GENERATION OF CELLS OF THE IMMUNE SYSTEM

STEM CELLS

EMBRYONIC STEM CELLS

BONE MARROW DERIVED

STEM CELLS

CD34+ HEMATOPOIETIC MESENCHYMAL

Spleen of irradiated mouseColony forming units (CFU)

Discovery of stem cellsDiscovery of stem cellsTill és McCullogh 1960Till és McCullogh 1960

FERTILIZED EGGFERTILIZED EGG

OmnipotentOmnipotent

EMBRYONAL STEM CELLEMBRYONAL STEM CELLPluripotentPluripotent

TISSUE STEM CELLTISSUE STEM CELLMultipotentMultipotent

MYELOIDMYELOID

LYPHOIDLYPHOID

DECISION OF CELL DIFFERENTIATIONDECISION OF CELL DIFFERENTIATION

EARLY MOUSE EMBRYOS Blastocyst stage of differentiation

4.5 DAY 5.5 DAY

Ectoplacental part

EXTRAEMBRYONAL PARTS

EMBRYONAL PARTS

Blastocoel

Dorsal part

Trophectoderm

Primitive ectoderm

Primitive endoderm

Extraembryonal ectoderm

Embryonal ectodermInner endoderm

Primitive amnion

Primitive sheet

Inner Cell Mass ICM

In vitroIn vitro fertilization – IVF – human embryos fertilization – IVF – human embryos

00

20

40

60

80

1 2 3 4 5 6 7 8 9 10 20 30 40 50 60 70

GENERATION OF BLOOD CELLS DURING LIFE SPAN

BEFORE BIRTH AFTER BIRTH

Spleen

Liver

Yolk sac

Cel

l num

ber

(%)

BIRTH

months years

Flat bones

Tubular bones

BONE MARROW TRANSPLANTATION

centrálissinus

csont

CELL TYPES OF THE BONE MARROW

Dendritic cell

B-cell precursors

Stem cells

Stromal cellsBONE

Centralsinus

Unspecialized stem cells with unlimited proliferating capacity

Osteoblasts

Osteoclasts

ProgenitorsProgenitors

PrecursorsPrecursors

Blood circulation

MYELOID LYMPHOID

BONE MARROW

CMP CLP

CD34+ HSC

ERYTHROID

BLOOD CELLSEndothelial cells Mesenhymal Stem Cells

(MSC)

Fat Bone CartilageOther Stem Cells

Neuronal cells Epithelial cells of the liver, kidney, skin, myocytes of the heart and muscle, GI tract

• Continuous replenishment of the hematopoietic system Continuous replenishment of the hematopoietic system

• Continuous generation of peripheral immune cellsContinuous generation of peripheral immune cells

• Circulating progenitors/precursors - BLOODCirculating progenitors/precursors - BLOOD

• Tissue-specific progenitors/precursors - TISSUESTissue-specific progenitors/precursors - TISSUES

LIMITED TISSUE – SPECIFIC REGENERATIVE POTENTIALLIMITED TISSUE – SPECIFIC REGENERATIVE POTENTIAL

At least one differentiated cellProgenitor/Precursor

More differentiated cellProgenitors/Precursors

Self renewal+

Assimmmetric cell division

IMPORTANCE OF TISSUE IMPORTANCE OF TISSUE STEM CELLSSTEM CELLS

SOMATIC CELLS

STEM CELLS

Telomerase +

ARE STEM CELLS EVER - YOUNG CELLS?

What about aging?

Replicative scenescence is inhibited by telomerase

Stromal cells – ‘niche’ is aging as other cell types

The number and the differentiating capacity of pluripotent stem cells

is decreasing with age

GC, HSC

Telomer length

HSC – assymetric cell division self renewal cell differentiation

centrálissinus

csont

Dendritic cell

HSC

Stromal cell

Centralsinus

Bone

SELF RENEWAL AND POTENCY OF DIFFERENTIATION OF STEM CELLS IS REGULATED BY:

• The stem cell ‘niche’

• Cytokines (LIF, SCF)

