Stem Cell Stem Cell TechnologyTechnology

About the presenterAbout the presenter

Dr.B.Victor is a highly experienced postgraduate Dr.B.Victor is a highly experienced postgraduate biology teacher, recently retired from the reputed biology teacher, recently retired from the reputed educational institution St. Xavier’ s College, educational institution St. Xavier’ s College, Palayamkottai, India-627001.Palayamkottai, India-627001.

He was the dean of sciences and assistant He was the dean of sciences and assistant controller of examinations.controller of examinations.

He has more than 32 years of teaching and He has more than 32 years of teaching and research experienceresearch experience

He taught a diversity of courses ranging from pre- He taught a diversity of courses ranging from pre- university to post graduate classes. university to post graduate classes.

Send your comments to : Send your comments to : bonfiliusvictor@gmail.combonfiliusvictor@gmail.com

Presentation outlinePresentation outline

Stem cell Stem cell characteristicscharacteristics

Embryonic stem Embryonic stem cells (ESC)cells (ESC)

Adult Stem cells Adult Stem cells (ASC)(ASC)

Stem Cell LinesStem Cell Lines Classification of Classification of

stem cells stem cells Culture andCulture and

Stem cell therapy Stem cell therapy Recent Recent

DevelopmentsDevelopments

Diversity of Human CellsDiversity of Human CellsAdult humans consist of more than 200 Adult humans consist of more than 200 kinds of cells.kinds of cells.They are nerve cellsThey are nerve cells ( (neuronsneurons), ), muscle cellsmuscle cells ((myocytesmyocytes), ), skinskin (epithelial) (epithelial) cellscells, , blood blood cellscells (erythrocytes, (erythrocytes, monocytesmonocytes, , lymphocyteslymphocytes, etc.), , etc.), bone cellsbone cells ( (osteocytesosteocytes), ), and and cartilage cellscartilage cells ( (chondrocyteschondrocytes).).cells essential for embryonic development cells essential for embryonic development but not incorporated into the body of the but not incorporated into the body of the embryo, include the embryo, include the extra-embryonic extra-embryonic tissuestissues, , placentaplacenta, and umbilical cord. , and umbilical cord. All of these cells are generated from a All of these cells are generated from a single, totipotent cell, single, totipotent cell, the the zygotezygote, or , or fertilized egg. fertilized egg.

What is a stem cell?What is a stem cell?

A A stem cell is a "blank" cell/ stem cell is a "blank" cell/ precursor cell that can give precursor cell that can give rise to multiple tissue types rise to multiple tissue types such as a skin, muscle, or such as a skin, muscle, or nerve cell.nerve cell.

A stem cell is essentially the A stem cell is essentially the building block of the human building block of the human body. body.

Features of Stem Features of Stem CellsCells1.1. Stem Cells are very unique cells.Stem Cells are very unique cells.

2.2. Stem Cells have the amazing ability to develop Stem Cells have the amazing ability to develop into several distinct cell types in the body. into several distinct cell types in the body.

3.3. Stem Cells can be used as a repair system for Stem Cells can be used as a repair system for the body.the body.

4.4. Stem Cells can theoretically divide without Stem Cells can theoretically divide without limit in a living organism in order to replenish limit in a living organism in order to replenish various types of cells. various types of cells.

5.5. When a stem cell divides, each new cell has the When a stem cell divides, each new cell has the potential to either remain a stem cell or potential to either remain a stem cell or become another type of cell with a more become another type of cell with a more specialized function (i.e. a muscle cell, a red specialized function (i.e. a muscle cell, a red blood cell, a brain cell, etc.). blood cell, a brain cell, etc.).

Three unique properties of Three unique properties of stem cellsstem cells

Stem cells are capable of Stem cells are capable of dividing dividing and renewing themselves for long and renewing themselves for long periodsperiods;;

They are They are ““unspecialized”unspecialized” and they and they can can give rise to specialized cell give rise to specialized cell types. types.

A stem cell is A stem cell is "uncommitted,""uncommitted," until until it receives a signal to develop into it receives a signal to develop into a specialized cell.a specialized cell.

