The document discusses liver tissue engineering and technologies for implantable liver therapies. It describes: 1. The types of cells in the liver and their functions. 2. Complications that can result from liver damage like cirrhosis and failure. 3. The history and development of implantable technologies including cell encapsulation, 3D printing, scaffolds, and decellularization/recellularization techniques to engineer liver tissue for transplantation. 4. Applications include using decellularized liver scaffolds that can be repopulated with cells to create functional liver tissue for transplantation or models for drug testing.

1. LIVER TISSUE
ENGINEERING
Kolla Srivalli
201709010
MSc Systems Biology
Manipal School of Lifesciences

2. Liver
• Liver is large meaty organ which sits on right side
of belly.
• Contain gall bladder which is used for the
synthesis of bile juice.
• Functions
- Biochemical defense
- Synthesis of bile
- Regulator of plasma glucose and ammonia levels
- Optimal function of brain
• Loss of liver function leads to “hepatic
encephalopathy” and sometimes leads to coma.

3. Liver cells
CELL TYPES FUNCTIONS
Parenchymal cells
- hepatocytes
Metabolism of proteins , steroids,
fats ,bile secretion xenobiotic
metabolism
Non parenchymal
cells –sinusoidal
cells(LSECS)
Filtration & transport of nutrients ,
adhesion for leukocytes ,Ag
presentation , secretion of cytokines
,ECM components
Kupffer cells
(macrophages)
Phagocytosis, inflammatory
response and iron metabolism
Hepatic stellate
cells (HSC)
(Fibroblast)
Fat storing cells, vit-A storage ,
control and turnover of ECM
components, secretion of growth
factors

4. Complications of liver
• Hepatitis – liver inflammation
• Cirrhosis – long term damage to liver which
lead to permanent scarring
• Liver failure – may be due to infection,
genetic diseases and excessive alcohol
• Ascites – liver leaks fluids into belly
• Gall stones – gall stone stuck can result in
hepatitis and bile duct infection
• Hemochromatosis – iron deposition in liver

5. History
Extracorporeal bioartificial
liver devices
3D scaffolds
ECM engineered scaffold
Implantable liver constructs,
whole organ engineering

6. Implantable technologies for liver
therapies
• It overcomes the limitations of current cell-therapy strategies, including lack of
engraftment and inherent lag phase.
• These are typically developed by immobilizing or encapsulating hepatic cells in
scaffolds made of different biomaterials in conjugation with strategies to optimize
hepatocyte survival and function.
• For therapeutic liver development , functional hepatocytes with efficient
transport of nutrients and which secretes hepatic factors must be present .
• Long term implantation in host is necessary .
• Similar cell-cell interactions ,cell-matrix interactions must be maintained.
• Methods – Cell encapsulation , 3D printing , scaffolds ,decellularization-
recellularization technologies.

7. 1. Cell encapsulation
• Human hepatocytes are cultured on
alginate micro beads invitro for 3 days
produced albumin and urea.
• Intraperitoneal transplantation of
hepatocyte micro beads improved liver
function in acute liver failure.
• Hepatocytes derived from inducible
pluripotent stem cells(iPSCs) are
encapsulated in alginate beads
together with human hepatic stellate
cells.
• Aimed in exploring specific diseased
models where additional parallel
strategies are involved for reducing
foreign body fibrotic reactions.

8. 2. 3D- Printing
• Uses ink which support cell differentiation and function.
• Techniques to 3D print hepatic-like structures are biomimicry
and mini tissue building blocks.
• Cells of hepatic cell line Hepg2 were printed with alginate as
the crosslinking agent.
• Gelatin is used to ensure the control of ink thickness and
higher printability.
• 3D-printed tissues were fabricated using iPSC-derived
hepatocytes mixed with alginate hydrogels. It increased level
of metabolic function during in vitro development.
• Ideal bio ink – analyze the composition and distribution of
ECM proteins in decellularized tissue scaffold.

9. 3. Artificial and natural
scaffolds
• Synthetic – easily manufactured but lack physiological
bioactivity and the biomechanics of natural ECM.
• Synthetic polymers – polylactide co-glycoslide , PEG ,
polycaprolactone.
• Natural polymers – alginates , celluloses,
polyethylene.
• ECM is made of collagen type 1.
• ECM hydrogels have been proposed which can be
used for increasing viability and improved hepatic
functions.

10. 4.Decellularization
and whole organ
engineering
• Used for development of perfusable ECM
derived scaffolds with preserved vascular
integrity.
• Liver bioengineering can be used for
transplantation and drug toxicity testing in
3D in invitro cultures.
• Decellularization–recellularization
technologies provide a valuable platform
for liver bioengineering through the
repopulation of liver ECM scaffolds with
parenchymal and nonparenchymal liver
cells.
• Tissues from other organisms may lead to
incompatibility and hence human
organisms’ tissues must be collected and
engineered.

11. Decellularization
• First decellularization was done to develop
acellular heart from mice by using
retrograde coronary perfusion at constant
pressure.
• Decellularization – removal of cellular
material while preserving vascular network ,
ECM composition, and 3D architecture of
native tissue.
• Liver decellularization used antegrade
perfusion through portal vein at constant
flow rate which obtained the translucent
acellular tissue.
• The first successful decellularization of a
human liver was done by using a novel
retrograde, two-step, perfusion flow-rate
methodology able to preserve the fine 3D
hepatic architecture and the liver ECM
biochemical composition is same.
•Repopulation of
rat acellular liver
scaffold
2010
•Repopulation of
pig liver scaffold
with human fetal
hepatocytes and
stem cells
2012
•First successful
decellularization
of liver
2015

12. Whole liver engineering
• Whole liver engineering was based on Perfusion
decellularization and recellularization strategies.
• Decellularized organs act as a platform for
whole liver tissue engineering as it provides 3D-
vascularized scaffold for nutrient delivery and
provides Environment which is necessary for
progenitor hepatic cells to grow and
differentiate to maintain functionality.

13. Applications
of Liver
tissue
engineering

14. Happy
Liver