A role for abdominal ultrasound in discriminating suspected necrotizing enterocolitis in congenital heart disease patients.

PURPOSE: We evaluated the diagnostic utility of abdominal ultrasound (AUS), an adjunct to abdominal X-ray (AXR), for necrotizing enterocolitis (NEC) in congenital heart disease (CHD) patients. METHODS: 86 patients with suspected NEC from 2009 to 2018 were classified as with CHD (n = 18) if they required cardiac intervention versus without CHD (n = 68). Clinical and radiological data were collected, including AXR and AUS concordance. Wilcoxon rank-sum test and Fisher's exact test were performed. RESULTS: CHD patients had higher birth weights (p < 0.001) and gestational ages (p < 0.001) than non-CHD patients. CHD patients presented more frequently with hypotension (p = 0.041) and less frequently with bilious emesis (p < 0.001). Overall, CHD patients were less likely to have AUS findings of pneumatosis (33.3 vs. 72.1%; p = 0.005) and decreased mural flow (0 vs. 20.6%; p = 0.035) compared to non-CHD patients. On concordance analysis, CHD patients had 3.9-fold more discordant studies with pneumatosis on AXR but not on AUS (33.3 vs. 8.8%; p = 0.016) compared to non-CHD patients. Urgent surgery was required in 5.6% of CHD patients versus 16.2% of non-CHD patients. CONCLUSION: CHD patients with suspected NEC represent a distinct clinical population. AUS has particular utility in assessing findings of bowel viability in the CHD NEC population, reflecting reduced rates of surgical NEC.

Abdominal ultrasound findings contribute to a multivariable predictive risk score for surgical necrotizing enterocolitis: A pilot study.

BACKGROUND: Abdominal ultrasound (AUS) is a promising adjunct to abdominal x-ray (AXR) for evaluating necrotizing enterocolitis (NEC). We developed a multivariable risk score incorporating AUS to predict surgical NEC. METHODS: 83 patients were evaluated by AXR and AUS for suspected NEC. A subset had surgical NEC. Multivariate logistic regression determined predictors of surgical NEC, which were incorporated into a risk score. RESULTS: 14/83 patients (16.9%) had surgical NEC. 10/83 (12.0%) patients required acute intervention, while 4/83 (4.8%) patients only required delayed surgery. Four predictors of surgical NEC were identified: abdominal wall erythema (OR: 8.2, p = 0.048), portal venous gas on AXR (OR: 29.8, p = 0.014), and echogenic free fluid (OR: 17.2, p = 0.027) and bowel wall thickening (OR: 12.5, p = 0.030) on AUS. A multivariable risk score incorporating these predictors had excellent area-under-the-curve of 0.937 (95% CI: 0.879-0.994). CONCLUSIONS: AUS, as an adjunct to physical exam and AXR, has utility for predicting surgical NEC.

Transamniotic Stem Cell Therapy for Experimental Congenital Diaphragmatic Hernia: Structural, Transcriptional, and Cell Kinetics Analyses in the Nitrofen Model.

PURPOSE: We examined select pulmonary effects and donor cell kinetics after transamniotic stem cell therapy (TRASCET) in a model of congenital diaphragmatic hernia (CDH). METHODS: Pregnant dams (n = 58) received nitrofen on gestational day 9.5 (E9) to induce fetal CDH. Fetuses (n = 681) were divided into 4 groups: untreated (n = 99) and 3 groups receiving volume-matched intra-amniotic injections on E17 of either saline (n = 142), luciferase-labeled amniotic fluid-derived mesenchymal stem cells (afMSCs; n = 299), or acellular recombinant luciferase (n = 141). Pulmonary morphometry, quantitative gene expression of pulmonary vascular tone mediators, or screening for labeled afMSCs were performed at term (E22). Statistical comparisons were by Mann-Whitney U-test, nested ANOVA, and Wald test. RESULTS: TRASCET led to significant downregulation of endothelial nitric oxide synthase and endothelin receptor-A expressions compared to both untreated and saline groups (both p < 0.001). TRASCET also led to a significant decrease in arteriole wall thickness compared to the untreated group (p < 0.001) but not the saline group (p = 0.180). Donor afMSCs were identified in the bone marrow and umbilical cord (p = 0.035 and 0.015, respectively, vs. plain luciferase controls). CONCLUSIONS: The effects of TRASCET in experimental CDH appear to be centered on the pulmonary vasculature and to derive from circulating donor cells.

