Hematogenous Donor Cell Routing Pathway After Transamniotic Stem Cell Therapy

Despite routing to GI and pulmonary tissues, donor cells fail to engraft after intra-amniotic or intravascular cell delivery in a healthy allogeneic mouse model

In utero hematopoietic cell transplantation (IUHCT) exploits tolerogenic fetal immunologic development to facilitate engraftment of donor. Non-hematopoietic donor-derived cells have been described in both in-utero and post-natal models of hematopoietic cell transplantation. However, while epithelial routing has been reported, long-term engraftment following IUHCT has not been well studied. We utilized intra-amniotic (IA) or intravascular (IV) IUHCT to evaluate routing and engraftment within the pulmonary and gastrointestinal (GI) tract. High donor-cell viability is observed in the amniotic fluid 24 h after IA injection (mean 89.1 %). At 24 and 72 h, donor cells were present within the lumens of GI and pulmonary tissues and in the parenchyma of the liver, suggesting that donor cells route effectively to epithelial surfaces and hematogenous targets following IA injection. However, following IA delivery, long-term engraftment was not observed in peripheral blood, and there was no evidence of donor-derived cells in any target tissue including lung, bowel, or liver. Following IV injection, mean peripheral blood chimerism at terminal harvest was 23.86 % (SEM 12.44; Range 0.00-98.90). Following IV delivery, donor-derived cells were noted in the bowel, liver, and lung but not in the epithelium, suggesting these cells are circulating or tissue-resident leukocytes. Despite the routing of donor cells to multiple fetal sites, the IA injection was an extremely inefficient method for long-term engraftment in the hematopoietic niche, in organ parenchyma, or on epithelial surfaces. In contrast, despite IV IUHCT being able to consistently produce hematopoietic engraftment, epithelial engraftment was not observed, suggesting a limited role for IV IHUCT in epithelial disorders.

Transamniotic Stem Cell Therapy Modulates Uterine Natural Killer Cell Activity in the Hypoxia Model of Intrauterine Growth Restriction

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.

Comparative Effects on Fetal Hematopoiesis and Placental Inflammation From Mesenchymal and Hematopoietic Stem Cells as Agents of Transamniotic Stem Cell Therapy (TRASCET) in a Syngeneic Model of Intrauterine Growth Restriction

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).

Bidirectional Feto-Maternal Traffic of Donor Mesenchymal Stem Cells Following Transamniotic Stem Cell Therapy (TRASCET)

PURPOSE

Transamniotic stem cell therapy (TRASCET) with mesenchymal stem cells (MSCs) has emerged experimentally as a potential treatment for different congenital diseases and maternal diseases of pregnancy. The broad applicability of TRASCET is predicated on hematogenous routing of donor MSCs via the placenta. We investigated whether donor MSC kinetics includes bidirectional traffic between the fetus and mother.

METHODS

Eight time-dated dams had their fetuses (n = 96) divided in 4 groups on gestational day 17 (E17, term = E21). Groups populating one uterine horn received intra-amniotic injections (50 μL) of either donor amniotic fluid-derived MSCs (2×106 cells/mL) labelled with a firefly luciferase reporter gene (MSC-injected, n = 32), or of acellular luciferase (luciferase-injected, n = 26). Contra-lateral (CL) horn fetuses received no injection (MSC-CL, n = 20 and luciferase-CL, n = 18). At term, samples from 11 fetal anatomical sites from CL fetuses, along with placentas from all fetuses and maternal blood were screened for luciferase activity via microplate luminometry.

RESULTS

Overall survival was 95 % (91/96). When controlled by the acellular injection, positive luciferase activity was observed in the placentas of all MSC-injected fetuses, confirming viability of the donor cells at term. When controlled by the acellular injection group, MSC-CL fetuses showed positive luciferase activity in the bone marrow, peripheral blood, brain and skin (p = <0.001-0.048). No luciferase activity was detected in any maternal blood sample.

CONCLUSION

Amniotic fluid-derived MSCs can traffic between the fetus and mother in both directions after simple intra-amniotic injection, in a healthy rat model. This phenomenon must be considered in TRASCET performed in twin/multiple pregnancies.

LEVEL OF EVIDENCE

N/A (animal and laboratory study).

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.

Hematogenous Routing of Exogenous mRNA Delivered Into the Amniotic Fluid

INTRODUCTION

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.

METHODS

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.

RESULTS

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).

CONCLUSIONS

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.

