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Intrauterine growth restriction (IUGR) pathophysiology is driven by abnormal uterine natural killer cell (uNK) activity leading to placental dysfunction. Transamniotic stem cell therapy (TRASCET) with mesenchymal stem cells (MSCs) can improve experimental IUGR by mechanisms not fully understood. We sought to examine TRASCET's effects in downstream products of uNKs in a model of IUGR: 15 Sprague–Dawley dams were exposed to alternating hypoxia (10.5% O2) from gestational day 15 (E15) until term (E21). Their fetuses (n = 189) were divided into four groups. One group remained untreated (n = 52), whereas three groups received volume-matched intraamniotic injections of either saline (sham, n = 44) or a suspension of amniotic fluid-derived MSCs, either in their native state (TRASCET, n = 50) or "primed" to an enhanced antiinflammatory phenotype (TRASCET-Primed, n = 43). Normal fetuses served as controls (n = 33). At term, various analyses were performed, including ELISA for surrogates of placental inflammation and uNK activity. Statistical comparisons included Bonferroni-adjusted criterion. Overall survival from hypoxia was 74% (140/189). Placental efficiency was lower in untreated and sham but normalized in both TRASCET groups (P < 0.01–0.47). Interleukin-17, a stimulator of uNKs, was elevated from normal in all groups (P < 0.01 for all). Interferon-gamma, released from activated uNKs, was elevated in all groups except sham but lower than the untreated in both TRASCET groups (P ≤ 0.01–0.06). Tumor necrosis factor-alpha, also produced by uNKs, was elevated in untreated and sham (P < 0.01 for both), but normalized by TRASCET (P = 0.05) and even lowered from normal in TRASCET-Primed (P < 0.01). Vascular endothelial growth factor, also released by uNKs, was elevated in untreated and sham but lower than normal in both TRASCET groups (P < 0.01 for all). We conclude that TRASCET with MSCs modulates the activity of placental uNKs in experimental IUGR, with distinct effects on their downstream products. This mechanistic insight may inform the development of novel strategies for the management of this disease. [ABSTRACT FROM AUTHOR]

Therapies based on exogenous messenger RNA (mRNA) administration have emerged as a powerful novel strategy for the actual or potential treatment of an assortment of diseases, including congenital surgical pathologies. We sought to determine whether the minimally invasive transamniotic route could be an alternative for prenatal mRNA delivery. Pregnant Sprague–Dawley dams underwent laparotomy followed by volume-matched intra-amniotic injections in all their fetuses (n = 120) of either a suspension of a custom firefly luciferase mRNA encapsulated by a lipid- and synthetic cationic polymer-based composite, or of a suspension of the same encapsulation components without mRNA, on gestational day 17 (E17; term = E21-22). On E18, E19, E20, and E21, samples from 14 fetal anatomical sites and maternal serum were procured for the screening of mRNA incorporation by host cells by measurement of luciferase activity via microplate luminometry. Statistical analysis was by Mann–Whitney U -test, including Bonferroni-adjustment. Overall survival was 87.5% (105/120). Controlled by the encapsulating composite without mRNA, luciferase activity was detected in the animals that received encapsulated mRNA in the following fetal annexes: amniotic fluid, amnion, chorion, umbilical cord, and placenta (P = 0.033 to <0.001), as well as in the following fetal sites: liver, stomach, intestines, and lungs (P = 0.043-0.002). Packaged exogenous mRNA can be incorporated by the fetus at least at select anatomical sites after simple intra-amniotic administration in a rodent model. The pattern and chronology of mRNA incorporation are compatible with transplacental hematogenous routing, as well as with fetal swallowing/aspiration. Further study of transamniotic mRNA administration is warranted. [ABSTRACT FROM AUTHOR]

Introduction: Secretory immunoglobulin-A (SIgA), which is not produced perinatally, binds bacteria enhancing mucosal immunity. Higher levels of intestinal bacteria bound by SIgA are protective against necrotizing enterocolitis. Transamniotic fetal immunotherapy (TRAFIT) has previously been used to deliver SIgA to the fetal digestive tract, however, with unclear functional impact. We sought to determine whether SIgA administered via TRAFIT could functionally bind intestinal bacteria postnatally., Methods: Fetuses (n = 38) from 4 dams underwent intra-amniotic injections of human SIgA on gestational day 19 (E19; term = E22-E23). After spontaneous delivery, pups were survived for 1-2 days postnatally before intestinal contents were procured and submitted to flow cytometry. Specimens were stained for bacteria (Syto-GFP) and human SIgA (PE) to prevent cross-reactivity with maternal rat SIgA., Results: Overall survival was 94.7% (36/38). SIgA-bacterial complexes were identified in all samples at all time points showing significantly higher positive PE events than unstained controls (p = 0.03-0.05). The proportion of bacteria bound by IgA decreased daily, from 45.6% to 29.9% bound at 4-6 days post-TRAFIT, respectively (overall p = 0.05)., Conclusions: TRAFIT with secretory IgA leads to functionally IgA-bound bacteria into the postnatal period and may be a novel strategy for enhancing early mucosal immunity, potentially protecting the neonate against necrotizing enterocolitis., (© 2024 S. Karger AG, Basel.)