Enhancement of Transamniotic Stem Cell Therapy for Spina Bifida by Genetic Engineering of Donor Mesenchymal Stem Cells with an Fgf2 Transgene
Stefanie P Lazow, MD; Daniel F Labuz, MD; Ina Kycia, PhD; David Zurakowski, PhD; Dario O Fauza, MD, PhD
Boston Children's Hospital, Boston, MA
Background: Transamniotic stem cell therapy (TRASCET) with amniotic fluid-derived mesenchymal stem cells (afMSCs) induces prenatal coverage of experimental spina bifida in some fetuses. Variation in defect fibroblast growth factor-2 (Fgf2) expression is associated with increased coverage. We examined whether overexpression of Fgf2 in donor afMSCs could enhance coverage rates.
Methods: Pregnant Sprague-Dawley dams (n=24) exposed to retinoic acid for induction of fetal spina bifida were divided in three groups. An untreated group had no further manipulations. Two groups received volume-matched intra-amniotic injections of labeled afMSCs, either without further manipulation (afMSC; n=85) or transduced to overexpress Fgf2 (Fgf2-afMSC; n=72) on gestational day 17 (term=21-22 days). afMSCs were syngeneic Lewis rat cells phenotyped by flow cytometry. Fgf2 mRNA expression and protein levels were measured by RT-qPCR and ELISA, respectively, in both cell populations. Defect coverage was histologically categorized at term and compared by logistic regression.
Results: Fgf2 mRNA expression and protein levels were 10.1-fold and 3.1-fold higher, respectively, in Fgf2-afMSCs than in afMSCs. Among 84 survivors with isolated spina bifida, 71 had definitive histology. Defect coverage rates in both the afMSC (38.5%) and Fgf2-afMSC (73.3%) groups were significantly higher than in the untreated group (10%; p<0.001 for both). There was a significantly higher rate of coverage in the Fgf2-afMSC group compared with the afMSC group (p=0.025). Conclusions: Fgf2 overexpression in donor mesenchymal stem cells increases defect coverage rates in a rodent model of transamniotic stem cell therapy for spina bifida and represents a promising strategy for the enhancement of this emerging therapy.
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