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Cord Blood

April 17, 2009

Chelsea Pearson, Whitney Pollard, Stacie Severson,
Heather Yeager, Angie Willie

What is cord blood?

Cord blood is the blood that is left in the umbilical cord when a baby is born1. The umbilical cord is connected to the placenta which facilitates exchange between the circulatory systems of mother and child without combining the two10. The blood collected from the umbilical cord would be the from the babies circulatory system not the mothers. After the umbilical cord is cut, the cord blood has to be collected relatively quickly1. If cord blood cells aren’t collected they are disposed of as medical waste1. So why is cord blood getting so much attention? Cord blood contains stem cells. When most people think of stem cell they think of embryonic stem cells. Embryonic stem cells are harvested from embryos and are surrounded by controversy and ethical debate which keeps them in the public eye. For more information on this subject see the CLS research page: Stem Cells

Somatic stem cells are adult stem cells which can be found in adult bone marrow, cord blood, and in infant circulation. Cord blood has been being used in blood and stem cell transplants and treatments since 19881,11. Stem cells can also be transplanted from adult bone marrow, but transplants have a smaller chance of rejection if the stem cells come form cord blood4. Cord blood cells are immature cells so they are not as easily recognized as foreign by the body and less likely to cause a transfusion reaction5.

The idea to use cord blood as a different source of stem cells came about in the early 80’s11. Cord blood was first used successfully for a transplant in 1988 to regenerate blood cells in a child with anemia11. The first public bank for cord blood wasn’t established until 1992, followed by a family bank in 199511. New ground was broken in 2000 when genetic testing was performed on cord blood to ensure a perfect match to the recipient11.

Collection

cord blood packageSince cord blood can only be collected in the short time after childbirth and cutting the cord, donation has to be planned in advance. Usually the delivering doctor will collect the cord cells1. The cord blood is collected after the umbilical cord has been clamped so it doesn’t cause any harm to the baby (to see an animation of cord blood collection click here). It can be collected with a syringe or a blood bag1. After the doctor collects the blood cells usually a medical courier will take the cord blood to a laboratory for processing3. Some Cord Blood Programs have their own trained employees collect the cord blood2. They also collect a blood sample from the mother, a saliva sample from the baby, and family histories2. If someone besides the doctor collects the cord blood cells they may be taken in a sterile container to a lab to be collected2. 80-100 ml (roughly 3 oz) can be required from collection for donation to be accepted2. blood storage

Lab technicians will reduce thecord blood to stem cells only by removing red blood cells and plasma. They may analyze the cord blood to see how many transplantable cells are present and include this information in a report. A cryopreservative is added to the collection and the temperature is dropped by 1 degree C/minute until it reaches -130 degree C. The stem cell collection is then transferred into storage3. Cord blood cells may be stored in liquid nitrogen and have been successfully transplanted after 10 years, though it is believed they can be stored for much longer6.

Banking

The Elements in the picture are shape-coded so that ovals mean family ownership and rectangles mean bank ownership of the cord blood. The elements are also color-coded so that green means for-profit and blue means non-profit programs14.

 

In private banking or family banking, the parents have their children’s cord blood banked for their personal use or for a direct donor use for a family member12. The family pays for the storage and the preservation of the cord blood. The average cost for this is between $1,500 and $2,000 dollars and there is an annual storage fee for the child’s cord blood averaging between $100 and $150 dollars depending on where the cord blood is banked13.

In public banking, the parents donate the baby’s cord blood and they give up the rights to the cord blood. However, the bank needs to maintain a confidential link to your identity. The bank may need to contact you in the future if they find a disease marker in the cord blood. The parents should also contact the bank if the donor develops cancer or another disease which may cause the blood to be abnormal12. The cord blood is used for patients who require a transplant and it can also be used for medical research. Public banks charge the patient around $28,000 to $35,000 dollars for the transplant13.

All cord blood units banked get tested for infectious diseases similar to those tested in a blood bank(or full list of test and cost of banking cord blood click here)14.

