Current protocols and clinical efficacy of human fetal liver cell therapy in patients with liver disease: A literature review

The fetal liver is unique because of the coexistence of cells with endodermal and mesenchymal origins, making it a potential source of hepatic and pancreatic regenerative medicine. The liver appears at about the third week of gestation, growing rapidly from the fifth to the 10th week. We define fetal liver from 10 weeks of gestation, when hematopoietic progenitor cells gradually migrate from the aorta-mesonephros-gonad region to colonize the liver. Indeed, the fetal liver may be the most available source of cell therapy for liver disease. We conducted a review of the literature using Medline and EMBASE (up to May 2021) to identify clinical studies in which patients with liver disease had been given fetal liver cell therapy. This literature review highlighted the heterogeneity of cell isolation and selection protocols, which hinders the ability to pool data and perform a meta-analysis. A limitation of the studies analyzed was the scarcity of reports (n = 8) and the extremely small sample sizes (median sample size of treated patients was two), although there was a fairly long follow-up (median 12 months). The weeks after conception ranged from 16 to 34. There were no randomized controlled trials, and therefore no study was stratified as being of good methodological quality. Cryopreservation may help to circumvent the critical logistic issues that hamper the use of fetal liver cell therapy in clinical practice. To help consolidate the role of the fetal liver in regenerative medicine, good preclinical translational studies are necessary, whereas tracing strategies and biopsy-based endpoints are crucial in the clinic, along with well-designed, large, multicenter, randomized controlled trials using clinically applicable primary outcomes and refined imaging assessment.