Bone marrow: What to know

What is bone marrow?

The spongy tissue inside parts of the body’s bones, such as the hip and thigh bones, is known as bone marrow. Stem cells are immature cells found in bone marrow.

Many patients with blood malignancies, including leukemia, lymphoma, sickle cell anemia, and other life-threatening illnesses, need bone marrow or cord blood transplants to live.

To live, people require healthy bone marrow and blood cells. A marrow or cord blood transplant may be the best therapeutic choice when a disorder or illness damages the bone marrow to the point that it can no longer function efficiently. It may be the only choice for some folks.

The purpose of this page is to provide all there is to know about bone marrow.

What exactly is bone marrow?

The soft, gelatinous substance that fills the medullary cavities, or the cores of bones, is known as bone marrow. Red bone marrow, also known as myeloid tissue, and yellow bone marrow, sometimes known as fatty tissue, are the two varieties of bone marrow.

What is bone marrow?

Blood arteries and capillaries are abundant in both forms of bone marrow.

Every day, bone marrow produces almost 220 billion new blood cells. The bone marrow produces the majority of the body’s blood cells.

Bone marrow stem cells

There are two kinds of stem cells in bone marrow: mesenchymal and hematopoietic.

Hematopoietic stem cells are found in red bone marrow, which is a fragile, highly vascular fibrous tissue. These are stem cells that create blood.

Marrow stromal cells, or mesenchymal stem cells, are found in yellow bone marrow. These are the cells that make fat, cartilage, and bone.

Stem cells are immature cells that can differentiate into a variety of cell types.

In the bone marrow, hematopoietic stem cells give birth to two kinds of cells: myeloid and lymphoid lineages. Monocytes, macrophages, neutrophils, basophils, eosinophils, erythrocytes, dendritic cells, and megakaryocytes (platelets), as well as T cells, B cells, and natural killer (NK) cells, are all examples of these cells.

The regeneration ability and potency of different kinds of hematopoietic stem cells varies. Depending on how many different types of cells they can make, they can be multipotent, oligopotent, or unipotent.

Pluripotent hematopoietic stem cells have the ability to replenish and differentiate. They can develop one or more subgroups of more mature cells and duplicate another cell that is identical to themselves.

Hematopoiesis is the process of producing various blood cells from pluripotent stem cells. In bone marrow transplants, these stem cells are required.

Stem cells divide and make new cells on a regular basis. Some new cells stay stem cells, while others evolve into precursor or blast cells before becoming formed, or mature, blood cells. Every day, stem cells proliferate rapidly to produce millions of blood cells.

The lifespan of blood cells is limited. For red blood cells, this takes around 120 days. They are continually being replaced by the body. It is critical to produce healthy stem cells.

Immature blood cells are prevented from exiting the bone marrow by the blood arteries, which operate as a barrier.

Only developed blood cells have the membrane proteins necessary to adhere to and pass through the endothelium of blood vessels. Hematopoietic stem cells, on the other hand, may pass through the bone marrow barrier. These can be extracted from circulating blood by healthcare practitioners.

Red bone marrow’s blood-forming stem cells may grow and develop into three distinct types of blood cells, each with their own function:

  • Red blood cells (erythrocytes): These transport oxygen around the body.
  • White blood cells (leukocytes): These help fight infection and disease. White blood cells include lymphocytes, which make up the cornerstone of the immune system, and myeloid cells, which include granulocytes, neutrophils, monocytes, eosinophils, and basophils.
  • Platelets (thrombocytes): These help with blood clotting after injury. Platelets are fragments of the cytoplasm of megakaryocytes, which are another type of bone marrow cell.

These blood cells develop in the bone marrow and then enter the circulation, where they perform vital function that keep the body alive and well.

The bone marrow cavity contains mesenchymal stem cells. They can divide into a variety of stromal lineages, including:

  • chondrocytes (cartilage generation)
  • osteoblasts (bone formation)
  • osteoclasts
  • adipocytes (adipose tissue)
  • myocytes (muscle)
  • macrophages
  • endothelial cells
  • fibroblasts

Red bone marrow

In adults, the red bone marrow generates all red blood cells and platelets, as well as 60–70 percent of lymphocytes. Other lymphocytes start their lives in red bone marrow and mature in lymphatic organs such the thymus, spleen, and lymph nodes.