Current regulations

As of January 2004 all blood banks must register with the FDA8(for full FDA regulations of cord blood click here). In May 2004 it became necessary for all cord blood banks to screen mother and baby’s blood for diseases,, this is also the year funding was acquired to create a National cord blood program 8,11. In 2007, President Bush gave had researchers to direct their efforts into researching alternative sources of stem cells, including umbilical cord blood11. Cord blood is regulated as a biological drug in many of the same ways blood is9. Many cord blood companies have sought accreditation from the American Association of Blood Banks (AABB)8. In order to get accredited the cord blood bank has to contact the AABB, the facility has to have equipment and procedures inspected, and anything that doesn’t meet the standards of the AABB must be changed8.

Cord blood regulations have not been as controversial as those of embryonic stem cells because it poses no risk and would otherwise be considered medical waste7. Regulations for cord blood have closely followed those of regular blood donations7. Some believe that cord bloods changing status, from “waste” to something of great value, should also change the regulations that affect it7.

Current Uses

Cord blood transplants have the potential to be used to treat diseased by regenerating healthy blood cells in place of abnormal ones16. The transplanted cells circulate in the blood stream and travel to the bone marrow, and begin to grow and produce new red blood cells, white blood cells, and platelets. After a few weeks, blood cell counts rises toward normal15. Cord blood is used more often in children than in adults because of the umbilical cord hold a limit amount of blood16. Double cord blood transplantation is being used to increase the number of cells in a cord blood unit to treat adults.

Phagocytic Disorders

Chediak-Higashi Syndrome
Chronic Granulomatous Disease
Neutrophil Actin Deficiency
Reticular Dysgenesis

Acute Leukemias

Acute Lymphoblastic Leukemia (ALL)
Acute Myelogenous Leukemia (AML)
Acute Biphenotypic Leukemia
Acute Undifferentiated Leukemia

Chronic Leukemias

Chronic Myelogenous Leukemia (CML)
Chronic Lymphocytic Leukemia (CLL)
Juvenile Chronic Myelogenous Leukemia (JCML)

Juvenile Myelomonocytic Leukemia (JMML)

Myelodysplastic Syndromes

Myelodysplastic Syndrome
Refractory Anemia (RA)
Refractory Anemia with Ringed Sideroblasts (RARS)
Refractory Anemia with Excess Blasts (RAEB)
Refractory Anemia with Excess Blasts in Transformation (RAEB-T)
Chronic Myelomonocytic Leukemia (CMML)

Hematopoitic Cell Disorders

Aplastic Anemia (Severe)
Fanconi Anemia
Congenital Dyserythropoietic Anemia

Paroxysmal Nocturnal Hemoglobinuria (PNH)
Pure Red Cell Aplasia
Acute Myelofibrosis
Agnogenic Myeloid Metaplasia (myelofibrosis)
Polycythemia Vera
Essential Thrombocythemia

Lymphoproliferative Disorders

Non-Hodgkin's Lymphoma
Hodgkin's Disease

Inherited Metabolic Disorders

Mucopolysaccharidoses (MPS) (Click here for all MPS disorders
Hurler's Syndrome (MPS-IH)

Scheie Syndrome (MPS-IS)
Hunter's Syndrome (MPS-II)
Sanfilippo Syndrome (MPS-III)
Morquio Syndrome (MPS-IV)
Maroteaux-Lamy Syndrome (MPS-VI)
Sly Syndrome, Beta-Glucuronidase Deficiency (MPS-VII)
Adrenoleukodystrophy
Mucolipidosis II (I-cell Disease)
Krabbe Disease
Gaucher's Disease
Sandoff Disease
Tay-Sachs Disease
Niemann-Pick Disease

Wolman Disease
Metachromatic Leukodystrophy

Histiocytic Disorders

Familial Erythrophagocytic Lymphohistiocytosis
Histiocytosis-X
Hemophagocytosis

Inherited Erythrocyte Abnormalities

Beta Thalassemia Major
Blackfan-Diamond Anemia
Sickle Cell Disease

Inherited Immune System Disorders

Ataxia-Telangiectasia
Kostmann Syndrome
Myelokathexis
Leukocyte Adhesion Deficiency
DiGeorge Syndrome
Bare Lymphocyte Syndrome
Omenn's Syndrome
Severe Combined Immunodeficiency (SCID)
SCID with Adenosine Deaminase Deficiency
SCID with absence of T & B Cells
SCID with absence of T Cells, Normal B Cell
Common Variable Immunodeficiency
Wiskott-Aldrich Syndrome

