BackgroundLiver fibrosis can progress to end-stage cirrhosis and liver cancer. Mesenchymal stem cells (MSCs) were considered the most promising therapeutic strategy, but most of the MSCs injected intravenously traditionally are trapped in the lungs, rapidly reducing their survival ability. MSC spheroids cultured in 3D have shown higher tolerance to fluid shear stress and better survival than dissociated MSCs. Simulating the route of orthotopic liver transplantation, transplanting MSC spheroids into the liver via hepatic portal vein may impact superior therapeutic effects.MethodsIn the present study, human umbilical cord-derived MSC spheroids (hUC-MSCsp) were transplanted into rhesus monkey models of liver fibrosis via B-ultrasound-guided percutaneous portal vein puncture with minimized body invasion. The therapeutic effect is evaluated through hematology, ultrasound, and pathology. To study the effect of hUC-MSCsp on gene expression in rhesus monkeys with liver injury, transcriptome sequencing analysis was performed on the livers of rhesus monkeys. The distribution of transplanted hUC-MSCsp was traced with RNA scope technology.ResultsWe found that hUC-MSCsp significantly restored liver function, including ALT, AST, ALB, GLOB and bilirubin. hUC-MSCsp also significantly reduced liver collagen deposition and inflammatory infiltration, and promote dismission of liver ascites. Subsequently, the therapeutic effects were further validated in TGF-beta 1/Smad pathway by global transcription profile. The distribution of transplanted hUC-MSCsp were also tracked, and we found that hUC-MSCsp distributed in the liver in a sphere status at 1 h after transplantation. After 16 days, the hUC-MSCsp were dispersed into dissociated cells that were predominantly distributed in the spleen, and a significant number of dissociated cells were still present in the liver.ConclusionsThis study reveals the distributions of transplanted hUC-MSCsp after liver portal vein transplantation, and provides a novel approach and new insights into the molecular events of potential molecular events underlying the treatment of liver fibrosis with hUC-MSCsp.