugs that the mother may have misused during pregnancy. Umbilical cord blood testing can find many drugs, including sedatives, cocaine, and opioids such as heroin and fentanyl. If harmful drugs are found in cord blood, a provider can treat the baby to help reduce the chance of problems, such as developmental delays.

Cord blood banking is used to save cord blood so that the stem cells can be used to treat certain blood disorders and cancers.

You may want to consider donating cord blood if you want to help others. A public blood cord bank provides lifesaving stem cells to people who need treatment now.

You may want to consider family cord blood banking if:

• You have a family history of a genetic disorder or cancer that can be treated with stem cells.
• You or a family member currently has a disorder that may be treated with stem cells.

If neither of these situations applies to you, providers don't recommend saving your baby's cord blood in a family cord blood bank. There are two main reasons:

• The conditions that are currently treated with stem cells from cord blood aren't common. That means your child and other family members are unlikely to ever need the cord blood. Most cord blood that's saved in case of a future illness is never used. But as research continues, it is possible that stem cell treatment may be developed for more common diseases.
• If your child should someday need stem cell treatment for a genetic disorder or cancer, they won't be able to use their own stem cells for treatment. That's because their stem cells will have the same genes or pre-cancerous cells that caused the disease in the first place.

Collecting cord blood does not change anything about your birth experience. After your baby is born, the umbilical cord will be pinched closed with a clamp and cut. Then the provider will either use a needle to remove blood from the cord or let the blood drip out of the cord. The blood is collected in a special bag and sent to a lab for testing or to a cord blood bank for long-term storage.

Sometimes, the cord doesn't contain enough blood to use for cord blood banking.

For cord blood testing, you don't need to prepare anything.

For cord blood banking, you need to plan in advance. If you're considering donating cord blood or privately banking it, talk with your provider at least three months before your baby is due. This will give you time to:

• Decide whether to donate the blood to a public bank or save it in a family cord blood bank.
• Get information about your options for collecting the blood. Not all hospitals can collect blood for public cord blood banks. If you choose to use a family cord blood bank, you'll need to select which bank to use.
• Finish paperwork about your medical history and your family health history.
• Receive a cord blood collection kit if you are using a family cord blood bank. Your provider will use this kit to collect and send the blood to the bank.

Cord blood testing has no risks.

With cord blood banking, the mother will need to have a blood test to check for infections to help make sure the cord blood is safe to use. There is very little risk to having a blood test. You may have slight pain or bruising where the needle was put in, but any discomfort or bruises usually go away quickly.

Some cord blood banks may require testing of the mother's blood for genetic disorders, too. If you find out you have a gene that could cause a serious disease, you or your family members may feel upset.

If you choose family cord blood banking, the costs can be very high.

The joy of your baby’s birth could be shared with someone who has a life-threatening illness.

After a baby is born, the umbilical cord and placenta are no longer needed and are usually thrown away. However, the blood left in the umbilical cord and placenta contains blood-forming cells. (These cells are not embryonic stem cells.) By collecting and freezing this blood, the healthy blood-forming cells can be stored and may later be used by a patient who needs them.

Patients with leukemia, lymphoma, or certain inherited metabolic or immune system disorders have diseased blood-forming cells. For some patients, an umbilical cord blood or bone marrow transplant (also called a BMT) may be their best treatment option.

Each year, thousands of people are diagnosed with leukemia, lymphoma, or certain immune system or genetic metabolic disorder. Many of these patients need an umbilical cord blood or bone marrow transplant (also called a BMT). Because the qualities that make a suitable match for bone marrow or umbilical cord blood are inherited, a match from a sibling or other family member is often checked first. However, 70% of patients do not have a fully-matched donor in their family. For these patients, a transplant of bone marrow or cord blood from an unrelated donor may be their only transplant option.