• Special signalling molecules

• JAK – STAT variants

• Transcription factors Oct-4

• Pluripotency maintaining factor Nanog

• HSC self renewing factor Bmi-1

• - inhibits the anti-proliferative, apoptosis promoting factors p16/p19Arf

• - enhances telomerase function

PLURIPOTENT BONE MARROW STEM CELLSPLURIPOTENT BONE MARROW STEM CELLS

REGENERATIVE MEDICINEREGENERATIVE MEDICINE

Ectodermal Mesodermal Endodermal

ADULT

Liver Pancreas Gut

Asahara & Kawamoto 2004 Am J Physiol Cell Physiol

L M

HMB

PericyteEPC

endothel

VASCULO / ANGIOGENESIS

Skin Neuro HSC Endothel

BoneBoneCartilage,

Muscle, Fat

MSC

OsteoblastOsteoblastOsteoclastOsteoclast

Differentiation of HSC from a more

pluripotent SC

HYERARCHY

PROPOSED MECHANISMS FOR ADULT STEM CELL PLASTICITY

HSC HSC HSC

Indirect trans-differentiation of HSC through a

more pluripotent SC

HSC

Direct trans-differentiation of

HSC

Fusion of HSC with tissue cell

TRANSDIFFERENTIATION - FLEXIBILITYGET THROUG ECTO-/ENDO-/MEZODERM BARRIERS

LYMPHOID/MYELOID BARRIERS

HEMOGENIC HEMOGENIC ENDOTHELIUMENDOTHELIUM

HSCHSC

EMBRYONAL DEVELOPMENT OF ENDOTHELIAL CELLS

Chen MJ et al. Nature 457:887, Lancrin C et al. Nature 457:892, Eilken HM et al. Nature 457:896, 2009

HemangioblasztHemangioblaszt

Flk-1Flk-1++brachurybrachury++

Hemogenic endotheliumHemogenic endotheliumTie2Tie2highhighc-Kitc-Kit++CD41CD41--

Primitive Primitive hematopoesishematopoesis

CD41CD41--CD45CD45--

Scl/Tal1Scl/Tal1

Hematopoesis Hematopoesis CD41CD41++CD45CD45--

Runx1/AML1Runx1/AML1

LT-HSCLT-HSC ST-HSCST-HSC

CMP CLPCMP CLP

Biomechanic stressBiomechanic stress

GENERATION OF GENERATION OF HEMATOPOETIC CELLSHEMATOPOETIC CELLS

Blood Blood cellcell

AORTAAORTA

HSCHSC

COUPLED DEVELOPMENT OF COUPLED DEVELOPMENT OF ENDOTHELIAL AND HEMATOPOETIC ENDOTHELIAL AND HEMATOPOETIC

STEM CELLS (HSC)STEM CELLS (HSC)

Adamo et al., Nature 2009, North TE, et al. Cell 2009Adamo et al., Nature 2009, North TE, et al. Cell 2009

A FELNŐTT HEMATOPOETIKUS ŐSSEJTEK KÉPZŐDÉSÉT A FELNŐTT HEMATOPOETIKUS ŐSSEJTEK KÉPZŐDÉSÉT BIZTOSÍTÓ CSONTVELŐI MIKROKÖRNYEZET BIZTOSÍTÓ CSONTVELŐI MIKROKÖRNYEZET „NICHE”„NICHE”

OsteoblastOsteoblast

MSCMSC HSCHSC

HSCHSC

HSCHSC

HSCHSC

Mobilised hematopoetic stem cells (HSC) develop in close contact with Mobilised hematopoetic stem cells (HSC) develop in close contact with osteoblasts, mesenchymal stem cells (MSC) and endothelial cellsosteoblasts, mesenchymal stem cells (MSC) and endothelial cells

Uccelli A et al. Nat Rev Immunol 2008Uccelli A et al. Nat Rev Immunol 2008

NestinNestin++MSCMSC

MULTIPOTENT MESENCHYMAL STEM CELL MULTIPOTENT MESENCHYMAL STEM CELL

Mesenchymal stem cells (MSC) modulate the functions of other cells throughMesenchymal stem cells (MSC) modulate the functions of other cells through cell – to – cell interactions and through soluble factors produced by them cell – to – cell interactions and through soluble factors produced by them

Uccelli A et al. Nat Rev Immunol 2008Uccelli A et al. Nat Rev Immunol 2008

CHARACTERISTICS AND FUNCTIONS OF MESENCHYMAL CHARACTERISTICS AND FUNCTIONS OF MESENCHYMAL STEM CELLSSTEM CELLS

• Regulation of bone marrow HSC

• Integrate to the bone • Not immunogenic• Migrate to the site of tissue

demage• Traverse vessel wall• Similar action in different

tissues• Produce trophic and induced

factors• React to inflammatory signals• Immune suppressive - GVHD• Support tumor growth

– Integration– Immune suppression

• BYSTANDER EFFECTS– Modulation of demaged tissue

environment• Inhibition of proliferation• Anti-inflammatory effect• Inhibition of immune cells• Inhibition of apoptosis• Trophic effects – HSC function

– WNT signaling– Notch signaling

– Similar effects to bone marrow functions

– Augmentation of endogenous regenerative mechanisms

– Low level of integration– Low level of trans-differentiation– „Touch and go”