Transamniotic stem cell therapy (TRASCET): An emerging minimally invasive strategy for intrauterine stem cell delivery

Transamniotic stem cell therapy (TRASCET) is an emerging strategy for prenatal stem cell therapy involving the least invasive method described to date of delivering select stem cells to virtually any anatomical site in the fetus, including the blood and bone marrow, as well as to fetal annexes, including the placenta. Such broad therapeutic potential derives, to a large extent, from unique routing patterns following stem cell delivery into the amniotic fluid, which have commonalities with naturally occurring fetal cell kinetics. First reported experimentally only less than a decade ago, TRASCET has yet to be attempted clinically, though a first clinical trial appears imminent. Despite significant experimental advances, much promise and perhaps excessive publicity, most cell-based therapies have yet to deliver meaningful large-scale impact to patient care. The few exceptions typically consist of therapies based on the amplification of the normal biological role played by the given cells in their natural environment. Therein lays much of the appeal of TRASCET, in that it, too, is in essence a magnification of naturally occurring processes in the distinctive environment of the maternal-fetal unit. As much as fetal stem cells possess unique characteristics compared with other stem cells, so does the fetus when compared with any other age group, converging into a scenario that enables therapeutic paradigms exclusive to prenatal life. This review summarizes the diversity of applications and biological responses associated with the TRASCET principle.

Transamniotic stem cell therapy (TRASCET) for intrauterine growth restriction (IUGR): A comparison between placental and amniotic fluid donor mesenchymal stem cells

PURPOSE

Transamniotic stem cell therapy (TRASCET) with donor mesenchymal stem cells (MSCs) has been shown experimentally to reverse central effects of intrauterine growth restriction (IUGR). We sought to compare amniotic-fluid and placenta-derived MSCs (afMSCs and pMSCs, respectively) as TRASCET donor cells in a murine IUGR model.

METHODS

Pregnant Sprague-Dawley dams (n=8) were exposed to alternating 12-hour hypoxia (10.5% O₂) cycles, starting on gestational day 15 (E15; term=E21-22). On E17, fetuses (n=100) were divided into four groups. An untreated group had no further manipulations (n=24). Three groups received volume-matched intra-amniotic injections of either saline (sham; n=27), or suspensions of afMSCs (n=24), or pMSCs (n=25). Normal fetuses served as controls (n=21). All infused MSCs consisted of syngeneic Lewis rat cells phenotyped by flow cytometry and GFP-labeled. At term, fetal and placental morphometrics were calculated, and placental TNF-α levels were determined by ELISA. Statistical comparisons were by Fischer's T-test or Wilcoxon rank sum test (p≤0.05).

RESULTS

Overall survival of the hypoxic groups was 83% (83/100). Compared to normal, maternal-adjusted fetal weights were significantly decreased in all hypoxia groups (pairwise p<0.001), however only the afMSC group showed higher adjusted-fetal weights than sham (p<0.001). Placental efficiency was decreased in untreated, sham, and pMSC groups (p<0.001-0.056) but normalized in the afMSC group (p=0.205). Maternal-adjusted placental weights were lower than normal in all hypoxia groups (p<0.001-0.045), except for the pMSC group (p=0.387).

CONCLUSIONS

Amniotic fluid-derived mesenchymal stem cells are superior to their placenta-derived counterparts in transamniotic stem cell therapy for intrauterine growth restriction in a rat model.

LEVEL OF EVIDENCE

Basic/Translational science.

Brain protection by transamniotic stem cell therapy (TRASCET) in a model of intrauterine growth restriction (IUGR)

PURPOSE

Transamniotic stem cell therapy (TRASCET) with mesenchymal stem cells (MSCs) has been shown experimentally to reverse some of the effects of intrauterine growth restriction (IUGR), apparently by attenuating placental inflammation. Neurodevelopmental deficits driven by neuroinflammation are major complications of IUGR. We sought to determine whether MSC-based TRASCET also mitigates inflammation in the fetal brain.

METHODS

Pregnant Sprague-Dawley dams (n = 8) were exposed to alternating 12-hour hypoxia (10.5% O₂) cycles from gestational day 15 (E15) until term (E21). One group remained untreated (n = 28 fetuses). Three groups received volume-matched intra-amniotic injections into all fetuses (n = 72) of either saline (sham; n = 19), or a suspension of amniotic fluid-derived MSCs, either in native state (TRASCET; n = 20), or primed by exposure to interferon-gamma (IFN-γ) and interleukin-1beta (IL-1β) for 24 h prior to administration in vivo (TRASCET-Primed; n = 29). Donor MSCs were syngeneic Lewis rat cells phenotyped by flow cytometry. Normal fetuses served as controls (n = 20). Multiple analyses were performed at term, including ELISA in fetal brains for the pro-inflammatory cytokines tumor necrosis factor-alpha (TNF-α) and IL-1β. Statistical comparisons were by Wilcox-rank sum test, including Bonferroni-adjusted significance.

RESULTS

Overall survival was 75% (88/116). Gross brain weights were significantly decreased from normal in both the untreated and sham groups (both p<0.001) and significantly increased in both TRASCET groups when compared to untreated and sham (p = 0.003 to <0.001). TRASCET-Primed led to significantly lower levels of TNF-α and IL-1β compared to untreated (both p<0.001) and sham (p = 0.017 and p = 0.011, respectively). Non-primed TRASCET led to significantly lower levels of TNF-α and IL-1β compared to untreated (p = 0.009 to <0.001), but not sham (p = 0.133 and p = 0.973, respectively).