A bone marrow or cord blood transplant replaces diseased blood-forming cells with healthy cells. Cells for a transplant can come from the marrow of a donor or from the blood of the umbilical cord collected after a baby is born. Sometimes special qualities of umbilical cord blood make it a better choice of blood-forming cells for transplant.

The United States Congress saw the need to help more patients who need a bone marrow or cord blood transplant and passed:

• The Stem Cell Therapeutic and Research Act of 2005, Public Law 109-129 (Stem Cell Act 2005)
• The Stem Cell Therapeutic and Research Reauthorization Act of 2010, Public Law 111-264 (Stem Cell Act 2010)
• The Stem Cell Therapeutic and Research Reauthorization Act of 2015, Public Law 114-104 (Stem Cell Act of 2015)
• The Timely ReAuthorization of Necessary Stem-cell Programs Lends Access to Needed Therapies Act of 2021, Public Law 117-15 (TRANSPLANT Act of 2021)

These acts include support for umbilical cord blood transplant and research.

Umbilical cord blood may help when other sources cannot

The chances of a successful bone marrow or cord blood transplant are better when the blood-forming cells are from a donor who closely matches the patient. However, studies show that cord blood may not need to match as closely as is necessary for a marrow donor. Umbilical cord blood may be especially promising for:

• Patients who have trouble finding a matched marrow donor
• Patients from diverse heritages who often have an uncommon tissue type
• Patients who have a life-threatening genetic disorder
• Patients who need a transplant quickly

Racial and ethnic diversity is needed

Although cord blood can help patients who cannot find a well-matched marrow donor, matching is still important. Cord blood is especially needed from communities such as:

• Black and African American
• American Indian and Alaska Native
• Asian
• Hispanic and Latino
• Native Hawaiian and Other Pacific Islander
• Multiple-race

Umbilical cord blood may help more people from many diverse racial and ethnic communities have a second chance at life.

Helping patients

The Stem Cell Acts of 2005, 2010, 2015, and 2021 help patients who have life-threatening diseases and may need a cord blood or marrow transplant. These acts:

• Started the National Cord Blood Inventory (NCBI). The goal of the NCBI is to collect and store at least 150,000 new cord blood units. These cord blood units are used for patients who need a transplant but do not have a matching donor within their family. To continue to help the success of transplants, the NCBI banks will provide additional cord blood units for research.
• Increased in funding for marrow and umbilical cord blood transplantation and research through the C.W. Bill Young Cell Transplantation Program (CWBYCTP).

One function of the program is to partner with a network of cord blood banks, including some banks that get Federal support to build the NCBI. In this role, the program works with its network of cord blood banks to recruit expectant parents for umbilical cord blood donations and to distribute cord blood units listed on the registry of the C.W. Bill Young Cell Transplantation Program, also called the Be The Match Registry®. The registry is a listing of potential marrow donors and donated cord blood units.

Blood from the umbilical cord and placenta is special because it has a large number of blood-forming cells. These cells might be life-saving for someone who has a disease such as leukemia, or lymphoma, or certain inherited metabolic or immune system disorders. An umbilical cord blood transplant, like a bone marrow transplant (also called a BMT), takes the place of a patient's diseased cells with healthy cells.

The umbilical cord is routinely thrown away after the baby is born—unless the parents are able to do something else. Today, expectant parents may have the blood left in the umbilical cord and placenta collected and:

• Donated to a public cord blood bank. Cord blood donated to a public cord blood bank is available to patients who need a transplant. The donation process doesn’t cost anything to the parents donating the umbilical cord blood. Today, however, only certain hospitals can collect umbilical cord blood for storage in public cord blood banks.
• Stored in a family (private) cord blood bank. Cord blood stored in a family cord blood bank is saved for that family. Family cord blood banks are available throughout the country for anyone who wants to pay for the collection and storage of the umbilical cord blood. If you are thinking about family banking, call a family cord blood bank as soon as possible.
• Saved for a family member who has a medical need. When a family member has a disease that may be treated with a bone marrow or cord blood transplant, parents can choose to save their baby's cord blood for directed donation. Collecting and storing cord blood for directed donation is offered at little or no cost to eligible families.
• Donated for research. Ask your doctor, midwife or cord blood bank for more information.

