DASAR STEM CELL DAN PENGEMBANGAN

TERAPI ORGAN

Prof. Dr. Marlina, MS, Apt

Seminar Nasional FarmasiRocky Hotel, Padang, 23 Juni 2012

STEM CELL RESEARCH - WHAT IS IT ALL ABOUT?

http://stemcells.nih.gov/info/basics/ "Image courtesy of NIH resource for stem cell research"

What are stem cells? Stem cells are undifferentiated cells that

have many potential scientific uses: Cell based therapies

Often referred to as regenerative or reparative medicine

Therapeutic cloning Gene therapy Cancer research Basic research

Two types of stem cells

Embryonic Stem Cells (ESC): received from: Embryos created in vitro fertilization Aborted embryos

Adult Stem Cells (ASC): can be received from: Limited tissues (bone marrow, muscle,

brain)Discrete populations of adult stem cells

generate replacements for cells that are lost through normal wear and tear, injury or disease

Placental cord

“ADULT” STEM CELLS ARE OBTAINED IN A VARIETY OF WAYS

Illustration by Matt Bohan, 2007

STEM CELLS HAVE ALSO BEEN FOUND IN “MATURE”

ORGANS

Illustration by Matt Bohan, 2007

Source of ESC Blastocyst

3-5 day old embryo Stem cells give rise to multiple

specialized cell types that make up the heart, lung, skin, and other tissues

Human ESC were only studied since 1998 It took scientists 20 years to learn how

to grow human ESC following studies with mouse ESC

How are embryonic stem cells harvested?

Human ES cells are derived from 4-5 day old blastocyst

Blastocyst structures include: Trophoblast: outer layer of cells that surrounds

the blastocyst & forms the placenta Blastocoel: (“blastoseel”) the hollow cavity inside

the blastocyst that will form body cavity Inner cell mass: a group of approx. 30 cells at

one end of the blastocoel: Forms 3 germ layers that form all embryonic tissues

(endoderm, mesoderm, ectoderm)

Blastocyst

http://www.ivf-infertility.com/infertility/infertility5.php

Unique characteristics of Stem Cells

Stem cells can regenerate Unlimited self renewal through cell

division Stem cells can specialize

Under certain physiologic or experimental conditions

Stem cells then become cells with special functions such as:Beating cells of the heart muscleInsulin-producing cells of the pancreas

Self - Renewal (Regeneration)

Stem cells are capable of dividing & renewing themselves for long periods This is unlike muscle, blood or

nerve cells – which do not normally replicate themselves

In the lab, a starting population of SCs that proliferate for many months yields millions of cells that continue to be unspecializedThese cells are capable of long-term self-renewal

Specialization of Stem Cells: Differentiation

Differentiation: unspecialized stem cells give rise to specialized (differentiated) cells in response to external and internal chemical signals Internal signals: turn on specific

genes causing differential gene expression

External signals include:Chemicals secreted by other cells such as growth factors, cytokines, etc.

Physical contact with neighboring cells

Potential of Stem Cells

Totipotent (total): Total potential to differentiate into

any adult cell type Total potential to form specialized

tissue needed for embryonic development

Pluripotent (plural): Potential to form most or all 210

differentiated adult cell types

Multipotent (multiple): Limited potential Forms only multiple adult cell

typesChondrocyteNeurons

Unipotent – these cells only produce one cell type., but have the property of self renewal which distinguishes them from the non stem cells.

http://www.stemcellresearch.org/testimony/20040929prentice.htm Reprinted with permission of Do No Harm.

Adult Stem CellsAdult or somatic stem cells

have unknown origin in mature tissuesUnlike embryonic stem cells, which are defined by their origin (inner cell mass of the blastocyst)

Potential of Adult Stem Cells

Adult stem cells continued

Adult stem cells typically generate the cell types of the tissue in which they reside Stem cells that reside in bone

marrow give rise to RBC, WBC and platelets

Recent experiments have raised the possibility that stem cells from one tissue can give rise to other cell typesThis is known as PLASTICITY

Adult Stem Cell Plasticity Examples

Blood cells becoming neurons Liver cells stimulated to produce insulin Hematopoietic (blood cell producing)

stem cells that become heart cells

CONCLUSION: Exploring the use of adult stem cells for cell-based therapies has become a very important (and rapidly increasing) area of investigation by research scientists!

Adult stem cells: A brief history

Adult stem cell research began about 40 years ago

Stem cell discoveries in 1960s: Bone marrow contains 2 populations of

stem cellsHematopoietic stem cells – forms all

blood cell typesBone marrow stromal cells – mixed cell

population that generates bone, cartilage, fat and fibrous connective tissue

Rat brain contains two regions of dividing cells, which become nerve cells

History Cont. Stem Cell

Discoveries in the 1990s Neural stem cells in

brain are able to generate the brain’s three major cell types

Astrocytes Oligodendroglial

cells Neurons

http://www.alsa.org/images/cms/Research/Topics/cell_targets.jpg

Potential Uses of Stem Cells

Basic research – clarification of complex events that occur during human development & understanding molecular basis of cancerMolecular mechanisms for gene control

