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

Abstract

<b><i>Purpose:</i></b> 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. <b><i>Methods:</i></b> Pregnant dams (<i>n</i> = 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; <i>n</i> = 105) or saline (<i>n</i> = 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. <b><i>Results:</i></b> Defect coverage was associated with significant downregulation of both epidermal growth factor (<i>Egf</i>; <i>p</i> = 0.031) and fibroblast growth factor-2 (<i>Fgf-2</i>; <i>p</i> = 0.042) expressions at the defect and with significant downregulation of transforming growth factor-beta-1 (<i>Tgfb-</i>1<i>; p</i> = 0.021) and <i>CD45</i> (<i>p</i> = 0.028) expressions at the fetal bone marrow. <b><i>Conclusions:</i></b> 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.