Asymmetric division ofAsymmetric division of stem cells stem cellsStem cells have the ability Stem cells have the ability to to divide asymmetrically .divide asymmetrically .

One portion of the cell One portion of the cell division becomes a division becomes a differentiated cell while differentiated cell while the other becomes the other becomes another stem cell.another stem cell.

1. Stem cells are 1. Stem cells are unspecializedunspecializedA stem cell A stem cell does not have any does not have any tissue-specific structurestissue-specific structures that allow that allow it to perform specialized functions. it to perform specialized functions. A stem cell cannot work with its A stem cell cannot work with its neighbors to pump blood through neighbors to pump blood through the body (the body (like a heart muscle cell); like a heart muscle cell); It cannot carry molecules of oxygen It cannot carry molecules of oxygen through the bloodstream (through the bloodstream (like a red like a red blood cellblood cell); and); and It cannot fire electrochemical It cannot fire electrochemical signals to other cells that allow the signals to other cells that allow the body to move (body to move (like a nerve cell).like a nerve cell).

2.2.Stem cells are capable of Stem cells are capable of dividing and renewing dividing and renewing themselves for long periods.themselves for long periods.

Stem cells may replicate many Stem cells may replicate many times. times. When cells replicate themselves When cells replicate themselves many times it is called many times it is called proliferation. proliferation. The stem cells that proliferate for The stem cells that proliferate for many months in the laboratory can many months in the laboratory can yield millions of cells. yield millions of cells. Stem cells are capable of long-term Stem cells are capable of long-term self-renewal.self-renewal.

3.3.Stem cells can give rise Stem cells can give rise to specialized cellsto specialized cells

When unspecialized stem cells give rise When unspecialized stem cells give rise

to specialized cells, the process is called to specialized cells, the process is called differentiation. differentiation.

There are signals inside and outside cells There are signals inside and outside cells that trigger stem cell differentiation.that trigger stem cell differentiation.

The The internal signalsinternal signals are controlled by a are controlled by a cell's genes. cell's genes.

The The external signalsexternal signals include chemicals include chemicals secreted by other cells, physical contact secreted by other cells, physical contact with neighboring cells, and certain with neighboring cells, and certain molecules in the microenvironmentmolecules in the microenvironment

In embryosIn embryos, stem cells , stem cells function to generate new function to generate new organs and tissues. organs and tissues. In adultsIn adults, they function to , they function to replace cells during the replace cells during the natural course of cell natural course of cell turnover. turnover.

4.Stem cells exist in both embryos and adults.

Distinguishing Features of Distinguishing Features of Progenitor/Precursor Cells and Progenitor/Precursor Cells and Stem Cells.Stem Cells.

A stem cellA stem cell is an unspecialized cell that is an unspecialized cell that develops into a variety of specialized cell develops into a variety of specialized cell types. types.

a stem cell divides and gives rise to one a stem cell divides and gives rise to one additional stem cell and a specialized cell. additional stem cell and a specialized cell.

Example:Example: a hematopoietic stem cell produce a hematopoietic stem cell produce a second generation stem cell and a neuron. a second generation stem cell and a neuron.

A progenitor cell (a precursor cellA progenitor cell (a precursor cell)) is is unspecialized that is capable of undergoing unspecialized that is capable of undergoing cell division and yielding two specialized cell division and yielding two specialized cells. cells.

Example:Example: a myeloid progenitor/precursor cell a myeloid progenitor/precursor cell undergoing cell division to yield two undergoing cell division to yield two specialized cells (a neutrophil and a red specialized cells (a neutrophil and a red blood cell). blood cell).

Stem cell Stem cell ClassesClasses

Embryonic Type stem Embryonic Type stem cellscells

1.Embryonic Type

Embryonic Stem Cells Embryonic Germ Cells

2. Adult Type 

Umbilical Cord Stem CellsPlacental Stem Cells Adult Stem Cells

Adult type Stem cellsAdult type Stem cells

Sources of embryonic Sources of embryonic type stem cellstype stem cells    * * Embryos -Embryos - Embryonic stem cells are Embryonic stem cells are

obtained by harvesting living embryos obtained by harvesting living embryos which are generally 5-7 days old. The which are generally 5-7 days old. The removal of embryonic stem cells removal of embryonic stem cells invariably results in the destruction of invariably results in the destruction of the embryo.the embryo.