Initial Mechanistic Screening of Transamniotic Stem Cell Therapy in the Rodent Model of Spina Bifida: Host Bone Marrow and Paracrine Activity.

PURPOSE: Transamniotic stem cell therapy (TRASCET) with mesenchymal stem cells (MSCs) can induce spina bifida coverage with neoskin. We initiated a mechanistic analysis of this host response. METHODS: Pregnant dams (n = 28) exposed to retinoic acid to induce fetal spina bifida were divided into an untreated group and 2 groups receiving intra-amniotic injections on gestational day 17 (E17; term = E21-22) of either amniotic fluid-derived MSCs (afMSCs; n = 105) or saline (n = 107). Gene expressions of multiple paracrine and cell clonality markers were quantified at term by RT-qPCR at the defect and fetal bone marrow. Defects were examined histologically for neoskin coverage. Comparisons were by Mann-Whitney U tests and logistic regression. RESULTS: Defect coverage was associated with significant downregulation of both epidermal growth factor (Egf; p = 0.031) and fibroblast growth factor-2 (Fgf-2; p = 0.042) expressions at the defect and with significant downregulation of transforming growth factor-beta-1 (Tgfb-1; p = 0.021) and CD45 (p = 0.028) expressions at the fetal bone marrow. CONCLUSIONS: Coverage of experimental spina bifida is associated with local and bone marrow negative feedback of select paracrine factors, as well as increased relative mesenchymal stem cell activity in the bone marrow. Further analyses informed by these findings may lead to strategies of nonsurgical induction of prenatal coverage of spina bifida.

Hematogenous Donor Cell Routing Pathway After Transamniotic Stem Cell Therapy.

Donor mesenchymal stem cells (MSCs) have been documented in fetal and maternal circulations after plain intra-amniotic injection, with diverse therapeutic effects. We sought to determine the pathway of this unique cell kinetic route. Rat fetuses (n = 226) were divided into two groups based on the content of intra-amniotic injections performed on gestational day 17 (E17): either a concentrated suspension of luciferase-labeled syngeneic amniotic fluid-derived MSCs (afMSCs; n = 111), or acellular luciferase (n = 115). Samples from placenta, chorion, amnion, amniotic fluid, stomach fluid, peripheral blood, and umbilical cord were procured at five daily time points thereafter until term (E18-22) for luminometry. In addition, 53 sets of fresh gestational membranes (chorion/amnion combined) from nonmanipulated term fetuses were secured to transwell inserts for in vitro analysis of MSC migration using luciferase-labeled afMSCs. Statistical analyses included the Mann-Whitney U-test, Wald test, nonlinear regression modeling, and Fisher's exact test. In vivo, luciferase activity was observed in the amnion, chorion, and placenta of fetuses receiving cells, but not in those receiving acellular luciferase (P < 0.001). There was a consistent nonlinear age-dependent relationship of luciferase activity between the amnion, chorion, and placenta following a parabolic bimodal pattern characterized by significantly higher early preterm (E18) and late-term (E22) activities (P < 0.001), with no differences between E21 and E22 (P = 0.12). In vitro, the presence of cells was documented by luminometry in 21/53 (39.6%) of the assays, in suspension and/or attached to the plastic substrate, and within all screened gestational membrane sets, irrespective of stimuli with collagen coating or fetal bovine serum. We conclude that, after intra-amniotic injection, donor MSCs undergo controlled cell routing, as opposed to passive clearance. Transgestational membrane transport appears to constitute the path for donor cells to reach the placenta, a known gateway to the fetal circulation, significantly expanding the potential applications of transamniotic stem cell therapy.

Postnatal fate of donor mesenchymal stem cells after transamniotic stem cell therapy in a healthy model.