Role of signals in gene expression & differentiation of the stem cell

Stem cell theory of cancer

Potential uses cont. Biotechnology(drug discovery &

development) – stem cells can provide specific cell types to test new drugs Safety testing of new drugs on

differentiated cell lines Screening of potential drugs

Cancer cell lines are already being used to screen potential anti-tumor drugs

Availability of pluripotent stem cells would allow drug testing in a wider range of cell types & to reduce animal testing

Potential uses cont. Cell based therapies:

Regenerative therapy to treat Parkinson’s, Alzheimer’s, ALS, spinal cord injury, stroke, severe burns, heart disease, diabetes, osteoarthritis, and rheumatoid arthritis

Stem cells in gene therapyStem cells as vehicles after they have

been genetically manipulated Stem cells in therapeutic cloning Stem cells in cancer

Embryonic vs Adult Stem Cells

Totipotent Differentiation

into ANY cell type Known Source Large numbers can

be harvested from embryos

May cause immune rejection Rejection of ES

cells by recipient has not been shown yet

Multi or pluripotent Differentiation into

some cell types, limited outcomes

Unknown source Limited numbers,

more difficult to isolate

Less likely to cause immune rejection, since the patient’s own cells can be used

Application of stem cells

Stem cell research:1. It provides an ideal model

for the study of development of organisms

2. It replaces damaged cells of the body

3. It also aids in drug discovery

Regenerative medicine andTherapeutic issues

Bone marrow transplant:Example of adult stem cell-based

therapy

Haematopoeitic stem cells

Derived from bone marrow in adults and umbilical cord blood

Option given to the parents regarding stem cell banking during antenatal visits

25% chance that sibling also can have a perfect match

The Nobel Prize, 1990

E. Donnall Thomas

first succsessful HSCT in treatment of acute leukemias

Thomas ED, Lochte HL, Lu WC, Ferrebee JW. Intravenous infusion of bone marrow in patients receiving radiation and chemotherapy. N. Engl. J. Med.

1957; 257: 491.

Blood is collected from umb cord immediately after delivery about 100-150cc

The number of cells in 1 ml is 40,000

They are stored in blood banks at -196deg celsius in a state of suspended animation and restart their activity on thawing

Hematopoietic and Stromal Adult Stem Cell Differentiation

stemcells.nih.gov/.../images/figure2_lg.jpg

Ailments for which stem cells are being

used now Acute leukemias

Chronic leukemias

Myelodysplastic syndromes

Marrow failure Myeloprolifera

tive disorders Lymphoprolife

rative disorders

Trials underway Cardiac disease Diabetes Multiple Sclerosis Muscular Dystrophy Parkinson’s disease Spinal cord injury Stroke

Cell Therapy in Failing Heart GOAL

Transfer of functional myocytes to heart – Improve its function

The DEALS “ Homing of grafted cells” Engraft into non functional scar Electromechanical coupling and synchronisation Neo angiogenesis and myogenesis Good craft survival Low immunogenecity Ethical acceptance Low oncogenicity Case of application

Stem cells for myocardial regeneration

HETEROLOGOUS• Fetal

cardiomyocytes• Embryonal stem

cells

AUTOLOGOUS•Skeletal myoblast•Endothelial progenitors•Bone marrow stem cells

Stem cells therapy

Cardiovascular note Infarct repair Cardiomyopathy treatment End stage coronary artery disease

Bone marrow stem cells

Hemapoeitic Stem cells T-2%

Endothelial Progenitor cells <0.05% (Stromal stem cells)

(Lin – c Kit (+ve) ; AC 133+)

Transplantation HEART Translocation(Endogenous stem cell mobilization)

CARDIOMYOCYTESEndothelium sm cells

G – CSFGM - CSF

CD 34+

Diabetes ResearchWhat is known cells are not generated from

adult stem cells in the pancreas. It is unlikely that a cure for

diabetes will come from adult stem cells.

Embryonic stem cells have been shown to generate insulin-producing cells.

What Has Been Tried:Whole organ pancreas transplants

Problem: not enough organs to meet the demand

Problem: must take powerful immunosuppressants

What Has Been Tried:

Injections of pancreatic islet cellsProblem: less than 8% of

these transplants have been successful

Problem: immunosuppressants are required

Problem: There is much work to be done before this technique will be ready—if it is ever ready.

Possible Next Step:Inject cells into the patient’s pancreas

Possible Next Step:Activate cells in the patient’s own pancreas Problem: There may be no

cells left in the pancreas of a patient to activate.

Possible Next Step

Provide type l diabetics with transplants of cells derived from embryonic stem cells.

What We Need to Know What properties make

embryonic stem cells unique? Where do these cells come

from? How are they involved in the

formation of the pancreas, cells, and other tissues?

What makes them unique?

can regenerate an infinite number of times

can be grown in culture indefinitely

are classified as pluripotent

are able to differentiate into specialized cells as needed

Germ Layer Differentiation

Forming Specialized Cells

Growth factors and other signals tell a stem cell when to differentiate and what type of cell to become.

Forming Specialized Cells

The same growth factors and signals could be used to direct the differentiation of human embryonic stem cells grown in culture.

What is Known