* Fetuses -* Fetuses - Another kind of stem cell, Another kind of stem cell, called an embryonic germ cell, can be called an embryonic germ cell, can be obtained from either miscarriages or obtained from either miscarriages or aborted fetuses. aborted fetuses.

Sources of adult type Sources of adult type stem cellsstem cells Umbilical Cords, Placentas and Amniotic Umbilical Cords, Placentas and Amniotic

Fluid -Fluid - Adult type stem cells can be Adult type stem cells can be derived from various pregnancy-related derived from various pregnancy-related tissues.tissues.

Adult Tissues -Adult Tissues - In adults, stem cells are In adults, stem cells are present within the bone marrow, liver, present within the bone marrow, liver, epidermis, retina, skeletal muscle, epidermis, retina, skeletal muscle, intestine, brain, dental pulp and intestine, brain, dental pulp and elsewhere. elsewhere.

Cadavers -Cadavers - Neural stem cells have been Neural stem cells have been removed from specific areas in post-removed from specific areas in post-mortem human brains as late as 20 hours mortem human brains as late as 20 hours following death. following death.

Comparison of Comparison of embryonic and embryonic and adult stem cellsadult stem cells Advantages of  Embryonic Stem Cell   Advantages of  Embryonic Stem Cell   

1. Flexible1. Flexible - appear to have the potential - appear to have the potential to make any cell.to make any cell.    2. Immortal2. Immortal - one embryonic stem cell - one embryonic stem cell line can potentially provide an endless line can potentially provide an endless supply of cells with defined supply of cells with defined characteristics.characteristics.  3. Availability  3. Availability - embryos from - embryos from in vitroin vitro fertilization clinics. fertilization clinics.

Disadvantages of Disadvantages of Embryonic Embryonic

Stem CellStem Cell 1.1.Difficult to differentiate uniformly and Difficult to differentiate uniformly and

homogeneouslyhomogeneously into a target tissue. into a target tissue.2.2.Immunogenic -Immunogenic - embryonic stem cells embryonic stem cells

from a random embryo donor are from a random embryo donor are likely to be rejected after likely to be rejected after transplantationtransplantation

3.3.Tumorigenic Tumorigenic - capable of forming - capable of forming tumors or promoting tumor formation.tumors or promoting tumor formation.

4.4.Destruction of developing human lifeDestruction of developing human life. .

Advantages of Adult Stem Advantages of Adult Stem CellCell

1.1. Adult stem cells from bone marrow and Adult stem cells from bone marrow and umbilical cords appear to be as umbilical cords appear to be as flexible as flexible as the embryonic typethe embryonic type

2.2. Somewhat specialized -Somewhat specialized - inducement may be inducement may be simpler.simpler.

3.3. Not immunogenic -Not immunogenic - recipients who receive recipients who receive the products of their own stem cells will not the products of their own stem cells will not experience immune rejection.experience immune rejection.

4.4. Relative ease of procurementRelative ease of procurement - some adult - some adult stem cells are easy to harvest (skin, stem cells are easy to harvest (skin, muscle, marrow, fat) muscle, marrow, fat)

5.5. Non-tumorigenic-Non-tumorigenic-tend not to form tumors.tend not to form tumors.6.6. No harm doneNo harm done to the donor. to the donor.

Disadvantages of Adult stem cells

  1. Limited quantity1. Limited quantity - can - can sometimes be difficult to obtain sometimes be difficult to obtain in large numbers.in large numbers.  2. Finite -  2. Finite - may not live as long may not live as long as embryonic stem cells in as embryonic stem cells in culture.culture.  3. Less flexible -  3. Less flexible - may be more may be more difficult to reprogram to form difficult to reprogram to form other tissue types other tissue types

Why are adult stem cells Why are adult stem cells preferable to embryonic stem preferable to embryonic stem cells?cells?

