Insights into Hematogenous Donor Cell Routing after Transamniotic Stem Cell Therapy
Sarah A Tracy1; Alexander V Chalphin1; Ina Kycia1; Christopher Chan2; Adam Finkelstein3; David Zurakowski1; Dario O Fauza1
1 Harvard Medical School, Boston Children's Hospital, Boston, MA, USA 2 Boston University, Boston, MA, USA 3 Lafayette College, Easton, PA, USA
Background: Donor mesenchymal stem cells (MSCs) have been documented in maternal and fetal circulation after intra-amniotic injection, but the mechanisms behind this phenomenon remain unclear. In a normal model, we sought to determine how MSCs from the amniotic fluid reach the fetal circulation.
Methods: Sprague-Dawley rat fetuses (n=212) were divided into two groups, receiving intra-amniotic injections on gestational day 17 (E17) of either a concentration suspension of luciferase-labeled syngeneic rat amniotic fluid MSCs (n=103) or an acellular suspension of luciferase (n=109). MSC identity was confirmed by flow cytometry. Samples from placenta, umbilical cord, gestational membranes, amniotic fluid, and peripheral blood were procured at five time points (E18-22) and screened for luciferase activity via microplate luminometry. Statistical analysis was by the Mann-Whitney U-test, Wald test, and nonlinear regression modeling.
Results: Luciferase activity was seen in the amnion, chorion and placenta of fetuses receiving cells, but not those receiving luciferase (P<0.001). There was a consistent nonlinear age-dependent relationship of luciferase activity between the gestational membranes and placenta. A parabolic bimodal pattern was observed, with higher early preterm and late term activities (P<0.001), and higher activity in the amnion compared with chorion and placenta (P<0.01) (figure).
Conclusion: The chronology of donor MSC trafficking after intra-amniotic injection suggests controlled routing, and transport through gestational membranes appears to be one path for donor cells to reach the placenta and consequently, the fetal circulation.
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