Other Inherited Disorders

Lesch-Nyhan Syndrome
Cartilage-Hair Hypoplasia
Glanzmann Thrombasthenia
Osteopetrosis

Inherited Platelet Abnormalities

Amegakaryocytosis / Congenital Thrombocytopenia

Plasma Cell Disorders

Multiple Myeloma
Plasma Cell Leukemia
Waldenstrom's Macroglobulinemia

Other Malignancies

Breast Cancer
Ewing Sarcoma
Neuroblastoma
Renal Cell Carcinoma

 

Research

Unresricted Somatic Stem Cells

What are unrestricted somatic stem cells?

Unrestricted somatic stem cells (USSCs) are a small population of intrinsically pluripotent cells found in human cord blood. Pluripotent stem cells can give rise to cells from all three embryonic germ layers even after being grown in culture for a long time. The three germ layers and examples of cell types derived from each layer are listed below18.

Mesoderm

This germ layer gives rise to the muscles, blood, blood vessels, connective tissues, and the heart.

Blood cells: Hematopoietic stem cells (HSCs) have a number of unique properties. Some of the most significant of these properties are that the stem cells can choose to remain in their starting form after cell division (self-renewal) or they can change forms or structure after dividing and become hematopoietic cells. Figure 1 is an example of the different types of blood cells that are derived from the maturing of hematopoietic cells. HSCs have the ability to migrate through the body and are regulated by apoptosis which is programmed cell death. The balance between these activities determines the number of stem cells that are present in the body19. There have been studies and research in the use of these cells for transplantation and therapy but progress has been slowed in some areas due to problems with cell dose. Due to this problem the following areas of study are testing procedures that will overcome the cell dose issue, pooling of cord blood samples, Ex vivo expansion in tissue cultureand the use of double cord blood transfusions19.

These cells have a variety of current uses in the treatment of children. See table of current uses.
There are also ongoing case studies covering the research of new uses for pediactrics and adult medicine.

Heart: Heart Online has published the online article, Transplanted human cord blood-derived unrestricted somatic stem cells improve left-ventricular function and prevent left-ventricular dilation and scar formation after acute myocardial infarction. This article discusses the results of the use of URSSCs in the treatments of acute coronary syndromes20.

Figure 1

Ectoderm

The germ layer gives rise to the brain, spinal cord, nerve cells, hair, skin, teeth, sensory cells of eyes, ears, nose, and mouth, and pigment cells.

Brain and Spinal Cord

human umbilical cord blood(HUCB) cells have been used clinically to treat malignanat and nonmalignant diseases. Research is being done with the use of animals(mostly rats) to investigate the pre-clinical use to treat spinal cord and brain injuries21.
The Journal of Hematotherapy & Stem Cell Research also reports on the use of rats in similar studies supporting the use of HUCB for spinal injury repair22.

Endoderm

This germ layer gives rise to the gut (pancreas, stomach, liver, etc.), lungs, bladder, and germ cells (eggs or sperm)

Pancreas

The Viacord Research Institute reports that cord blood cells are being used in a significant amount of reasearch for the treatment of juvenile diabetes23.

For further information see the CLS research page Diabetes

http://www.clinlabnavigator.com/transfusion/umbilicalcordbloodstemcells.html

http://en.wikipedia.org/wiki/File:Stem_cells

http://www.csa.com/discoveryguides/stemcell/images/pluri.jpg

Double cord blood transplantation

What are Double cord blood transfusions?
Double cord blood transfusions are unrestricted somatic stem cell transfusions that are composed of two separate and non-related sources of cord blood. Instead of a single compatible donor there are multiple donors that may only be partial matches to the recipient. This transfusion technique has been quite successful in the treatment of children with certain cancers and blood disorders. Although one would expect to see increased graft host reactions in multiple donors there has actually been significantly positive results seen. It is thought that one set of the stem cells lays the ground work so that the other set will successfully take over. Although this is the most agreed upon conclusion at this time the exact reasons or mechanisms that make this procedure successful are not currently known. Due to this, research has been expanded and includes trials and current case studies involving the treatment of adults. The use of multiple sources has been significant in overcoming some of the volume issues associated with cord blood.

