6 - Cell Therapy to Treat Liver Disease Flashcards
How much has liver disease increased by since 1970
400%
LIver functions
- Prevents shortages of nutrients by storing vitamins minerals and sugar
- Produces most proteins needed by the body
- Produces bile, a compound needed to digest fat and absorb vitamins
- Produces substances that regulate blood clotting
- Helps the body fight infection by removing bacteria
- Removes toxins
- Breaks Down nutrients from food to produce energy
LIver lobule
- Blood from portal vein and the hepatic artery flows towards central vein between hepatocytes through the sinusoids
- Bile produced by hepatocytes is collected into bile ducts bia the bile canaliculi
- Sinusoids are lined with endothelial cells
Kupffer cells
- Resident macrophages of the liver
- Located at the luminal side of sinusoids
Canal of hering
The junctional region between hepatocytes and bile ducts
Regeneration of liver cells
- Gut derived factors (e.g. LPS) are upregulated, activating hepatic non parenchymal cells increasing the production of TNF and IL-6
- Other factors are released that allow the hepatocytes to overcome cell cycle checkpoint controls and move through cell cycle
- TGF is blocked
Transforming growth factor (TGF)
Inhibits hepatocyte DNA synthesis
Other factors released that allow hepatocytes to overcome cell cycle checkpoint controls
- Pancreas (insulin)
- Duodenum
- Salivary gland (EGF)
- Adrenal gland (norepinephrine)
- Thyroid gland (T4)
Cholangiocytes
- Epithelial cells of the bile duct.
- Derived from hepatoblasts /oval cells
- Peak of proliferation occurring a few hours after hepatocytes
Liver sinusoidal endothelial cells (LESCs)
- Lasts several days - weeks
- Includes precursors that migrate from the bone marrow
Kupffer cells and immune cells
Local proliferation of Kupffer cells plus migration of
mononuclear cells from the blood
Hepatic stellate cells
- Not well understood
- Synthesise components of the extracellular matrix
- Produce signalling molecules essential for liver regeneration
Hepatic stem/progenitor cell (oval cells)
- Bipotential stem cells residing in human and animal livers that are able to differentiate towards the hepatocytic and the cholangiocytic lineages.
- Resides in canal of Hering
Canals of Hering
Represent the smallest and most peripheral branches of the biliary tree connecting the bile canalicular system
with interlobular bile ducts
Stem/progenitor cells under normal physiological conditions
Homeostasis is achieved predominantly by
proliferation of mature hepatocytes.
Stem/progenitor cells under injury conditions
Results in extensive reprogramming of hepatocytes and cholangiocytes, activation and differentiation of LPCs, immune infiltration, and formation of several
intermediate cell types expressing markers of hepatocytes, cholangiocytes,
Regenerative medicine
Process of replacing, engineering or regenerating human cells, tissues or organs to restore or establish normal function
Cell therapy
The introduction of cells into the tissues of an organism (humans) to treat a disease
Liver disease
- Genetic liver disease (blood proteins or inborn errors of metabolism)
- Lifestyle causes (alcohol, obesity, viral)
Induced pluripotent stem cells to treat genetic liver disease (iPSCs)
- Derived from adult cells and reprogrammed using defined factors (e.g. Oct4), back into an embryonic-like pluripotent state.
- Promising alternative for an ex vivo gene therapy approach that could be used for cell therapy applications and curing diseases.
Gene correction to treat genetic liver disease
- Viral vectors (adeno associated virus)
- CRISPR/CAS9
Gene correction in hemophilia B
- Bleeding disorder caused by a deficiency of clotting factor IX
- Gene therapy using viral vectors, such as adeno-associated virus (AAV), has shown success in increasing factor IX levels and reducing bleeding episodes in patients.
Gene correction in alpha 1 antitrypsin deficiency
- Genetic disorder that leads to liver and lung diseases
- Researchers have been exploring CRISPR-based approaches to correct the genetic mutation responsible
Wilson disease
- Genetic disorder that causes copper to accumulate in the liver, leading to liver damage
- AAV mediated gene therapy and CRISPR treatment
Metabolic liver disease progression
Healthy –> NAFLD –> NASH –> Cirrhosis –> Hepato-cellular Carcinoma
Non-Alcoholic Fatty Liver Disease (NAFLD)
- Affects 30% of population
- Condition in which fat builds up in liver
Nonalcoholic steatohepatitis (NASH)
- Is a type of NAFLD
- If you have NASH, you have
inflammation and liver cell damage, along with fat in your liver.
Early stage liver disease treatment
Resection (needs early diagnosis)
End stage liver disease treatment
Transplant
Treatment for liver cancer
- Radiofrequency, cryoablation, radiotherapy
- Partial hepatectomy
- Transplantation
- Immunotherapy
Bio artificial liver device
The patient’s plasma passes through 4 cartridges where it contacts human liver cells allowing appropriate two-way transfer of toxins, metabolites
and nutrients, mimicking liver
function.
Hepatocyte transplantation limitations
- Rejection (better understanding of immunological mechanisms and improvement of immunosuppression required)
- Lack of donors
- Needs high grade of cell engraftment
Stem cells
- Capable of self renewal
- Can divide and produce cells that have the potential to become other more specific cell types, tissues or organs.
Mesenchymal Stem Cells
- Multipotent adult stem cells
- Candidate stem cell types for treatment of liver fibrosis/cirrhosis
- Can attenuate acute or chronic liver inflammation and consequent hepatocyte
injury by modulating the immune cell function including HSCs
Hepatic stellate cells (HSC)
- Activated when the liver is injured triggered by cytokines and growth factors
- Can change to a myofibroblast-like phenotype.
- Activated HSCs become the main source of excessive ECM
production in the liver (synthesize collagen, fibronectin) - Activated HSCs also secrete various profibrogenic factors
such as TGF-β, PDGF, and CTGF which promote the activation and proliferation of HSCs and stimulate the production of ECM. - Targeting HSC activation and function is an important
therapeutic strategy for treating fibrotic liver diseases.
Human pluripotent stem cells
Generating hepatocyte-like cells from pluripotent stem cells by using various growth factors eg FOXA2, HNF1a.
Limitations of human pluripotent stem cells
- Incomplete gene expression
- Scale-up limitations
- Heterogenous culture
Hepatocyte characteristics
- Cytochrome p450 enzyme activity
- Uptake LDL
- Store glycogen
- Synthesize urea
Improving hepatocyte like cell function and number
- Use of chemically defined conditions (e.g. laminin)
- Small molecules to induce rapid proliferation (e.g. TGFb)
Complex liver organoids for transplantation
- Two cell types are isolated from the samples liver progenitor cells that change into the main cells that make up the organ, and liver
endothelial cells which form the blood vessels. - Uses a unique liver gel made from human liver tissue samples to provide additional factors
- A third cell that stimulates growth is combined with the gel and cells and injected
into a scaffold that holds the 3mm organoid together.
