Download Liver regeneration from stem cells

Manifestation of Novel Social Challenges of the
European Union
in the Teaching Material of
Medical Biotechnology Master’s Programmes
at the University of Pécs and at the University
of Debrecen
Identification number: TÁMOP-4.1.2-08/1/A-2009-0011
Manifestation of Novel Social Challenges of the
European Union
in the Teaching Material of
Medical Biotechnology Master’s Programmes
at the University of Pécs and at the University
of Debrecen
Identification number: TÁMOP-4.1.2-08/1/A-2009-0011
Dr. Péter Balogh and Dr. Péter Engelmann
Transdifferentiation and regenerative medicine –
Lecture 8
LIVER REGENERATION
FROM STEM CELLS
TÁMOP-4.1.2-08/1/A-2009-0011
Structure of the hepatic
lobe
Bile
canaliculi
Central vein
Central vein
Portal tracts
(triads)
Sinusoids
Portal tract
Bile duct
Branch portal Branch hepatic
vein
artery
Periportal
Centrilobular Glutamine synthetase +
(6-8 cells)
(8-10 cells) (1-3 cells)
Limiting plate
TÁMOP-4.1.2-08/1/A-2009-0011
Clinical necessity of liver
regeneration
• Shortage of livers for orthotopic
liver transplantation
• Liver cell transplantation – limited
amount
• Choice of stem cell candidates –
variable success in experimental
conditions
Main phases of liver
regeneration
Physical/chemical/genetical
1 Migration
stimulus
TÁMOP-4.1.2-08/1/A-2009-0011
Gadolinium chloride/
monocrotaline
3 Clearance
Organ damage
MMP-9
Central vein
2 Integration VEGF
Monocrotal
ine
Doxorubici
n
Hepatic
injury
VEGF
Sinus endothel
permeability
Recruitment
SDF-1
HGF
(SCF)
Stem cells
c-kit, c-met, CXCR4)
Organ damage
HGF
TGF
FGF
MMP-9
MMP-2
MT1-MMP
Cell loss of
Dead cell
Kupffer cells
Central vein
(phagocytosis)
Effector cells
Immunosuppressi
on
Encapsulation
Cotransplantation
Central vein
Alteration of blood flowVasodilatators
Gap junctions
Variable in vivo cell phenotype
Developmental relationship
between hepatic-pancreatic
differentiation
TÁMOP-4.1.2-08/1/A-2009-0011
?
Oval cell progenitor
Pancreatic progenitor(s)
Hepatic ovalPancreatic
cell
oval cell
Bile duct
HepatocyteEndocrine cell
Pancreatic duct
Acinar cell
TÁMOP-4.1.2-08/1/A-2009-0011
Transcriptional control of
hepatoblast development
Hepatoblast
HGF
C/EBP
HNF-6
Tbx3
HNF-1
HNF-4
Notch2
Hepatocyte
Core transcription
factor network:
Albumin
ECM
?
Jagged
Wnt
BMP+FGF
FoxM1B
ECM
Cholangiocyte
Hex
C/EBP
TGF
HNF-6/OC-2
HNF-4
HNF-1
HNF-6
LRH-1
Foxa2
HNF-1
Hepatocyte
maturation cords
Parenchyma Periportal
HNF-1
Sox9
Cholangiocyte
maturation ducts
TÁMOP-4.1.2-08/1/A-2009-0011
Oval cells – adult liver
stem/progenitor cells
• Origin: debated (their precursors are
associated with the biliary tree)
• Bipotential differentiation:
hepatocyte and cholangiocyte
• Phenotype: shared markers with adult
hepatocytes (albumin, cytokeratins 8
and 18), bile duct cells (cytokeratins
7 and 19, OV-6, A6), fetal
hepatoblasts (AFP), and haematopoietic
stem cells (Thy -1, Sca-1, c-kit).
Cellular targets for
hepatic regeneration
TÁMOP-4.1.2-08/1/A-2009-0011
• Hepatocytes: metabolic activity of the
liver
• Cholangiocytes: formation of bile
ducts
• Both derive from embryonic endodermal
epithelium.
TÁMOP-4.1.2-08/1/A-2009-0011
Stages and forms of liver
regeneration
• Surgical partial hepatectomy – from
hepatocytes (often polyploid cells)
• Possible sources: hepatocytes, oval cells
and extrahepatic stem cells (HSC?)
• Assessment of lineage commitment: albumin,
glucose-6-phosphatase, transferrin and
transthyretin (hepatic).
• Fibrotic regeneration: transformation of
fibrocytes into myofibroblasts
• Parenchymal regeneration: regeneration of
hepatocytes
TÁMOP-4.1.2-08/1/A-2009-0011
Sequence of parenchymal
regeneration of the liver
• Stem cell migration into the liver
parenchyma is directed by chemoattractive
agents (as SDF-1, HGF and SCF) secreted by
damaged liver cells
• Increased MMP-9 expression by host
hepatocytes after injury, leading to ECM
remodeling and increased vascular
permeability
• Transformation of local microenvironment for
the integration and proliferation of the
transplanted cells, including local
secretion of cytokines/growth factors (HGF,
FGF, TGF). Dead cells will be phagocyted by
Kupffer cells.
TÁMOP-4.1.2-08/1/A-2009-0011
Oval cell activation and
expansion
• Liver injury activates oval cells (their
precursors in the biliary tree?) AND other
support cells (stellate cells,
macrophages/Kupffer’s cells, NK cells,
endothelium, etc)
• Homing/intrahepatic migration to the site of
injury
• Proliferation and bidirectional
differentiation (hepatocyte/cholangiocyte)
TÁMOP-4.1.2-08/1/A-2009-0011
Non-hepatic cells for liver
regeneration
Autologous: Bone marrowderived/mesenchymal stem cells –
fibroblastic regeneration
Allogenic: Fetal-derived hepatocytes or
embryonic stem cell-derived liver cells
TÁMOP-4.1.2-08/1/A-2009-0011
Differentiation of iPS
cells into hepatocytes
• Induction of iPS cells: transfection with
TFs
• Formation of embryoid bodies
• Induction of endodermal commitment:
treatment with Activin A and bFGF
• Differentiation into hepatocytes: treatment
with hepatocyte growth factor (HGF)
• Assessment: gene expression, albumin
secretion, glycogen storage, urea
production, and inducible cytochrome
activity
TÁMOP-4.1.2-08/1/A-2009-0011
Summary
• Depending on the origin/type of liver
damage, different regeneration processes
operate, thus (a) in loss of liver mass, the
regeneration is initiated from hepatocytes,
whereas (b) in toxicity from hepatocholangiocyte progenitors.
• Oval cells as adult-type
hepatocyte/cholangiocyte progenitors are
most likely to be facultative stem cells,
although cells with stem cell activity from
extrahepatic sources may also operate in
liver regeneration.