Red bone marrow, along with the liver and spleen, aids in the elimination of old red blood cells.

Yellow bone marrow

The major function of yellow bone marrow is to store lipids. It aids in the provision of nutrition and the maintenance of the proper environment for bone function. Yellow bone marrow can return to red bone marrow in certain circumstances, such as when there is a lot of blood loss or when there is a fever.

Long bones have yellow bone marrow in the core chambers, which is bordered by a layer of red bone marrow with long trabeculae (beam-like structures) inside a sponge-like reticular framework.

Bone marrow timeline

The clavicle is where bone marrow forms initially, before delivery but near the conclusion of fetal development. It becomes active after around 3 weeks. At 32–36 weeks of pregnancy, bone marrow takes over as the primary hematopoietic organ from the liver.

Because of the enormous demand for new continuous blood creation, bone marrow remains red until approximately the age of seven. The body eventually replaces red bone marrow with yellow fat tissue as it ages. Bone marrow weighs roughly 2.6 kilograms (5.7 pounds) on average in adults, with about half of it being red.

The vertebrae, hips (ilium), breastbone (sternum), ribs, and skull, as well as the metaphyseal and epiphyseal ends of the long bones of the arm (humerus) and leg (femur), have the largest concentration of red bone marrow in adults (femur and tibia).

The central cavities of the long bones and all other cancellous, or spongy, bones are filled with yellow bone marrow.


The red bone marrow produces the majority of red blood cells, platelets, and white blood cells. Fat, cartilage, and bone are all produced by yellow bone marrow.

White blood cells can last anywhere from a few hours to a few days, platelets around ten days, and red blood cells about 120 days. Because each blood cell has a finite lifespan, the bone marrow must continually replenish these cells.

Additional blood cell synthesis may be triggered by certain circumstances. When the oxygen level of bodily tissues is low, blood loss or anemia occurs, or the number of red blood cells drops, this can occur. The kidneys manufacture and release erythropoietin, a hormone that encourages bone marrow to make more red blood cells, when these things happen.

Infections cause the bone marrow to generate and release more white blood cells, whereas bleeding causes the bone marrow to produce and release more platelets. Yellow bone marrow can activate and convert into red bone marrow if a person loses a lot of blood.

Bone marrow health is essential for a variety of systems and activities.

Circulatory system

Every organ and system in the body is influenced by the circulatory system. It entails a number of distinct cells, each with a particular purpose. Red blood cells carry oxygen to cells and tissues, platelets aid in clotting after an injury, and white blood cells move to infection or damage areas.


Hemoglobin is the protein that gives red blood cells their color. It gathers oxygen in the lungs, carries it in red blood cells, and then delivers it to tissues including the heart, muscles, and brain. Carbon dioxide (CO2), a waste product of respiration, is also removed by hemoglobin and returned to the lungs for exhale.


Iron is an essential component for human health. It is required for the production of red blood cells because it mixes with protein to form hemoglobin in red blood cells (erythropoiesis). The liver, spleen, and bone marrow store iron in the body. The recycling of old red blood cells provides the majority of the iron a person need each day for hemoglobin production.

Red blood cells

Erythropoiesis is the process of making red blood cells. A committed stem cell matures into a fully functioning red blood cell in around 7 days. Red blood cells become less active and more brittle as they age.

Phagocytosis is a process in which white blood cells called macrophages destroy aged red blood cells. These cells’ contents are discharged into the bloodstream. The iron released during this process is either stored in the liver or transferred to bone marrow for the formation of new red blood cells.

Every day, the body replaces around 1% of its overall red blood cell count. This indicates that a healthy person’s body generates roughly 200 billion red blood cells every day.

White blood cells

Many different kinds of white blood cells are produced in the bone marrow. These are essential for a strong immune system. They work to both prevent and treat infections.

The following are the several kinds of white blood cells, sometimes known as leukocytes.


Bone marrow is where lymphocytes are made. They produce natural antibodies to combat viruses that enter the body through the nose, mouth, or other mucous membranes, as well as wounds and grazes. When intruders (antigens) enter the body, certain cells detect them and send a signal to other cells to destroy them.