Adult stem cells are naturally exist Adult stem cells are naturally exist in our bodies, and they provide a in our bodies, and they provide a natural repair mechanism for many natural repair mechanism for many tissues. tissues.

They belong in the They belong in the microenvironment of an adult body, microenvironment of an adult body, while embryonic stem cells belong while embryonic stem cells belong in the microenvironment of the in the microenvironment of the early embryo, where they tend to early embryo, where they tend to cause tumors and immune system cause tumors and immune system reactions.reactions.

Superior features of Superior features of ESCsESCs Embryonic stem cells are easier to Embryonic stem cells are easier to

identify, isolate and harvest.identify, isolate and harvest. There are more of them.There are more of them. They grow more quickly and They grow more quickly and

easily in the lab than adult stem easily in the lab than adult stem cells.cells.

They can be more easily They can be more easily manipulated (they are more manipulated (they are more plastic)plastic)

Classification based Classification based on level of on level of differentiationdifferentiation

TTotipotentotipotent

PluripotentPluripotent

Multipotent Multipotent

Unipotent stem cellsUnipotent stem cells

Types of Stem cellsTypes of Stem cells

Totipotent stem cellsTotipotent stem cells

1.1. The fertilized egg is said to be The fertilized egg is said to be totipotent totipotent from the Latin from the Latin totus,totus, meaning meaning “entire”.“entire”.. .

2.2. It has the potential to generate It has the potential to generate all the cells and tissues that all the cells and tissues that make up an make up an embryoembryo. .

3.3. It supports embryonic It supports embryonic development development in uteroin utero. .

Pluripotent stem cellsPluripotent stem cells

Pluripotent stem cellsPluripotent stem cells are are descendants of the totipotent descendants of the totipotent stem cells of the embryo. stem cells of the embryo.

These cells develop about four These cells develop about four days after fertilizationdays after fertilization

They can differentiate into any They can differentiate into any cell type, except for totipotent cell type, except for totipotent stem cells and the cells of the stem cells and the cells of the placenta.placenta.

Pluripotent stem cellsPluripotent stem cells

““Pluri”Pluri” is derived from the is derived from the Latin Latin plures plures means means several or several or many. many. Thus, pluripotent cells have Thus, pluripotent cells have the potential to give rise to the potential to give rise to any type of cell. any type of cell.

Pluripotent stem cellsPluripotent stem cells

These cells cannot re-These cells cannot re-create a complete create a complete organism but differentiate organism but differentiate to a large number of to a large number of mature tissue types, for mature tissue types, for example, brain and example, brain and muscle. muscle.

Multipotent stem Multipotent stem cellscells

Multipotent stem cells are Multipotent stem cells are descendents of pluripotent stem descendents of pluripotent stem cells and antecedents of specialized cells and antecedents of specialized cells incells in particular tissues. particular tissues.

For example, hematopoietic stem For example, hematopoietic stem cells, which are found primarily in cells, which are found primarily in the the bone marrow,bone marrow, give rise to all of give rise to all of the cells found in the the cells found in the blood,including red blood cells, blood,including red blood cells, white blood cells, and platelets.white blood cells, and platelets.

Unipotent stem cellUnipotent stem cell

Unipotent stem cellUnipotent stem cell,, a term a term that is usually applied to a that is usually applied to a cell in adult organisms, means cell in adult organisms, means that the cells in question are that the cells in question are capable of differentiating capable of differentiating along only one lineage. along only one lineage. "Uni""Uni" is derived from the Latin is derived from the Latin word word unus,unus, which means one. which means one.

Progenitor Progenitor cellscells

Progenitor cellsProgenitor cells (or (or unipotent stem cellsunipotent stem cells) can ) can produce only one cell type. produce only one cell type.

For example, For example, erythroid erythroid progenitor cellsprogenitor cells differentiate into only red differentiate into only red blood cells.blood cells.