Case Studies

http://clinicaltrials.gov/ct2/results?term=cord+blood
http://bloodjournal.hematologylibrary.org/cgi/content/full/105/3/1343
http://www.ncbi.nlm.nih.gov/pubmed/17572710?dopt=Abstract
http://findarticles.com/p/articles/mi_m1200/is_1_163/ai_96501830/


The following government website has a list of current and recruiting case studies that are using cord blood in a variety of new treatment possibilities. http://clinicaltrials.gov/ct2/results?term=cord+blood


Hematopoietic Transplantation

Human Leukocyte Antigens

One of the benefits of using cord blood for hematopoietic transplantation is the fact that the human leukocyte antigens (HLA) in cord blood don’t have to be as closely matched as stem cells from bone marrow. The HLA markers are used to match donors and recipients. HLA are proteins found of the surface of most cells and are inherited; half coming from each parent. Thus, family members are looked at first for matches. The closer matched the HLA markers, the less risk of rejection, such as graft-versus-host disease (GVHD), and thus an increased chance for a successful transplantation.24 The chance of siblings being a complete match are as follows:25

*HLA molecule

One sibling:

25%

Two siblings:

44%

Three siblings:

58%

Four siblings:

68%

Five siblings:

76%

Six siblings:

82%

Seven siblings:

87%

Eight siblings:

90%

Nine siblings:

92%

Ten siblings:

94%

>There are three general HLA groups; HLA-A, HLA-B, and HLA-DR. Within these groups there are also many specific proteins. However, research has shown that only a few are important as far as transplants are concerned. There are six HLA markers that are looked for when matching donors to recipients as minimum requirements; two A, two B, and two DRB1. A minimum of 5 matches are required for bone marrow transplants and 4 for cord blood transplants, making cord blood a little more accessible for transplantation, although it has been found that a large cell dose in cord blood is just as important as the HLA match.24 .

Many sources consider cord blood cells as a good alternative for hematopoietic stem cells because of the HLA requirements. The outcomes of bone marrow transplants and cord blood transplants have been compared for effectiveness in patients with acute leukemia. Cord blood recipients were slightly younger (mean of 24.5 verses 32), weighed slightly less, and had more advanced stages of disease. The cord blood recipients were HLA-incompatible with the donor, whereas those receiving bone marrow stem cells all had to be HLA-compatible The findings shows that neutrophils recovery was significantly delayed compared to bone marrow stem cells. However, the risk of acute graft-verses-host disease (GVHD) was lower in cord blood recipients and there was no real difference in the transplant-related mortality of the two groups. This study shows that cord blood definitely can be a good alternative for adults requiring hematopoietic stem cells who cannot find an HLA-matched bone marrow donor.26

In order to decrease the time of neutrophil recovery (increased time seen in above research), one study first conditioned the patient with a nonmyeloablative regimen. Current nonmyeloablative regimens have significant morbidity and mortality, but they are not necessarily performed on individuals receiving cord blood stem cell transplantation. A new regimen has been tested and has been found that in qualifying patients, 92% reached neutrophil recovery in an average of 12 days, much sooner then without the conditioning.27

 

Increasing the Number of Hematopoietic Stem Cells

Hematopoietic umbilical cord blood transplantation has been performed mainly on children. This is due to the fact that there are a small number of the hematopoietic stem cells (HSC) found in the cord blood. In adults this causes a delayed engraftment after they have been transplanted, which also enhances the probability of infectious complications. Research has been done to increase the number of HSC outside of the specimen (called ex vivo expansion). The initial research was unsuccessful because rather than expanding the number of immature HSC, it was expanding the number of mature HSC which resulted in increased cell apoptosis and other detrimental problems. Suggestions have been made for future research in order to expand the number of HSC with decreased maturation such as manipulating newly discovered signaling pathways, as well as mediators inside of the cells. This will also help to shorten the engraftment time and allow the immune system to return to normal functioning.28

Efforts have also been taken to improve the harvesting of HSC from cord blood. One such method involved designing a two-step collection method. The first step entails obtaining blood from the cord by umbilical venipuncture (standard procedure). In the second step a second sample is harvested following placental perfusion and is added to the first sample. Adding this second collection increased the volume by 32% and added about 15% of nucleated cells to the unit.29 Research regarding hematopoietic transplantation of cord blood stem cells is ongoing and advances in technique and protocol will be seen in years to come.

