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

Morphometric, Developmental, and Anti-Inflammatory Effects of Transamniotic Stem Cell Therapy (TRASCET) on the Fetal Heart and Lungs in a Model of Intrauterine Growth Restriction

Transamniotic stem cell therapy (TRASCET) with mesenchymal stem cells (MSCs) can attenuate placental inflammation and minimize intrauterine growth restriction (IUGR). We sought to determine whether MSC-based TRASCET could mitigate fetal cardiopulmonary effects of IUGR. Pregnant Sprague-Dawley dams were exposed to alternating 12-h hypoxia (10.5% O2) cycles in the last fourth of gestation. Their fetuses (n = 155) were divided into 4 groups. One group remained untreated (n = 42), while three groups received volume-matched intra-amniotic injections of either saline (sham; n = 34), or of syngeneic amniotic fluid-derived MSCs, either in their native state (TRASCET; n = 36) or "primed" by exposure to interferon-gamma and interleukin-1beta before administration in vivo (TRASCET-primed; n = 43). Normal fetuses served as additional controls (n = 30). Multiple morphometric and biochemical analyses were performed at term for select markers of cardiopulmonary development and inflammation previously shown to be affected by IUGR. Among survivors (75%; 117/155), fetal heart-to-body weight ratio was increased in both the sham and untreated groups (P < 0.001 for both) but normalized in the TRASCET and TRASCET-primed groups (P = 0.275, 0.069, respectively). Cardiac b-type natriuretic peptide levels were increased in all hypoxia groups compared with normal (P < 0.001), but significantly decreased from sham and untreated in both TRASCET groups (P < 0.0001-0.005). Heart tumor necrosis factor-alpha levels were significantly elevated in sham and TRASCET groups (P = 0.009, 0.002), but normalized in the untreated and TRASCET-primed groups (P = 0.256, 0.456). Lung transforming growth factor-beta levels were significantly increased in both sham and untreated groups (P < 0.001, 0.003), but normalized in both TRASCET groups (P = 0.567, 0.303). Similarly, lung endothelin-1 levels were elevated in sham and untreated groups (P < 0.001 for both), but normalized in both TRASCET groups (P = 0.367, 0.928). We conclude that TRASCET with MSCs decreases markers of fetal cardiac strain, insufficiency, and inflammation, as well as of pulmonary fibrosis and hypertension in the rodent model of IUGR.

Amniotic fluid-derived stem cell potential for therapeutic and surgical use: A review of the literature

OBJECTIVE

Spina bifida is a debilitating neutral tube defect affecting many infants. The impact and severity of spina bifida depends on whether the patient exhibits a closed defect, spina bifida occulta, or an open defect, spina bifida aperta. Patients with spina bifida have physical and mental disabilities which merit further research into less invasive, more successful treatments. In addition to serving as protection for the growing fetus and facilitating nutrient exchange, amniotic fluid (AF) is a rich source of a mixed population of stem cells. As such, in vitro culture of AF-derived stem cells has shown promise among therapeutic and surgical applications. We present a critical evaluation of the current preclinical efforts, amniotic fluid-derived stem cell (AFSC) culture process, and the subsequent therapeutic application, with a focus on improvements for spina bifida outcomes in the pediatric patient population.

METHOD

An evidence - based literature review to investigate the current literature surrounding AFSC culture and use, with an emphasis on the benefits for spina bifida treatment.

RESULTS

47 literature sources from PubMed and three studies from ClinicalTrials.gov.

CONCLUSION

This review synthesizes the current literature, which shows promising data on AFSC pluripotency, as well as successful in utero coverage from AFSC - supported environments in a multitude of animal models.

Fetal hematogenous routing of a donor hematopoietic stem cell line in a healthy syngeneic model of transamniotic stem cell therapy

BACKGROUND/PURPOSE

In utero administration of hematopoietic stem cells (HSCs) has a variety of actual or potential clinical applications but is hindered by invasive, morbid administration techniques. We sought to determine whether donor HSCs could reach the fetal circulation after simple intra-amniotic delivery in a syngeneic rat model of transamniotic stem cell therapy (TRASCET).

METHODS

Pregnant Lewis rat dams underwent volume-matched intra-amniotic injections in all fetuses (n = 90) on gestational day 17 (E17; term=E21-22) of a suspension of commercially available syngeneic Lewis rat HSCs labeled with luciferase (n = 37 fetuses) or an acellular suspension of recombinant luciferase (n = 53). HSC phenotype was confirmed by flow cytometry. Fetuses were euthanized at term for screening of luciferase activity at select anatomical sites. Statistical comparisons were by Fisher's exact test.

RESULTS

Among survivors (47/90; 52.2%), donor HSCs were identified selectively in the placenta (p = 0.003), umbilical cord (p < 0.001), bone marrow (p < 0.001), thymus (p = 0.009), bowel (p = 0.003), kidney (p = 0.022), and skin (p < 0.001) when compared with acellular luciferase controls.

CONCLUSIONS

Donor hematopoietic stem cells undergo hematogenous routing and can reach the fetal bone marrow after simple intra-amniotic delivery in a syngeneic rat model. Transamniotic stem cell therapy may become a practicable, minimally invasive strategy for the prenatal administration of these cells.

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.

Preclinical stem cell therapy in fetuses with myelomeningocele: A systematic review and meta-analysis

OBJECTIVE

We performed a systematic review to summarize the efficacy and safety of in utero stem cells application in preclinical models with myelomeningocele (MMC).

METHODS

The study was registered with PROSPERO (CRD42019160399). We searched MEDLINE, Embase, Web of Science, Scopus and CENTRAL for publications articles on stem cell therapy in animal fetuses with MMC until May 2020. Publication quality was assessed by the SYRCLE's tool. Meta-analyses were pooled if studies were done in the same animal model providing similar type of stem cell used and outcome measurements. Narrative synthesis was performed for studies that could not be pooled.

RESULTS

Nineteen and seven studies were included in narrative and quantitative syntheses, respectively. Most used mesenchymal stem cells (MSCs) and primarily involved ovine and rodent models. Both intra-amniotic injection of allogeneic amniotic fluid (AF)-MSCs in rat MMC model and the application of human placental (P)-MSCs to the spinal cord during fetal surgery in MMC ovine model did not compromise fetal survival rates at term (rat model, relative risk [RR] 1.03, 95% CI 0.92-1.16; ovine model, RR 0.94, 95% CI 0.78-1.13). A single intra-amniotic injection of allogeneic AF-MSCs into rat MMC model was associated with a higher rate of complete defect coverage compared to saline injection (RR 16.35, 95% CI 3.27-81.79). The incorporation of human P-MSCs as a therapeutic adjunct to fetal surgery in the ovine MMC model significantly improved sheep locomotor rating scale after birth (mean difference 5.18, 95% CI 3.36-6.99).

CONCLUSIONS

Stem cell application during prenatal period in preclinical animal models is safe and effective.