Physical stress – shear Physical stress – shear STRESSSTRESS

Differenciated entothelial Differenciated entothelial cellscells

Permeability is increasingPermeability is increasingRetention and modulation of lipoproteinsRetention and modulation of lipoproteins

Decrease vessel wall Decrease vessel wall demagedemage

Restore regenerative mechanismsRestore regenerative mechanisms

EGYENSÚLYEGYENSÚLY

TISSUE ENVIRONMENTTISSUE ENVIRONMENT

Pro-angiogenic Anti-angiogenicPro-angiogenic Anti-angiogenic

HOMEOSTASIS OF HEALTHY ENDOTHELIAL CELLS REQUIRES HOMEOSTASIS OF HEALTHY ENDOTHELIAL CELLS REQUIRES CONTINUOUS REGENERATIONCONTINUOUS REGENERATION

CRONIC STRESSCRONIC STRESSAgeAge

SmokingSmokingHigh cholesterin levelsHigh cholesterin levels

High blood pressureHigh blood pressureDiabetesDiabetes

PROTECTIVE RESPONSEPROTECTIVE RESPONSEINFLAMMATIONINFLAMMATION

Modified endothelial Modified endothelial functionsfunctions

Plaque formationPlaque formationThrombosisThrombosis

Moreno et al. J Am Coll Cardiol 2009Moreno et al. J Am Coll Cardiol 2009

Decrease demage of vessel Decrease demage of vessel wallwall

Restore regenerative mechanismsRestore regenerative mechanisms

EQUILIBRIUMEQUILIBRIUMRemoval of cholesterolRemoval of cholesterol

Generation of new vesselsGeneration of new vesselsAngiogenesisAngiogenesis

VESSEL REGENERATION BY BONE MARROW-DERIVED STEM- AND VESSEL REGENERATION BY BONE MARROW-DERIVED STEM- AND PROGENITOR CELLSPROGENITOR CELLS

Biomechanic stress Biomechanic stress STRESSSTRESS

Smooth muscle Smooth muscle progenitor cells (SMPC)progenitor cells (SMPC)

Differentoated endothelial Differentoated endothelial cellscells

HemangioblastHemangioblast

Mesenchymal stroma cellsMesenchymal stroma cells EPCEPC

Endothelial progenitor cells Endothelial progenitor cells (EPC)(EPC)

Circulating EPC Circulating EPC numbernumberTrainingTraining

Statin therapyStatin therapyMobilisationMobilisation

Lipid reducing & anti-Lipid reducing & anti-inflammatory effectsinflammatory effects

COMPETENT BONE COMPETENT BONE MARROWMARROW

A GYULLADÁSOS FOLYAMATOK ELŐSEGÍTIK A CSONT A GYULLADÁSOS FOLYAMATOK ELŐSEGÍTIK A CSONT LEBONTÁSTLEBONTÁST

PROTECTIVE PROTECTIVE MECHANISMSMECHANISMS

INHIBITION OF BONE INHIBITION OF BONE FORMATIONFORMATION

INFLAMMATORY T INFLAMMATORY T CELL RESPONSECELL RESPONSE

BONE BONE DESORPTIONDESORPTION

InhibitionInhibition

GátlásGátlás

EnhancementEnhancement

MMMM RARA

THE INFLAMMATORY CYTOKINE IL-20 PLAYS A ROLE IN BONE RESORPTION AFTER MENOPAUSE

IL-20 citokine-specific anti-body inhibits RANK receptor expression on osteoclast precursors and RANKL expression on osteoblasts

Hsu Y-H et al. JEM 2011

BONE MARROW TRANSPLANTATIONBONE MARROW TRANSPLANTATION

• Increasing age limit• Increased number of typed

donors• Umbilical cord banks• Developing countries• New indications

– Autoimmune diseases– Tolerance induction– Regenerative medicine

• Non HSC-derived stem cells– adipose tissue-derived MSC-

Gratwohl & Baldomero Curr Opin Hematol 2009Gratwohl & Baldomero Curr Opin Hematol 2009

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CsoportCsoport

•Replacement of complex tissuesReplacement of complex tissues•Heterogenous cell populationsHeterogenous cell populations•Stem- and progenitor cell reservoire in Stem- and progenitor cell reservoire in adultsadults•Circulation and migration to tissue Circulation and migration to tissue through the blood through the blood •Reverse migration of peripheral immune Reverse migration of peripheral immune cells to the bone marrowcells to the bone marrow

Increasing number of bone marrow Increasing number of bone marrow transplantationstransplantations

1990-20071990-2007