In reaction to these invasions, the number of lymphocytes rises. B and T lymphocytes are the two main kinds of lymphocytes.


Bone marrow is where monocytes are made. Monocytes have just 3–8 hours of life in the circulation, but as they go into tissues, they grow into bigger cells known as macrophages.

Macrophages can live for long periods of time in the tissues, where they absorb and eliminate bacteria, fungus, dead cells, and other foreign material.


The term “granulocytes” refers to three different types of white blood cells: neutrophils, eosinophils, and basophils. A granulocyte can take up to two weeks to mature, although this period is reduced when there is a greater hazard, such as a bacterial infection.

A substantial number of adult granulocytes are stored in the bone marrow. There may be 50–100 cells in the bone marrow ready to be released into the bloodstream for every granulocyte circulating in the blood. As a result, within 7 hours of identifying an infection in the body, 50% of the granulocytes in the circulation can be active in fighting it.

A granulocyte that has left the blood normally does not return. A granulocyte can live for up to 5 days in the tissues, depending on the circumstances, but just a few hours in circulating blood.


The most prevalent kind of granulocyte is neutrophil. They have the ability to fight and kill germs and viruses.


Eosinophils are involved in the battle against a variety of parasitic illnesses, as well as parasitic worms and other species’ larvae. They are also implicated in allergic responses in some cases.


Basophils are the white blood cells with the smallest population. They react to a variety of allergens by releasing histamines, heparin, and other chemicals.

Heparin is a blood thinner. It works to keep blood from clotting. Histamines are irritants and inflammation-causing vasodilators. When these compounds are released, the pathogen becomes more permeable, allowing white blood cells and proteins to penetrate the tissues and engage the infection.

Allergens cause irritation and inflammation in tissues, which is part of the reaction that causes hay fever, some types of asthma, hives, and, in its most severe form, anaphylactic shock.


Thrombopoiesis is the process through which bone marrow creates platelets. Platelets help blood clot and stop bleeding by allowing blood to coagulate and form clots.

Platelet activity is triggered by sudden blood loss at the site of an injury or wound. Platelets cluster together and create fibrin when they come into contact with other substances. Fibrin has a thread-like structure and produces a scab or clot on the outside.

Platelet insufficiency makes it easier for the body to bruise and bleed. Blood may not clot properly in an open cut, and a low platelet count may increase the risk of internal bleeding.

Lymphatic system

Lymphatic organs such as bone marrow, tonsils, thymus, spleen, and lymph nodes make up the lymphatic system.

All lymphocytes begin as immature cells called stem cells in the bone marrow. T cells are lymphocytes that develop in the thymus gland (behind the breastbone). B cells are those that develop in the bone marrow or lymphatic tissues.

Immune system

The immune system defends the body against infection. It eliminates harmful microbes such as bacteria and viruses before they can infect the body.

How does the immune system fight infection?

Lymph nodes are small glands that are found all over the body. After being produced in the bone marrow, lymphocytes move to the lymph nodes. Lymphocytes can then migrate between nodes via lymphatic channels that connect to huge drainage ducts that flow into blood vessels. These channels allow lymphocytes to reach the bloodstream.

B lymphocytes, T lymphocytes, and NK cells are the three primary kinds of lymphocytes that play a role in the immune system.

B lymphocytes (B cells)

In animals, these cells come from hematopoietic stem cells in the bone marrow.

On the surface of B cells are B cell receptors. These enable the cell to bind to an antigen on an invading microbe’s surface or another antigenic substance.

B cells are called antigen-presenting cells because they warn other immune system cells to the presence of an invading invader.

Antibodies are also produced by B cells, which bind to the surface of infection-causing bacteria. Each of these antibodies is designed like a customized “lock” into which a matching antigen “key” fits. As a result, each Y-shaped antibody interacts to a particular microorganism, eliciting a stronger immune response to combat illness.

In certain cases, B cells mistakenly designate healthy cells as antigens that necessitate an immune response. This is the process that causes autoimmune diseases including multiple sclerosis, scleroderma, and type 1 diabetes to develop.

T lymphocytes (T cells)

The thymus, a tiny organ in the upper chest right beyond the sternum, is where these cells develop, thus the name. (The tonsils are where some T lymphocytes develop.)

