Stem cells and Immune System Cells - PowerPoint Presentation

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Stem cells and Immune System Cells

Lecturer Dr Samah A. Jassam BSc MSc PhD MRSB

Al-Mustansiriya University Collage of Pharmacy

Two

major types of stem cells in

mammals:

1- Embryonic

stem cells

, that are isolated from the inner cell mass of

blastocytes

.2- Adult stem cells, which are found in various types of tissues in adult organisms.

Stem cells are undifferentiated cells, these cells can divide by mitosis to produce more stem cells (self-renew) cells. They are found in multicellular organisms.

Stem cells

The discovery of

s

tem cells

In 1981. the detailed study of the biology of mouse stem cells has led to the discovery of the stem cells

.

In 1998, a discovery of a method to derive human stem cells from human embryos and grow the cells in the laboratory

.

Ethics



The

embryos used in these studies were created for reproductive purposes through

in

vitro

fertilization

procedures.

When they were no longer needed for that purpose, they were donated for research with the informed consent of the donor.

Stem cells are recognized from other cell types by

three major characteristics as follow:

Stem cells are

undifferentiated

cells.

Capable of renewing themselves through cell division, even after long periods of inactivity.

They have the potential to become specialized cells, such as muscle cells, blood cells, and brain cells.

Types of Adult Stem Cells

Stem cells are classified into two major categories

Embryonic stem cells (ESC)

:

these cells are derived from embryos at a developmental stage before the time of implantation would normally occur in the uterus. can give rise to cells from all three embryonic germ layers i.e. ectoderm, mesoderm and endoderm,

Adult stem cells (ASC):

Adult stem cells are undifferentiated cells found throughout the body that divide to replenish dying cells and regenerate damaged tissue. They are also known as somatic stem cells which can be found in children as well as adults.

Types of Adult Stem Cells

Bone marrow hematopoietic stem

cells

Hematopoietic stem cells are the early precursor cells which

give

rise to all the blood cell types that includes both the myeloid

and lymphoid lineages

2. Bone marrow stromal stem cells: Mammary stem cells provide

the source of cells for growth of mammary gland.

3. Neural

stem cells

: The existence of stem cells in the adult

brain

following

the discovery that the process of neurogenesis4. Olfactory adult stem cells: Olfactory adult stem cells

isolated from

human olfactory mucosa

cells.

5. Adipose

derived adult stem cells

: These

cell shave

also been isolated

from

human

fat tissue.

Present scenario in stem cell

therapy

Allogenic

stem cell therapy: matched or unmatched

Syngenic

stem cell transplant: Identical twin

Autologous stem cell transplant

Cord blood stem cell transplant

Complications of stem cell therapy infection

, regimen toxicity,carcinogenicity,

immune deficiency and,

mortality due to co-occurrence of complications.

Blood tissue

Structure of Blood tissue

Blood tissue is found inside the blood vessels (arteries, arterioles, capillaries, venules and veins). Blood consists of many components (constituents) :

55% plasma,

45% which are the blood

cells

99

% of the blood cells are red blood cells (erythrocytes) and 1% are the white blood cells (leukocytes) and blood platelets

(thrombocytes).

Haematopoiesis

is the production of all types of blood cells including formation, development, and differentiation. It occurs in the

yolk sack, then in the liver, and lastly in the bone marrow

. In the normal situation, haematopoiesis in adults occurs in the bone marrow and lymphatic tissues.

Haematopoietic stem cells (HSCs)

HSCs are localised in the medulla of the bone marrow and have the unique ability to give rise to all of the different mature blood cell types and tissues. HSCs are self-renewing cells, some of their daughter cells remain as HSCs, and this phenomenon is called asymmetric division.

The other daughter cells will be either myeloid or lymphoid progenitor cells, they can differentiation, but cannot renew themselves.

All

blood cells are divided into three

lineages

Erythroid cells

are the oxygen carrying red blood cells.

Lymphocytes

are derived from common

lymphoid progenitors. The lymphoid lineage is primarily composed of T-cells and B-cells (types of white blood cells).

Myelocytes, which include granulocytes, megakaryocytes and macrophages and are derived from common myeloid progenitors

, are involved in such diverse roles as innate immunity,

adaptive

immunity, and blood clotting.

Formation of red blood cells (RBC) (erythrocytes)

Red blood cell production takes place in the

bone marrow

under the control of the

hormone EPO

. This hormone (EPO) is produced in the

kidney

in response to decreased O2

delivery (as in anemia and hypoxia).

RBC

production requires adequate supplies of substrates, mainly

iron, vitamin

B

12

, and folate

. RBCs survive about 120 days. They then lose their cell membranes and are largely cleared from the circulation by the phagocytic cells of the spleen, liver, and bone marrow.

Formation of platelets

Platelets are produced during haematopoiesis from common myeloid progenitor cells in the bone marrow, which differentiate into

promegakaryocytes

and then into megakaryocytes. Megakaryocytes stay in the bone marrow and are thought to produce

protoplatelets

within their cytoplasm, which are released in cytoplasmic extensions upon cytokine stimulus. The protoplatelets then break up into hundreds of platelets that circulate throughout the

bloodstream

White blood

cells (WBC) (leukocytes)

All white blood cells are produced and derived from hematopoietic stem cells in the bone marrow. Leukocytes are found throughout the body, including the blood and lymphatic system. All white blood cells have nuclei, which distinguishes them from the other blood cells

.

Two pairs of major categories classify them

:

either by structure into (granulocytes or agranulocytes)

or by cell division lineage

into (myeloid cells or lymphoid cells).

Maturation of blood cells

As a stem cell matures it undergoes changes in gene expression. These changes can often be tracked by monitoring the presence of proteins on the surface of the cell.

Leukocytes

are rapidly increased during infection. The proliferation and self-renewal of these cells depend on growth factors. It is one of the key players in self-renewal and development of hematopoietic cells is stem cell factor (

SCF

).