PURPOSE: We sought to examine donor mesenchymal stem cell (MSC) fate after birth following transamniotic stem cell therapy (TRASCET) in a healthy model. METHODS: Lewis rat fetuses (n = 91) were divided into two groups based on the content of volume-matched intraamniotic injections performed on gestational day 17 (term = 21-22 days): either a suspension of amniotic fluid-derived MSCs (afMSCs) labeled with luciferase (n = 38) or acellular luciferase only (n = 53). Infused afMSCs consisted of syngeneic Lewis rat cells phenotyped by flow cytometry. Samples from 14 anatomical sites (heart, lung, brain, liver, spleen, pancreas, bowel, kidney, thyroid, skin, skeletal muscle, thymus, peripheral blood and bone marrow) from survivors were screened for luciferase activity 16 days after birth. Statistical analysis was by logistic regression and the Wald test (p < 0.05). RESULTS: Overall survival was 32% (29/91). When controlled by the acellular luciferase injections, donor afMSCs were not identified at any anatomical site in any neonate as measured by relative light units (all p > 0.05). Donor afMSC viability was confirmed in term placentas. CONCLUSIONS: Donor mesenchymal stem cells are not detectable in the neonate after intraamniotic injection in a normal syngeneic rodent model. This finding suggests that clinical trials of transamniotic stem cell therapy may be amenable to regulatory approval. LEVEL OF EVIDENCE: N/A (animal and laboratory study).

Is Abdominal Sonography a Useful Adjunct to Abdominal Radiography in Evaluating Neonates with Suspected Necrotizing Enterocolitis?

BACKGROUND: Abdominal sonography (AUS) is emerging as a potentially valuable adjunct to conventional abdominal radiography (AXR) in the setting of suspected necrotizing enterocolitis (NEC). We sought to evaluate concordance between AUS and AXR for signs of NEC to better understand the potential advantages and disadvantages of AUS. As a secondary aim, we characterized AUS-specific findings and evaluated the association of imaging results with clinical outcomes. STUDY DESIGN: Hospitalized infants with clinical concern for NEC from 2009 to 2018 were included in this multicenter retrospective review. All infant patients had at least 1 paired AXR followed by an AUS within 24 hours. Findings were abstracted from written radiology reports. Cohen's κ, nonparametric Mann-Whitney U test, and quantile regression were used to evaluate chance-corrected levels of agreement for concordance analyses and associations with clinical outcomes. RESULTS: In total, 66 patients and 96 paired studies were evaluated. Agreement between the 2 imaging modalities was 61 of 96 (63.5%) for pneumatosis (κ = 0.29; 95% CI, 0.10 to 0.48), 79 of 96 (82.3%) for portal venous gas (κ = 0.07; 95% CI, 0.00 to 0.47), and 91 of 96 (94.8%) for pneumoperitoneum (κ = 0.52; 95% CI, 0.11 to 0.93). Each finding was present more frequently on AUS than AXR. On AUS, pneumatosis and focal fluid collection were independently associated with a longer antibiotic course (4.1 days longer; p = 0.03 and 21.3 days longer; p < 0.001, respectively). CONCLUSIONS: AUS holds promise as a useful adjunct to radiography for neonates with possible NEC. It might be more sensitive for the presence or absence of bowel ischemia and can reveal findings not detectable by radiography, which can aid provider decision-making.

Donor mesenchymal stem cell kinetics after transamniotic stem cell therapy (TRASCET) in a rodent model of gastroschisis.

PURPOSE: We sought to comprehensively scrutinize donor mesenchymal stem cell kinetics following transamniotic stem cell therapy (TRASCET) in experimental gastroschisis. METHODS: A gastroschisis was surgically created in 102 rat fetuses at gestation day 18 (term = 22 days), immediately followed by volume-matched amniotic injections of either amniotic fluid mesenchymal stem cells (afMSCs) labeled with a luciferase reporter gene (n = 58), or luciferase protein alone (n = 44). Samples from multiple anatomical sites from survivors were screened for luciferase activity via microplate luminometry at term. Statistical analysis included Mann-Whitney U-test, Wald test, and kappa coefficient (p < 0.05). RESULTS: Overall survival was 42% (43/102), with no significant difference between the two groups (p = 0.82). When controlled by acellular luciferase, donor afMSCs were identified selectively in the placenta (p < 0.001) and bowel (p = 0.005), independently of the dams (respectively, p < 0.001 and p = 0.041). Bowel homing was documented exclusively in areas exposed to the amniotic cavity. There was no mutual correlation between placental and bowel homing (kappa = -0.02; p = 0.91). CONCLUSIONS: Amniotic mesenchymal stem cells home to specific sites after TRASCET in the setting of gastroschisis. Placental homing and intestinal homing are central yet seemingly independent constituents of cell trafficking, suggesting that both direct amniotic seeding and hematogenous routing take place. LEVEL OF EVIDENCE: N/A (animal and laboratory study).