If you are an expectant parent, talk with your doctor about the choices that may be available to you. By making this decision, you can have the umbilical cord blood collected and possibly give someone another chance at life.

Your decision to donate umbilical cord blood, which is full of blood-forming cells, may potentially save the life of someone who has a life-threatening disease.

Donating cord blood to a public cord blood bank involves talking with your doctor or midwife about your decision to donate and then calling a cord blood bank (if donation can be done at your hospital). Upon arriving at the hospital, tell the labor and delivery nurse that you are donating umbilical cord blood.

After your baby is born, the umbilical cord and placenta are usually thrown away. Because you are choosing to donate, the blood left in the umbilical cord and placenta will be collected and tested. Cord blood that meets standards for transplant will be stored at the public cord blood bank until needed by a patient. (It is not saved for your family.)

By donating umbilical cord blood, you may be helping someone who needs a transplant.

Approximately 3 months before your baby is due (between your 28th and 34th week of pregnancy)

1. Talk with your doctor or midwife about your decision to donate umbilical cord blood.
2. Find out if your hospital collects cord blood for public donation and save the phone number of the public cord blood bank.

Cord blood donation doesn’t cost anything for parents. Public cord blood banks pay for everything which includes the collection, testing, and storing of umbilical cord blood. This means that cord blood donation is not possible in every hospital.

If a public cord blood bank is not collecting in your area, perhaps there is another way you can help.

Contact the public cord blood bank that works with your hospital. Although each cord blood bank has its own instructions, they often include asking you to:

• See if you meet basic guidelines for cord blood donation. These questions are similar to those asked of blood donors. You can usually donate if you are:
  • Healthy
  • Pregnant with one baby (rather than two or more)
• Finish forms about the health history of you and your family. This information is important. It means that your blood is free from diseases that can be given to another person.

Medical staff at the public cord blood bank will check to see if you can donate. If you have had a disease that can be given to another person through blood-forming cells, such as hepatitis B, hepatitis C, or HIV (the AIDS virus), you will likely not be able to donate. However, other medical reasons may still allow you to donate, for example, hepatitis A or diabetes only during your pregnancy (gestational diabetes). The staff at the public cord blood bank will tell you.

• Tell your type of expected delivery. Most public cord blood banks collect donations after a vaginal or C-section delivery.
• Sign a consent form to donate. This consent form says that the donated cord blood may be used by any patient needing a transplant. If the cord blood cannot be used for transplantation, it may be used in research studies or thrown away. These studies help future patients have a more successful transplant.

Keep a copy of the consent form in case you need to call the cord blood bank.

Each cord blood bank has different directions for returning the consent form. Some banks may ask you to mail the consent form along with the health history forms or to bring the original consent form with you to the hospital. Other banks may have you finish the form at the hospital. Follow the directions from your public cord blood bank.

While you are in the hospital

• When you get to the hospital, tell the nurse that you are donating umbilical cord blood.
• While you are giving birth, everyone will be focused on you and your baby.
• After your baby is born:
  • The umbilical cord is clamped.
  • Blood from the umbilical cord and placenta is put into a sterile bag. (The blood is put into the bag either before or after the placenta is delivered, depending upon the procedure of the cord blood bank.)
  • The collected blood, called a cord blood unit, is given a special number and stored temporarily. (The cord blood unit is between one-third to a little over one-half cup or 90–150 cc.)
• Usually, the day after your baby is born, you will be asked for a sample of your blood to be tested for infectious diseases. This blood is taken from you only, not your baby.
• Shortly after your baby's birth, the cord blood unit is sent to the public cord blood bank.