Blood is made in the Bone Blood is made in the Bone Marrow-Blood Cell DevelopmentMarrow-Blood Cell Development

““Terminally differentiated" Terminally differentiated" cellscells

At the end of the long chain At the end of the long chain of cell divisions are of cell divisions are "terminally differentiated""terminally differentiated" cellscells, such as a liver cell or , such as a liver cell or lung cell, which are lung cell, which are permanently committed to permanently committed to specific functions.specific functions.

Adult stem cells Adult stem cells (ASC)(ASC)

Adult stem cells or Adult stem cells or somatic stem cellssomatic stem cells Adult stem cells are undifferentiated Adult stem cells are undifferentiated cells.cells.They are found in They are found in small numberssmall numbers in in most adult tissues.most adult tissues.They can also be extracted from They can also be extracted from umbilical cord blood. umbilical cord blood. They are also called They are also called “somatic stem “somatic stem cells,”cells,” They are multipotent in nature. They are multipotent in nature. They give rise to a closely related family They give rise to a closely related family of cells within the tissueof cells within the tissue. . An example is hematopoietic stem cells, An example is hematopoietic stem cells, which form all the various cells in the which form all the various cells in the blood.blood.

Adult stem cell Adult stem cell plasticity and plasticity and transdifferentiationtransdifferentiation

This ability to This ability to differentiate into differentiate into multiple cell types is multiple cell types is called plasticity or called plasticity or transdifferentiationtransdifferentiation..

DifferentiationDifferentiation pathways of adult pathways of adult stem cellsstem cells

Neural stem cellsNeural stem cells in the brain give rise to its in the brain give rise to its three major cell types: nerve cells (neurons) three major cell types: nerve cells (neurons) and two categories of non-neuronal cells — and two categories of non-neuronal cells — astrocytes and oligodendrocytes. astrocytes and oligodendrocytes.

Epithelial stem cellsEpithelial stem cells in the lining of the in the lining of the digestive tract occur in deep crypts and give digestive tract occur in deep crypts and give rise to several cell types: absorptive cells, rise to several cell types: absorptive cells, goblet cells, Paneth cells, and enteroendocrine goblet cells, Paneth cells, and enteroendocrine cells. cells.

Skin stem cellsSkin stem cells occur in the basal layer of the occur in the basal layer of the epidermis and at the base of hair follicles.epidermis and at the base of hair follicles.

The epidermal stem cellsThe epidermal stem cells give rise to give rise to keratinocytes, which migrate to the surface of keratinocytes, which migrate to the surface of the skin and form a protective layer.the skin and form a protective layer.

The follicular stem cellsThe follicular stem cells can give rise to both can give rise to both the hair follicle and to the epidermis the hair follicle and to the epidermis

The similarities and differences between embryonic and adult stem cells

Embryonic stem cellsEmbryonic stem cells can become all cell can become all cell types of the body because they are types of the body because they are pluripotentpluripotent..

Adult stem cells are generally limited Adult stem cells are generally limited to differentiating into different cell to differentiating into different cell types of their tissue of origin. types of their tissue of origin.

However, some evidence suggests that However, some evidence suggests that adult stem cell adult stem cell plasticityplasticity may exist, may exist, increasing the number of cell types a increasing the number of cell types a given adult stem cell can become.given adult stem cell can become.

Human embryonicHuman embryonic and and adult stem cellsadult stem cells

A potential advantage of using stem A potential advantage of using stem cells from an adult is that the patient's cells from an adult is that the patient's own cells could be expanded in culture own cells could be expanded in culture and then reintroduced into the patient.and then reintroduced into the patient.

The use of the patient's own adult The use of the patient's own adult stem cells would mean that the cells stem cells would mean that the cells would not be rejected by the immune would not be rejected by the immune system. system.

Embryonic stem cells from a donor Embryonic stem cells from a donor introduced into a patient could cause introduced into a patient could cause transplant rejection. transplant rejection.

Umbilical cord stem cells

Blood from the placenta and umbilical Blood from the placenta and umbilical cord that are left over after birth is a cord that are left over after birth is a rich source of hematopoietic stem cells. rich source of hematopoietic stem cells.