T cells come in a variety of shapes and sizes, and they play a variety of roles in adaptive cell-mediated immunity. T cells assist B cells in the production of antibodies against bacteria, viruses, and other organisms.

Some T cells, unlike B cells, engulf and eliminate infections immediately after binding to the antigen on the microbe’s surface.

NK T cells, which are not to be confused with innate immune system NK cells, serve as a link between the adaptive and innate immune systems. NK T cells distinguish antigens presented in a unique way from antigens given in other ways, and they can operate as both T helper cells and cytotoxic T cells. They can also identify and destroy certain tumor cells.

NK cells

These are lymphocytes that go after cells that have been infected by a virus.


A bone marrow transplant can be beneficial for a variety of reasons. For example:

  • It can replace diseased, nonfunctioning bone marrow with healthy functioning bone marrow. This is useful in conditions such as leukemia, aplastic anemia, and sickle cell anemia.
  • It can regenerate a new immune system that fights existing or residual leukemia or other cancers that chemotherapy or radiation therapy has not killed.
  • It can replace bone marrow and restore its usual function after a person receives high doses of chemotherapy or radiation therapy to treat a malignancy.
  • It can replace bone marrow with genetically healthy, functioning bone marrow to prevent further damage from a genetic disease process, such as Hurler’s syndrome or adrenoleukodystrophy.

Stem cells mainly occur in four places:

  • an embryo
  • bone marrow
  • peripheral blood, which is present in blood vessels throughout the body
  • cord blood, which is present in the umbilical cord and collectible after birth

Except for the fetus, any of them can provide stem cells for transplantation.

The intravenous (IV) injection of stem cells taken from bone marrow, peripheral blood, or umbilical cord blood is known as hematopoietic stem cell transplantation (HSCT).

This is beneficial for restoring hematopoietic function in persons with damaged or dysfunctional bone marrow or immune systems.

Every year, about 50,000 new HSCT treatments, 28,000 autologous transplantation procedures, and 21,000 allogeneic transplantation procedures are performed across the world. According to the Worldwide Network for Blood and Marrow Transplantation’s 2015 report.

This figure continues to rise at a rate of more than 7% every year. Organ damage, infection, and severe, acute graft-versus-host disease (GVHD) seem to be decreasing, which appears to be leading to better outcomes.

In a study of 854 patients who lived for at least two years after receiving autologous HSCT for a hematologic malignancy, 68.8% were still living ten years later.

Bone marrow transplants are the most common therapy for diseases that compromise bone marrow function, such as leukemia.

A transplant can assist in restoring the body’s ability to manufacture blood cells and bringing their quantities back to normal. Cancerous and noncancerous disorders are among the conditions that may benefit from a bone marrow transplant.

Cancerous disorders may or may not involve blood cells directly, although cancer therapy can impair the body’s capacity to produce new blood cells.

Chemotherapy is generally given to a cancer patient before transplantation. This removes the marrow that has been affected.

A healthcare expert then collects and prepares the bone marrow of a matching donor — often a close family member — for transplant.

Types of bone marrow transplant

The following are examples of bone marrow transplants:

  • Autologous transplant: People receive their own stem cells from their peripheral or cord blood to replenish bone marrow.
  • Syngeneic transplant: People receive stem cells from their identical twin.
  • Allogeneic transplant: People receive matching stem cells from a sibling, parent, or unrelated donor.
  • Haploidentical transplantation: This is a treatment option for the approximately 70%Trusted Source of people who do not have a human leukocyte antigen (HLA)-identical matching donor.
  • Umbilical cord blood (a type of allogeneic transplant): A healthcare professional removes stem cells from a newborn baby’s umbilical cord right after birth. They freeze and store the stem cells until they are needed for a transplant. Umbilical cord blood cells are very immature, so there is less of a need for matching, but blood counts take much longer to recover.

Tissue type

The kind of HLA found on the surface of the majority of a person’s cells determines their tissue type. HLA is a protein or marker that the body uses to identify whether a cell belongs to the body or not.

Doctors analyze how many proteins on the surface of the donor’s and recipient’s blood cells match to see if the tissue types are compatible. Although there are millions of distinct forms of tissue, some are more frequent than others.

