Maternal and fetal safety outcomes after in utero stem cell injection: A systematic review

Abstract

Objective: To investigate the maternal and fetal safety of In utero stem cell transplantation (IUSCT). Methods: Medline®, Embase and Cochrane library (1967−2023) search for publications reporting IUSCT in humans. Two reviewers independently screened abstracts and full-text papers. Results: Sixty six transplantation procedures in 52 fetuses were performed for haemoglobinopathies (n = 14), red cell/bleeding disorders (n = 4), immunodeficiencies (n = 15), storage disorders (n = 7), osteogenesis imperfecta (n = 2) and healthy fetuses (n = 10). The average gestational age was 18.9 weeks; of procedures reporting the injection route, cells were delivered by intraperitoneal (n = 37), intravenous (n = 19), or intracardiac (n = 4) injection or a combination (n = 3); most fetuses received one injection (n = 41). Haematopoietic (n = 40) or mesenchymal (n = 12) stem cells were delivered. The cell dose was inconsistently reported (range 1.8−3.3 × 109 cells total (n = 27); 2.7−5.0 × 109/kg estimated fetal weight (n = 17)). The acute fetal procedural complication rate was 4.5% (3/66); the acute fetal mortality rate was 3.0% (2/66). Neonatal survival was 69.2% (36/52). Immediate maternal and pregnancy outcomes were reported in only 30.8% (16/52) and 44.2% (23/52) of cases respectively. Four fetal/pregnancy outcomes would also classify as ≥ Grade 2 maternal adverse events. Conclusions: Short-, medium-, and long-term maternal and fetal adverse events should be reported in all IUSCT studies.