A comparison between placental and amniotic mesenchymal stem cells in transamniotic stem cell therapy for experimental gastroschisis.

PURPOSE: We compared placental and amniotic fluid-derived mesenchymal stem cells (pMSCs and afMSCs, respectively) in transamniotic stem cell therapy for experimental gastroschisis. METHODS: Gastroschisis was surgically created in 126 rat fetuses at gestational day 18 (term = 22 days), immediately followed by volume-matched intraamniotic injections of suspensions of afMSCs (n = 32), pMSCs (n = 33), or normal saline (NS) (n = 33). Untreated fetuses served as controls (n = 28). Blinded observers performed computerized measurements of total and segmental (serosa, muscularis, and mucosa) intestinal wall thickness on the herniated bowel at term. Statistical analysis included ANOVA, the Wald test, and Levene's test (p < 0.05). RESULTS: Among survivors, there were statistically significant decreases in segmental and total bowel wall thicknesses in both the afMSC and pMSC groups vs. the untreated (p < 0.001 to 0.003) and saline (p < 0.001 to 0.011) groups. There were significant differences between the afMSC and pMSC groups favoring the former in both therapeutic impact and its variability (p < 0.001 to 0.031). Labeled cells were comparably identified within the intestinal wall in the afMSC and pMSC groups. CONCLUSIONS: Both placental and amniotic mesenchymal stem cells can mitigate bowel damage in experimental gastroschisis as agents of transamniotic stem cell therapy. However, amniotic cells lead to improved and more consistent outcomes. LEVEL OF EVIDENCE: N/A (animal and laboratory study).

Congenital diaphragmatic hernia as a potential target for transamniotic stem cell therapy.

PURPOSE: We sought to determine whether TRASCET could impact congenital diaphragmatic hernia (CDH). METHODS: Twelve pregnant dams received Nitrofen on gestational day 9.5 (E9; term = 22 days) to induce fetal CDH. Fetuses were divided into three groups: untreated (n = 31) and two groups receiving volume-matched intraamniotic injections of either saline (n = 37) or a suspension of 2 × 106 cells/mL of amniotic fluid-derived mesenchymal stem cells (afMSCs; n = 65) on E17. Animals were euthanized at term. Expression of fibroblast growth factor-10 (FGF-10), vascular endothelial growth factor-A (VEGF-A), and surfactant protein-C (SPC) was quantified by qRT-PCR. Statistical analysis was by the Mann-Whitney U test with Bonferroni adjusted criterion (p ≤ 0.01). RESULTS: Among survivors with CDH (n = 27/133), the TRASCET group showed significant downregulation of FGF-10 and VEGF-A gene expressions compared to the untreated (p < 0.001 for both) and saline groups (p = 0.005 and p = 0.004, respectively). SPC expression was higher in the TRASCET group compared to the untreated group (p = 0.01), but not the saline group (p = 0.043). Lung laterality had minimal impact on these comparisons. CONCLUSIONS: Transamniotic stem cell therapy affects select processes of lung development in experimental congenital diaphragmatic hernia. Further scrutiny into this novel therapy as a potential component of the prenatal management of this disease is warranted. LEVEL OF EVIDENCE: N/A (animal and laboratory study).

Transamniotic stem cell therapy (TRASCET) in a rabbit model of spina bifida.

