The safety and efficacy of ultrasound histotripsy and human pluripotent stem cell-derived hepatic spheroid implantation as a potential therapy for treatment of congenital metabolic liver disease: Assessment in an immunocompetent rodent model.

Liver disease secondary to an inborn or genetic error of metabolism is a rare group of conditions often associated with chronic ill health and reduced survival. Curative treatment is mainly limited to liver transplantation with major long-term risks. Cell therapy is a promising alternative, but current approaches are ineffective. To develop histotripsy, a non-invasive high-intensity ultrasound procedure for liver tissue mechanical ablation, combined with hepatocyte stem cell implantation as a novel method of reversing liver failure from genetic disease. This study assessed the safety and feasibility of this approach in healthy rodents. Under general anaesthesia, adult rats (n = 12) underwent laparotomy and ultrasound histotripsy to the exposed liver. Around 1 million cells were injected into a single histotripsy cavity in each animal under direct vision (n = 10) with two receiving only histotripsy without cell injection. On completion of cell implant, haemostasis was secured, laparotomy incision closed and the animals recovered. Groups of animals were terminated immediately and after 4 h, 8 h, 24 h, 4 days and 7 days. Liver and vital organs were assessed for procedure-related injuries and evidence of viable implanted cells by histology and immunohistochemistry. All animals successfully recovered, and no complication was observed throughout the study. Created cavities were successfully identified in histological analysis of rat. The presence of human cells was verified using anti-human nuclei antibody confirming successful implantation of liver organoids into decellularised cavities. In this feasibility study, we demonstrated suitability of histotripsy to create decellularised cavities in liver parenchyma. In addition, feasibility of direct transplantation of undissociated liver organoids into the created cavities was demonstrated as a potential approach to treat inborn liver disease by creating nodules of healthy cells capable of performing loss metabolic function. Therapeutic efficacy of this approach will be evaluated in an upcoming study.