CONCLUSIONS

Transamniotic stem cell therapy with primed mesenchymal stem cells reverses some of the central nervous system effects of intrauterine growth restriction in a rat model, possibly by modulating neuroinflammation.

TYPE OF STUDY

Animal and laboratory study.

LEVEL OF EVIDENCE

N/A (animal and laboratory study).

Routing pathway of syngeneic donor hematopoietic stem cells after simple intra-amniotic delivery

BACKGROUND

We sought to determine the pathway through which syngeneic hematopoietic stem cells (HSCs) delivered into the amniotic fluid can reach the fetal circulation.

METHODS

Lewis rat fetuses were divided in two groups based on the content of intra-amniotic injections performed on gestational day 17 (E17; term=E21-22): either a suspension of luciferase-labeled syngeneic HSCs (n = 137), or acellular luciferase (n = 44). Samples from placenta, chorion, amnion, amniotic fluid, umbilical cord, and 8 fetal sites were procured at 5 daily time points thereafter until term for analysis.

RESULTS

When controlled by acellular luciferase, donor HSCs were identified in the amnion, chorion, placenta, and amniotic fluid of fetuses receiving cells at all time points (p = 0.033 to <0.001), peaking first at the amnion and subsequently at the chorion and placenta. Cells could be detected in the fetal liver as early as day 1, progressively expanding to all the other fetal sites over time, in parallel to their increased presence in the chorion and placenta.

CONCLUSIONS

The chronology of syngeneic donor hematopoietic stem cell trafficking after intra-amniotic injection is suggestive of controlled routing through the gestational membranes and placenta. Hematogenous donor cell routing is a constituent of transamniotic hematopoietic stem cell therapy, significantly expanding its potential applications.

Intrauterine Growth Restriction (IUGR) as a potential target for transamniotic stem cell therapy

BACKGROUND

We sought to determine whether intrauterine growth restriction (IUGR) could be a target for mesenchymal stem cell (MSC)-based transamniotic stem cell therapy (TRASCET).

METHODS

Pregnant dams subjected to hypoxia (10.5% O₂) cycles had their fetuses divided into four groups: untreated (n = 24) and three groups receiving volume-matched intra-amniotic injections of either saline (sham; n = 16), or suspensions of luciferase-labeled, syngeneic amniotic fluid-derived MSCs that were either native (TRASCET-unprimed; n = 29), or primed by exposure to IFNγ and IL-1β (TRASCET-primed; n = 31). Normal fetuses served as additional controls (n = 22). Multiple analyses were performed at term.

RESULTS

Compared to normal, fetal weights were significantly decreased in all hypoxia groups (p = 0.002 to <0.001), except for TRASCET-primed. Placental efficiency (fetal/placental weight) was significantly decreased in all hypoxia groups (p = 0.002 to <0.001), but normalized in both TRASCET groups. A significant increase in metrial expression of IFNγ in both the untreated and sham groups (p = 0.04 to 0.02) was reversed only in the TRASCET-primed group. Luciferase DNA was present in both TRASCET groups' placentas.

CONCLUSIONS

Transamniotic stem cell therapy with primed mesenchymal stem cells reverses some of the effects of intrauterine growth restriction in a rat model. Further study into this novel approach for the treatment of this disease is warranted.

LEVEL OF EVIDENCE

N/A (Animal and Laboratory Study).

Passive perinatal immunotherapy via transamniotic antibody delivery

PURPOSE

We sought to determine whether the amniotic cavity/fluid could be an attainable route of administration of therapeutic antibodies to the fetus/neonate.

METHODS

Time-dated pregnant dams (n = 9) received volume-matched intra-amniotic injections of either saline (n = 29), or different concentrations of a human IgG that lacked homology with rodents: 5 mg/mL (n = 28); 10 mg/mL (n = 28); or 15 mg/mL (n = 24). At term, the presence of the IgG was quantified by ELISA in the serum, bone marrow, spleen, thymus, and brain of all neonates, and in the maternal serum. Statistical analysis was by median regression with significance set at Bonferroni-adjusted p<0.008.

RESULTS

Overall fetal survival was 83% (90/109), with no difference between the groups. Human IgG was detected in the serum, bone marrow, spleen, thymus, and brain of all fetuses for all three injected concentrations, but not in the saline injected controls (p<0.001). A dose dependent relationship between injection concentration and final IgG load was noted in the bone marrow, spleen, and thymus (p = 0.004 to <0.001). Human IgG was also detected in maternal serum.

CONCLUSIONS

IgG antibodies can reach high levels in the fetal/neonatal circulation after simple intra-amniotic administration in a healthy rodent model. Transamniotic fetal immunotherapy (TRAFIT) may become a practicable strategy for the perinatal management of select diseases.

LEVEL OF EVIDENCE

N/A (animal and laboratory study) TYPE OF STUDY: Animal and laboratory study.

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.