PURPOSE: Transamniotic stem cell therapy (TRASCET) with select mesenchymal stem cells (MSCs) has been shown to induce partial or complete skin coverage of spina bifida in rodents. Clinical translation of this emerging therapy hinges on its efficacy in larger animal models. We sought to study TRASCET in a model requiring intra-amniotic injections 60 times larger than those performed in the rat. METHODS: Rabbit fetuses (n = 65) with surgically created spina bifida were divided into three groups. One group (untreated) had no further manipulations. Two groups received volume-matched intra-amniotic injections of either saline or a concentrated suspension of amniotic fluid MSCs (afMSCs) at the time of operation. Infused afMSCs consisted of banked heterologous rabbit afMSCs with mesenchymal identity confirmed by flow cytometry, labeled with green fluorescent protein. Defect coverage at term was blindly categorized only if the presence of a distinctive neoskin was confirmed histologically. Statistical comparisons were by logistic regression and the likelihood ratio test. RESULTS: Among survivors with spina bifida (n = 19), there were statistically significant higher rates of defect coverage (all partial) in the afMSC group when compared with the saline and untreated groups (0-50%; p = 0.022-0.036), with no difference between the saline and untreated groups (p = 1.00). Donor afMSCs were identified locally, though sparsely and not in the neoskin. CONCLUSIONS: Concentrated intra-amniotic injection of amniotic mesenchymal stem cells can induce partial coverage of experimental spina bifida in a leporine model. Transamniotic stem cell therapy may become a feasible strategy in the prenatal management of spina bifida. LEVEL OF EVIDENCE: N/A (animal and laboratory study).

A comparison of clinically relevant sources of mesenchymal stem cell-derived exosomes: Bone marrow and amniotic fluid.

BACKGROUND/PURPOSE: Exosomes may constitute a more practical alternative to live cells in select stem cell-based therapies. We sought to compare exosomes from two mesenchymal stem cell (MSC) sources relevant to perinatal and pediatric diseases. METHODS: Exosomes were isolated by reagent-enhanced centrifugation from cell culture media of banked human bone marrow (bm) and amniotic fluid (af) MSCs after serum starvation. Characterization was by flow exometry for tetraspanin markers CD9, CD63, and CD81, transmission electron microscopy for size and morphology, and tunable resistive pulse sensing for size distribution and concentration. Statistical comparisons of count data were made by Poisson regression modeling and Student's T-test. RESULTS: Exosomes of appropriate size and morphology were isolated with comparable expressions of CD9 (96% vs. 94%), CD63 (88% vs. 66%), and CD81 (71% vs. 63%) for bmMSC and afMSC, respectively. Total exosome yield (particles/mL) adjusted for number of cells was higher from afMSCs than bmMSCs by an estimated 25% (P < 0.001). CONCLUSIONS: While bone marrow and amniotic fluid mesenchymal stem cells are comparable sources of exosomes in size distribution, morphology, and expression of typical surface markers, yield may be higher from amniotic fluid cells. The amniotic fluid appears to be a preferable source of exosomes for clinical applications. LEVEL OF EVIDENCE: N/A (bench laboratory study).

Fetal bone marrow homing of donor mesenchymal stem cells after transamniotic stem cell therapy (TRASCET).

PURPOSE: Donor cell engraftment patterns following transamniotic stem cell therapy (TRASCET) with amniotic fluid mesenchymal stem cells (afMSCs) are incompatible with solely direct amniotic seeding. We sought to determine whether fetal bone marrow is a component of such engraftment and to examine the chronology of afMSC placental trafficking. METHODS: Two groups of Sprague-Dawley rat fetuses received volume-matched intraamniotic injections on gestational day 17 (E17; term E22): either afMSCs labeled with a luciferase reporter gene or luciferase protein alone. Placental samples were procured at daily time points thereafter until term. Fetal bone marrow was obtained at term only owing to size constraints. Specimens were screened for luminescence via microplate luminometry. RESULTS: Donor afMSCs were identified in the bone marrow and placenta of fetuses receiving labeled afMSCs, but not in those receiving luciferase alone (P<0.001). Luminescence was significantly higher in placentas at E18 compared to E19 (P<0.001), E20 (P=0.007), and E21 (P=0.004), with no difference with E22/term (P=0.97). CONCLUSIONS: Donor mesenchymal stem cells home to the fetal bone marrow after intraamniotic injection. The chronology of placental trafficking is suggestive of controlled cell routing rather than plain cell clearance. Fetal bone marrow engraftment of donor cells significantly expands potential applications of transamniotic stem cell therapy.