What happens at the cord blood bank

After the cord blood unit arrives at the cord blood bank, it is:

• Checked to make sure it has enough blood-forming cells for a transplant. (If there are too few cells, the cord blood unit may be used for research to improve the transplant process for future patients or to investigate new therapies using cord blood or discarded.)
• Checked to be sure it is free from contamination.
• Tissue typed and listed on the registry of the C.W. Bill Young Cell Transplantation Program, also called the Be The Match Registry®. (The registry is a listing of potential marrow donors and donated cord blood units. When a patient needs a transplant, the registry is searched to find a marrow donor or cord blood unit.)
• Frozen in a liquid nitrogen freezer and stored, so if the unit is selected as a match for a patient needing a transplant, it will be available.

Protecting Your privacy after you have donated

You and your baby's personal information are always kept private by the public cord blood bank. The cord blood unit is given a number at the hospital, and this is how it is listed on the registry and at the public cord blood bank.

Thank you for considering this generous gift

Taking time to consider helping another person when you are already busy planning for the birth of your child is greatly appreciated. A gift of cord blood may someday give someone a second chance at life.

Expecting a baby can be a very exciting time for soon-to-be-parents. It can also be very confusing, with many decisions to make. One choice prospective parents often face is whether to donate, bank or discard their baby's cord blood. Did you know that the Food and Drug Administration (FDA) regulates cord blood? Here is some information for expectant parents about the regulations in place designed to help ensure the safety of cord blood for transplantation.

What is cord blood?

Cord blood is the blood contained in the placental blood vessels and umbilical cord, which connects an unborn baby to the mother's womb. Cord blood contains hematopoietic progenitor cells. At birth, cord blood can be collected (or "recovered") from the umbilical cord.

What are hematopoietic progenitor cells?

Hematopoietic progenitor cells (HPCs) are blood-forming stem cells. HPCs are found in bone marrow, peripheral blood, and cord blood. These types of stem cells are routinely used to treat patients with cancers such as leukemia or lymphoma, and other disorders of the blood and immune systems.

How are patients and donated cord blood units “matched” so that a unit of cord blood can be used for a patient’s transplant?

Human leukocyte antigen (HLA) typing is used to match patients and donors for cord blood transplants. HLAs are proteins found on most cells in the body. A person’s immune system uses these proteins as markers to recognize which cells belong in their body and which do not. A close match between the patient’s and the donor's HLA markers can reduce the risk that the patient’s immune cells will attack the donor's cells, or that the donor's immune cells will attack the patient’s body after the transplant.

How are HPCs from cord blood different than HPCs from other sources?

There is evidence that cord blood HPCs may not require as exact a match as HPCs from bone marrow or the bloodstream because the antigens in cord blood are less mature. This suggests that transplants involving compatible HPCs from cord blood may be less likely to cause adverse reactions because the donor’s cells are less likely to see the patient’s cells as foreign bodies and attack them.

What are the options for cord blood banking?

Cord blood can be donated to a public cord blood bank, where it will be stored for potential future use by anyone who may need it. Alternatively, parents may arrange for the cord blood to be stored in a private cord bank, for potential use if it is later needed for treatment of the child from whom it was recovered, or for use in first- or second-degree relatives. Information on cord blood donation options may be found on the Health Resources and Services Administration (HRSA) web site.

You may also wish to consult your health care provider about the options.

How does FDA regulate cord blood stored for personal or family use?

Cord blood stored for personal use and for use in first- or second-degree relatives that also meets other criteria in FDA’s regulations does not require approval before use. Private cord banks must still comply with other FDA requirements, including establishment registration and listing, donor screening and testing for infectious diseases (except when used for the original donor), reporting and labeling requirements, and compliance with current good tissue practice regulations.

How does FDA regulate cord blood intended for use in patients unrelated to the donor (i.e., cord blood stored in public banks)?