Tissue types are inherited, and they are passed down from one generation to the next. This indicates that a relative is more likely to have a tissue type that matches yours.

If a potential bone marrow donor cannot be found among family members, healthcare experts search the bone marrow donor registry for someone with a matching tissue type.

Pre-transplant tests

Before a bone marrow transplant, doctors conduct a series of tests to rule out any potential complications.

These tests include the following:

  • tissue typing and a variety of blood tests
  • chest X-rays
  • pulmonary function tests
  • CT or CAT scans
  • heart function tests, including an electrocardiogram and echocardiogram (ECG)
  • bone marrow biopsy
  • skeletal survey

A full dental checkup is also required prior to a bone marrow donation to limit the risk of infection. Other precautions must be taken before the transplant to reduce the danger of infection.

Harvesting bone marrow

Bone marrow can be obtained for testing by bone marrow biopsy and aspiration.

Bone marrow extraction has become a very common practice. While the donor is under regional or general anesthesia, healthcare practitioners aspirate it from the posterior iliac crests.

Because it still includes a significant quantity of red bone marrow, healthcare workers can extract it from the sternum or upper tibia in youngsters.

They accomplish this by inserting a needle into a bone, generally the hip, and extracting bone marrow. The bone marrow is then frozen and stored.

The volume of detachable bone marrow allowed by the National Marrow Donor Program (NMDP) is limited to 20 milliliters (ml) per kilogram of donor weight. Engraftment in autologous and allogeneic marrow transplants requires doses of 1 x 103 and 2 x 108 marrow mononuclear cells per kilogram, respectively.

Bone marrow harvesting complications are uncommon. When they do happen, they usually entail anesthetics, infection, and bleeding issues.

Giving a person particular medicines that induce the release of stem cells from bone marrow into circulating blood is another technique to assess bone marrow function.

The stem cells are isolated from a blood sample and examined under a microscope by a healthcare practitioner. They may be able to extract stem cells from the umbilical cord in infants.

How do healthcare professionals transplant bone marrow?

Chemotherapy, radiation treatment, or both may be used prior to the transplant. A mini-transplant or ablative (myeloablative) therapy and lower intensity treatment are the two options.

A person undergoes high dosage chemotherapy, radiation therapy, or both in ablative (myeloablative) treatment to eliminate any cancer cells. This also destroys any remaining healthy bone marrow, allowing new stem cells to develop in the marrow.

Prior to a transplant, a person undergoes lesser doses of chemotherapy and radiation therapy in a reduced intensity treatment, often known as a mini-transplant. This enables older people and people with other health issues to have a transplant.

After chemotherapy and radiation therapy, a stem cell transplant is frequently performed.

The infusion of bone marrow or peripheral blood is a reasonably straightforward procedure that is performed at the patient’s bedside by a healthcare provider. Over the course of many hours, they administer the bone marrow product into a central vein through an IV catheter.

Cryopreservation is nearly often used for autologous items. They defrost at the bedside and absorb quickly over several minutes.

Hematopoietic stem cells go to the bone marrow after entering the circulation. In a process called as engraftment, they begin to create new white blood cells, red blood cells, and platelets. This happens about 30 days following the transplant.

There appears to be low toxicity in the majority of instances. Infusions of ABO-incompatible bone marrow can occasionally result in hemolytic responses.

Face flushing, a tickling feeling in the throat, and a strong garlic taste in the mouth may be caused by dimethyl sulfoxide (DMSO), which is used by healthcare experts for the cryopreservation of stem cells. Bradycardia, abdominal discomfort, encephalopathy or seizures, and renal failure are all possible side effects of DMSO.

Healthcare professionals infuse stem cell infusions that surpass 500 ml over two days and restrict the pace of infusion to 20 ml per minute to reduce the risk of encephalopathy, a brain disorder that can occur with DMSO concentrations exceeding 2 grams per kg per day.

Blood counts are checked on a regular basis by healthcare specialists. Immune function recovery can take several months for autologous transplant patients and 1–2 years for allogeneic or syngeneic transplant recipients.

Blood testing will determine whether or not the body is manufacturing new blood cells and whether or not the cancer has returned. Aspiration of bone marrow can also assist healthcare providers in determining how effectively the replacement bone marrow is functioning.