These so-called These so-called umbilical cord stem umbilical cord stem cellscells have been shown to be able to have been shown to be able to differentiate into bone cells and differentiate into bone cells and neurons, as well as the cells lining the neurons, as well as the cells lining the inside of blood vessels.inside of blood vessels.

Importance of Importance of Cord blood stem cellsCord blood stem cells

Cord blood stem cells have been Cord blood stem cells have been used to treat 70 different diseases, used to treat 70 different diseases, including leukemia, lymphoma, and including leukemia, lymphoma, and inherited diseases (of red blood inherited diseases (of red blood cells, the immune system, and cells, the immune system, and certain metabolic abnormalities). certain metabolic abnormalities). Cord blood collection is a safe, Cord blood collection is a safe, simple procedure that poses no simple procedure that poses no risk to the mother or newborn risk to the mother or newborn baby.baby.

Embryonic Stem Cells Embryonic Stem Cells (ESC). (ESC).

Embryonic Stem CellsEmbryonic Stem Cells

Embryonic Stem Cells are derived Embryonic Stem Cells are derived from embryos that develop from eggs from embryos that develop from eggs that have been fertilized that have been fertilized in vitroin vitro..

Embryonic Stem Cells are never Embryonic Stem Cells are never derived from eggs fertilized inside of derived from eggs fertilized inside of a woman's body. a woman's body.

The embryos from which Human The embryos from which Human Embryonic Stem Cells are derived are Embryonic Stem Cells are derived are typically four or five days old and are typically four or five days old and are a hollow microscopic ball of cells a hollow microscopic ball of cells called the blastocyst called the blastocyst

Embryonic stem cells Embryonic stem cells (ESC)(ESC)

Embryonic stem cells (ESC), as their Embryonic stem cells (ESC), as their name suggests, are derived from name suggests, are derived from embryos.embryos. Specifically, embryonic stem cells are Specifically, embryonic stem cells are derived from embryos that develop from derived from embryos that develop from eggs that have been fertilized eggs that have been fertilized in vitro in vitro ——donated for research purposes with donated for research purposes with informed consent of the donors.informed consent of the donors. They are They are not not derived from eggs fertilized derived from eggs fertilized in a woman's body. in a woman's body.

Properties of Embryonic Properties of Embryonic Stem CellsStem Cells

a Derived from the inner cell mass of the a Derived from the inner cell mass of the blastocyst. blastocyst.

a Capable of undergoing an unlimited a Capable of undergoing an unlimited number of symmetrical divisions without number of symmetrical divisions without differentiating (long-term self-renewal). differentiating (long-term self-renewal).

Exhibit and maintain a stable, full (diploid), Exhibit and maintain a stable, full (diploid), normal complement of chromosomes normal complement of chromosomes (karyotype). (karyotype).

Pluripotent ES cells can give rise to Pluripotent ES cells can give rise to differentiated cell types that are derived differentiated cell types that are derived from all three primary germ layers of the from all three primary germ layers of the embryo (endoderm, mesoderm, and embryo (endoderm, mesoderm, and ectoderm). ectoderm).

Potential sources of stem Potential sources of stem cells are:cells are:

fetal tissue that becomes available after an fetal tissue that becomes available after an abortion abortion excess embryos from assisted reproductive excess embryos from assisted reproductive technologies such as commonly used in technologies such as commonly used in fertility clinics fertility clinics embryos created through in vitro fertilization embryos created through in vitro fertilization specifically for research purpose, and specifically for research purpose, and embryos created asexually as a result of the embryos created asexually as a result of the transfer of a human somatic cell nucleus to transfer of a human somatic cell nucleus to an egg with its own nucleus removed.an egg with its own nucleus removed.Other sources of stem cells are those from Other sources of stem cells are those from umbilical cord blood, and bone marrow.umbilical cord blood, and bone marrow. In addition, neural stem cells, In addition, neural stem cells, haematopoetic stem cells and mesenchymal haematopoetic stem cells and mesenchymal stem cells can be harvested from fetal blood stem cells can be harvested from fetal blood and fetal tissue.and fetal tissue.