Cord blood stored for potential future use by a patient unrelated to the donor meets the definition of “drug” under the Food, Drug & Cosmetic Act and “biological product” under Section 351 of the Public Health Service Act. Cord blood in this category must meet additional requirements and be licensed under a biologics license application (BLA), or subject to an investigational new drug application (IND) before use.

Are there any FDA approved uses for cord blood?

Cord blood can be used in hematopoietic stem cell transplantation procedures in patients with some disorders affecting the hematopoietic (blood forming) system. For example, cord blood transplants have been used to treat patients with certain blood cancers and some inherited metabolic and immune system disorders.

If a cord blood bank is registered with FDA, does that mean that the cord bank is FDA approved?

Establishments that perform any of the manufacturing steps for cord blood must register with FDA and list their products and each of the manufacturing steps they perform. Registration with FDA doesn't mean a firm is "endorsed" by the agency, it simply means the firm has notified FDA that it is performing one or more manufacturing steps.

FDA’s website has a searchable database that includes information on registered cord blood banks.

Does FDA inspect facilities that store cord blood?

Yes. Registered establishments are subject to FDA inspection to ensure they are complying with the regulations. The inspections of private banks are designed to ensure prevention of infectious disease transmission.

Where can I get more information about donating my baby's cord blood?

To make your baby's cord blood available for use by anyone who needs a cord blood transplant, you may donate it to a public cord blood bank. Information on donating cord blood to a public cord blood bank is also found on the HRSA web site.

Where can I get more information about banking my baby's cord blood?

To make your baby's cord blood available for use by the child from whom it was recovered, or for use in first- or second-degree relatives, you may bank it with a private cord blood bank. Information on banking cord blood with a private cord blood bank is also found on the HRSA web site.

For some diseases, such as genetically heritable diseases, in the event that your child would need treatment, it is possible that the cord blood would not be recommended for such use.

Where can I get more information about FDA's regulations?

Information about the regulation of human cells, tissues, and cellular and tissue based products including cord blood is available on FDA's web site.

Blood stem cell transplants can be life-saving for people with a number of conditions. However, it can be challenging to find blood stem cells in needed quantities from a donor whose cells are similar enough to a patient’s cells to be a sufficient “match” for transplantation. Cells from bone marrow and from circulating blood have been used in treatments for many years, and blood from the umbilical cord, collected after a baby is born, has been another source of blood stem cells used more recently. Cord blood from donors is available in public cord blood “banks,” and the match between donor and recipient may not need to be quite as close as is needed for transplants of other types of blood cells. However, cord blood from each donor exists in only limited quantities. Researchers supported by NIDDK have discovered key factors that promote blood stem cell growth and maturation, and, with these insights, have developed ways to expand the numbers of cells from cord blood for use in transplants. This research may increase the availability of such treatments to benefit many more people.

Cord Blood Cell Transplantation

Cord blood is found in blood vessels of the placenta and the umbilical cord—tissue that is normally discarded. It is collected after a baby is born and after the umbilical cord is cut between the mother and the baby. Approved by the U.S. Food and Drug Administration only for use in blood (hematopoietic) stem cell transplantation procedures, cord blood has been transplanted into thousands of patients who have serious medical conditions such as bone marrow failure syndromes, blood disorders, immunodeficiencies, certain metabolic disorders, and cancers. Cord blood stem cells (which are different from embryonic stem cells) facilitate healing and repair of damaged cells and tissue—that is, they are early stage blood cells that, like other blood stem cells, provide a source for the regrowth of all the types of specialized blood cells. Cord blood transplantation, therefore, is an example of regenerative medicine.