Both early and late effects are related with HSCT complications.

The following are some examples of early-onset issues:

  • mucositis
  • hemorrhagic cystitis
  • prolonged, severe pancytopenia
  • infection
  • GVHD
  • graft failure
  • pulmonary complications
  • hepatic veno-occlusive disease
  • thrombotic microangiopathy

The following are some examples of late-onset issues:

  • chronic GVHD
  • ocular effects
  • endocrine effects
  • pulmonary effects
  • musculoskeletal effects
  • neurologic effects
  • immune effects
  • infection
  • congestive heart failure
  • subsequent malignancy

Increased infection susceptibility, anemia, graft failure, respiratory discomfort, and excess fluid, which can lead to pneumonia and liver dysfunction, are all significant hazards.

A mismatch between donor and recipient tissues can trigger an immunological response between the host’s cells and the graft’s cells.

GVHD is a hazardous disorder that occurs when transplant cells assault host cells. This can be acute or chronic, and symptoms include a rash, gastrointestinal symptoms, and liver damage. Through meticulous tissue matching, the danger of GVHD can be reduced.

Even when the donor antigen match is perfect, 20–50% of recipients suffer GVHD, which rises to 60–80% when only one antigen is mismatched. Autologous transplants are increasingly prevalent because of the risk of this consequence.

According to previous research, adults over the age of 50 had a greater risk of problems after a bone marrow transplant. As a result, specialists have traditionally advised against having a transplant after this age.

Medical technological advancements, on the other hand, have minimized these hazards. According to the authors of a 2013 paper, transplantation can be safe for adults beyond the age of 70 provided they match specific conditions.

Donors face little danger since they develop new bone marrow to replace the bone marrow that has been taken. There is, however, a small danger of infection, and any surgical treatment might result in an anesthetic response.


Because bone marrow impacts so many internal systems, a malfunction can lead to a variety of illnesses, including malignancies of the blood.

Bone marrow is threatened by a number of disorders that hinder it from converting stem cells into necessary cells.

Leukemia, Hodgkin disease, and other lymphoma malignancies can harm the bone marrow’s capacity to produce stem cells and kill them.

A bone marrow examination can assist in the diagnosis of:

  • leukemia
  • multiple myeloma
  • Gaucher’s disease
  • unusual cases of anemia
  • other hematological conditions

HSCT is being used to treat an increasing range of illnesses by doctors.

Someone in the United States is diagnosed with blood cancer every three minutes. The greatest chance for survival is frequently a bone marrow transplant.

Around 30% of patients can locate a matching donor within their family, while 70% rely on bone marrow donated by someone unrelated.

Autologous HSCT is now used to treat the following conditions by healthcare professionals:

  • multiple myeloma
  • non-Hodgkin lymphoma
  • Hodgkin lymphoma
  • acute myeloid leukemia
  • neuroblastoma
  • germ-cell tumors
  • autoimmune conditions, such as lupus and systemic sclerosis
  • amyloidosis

Healthcare professionals use allogeneic HSCT to treat:

  • acute myeloid leukemia
  • acute lymphoblastic leukemia
  • chronic myeloid leukemia
  • chronic lymphocytic leukemia
  • myeloproliferative disorders
  • myelodysplastic syndromes
  • multiple myeloma
  • non-Hodgkin lymphoma
  • Hodgkin lymphoma
  • aplastic anemia
  • pure red cell aplasia
  • paroxysmal nocturnal hemoglobinuria
  • Fanconi’s anemia
  • thalassemia major
  • sickle cell anemia
  • severe combined immunodeficiency
  • Wiskott-Aldrich syndrome
  • hemophagocytic lymphohistiocytosis
  • genetic conditions relating to metabolism, such as mucopolysaccharidosis
  • Gaucher’s disease, metachromatic leukodystrophies, and adrenoleukodystrophies
  • epidermolysis bullosa
  • severe congenital neutropenia
  • Shwachman-Diamond syndrome
  • Diamond-Blackfan anemia
  • leukocyte adhesion deficiency

HSCT may also help treat:

Bone marrow transplants are occasionally required following cancer therapies such as high-dose chemotherapy and radiation therapy. These therapies have the potential to harm healthy stem cells as well as cancer cells.