Gene Therapy

What is Gene Therapy?

Picture 1Picture 2

Gene therapy is a technique in which genes are inserted (or possibly deleted) into a diseased individual to prevent or treat disease.30 There are several ways to use gene therapy such as:

  1. A normal gene inserted into a nonspecific location within the genome to replace a nonfunctional gene. Most common.

  2. An abnormal gene swapped for a normal gene through homologous recombination.

  3. The abnormal gene repaired through selective reverse mutation; returns gene to its normal function.

  4. The regulation (extent to which gene is turned on or off) of a particular gene could be altered.31

In order for this to happen a carrier molecule must be used, known as a vector. The most common vector used is a genetically altered virus. Viruses encapsulate and deliver their own genes pathologically; because of this it proves to be efficient at delivering the needed new genes. There are several types of viruses that can be used as vectors such as retroviruses, adenoviruses, adeno-associated viruses, and herpes-simplex viruses.31

 

There are two major types of gene therapy, somatic and germ line. Somatic gene therapy is when DNA is transferred to actual body tissue of the diseased individual. Germ line gene therapy on the other hand is when DNA is transferred to reproductive cells (sperm and eggs). This means that changes using gene therapy will be passed on to the individual’s offspring, whereas somatic gene therapy will not. There are many ethical issues surrounding germ line gene therapy such as a denial of human rights and potentially abusing the therapy to not only eliminate disease but select for favorable traits.32 When referring to gene therapy on cord blood stem cells, somatic gene therapy is the process being used.

Vector Research:

It is obvious that gene therapy looks very promising for cord blood progenitor cells, but a major difficulty has been in finding a vector for efficient gene transfer. As metioned the vector of choice is viral; however there are may potential problems with such a vector including an immune/inflammatory response, acquiring precise gene targeting, and the potential recovery of the ability to cause disease.31

Because of these problems a lot of research has been and continues to be done in order to find an effective vector before gene therapy is used widespread as a therapeutic treatment. One study shows a new viral vector has been developed to increase the effectiveness of gene transfer, known as recombinant Sendai virus (SeV). SeV is very stable, can be easily concentrated to high titers, and is technically non-demanding, meaning it works well in a clinical lab where gene transfer will be taking place in a large number of target cells and requires a much simpler procedure. It has been shown to successfully transfer to quiescent (inactive) cells along with dividing cells.33

Research is also being conducted on the use of lentivirus vectors in gene therapy. A lentiivirus is a subfamily of the retrovirus34, the most common of which is HIV. Lentivirus vectors have been found to have several characteristics making them appealing for the use of gene therapy such as the ability to infect non-cycling cells and being able to infect a broader range of tissues because of the surrounding envelope of the vesicular stomatitis virus (VSV).35 The use of lentivirus vectors have been seen in research dealing with metastatic melanoma, HIV, and adult T-cell leukemia.36,37,38

Picture 3

*Lentivirus vector

 

Treatment of Disease:

One way gene therapy could possibly be used is to treat ischemic diseases by promoting endothelialization. One study showed when mononuclear cells present in cord blood were transfected with the human vascular endothelial growth factor (hVEGF) gene and transplanted into a rat model with chronic hindlimb ischemia, marked improvement in endothelialization and blood flow were observed, even greater than with control mononuclear cells.39

Another study showed the potential use of gene therapy to aid in the treatment of X-linked chronic granulomatous disease (X-CGD), an immunodeficiency in which phagocytes are not effective in their antimicrobial activities due to a mutation in the gp91phax gene. Two adults were transfected using a retroviral vector containing the altered hematopoietic stem cells, resulting in substantial gene transfer with corrected phagocytes. It was concluded that gene therapy, along with other bone marrow conditioning, can potentially be a successful therapeutic treatment for such inherited myeloid diseases.40