A critical advantage of cord blood is that cord blood stem cells can be easily transplanted; the transplanted cells do not have to be an exact match with the recipient’s tissues. However, the main disadvantage is that a single umbilical cord is insufficient; a single umbilical cord contains a limited number of stem cells that do not mature into a sufficient number of specialized types of blood cells needed for adults. Cord blood cell transplants (from a single umbilical cord) could thus place an adult patient at increased risk of life-threatening infections due to the inadequate number of infection-fighting types of blood cells. Such patients may need two or more units of cord blood. Yet, they may still be at risk because, compared with conventional bone marrow transplantation, it may take longer for transplanted cord blood stem cells to engraft—that is, to start working properly in a patient’s body—and give rise to other types of blood cells. For this reason, cord blood cell treatment is used more often in children, who have a small body size and thus require fewer cells. Basic research on blood cells has sparked ideas for expanding the numbers of cells in a unit of cord blood.

Notch: The Story Begins

In 1994, while investigating the cellular and molecular mechanisms underlying the production and function of blood cells—NIDDK-supported researchers discovered for the first time that in human early stage blood cells, a gene encoding a protein called Notch is “turned on.” NIDDK-supported researchers then set out to determine whether Notch influences the function of blood stem cells. Notch, which sits in the cell membrane, transmits signals originating from the outside of the cell to direct the turning on or turning off of genes. Using laboratory mice, they demonstrated, in 2002, that activated Notch had two distinct activities—1) the inhibition of stem cell maturation into different blood cell types and 2) the stimulation of stem cell self-renewal (i.e., an increase in stem cell number). In 2003, with support from NIDDK and other sources, researchers reported that they could induce early stage mouse blood cells to proliferate by exposing the cells to an engineered protein that binds to Notch; this protein was a modified version of a protein called Delta1. Interestingly, the researchers did not see this effect if they simply mixed the modified Delta1 protein into the liquid in which the cells were growing; through their experiments, they realized they had to immobilize this protein on the dish in which the cells were growing for it to have the desired effect of increasing the numbers of cells.

Notch-driven Engraftment of Cord Blood Cells in Human Pilot Study

Taking advantage of their knowledge of the Notch-signaling pathway and blood stem cells and the modified Delta1 protein, investigators supported by NIDDK and others were able to significantly increase, by greater than 100-fold, the number of early stage blood cells from a unit of cord blood. The researchers then conducted, and reported in 2010, a pilot clinical study of 10 participants with leukemia to begin to assess the safety of infusing patients with cord blood stem cells that had been expanded to greater numbers using the modified Delta1 protein/Notch procedure, and to begin evaluating the engraftment properties of the expanded stem cells. In the course of their treatment for leukemia, the participants were given radiation therapy and chemotherapy to destroy the blood cancer cells; these treatments also destroyed the stem cells in their bone marrow. Cord blood cell transplantation was subsequently used to repopulate the bone marrow. Each participant received two units of cord blood—one unit of non-expanded blood and one containing expanded numbers of blood cells, or two units of non-expanded blood. In this small group of participants, no safety issues were encountered. In addition, the time for engraftment, measured in terms of white blood cell recovery, was significantly shorter for participants who received Delta1/Notch-expanded cells than for those who received only non-expanded cord blood.

Manipulating Blood Stem Cells into Mature Blood Cells

Blood stem cells mature along two tracks—1) the myeloid lineage, which produces white blood cells (e.g., macrophages and neutrophils), red blood cells, and other cells, and 2) the lymphoid lineage, which produces T cells, B cells, and other cells. The immune system consists of two major pillars: the innate (general defense) and the adaptive (specialized defense). Both systems work closely together and take on different tasks. Researchers have sought to identify a minimum cocktail of factors necessary to enable the reconstitution of both myeloid and lymphoid lineages from blood stem cells. Previous NIH-supported research found that experimentally increasing production of a factor called HoxB4 in mouse early stage blood stem cells could reconstitute the myeloid lineage but only minimally reconstituted the lymphoid lineage. In further experiments to try to reconstitute both lineages, in 2016, investigators supported by NIDDK and others discovered that Delta1/Notch activation of mouse early stage blood stem cells, in combination with increased HoxB4 in these cells, enabled the cells to fully reconstitute the myeloid and lymphoid lineages when transplanted into mice lacking their own blood cells.