Bone marrow tests

Bone marrow testing can aid in the diagnosis of a variety of illnesses, particularly those involving blood and blood-forming organs. Iron reserves and blood production can be determined by testing.

A hollow needle is used to extract a tiny sample of bone marrow (approximately 1 ml) for examination under a microscope.

In adults, a needle is frequently inserted into the hip or sternum, whereas in children, it is inserted into the upper section of the tibia (the bigger bone of the lower leg). Suction is used to extract the sample.

When earlier blood tests have shown a need for it, they usually do bone marrow aspiration. It’s very beneficial for determining the developmental stages of immature blood cells.


Bone marrow donation may be divided into two categories.

The first procedure is removing bone marrow from the rear of the pelvis.

Peripheral blood stem cell (PBSC) donation is the second and more popular approach. This entails removing stem cells from the bloodstream. It is these blood stem cells, not bone marrow, that are required for the treatment of blood malignancies and other illnesses.

When a person signs up for a bone marrow donation registry, they agree to give their bone marrow through whichever technique the healthcare practitioner thinks acceptable.

The National Marrow Donor Program (NMDP) or a person’s medical insurance normally covers the cost of a blood marrow donation. Donors are never charged for their contributions, and they are never compensated for their contributions.

A donor faces very little danger. Over 98.5 percent of donors recover completely following the operation. The use of anesthetics during the process is a big danger with blood marrow donation.

The technique for donating PBSCs, which involves filtering blood through a machine, is not risky.

According to the NMDP’s Be The Match Registry, a person’s likelihood of finding a matching bone marrow donor varies between 23 – 77 percent depending on ethnicity.

Although 77 percent of white persons in the United States can locate a match on a donor registry, only 23% of Black people can. As the mixture of hereditary traits grows more complicated, the percentage of mixed race people reduces to 4%.

The NMDP has connections with registries all around the world, but additional donors are desperately needed. A number of researchers have called for “additional efforts” to overcome the obstacles.

Who is eligible to donate bone marrow?

The National Marrow Donor Program (NMDP) has provided some broad criteria for bone marrow donation.

The standards are designed to safeguard both the donor and the recipient’s health and safety. Donors should contact their local NMDP facility for further information and to speak with a healthcare professional about their gifts.

Potential donors must be healthy and between the ages of 18 and 60 to be placed in the register.

Before giving, each donor must pass a medical check and be clear of infection if they are matched with someone who needs a transplant.

People who use drugs are typically able to donate bone marrow if they are healthy and have any medical issues under control at the time of donation.

Medications that are acceptable include:

  • To be listed in the registry, potential donors must be healthy and aged 18–60 years.
  • If matched with a person needing a transplant, each donor must pass a medical examination and be infection-free before donating.
  • People who use medications can usually donate bone marrow, as long as they are healthy and any medical conditions they have are under control at the time of donation.

Acceptable medications include:

Antianxiety and antidepressant drugs are allowed as long as the condition is under control.

Donation is not possible:

  • during pregnancy
  • by anyone using nonprescription IV drugs
  • if the person has had a positive blood test for hepatitis B or hepatitis C
  • by those with specific medical conditions, such as most cancers and certain heart conditions

Before donating bone marrow, anyone with Lyme disease, malaria, or recent tattoos or piercings should wait at least a year.

How do doctors determine if a patient’s bone marrow is a match?

After registering to give, the individual takes an HLA-typing test, which is used by healthcare experts to link people with possible donors.

The healthcare practitioner then enters their HLA type into a register of possible donors and searches the database for a match.

Proteins in blood cells are compared to check if they are identical to those in the receiver. If there is a match, they will contact the possible donor.

The more similar the donor’s tissue type is to the recipient’s, the more likely the recipient’s body will accept the transplant.

The World Marrow Donor Association (WMDA) is a database comprising 55 nations’ hematopoietic cell donor registries. As of April 2021, there were over 37.9 million prospective donors and over 802,600 cord blood units available. The WMDA is also explored in preliminary searches using the NMDP.

When you donate bone marrow, what happens?