There is still a lot of research currently being done and will be done in the future regarding gene therapy before it becomes a widely used effective treatment. Some of the problems include keeping the integrated new genes permanent, immune responses, viral vector problems, and diseases that deal with multiple genes.31

Setbacks in Gene Therapy Research:

<>Gene therapy has experienced several setbacks over the last 10-15 years which has kept it from being studied and used to its full potential. In 1999 an 18 year-old male was participating in a gene therapy trial for >ornithine transcarboxylase deficiency (OTCD) and died four days after from multiple organ failure from a severe immune response to the vector, an adenovirus.31

Then in January 2003, the FDA placed a temporary halt on all gene therapy trials on blood stem cells that were using a retroviral vector after two children developed a leukemia-like condition after successfully being treated for X-linked severe combined immunodeficiency disease (X-SCID). This was a result of a French study being conducted, and the FDA identified three similar studies taking place in the United States and placed them on hold to review more data.41 In April of the same year the FDA lifted the halt on these studies as they found no link between leukemia and the gene therapy.42 As there is no other current treatment for X-SCID, and many other diseases, the research needs to continue with consideration to safeguards that could possibly be put in place.

Gene therapy is not yet approved for treatment and is in the experimental stage.31 Because of the setbacks and bans on research it has been difficult to break through and really advance in this area of study. However, more and more research is currently being performed to make gene therapy on cord blood stems cells a potential treatment for many diseases that are currently seeking such options.

Stem cell expansion

Cord blood has been recognized as a reliable source for stem cells. Research is being done on various uses of stem cells. However, the stem cells retrieved from a single cord blood collection is insufficient to transfuse an average size adult.43 Research is now being done on the expansion of the stem cell populations from an individual collection. This research is being done both in vivo with mainly mice44, ex vivo, and in vitro. Many different approaches are being researched. Probably the most widely used is the use of cytokines in various combinations.45 Along with cytokines, researchers are trying to mimic the niche of specific cell lines to influence the stem cell.46 One concern for researchers is once stem cells have undergone expansion will they still retain the same potential for populating in vivo. Studies have shown that they do retain this ability even after repeated cell divisions.47 All of the research to date has been very hopeful in being able to expand stem cells and still be able to use them in various treatments.

Controversy

Cord blood is a great resource for stem cells but it does not come without its own set of controversy. The main controversy is over private versus public banking. Parents that privately bank blood think they have a way to cure their children and are later told that the blood could not be used depending on the condition.48 Cord blood has many limitations, private banks are being paid for long term storage for a product that may not be viable when it is needed if stored too long.49 Private banks are also a private company and if the company dissolves what then happens to the blood. Is it an asset to be sold or does it belong to the parents and the parents must relocate it to keep ownership?50 This is something still being discussed. The use of public banks however gives no access to your child’s own cord blood. If a child needs a transfusion they would wait for a possible match and then pay for the cord blood used.

The need for cord blood easily established. There are 125,000 units stored both privately and publicly in the United States, and around 2,500 transplants have been performed worldwide. The chance a child will need a transplant is not high. However, if your child has a mixed-ethnicity it could be harder to find a genetic match. This may be a good reason to bank the child’s blood.49

Regardless of how the blood is bank many still question whether collection should even happen. The umbilical cord has to be clamped within 30 seconds of delivery and the collection take place for a significant volume to be collected. The cord is still pulsing pushing the blood to the infant at this time. It has been suggested that the cord not be clamped until it stops pulsing or even longer to make sure that the infant receives the most blood possible. There is not a consensus among medical professionals on what is best, but if cord blood is going to be harvested it is common practice to clamp and cut the umbilical cord as soon as possible after delivery.51

The possible benefits of cord blood are staggering. This fact alone makes it hard to know what is right and wrong. The controversy does not stop with parents. The national government is now trying to establish a cord blood program. Research is looking at similar products and the programs regulating them to find a program that might work. Last the government will have to set regulation for cord blood banking, uses of the banked blood, and the need for cord blood for research.52

References