Japanese researchers have come up with a new approach that could revolutionise the treatment and prevention of liver disease damage and possibly regenerate liver scarring.
This novel strategy involves small extracellular vesicles (sEVs), which are lipid-enclosed particles that are naturally released from a cell. The ones used in this study derived from interferon-γ (IFN-γ) pre-conditioned MSCs (γ-sEVs).
Cirrhosis (scarring of the liver) and other chronic liver diseases result in up to 2 million deaths reported annually around the world, these in turn account for approximately 3.5% of annual deaths globally. As the only treatment for clinically advanced cirrhosis liver transplantation, targeted therapies for modulating fibrosis and aiding tissue regeneration. The ability to control fibrosis–the growth of fibrous tissue in response to damage– is often lost in livers under advanced cirrhosis. The research builds upon this.
One of the most popular approaches is cell therapy, where mesenchymal stromal cells (MSCs) and macrophages have shown the potential to reduce liver fibrosis. MSCs are able to transform into a number of different cells. They are cost-effective, being available not only from bone marrow, but also from medical waste such as umbilical cord tissue, adipose (fatty) tissue, and dental pulp.
Apart from the ease of availability, MSCs can also be lab-grown. MSCs don’t replace tissue but instead have been shown to be medical signaling cells that indirectly produce cytokines, chemokines, growth factors, and exosomes that are crucial for repairing and regenerating damaged tissue.
Previous research showed that MSCs have anti-inflammatory, anti-fibrotic, and anti-oxidative effects through these humoural factors. MSCs also have lower potential for provoking an immune response and therefore rejection, enabling their use in both within the same individual and another.
In a series of experimental mice studies, researchers pre-conditioned fat extracellular vesicles with interferon gamma (IFN-γ), an important immune system signaller. They showed that this increases the number of anti-inflammatory macrophages, which are the key players in tissue repair, reducing fibrosis and promoting tissue regeneration.
They reported that both MSCs derived from fatty tissue (AD-MSC-sEVs) and AD-MSC-γ-sEVs can boost macrophage motility and phagocytic activity. In addition, they also show that AD-MSC-γ- sEVs can effectively control inflammation and fibrosis in mice with cirrhosis.
They found thatAD-MSC-derived sEVs can affect the shape and function of macrophages, effectively recruiting them into damaged areas to initiate tissue repair.
In an interview, researcher Dr Atsunori Tsuchiya at Niigata University, explained that, “Both mesenchymal stromal cells and macrophages are reported to have therapeutic effects for liver cirrhosis, however relationship of both cells and mechanisms of action was not clear. We challenged this problem.”
He continued, “We found the important fact that extracellular vesicles from interferon-γ can induce the tissue repair macrophages, which can regress fibrosis and promote liver regeneration effectively.”
Dr Suguru Takeuchi, another of the researchers at Niigata University, concurred: “In our previous study, we reported that intravenous administration of mesenchymal stromal cells migrated to the lung, can work as ‘conducting cells’ and affect to macrophages ‘working cells’ in the liver.
“In this study we first elucidated that extracellular vesicles from mesenchymal stromal cells are key molecules to affect the macrophages.”
This study, which complements macrophage therapy, holds potential as a strategy for treating liver diseases using small extracellular vesicles pre-conditioned with IFN-γ. However, further development is needed, as well as uncovering the mechanisms by which they increase Treg cell count.
“Our results showed that modified extracellular vesicles can become a new therapeutic strategy for liver cirrhosis,” said Professor Shuji Terai, Niigata University.
Source: News-Medical.Net
Journal information: Takeuchi, S., et al. (2021) Small extracellular vesicles derived from interferon-γ pre-conditioned mesenchymal stromal cells effectively treat liver fibrosis. npj Regenerative Medicine. oi.org/10.1038/s41536-021-00132-4.