The following tests are performed on hematopoietic stem cell donors:

  • medical history and physical examination
  • serum creatinine, electrolyte, and liver function studies
  • serologic studies for:
    • cytomegalovirus (CMV)
    • herpes viruses
    • HIV RNA
    • anti-HIV antibodies
    • hepatitis B and C viruses
    • human T cell lymphotropic virus-1/2
    • syphilis (VDRL)
  • ABO blood typing
  • HLA typing
  • chest radiography
  • ECG

In autologous donations, CMV and VDRL testing are not necessary.

Donating PBSC

Before donating PBSC, a person must get daily injections of a medicine called filgrastim for five days before to the procedure. Because this medicine takes stem cells from the bone marrow, the donor’s blood has more of them.

Apheresis is a process used to donate PBSC. A healthcare worker uses a catheter implanted into one arm to draw blood from the body. The blood is filtered via a machine that removes the stem cells, platelets, and white blood cells. The rest of the blood, mostly plasma and red blood cells, returns to the body through a vein in the opposite arm.

The method is similar to plasma donation in that it is absolutely painless. The majority of PBSC donations may be completed in an one 8-hour apheresis session. Approximately 10% of PBSC donations need two 4–6 hour apheresis procedures.

Anesthetics are not required for PBSC donation.

For many days after receiving filgrastim injections prior to donation, the following side effects may occur:

These negative effects, on the other hand, normally fade away quickly after the donation.

The majority of PBSC donors recover completely within 7–10 days of their donation.

Bone marrow donation

Filgrastim injections are not required if a person donates bone marrow rather than PBSC. Bone marrow donation is a surgical operation carried out in a hospital operating room. It necessitates the use of anesthetics and is therefore fully painless. It takes 1–2 hours to complete the operation.

Approximately 96 percent of the time, the donor is given general anesthetics, which means they are completely asleep throughout the process. Local anesthetics numb the region where the healthcare professional extracts bone marrow in a tiny percentage of instances. The donor is conscious during the process in this case.

The individual is lying on their stomach. A quarter-inch-long incision is made on both sides of the pelvic bone by a healthcare expert. They then put hollow needles into the bone and suck the liquid marrow through them. Stitches are typically not required for the incisions.

The donor is kept in a recovery room until they regain consciousness after the surgery. They can depart after they are able to eat, drink, and walk.


The typical recovery period after bone marrow donation is 20 days. Within 4–6 weeks, bone marrow replenishes itself.

Bone marrow donors frequently encounter the following:

  • headaches
  • fatigue
  • muscle pain
  • back or hip pain
  • bruising around the incision site
  • difficulty walking

These side effects might last anywhere from a few days to many weeks.

Other than bruising at the injection site, a person who gives PBSC is unlikely to have any negative effects after the donation. The time it takes to recover is virtually instantaneous.


The success of a bone marrow transplant is determined by the following factors:

  • the type of transplant
  • how closely the cells match
  • what type of condition the person has
  • the person’s age and overall health
  • the type and dosage of chemotherapy or radiation therapy they received before the transplant
  • any complications that arise

A person who undergoes a transplant when their health is stable or in remission has a greater chance of a successful result than someone who obtains a transplant later in life or who has relapsed disease. The likelihood of success is also increased when the patient is young at the time of the transplant.

Transplants for non-malignant illnesses have a higher success rate. For example, the overall 1-year survival rate for sickle cell anemia is 94–97 percent if the donor is a relative or matched sibling, and 83 percent if the donor is not related. The total 3-year survival rate for transplants from related donors is 89–95 percent, compared to 77 percent for unrelated donors.

The overall 1-year survival rate for recipients with acute leukemia in remission at the time of transplant is 69–75 percent if the donor is related, and 68 percent if the donor is unrelated. Overall, transplants from related donors have a 3-year survival rate of 49–58 percent, whereas transplants from unrelated donors have a 3-year survival rate of 53 percent.

Complications, such as infections and illnesses, have decreased in recent years. According to one 2020 review, the risk of mortality for patients of bone marrow transplants decreased by more than 20% between 2003 and 2017.

A bone marrow transplant can treat an illness entirely or partially. If the transplant goes well, the patient can resume most of their normal activities as soon as they feel well enough. It might take up to a year to fully recover.