RESUMO
INTRODUCTION: We sought to determine whether exogenous surfactant protein B (SPB) mRNA could be incorporated and translated by the fetal lung after simple transamniotic administration. METHODS: Fetuses (n=149) of twelve time-dated dams underwent intra-amniotic injections of either human SPB (hSPB) mRNA encapsulated into lipopolyplex (mRNA, n=99), or of lipopolyplex without mRNA (control; n=50) on gestational day 17 (E17, term=E21-22). Lungs were screened for hSPB by ELISA daily until term. Phosphatidylcholine (a surrogate for surfactant production) was measured in the amniotic fluid by fluorometric assay. Statistical analysis included nonparametric Wilcoxon rank sum test. RESULTS: Significantly improved survival in the mRNA group compared to controls was observed at E18 (100% vs. 85.7%) and E20 (100% vs. 83.3%) (both p<0.001). When controlled by mRNA-free injections, hSPB protein was detected in the mRNA group's lungs at E18, 19, and term (p=0.002 to <0.001). Amniotic fluid phosphatidylcholine levels were increased compared to control at term [285.9 (251.1, 363.9)µM vs. 263.1 (222.8, 309.1)µM], however this did not reach significance (p=0.33). CONCLUSIONS: Encapsulated exogenous SPB mRNA can be incorporated and translated by fetal lung cells following intra-amniotic injection in a healthy rat model. Transamniotic mRNA delivery could become a novel strategy for perinatal surfactant protein replacement.
RESUMO
PURPOSE: We compared transamniotic stem cell therapy (TRASCET) using either mesenchymal (MSCs) or hematopoietic (HSCs) stem cells on fetal hematopoiesis in a syngeneic model of intrauterine growth restriction (IUGR). METHODS: Lewis dams exposed to cycling hypoxia (10.5% O2) in late gestation had their fetuses (n = 83) either receiving no intervention (untreated; n = 9), or intra-amniotic injections of either HSCs (HSC; n = 34), MSCs primed to an enhanced anti-inflammatory phenotype (primed-MSC; n = 28), or saline (sham; n = 12). Normal controls (n = 18) were also studied. Complete peripheral blood counts and placental ELISA for inflammation and angiogenesis markers were performed at term. RESULTS: Overall survival from hypoxia was 41% (34/83). Red blood count (RBC), hematocrit (Hct) and hemoglobin levels (Hb) were all significantly decreased from normal in all hypoxia groups. TRASCET with primed-MSC had significantly higher RBC, Hct, and Hb levels than sham (p = 0.01-0.03, pairwise), though not than untreated (which had no surgical blood loss). The HSC group had only significantly higher Hb levels than sham (p = 0.005). TRASCET with primed-MSC had significantly lower levels of placental TNF-α than sham (p = 0.04), but not untreated. CONCLUSIONS: MCSs seem more effective than HSCs in enhancing hematopoiesis when used as donor cells for TRASCET in a syngeneic model of IUGR. LEVEL OF EVIDENCE: N/A (animal and laboratory study).