Cell therapy.Cell therapy.

Treatment of neural diseases such Treatment of neural diseases such as Parkinson's disease, as Parkinson's disease, Huntington’s disease and Huntington’s disease and Alzheimer's disease. Alzheimer's disease. Stem cells could be used to repair Stem cells could be used to repair or replace damaged neurons.or replace damaged neurons.Repair of damaged organs such as Repair of damaged organs such as the liver and pancreas. the liver and pancreas. Treatments for AIDS. Treatments for AIDS.

Stem cell Stem cell transplantation (SCT)transplantation (SCT) Stem cell transplantation (SCT) is the Stem cell transplantation (SCT) is the

term now used in preference to bone term now used in preference to bone marrow transplantation (BMT). marrow transplantation (BMT).

When a patient's bone marrow fails to When a patient's bone marrow fails to produce new blood cells, for whatever produce new blood cells, for whatever reason, he or she will develop anaemia, reason, he or she will develop anaemia, be prone to frequent, persistent be prone to frequent, persistent infections and may develop serious infections and may develop serious bleeding problems.bleeding problems.

In order to restore blood cell production In order to restore blood cell production a patient may be given healthy stem a patient may be given healthy stem cells. cells.

Therapeutic cloning/ Therapeutic cloning/ somatic cell nuclear somatic cell nuclear transfertransfer

Scientists first remove Scientists first remove the nucleusthe nucleus from a from a normal egg cell of a womannormal egg cell of a woman. They then . They then extract extract a nucleus from a somatic cella nucleus from a somatic cell - that - that is, any body cell other than an egg or is, any body cell other than an egg or sperm—from a patient who needs an sperm—from a patient who needs an infusion of stem cells to treat a disease or infusion of stem cells to treat a disease or injury, and injury, and insert the nucleus into the egg. insert the nucleus into the egg. The egg, which now contains the patient's The egg, which now contains the patient's genetic material, is allowed to divide and genetic material, is allowed to divide and soon forms a hollow sphere of cells called a soon forms a hollow sphere of cells called a blastocystblastocyst.. Cells from Cells from the inner cell massthe inner cell mass are isolated are isolated and used to develop new embryonic stem and used to develop new embryonic stem cell (ESC) lines.cell (ESC) lines.

Strategy for therapeutic Strategy for therapeutic cloning and tissue cloning and tissue engineeringengineering

Stem cells and cancer Stem cells and cancer treatmenttreatment

Intense chemotherapy damages a person’s Intense chemotherapy damages a person’s bone marrow, where the stem cells for blood bone marrow, where the stem cells for blood reside.reside.Depleted of a fresh supply of blood cells, the Depleted of a fresh supply of blood cells, the patient is left vulnerable to infection, anemia patient is left vulnerable to infection, anemia and bleeding. and bleeding. These side effects of chemotherapy are often These side effects of chemotherapy are often treated with a bone marrow transplant.treated with a bone marrow transplant. “ “Transplanting bone marrow tissue into a Transplanting bone marrow tissue into a chemo-cancer patient may involve hundreds chemo-cancer patient may involve hundreds of thousands or millions of cells – of which of thousands or millions of cells – of which only two or three may be actual stem cells. only two or three may be actual stem cells. It would be much more efficient if you could It would be much more efficient if you could inject a thousand purified stem cells,”inject a thousand purified stem cells,”

Therapeutic cloning for tissue repair

One human organ, skin, is readily One human organ, skin, is readily cultured to provide replacement cultured to provide replacement tissue for burns victims.tissue for burns victims.

Healthy skin cells from the Healthy skin cells from the patient can be grown rapidly patient can be grown rapidly in in vitro vitro to provide self-compatible to provide self-compatible skin grafts.skin grafts.

Is Stem Cell Research Is Stem Cell Research Ethical?Ethical?

