In a new study published in the Journal of Hepatology, researchers from the San Raffaele Telethon Institute for Gene Therapy (SR-Tiget) show that only 15-20 percent of hepatocytes in newborn mice – called clonogenic hepatocytes – are responsible for generating over 90 percent of the adult liver mass.
These findings have big implications for paediatric gene therapy. Understanding the dynamics of this subset of hepatocytes early in life can help scientists to achieve more effective and durable correction of inherited liver diseases.
Latest-generation technologies reveal cellular blueprints
The team combined single-cell and spatial transcriptomics, clonal tracing and mathematical modelling to analyse how hepatocytes proliferate and mature after birth. This approach allowed them to identify not only the clonogenic cells but also the molecular signals that regulate their activity.
“Using spatial transcriptomics, we captured the precise localisation and transcriptional identity of hepatocytes during postnatal liver growth,” explains Dr Michela Milani, co-first author of the study. “It gave us an unprecedented view into how different hepatocyte subsets proliferate and mature.”
Timing and cell identity shape gene therapy success
The researchers found that gene editing by homology-directed repair (HDR) is significantly enriched within the clonogenic hepatocytes – resulting in an expansion of the proportion of the gene-edited liver area at the end of organ growth.
In contrast, lentiviral vectors spread more evenly across hepatocytes, but their efficiency is influenced by the cells’ maturation and location in the liver. This is especially true during the development of peri-central (PC) identity after weaning, which reduces vector uptake due to higher proteasome activity.
“Knowing that the liver becomes less permissive to gene transfer in certain zones as it matures helps us refine not just what cells to target, but also when to treat,” says Dr Francesco Starinieri, co-first author.
Importantly, pre-treatment with a proteasome inhibitor restored lentiviral transduction in adult hepatocytes, suggesting that this barrier can be pharmacologically modulated to improve gene delivery in mature livers.
A shared niche for growth and proliferation
Another key finding is the discovery of a specialised instructive tissue niche in neonatal livers, where clonogenic hepatocytes are found in close proximity to hematopoietic progenitor cells. This spatial co-localisation suggests a shared pool of growth signals and could open up new possibilities for regenerative medicine.
Toward durable paediatric gene therapies
“This study extends our understanding of how the liver grows and matures and how we can intervene early in life to durably correct genetic diseases,” says Dr Alessio Cantore, senior and corresponding author. “By identifying the specific hepatocytes that fuel liver growth – and how they respond to gene delivery – we can now rationally design more effective and lasting therapies for children.”
The discovery of clonogenic hepatocytes and their specialised niches provides a clearer map of liver growth and maturation in early life. By understanding which cells drive organ expansion and how they respond to gene delivery, researchers can now develop more precise and durable paediatric gene therapies, helping many children who suffer with inherited liver diseases.