    * * Embryonic Stem CellsEmbryonic Stem Cells - - always morally always morally objectionable, because the human embryo must objectionable, because the human embryo must be destroyed in order to harvest its stem cells.be destroyed in order to harvest its stem cells.  *   * Embryonic Germ CellsEmbryonic Germ Cells - - morally objectionable morally objectionable when utilizing fetal tissue derived from elective when utilizing fetal tissue derived from elective abortions, but morally acceptable when utilizing abortions, but morally acceptable when utilizing material from spontaneous abortions material from spontaneous abortions (miscarriages) if the parents give informed (miscarriages) if the parents give informed consent.consent.  *   * Umbilical Cord Stem CellsUmbilical Cord Stem Cells - - morally acceptable, morally acceptable, since the umbilical cord is no longer required once since the umbilical cord is no longer required once the delivery has been completed.the delivery has been completed.    * * Placentally-Derived Stem CellsPlacentally-Derived Stem Cells - - morally morally acceptable, since the afterbirth is no longer acceptable, since the afterbirth is no longer required after the delivery has been completed.required after the delivery has been completed.  *   * Adult Stem CellsAdult Stem Cells - - morally acceptable. morally acceptable.

Sources ConsultedSources Consulted

Odorico, J.S., Kaufman, D.S., and Thomson, J.A. Odorico, J.S., Kaufman, D.S., and Thomson, J.A. (2001). Multilineage differentiation from (2001). Multilineage differentiation from human embryonic stem cell lines. Stem Cells. human embryonic stem cell lines. Stem Cells. 19,19, 193 -204. 193 -204.

Smith, A.G. (2001). Origins and properties of Smith, A.G. (2001). Origins and properties of mouse embryonic stem cells. Annu. Rev. Cell. mouse embryonic stem cells. Annu. Rev. Cell. Dev. Biol. Dev. Biol.

Thomson, J.A. and Marshall, V.S. (1998). Thomson, J.A. and Marshall, V.S. (1998). Primate embryonic stem cells. Curr. Top. Dev. Primate embryonic stem cells. Curr. Top. Dev. Biol. Biol. 38,38, 133-165. 133-165.

Chandross, K.J. and Mezey, E. (2001). Plasticity Chandross, K.J. and Mezey, E. (2001). Plasticity of adult bone marrow stem cells. Mattson, of adult bone marrow stem cells. Mattson, M.P. and Van Zant, G. eds. (Greenwich, CT: JAI M.P. and Van Zant, G. eds. (Greenwich, CT: JAI Press). Press).

Slack, J.M. (2000). Stem cells in epithelial Slack, J.M. (2000). Stem cells in epithelial tissues. Science. tissues. Science. 287,287, 1431-1433. 1431-1433.

Sources ConsultedSources Consulted Dzierzak, E., Medvinsky, A., and de Bruijn, M. Dzierzak, E., Medvinsky, A., and de Bruijn, M.

(1998). Qualitative and quantitative aspects of (1998). Qualitative and quantitative aspects of haematopoietic cell development in the haematopoietic cell development in the mammalian embryo. Immunol. Today. mammalian embryo. Immunol. Today. 19,19, 228- 228-236.236.

MacKey, M.C. (2001). Cell kinetic status of MacKey, M.C. (2001). Cell kinetic status of haematopoietic stem cells. Cell. Prolif. haematopoietic stem cells. Cell. Prolif. 34,34, 71- 71-83. 83.

J. A. Thomson, et al., 'Embryonic stem cell lines J. A. Thomson, et al., 'Embryonic stem cell lines derived from human blastocysts', Science, no. derived from human blastocysts', Science, no. 5391, vol. 282, November 1998, pp. 1145–7. 5391, vol. 282, November 1998, pp. 1145–7.

B. E. Reubinoff, M. F. Pera, C-Y Fong, A. B. E. Reubinoff, M. F. Pera, C-Y Fong, A. Trounson and A. Bongso, 'Embryonic stem cell Trounson and A. Bongso, 'Embryonic stem cell lines from human blastocysts: somatic lines from human blastocysts: somatic differentiation differentiation in vitroin vitro', ', Nature Biotechnology, Nature Biotechnology, vol. 18, pp. 399–404, 01 April 2000. vol. 18, pp. 399–404, 01 April 2000.