Postnatal fate of donor mesenchymal stem cells after transamniotic stem cell therapy in a healthy model.

PURPOSE: We sought to examine donor mesenchymal stem cell (MSC) fate after birth following transamniotic stem cell therapy (TRASCET) in a healthy model. METHODS: Lewis rat fetuses (n = 91) were divided into two groups based on the content of volume-matched intraamniotic injections performed on gestational day 17 (term = 21-22 days): either a suspension of amniotic fluid-derived MSCs (afMSCs) labeled with luciferase (n = 38) or acellular luciferase only (n = 53). Infused afMSCs consisted of syngeneic Lewis rat cells phenotyped by flow cytometry. Samples from 14 anatomical sites (heart, lung, brain, liver, spleen, pancreas, bowel, kidney, thyroid, skin, skeletal muscle, thymus, peripheral blood and bone marrow) from survivors were screened for luciferase activity 16 days after birth. Statistical analysis was by logistic regression and the Wald test (p < 0.05). RESULTS: Overall survival was 32% (29/91). When controlled by the acellular luciferase injections, donor afMSCs were not identified at any anatomical site in any neonate as measured by relative light units (all p > 0.05). Donor afMSC viability was confirmed in term placentas. CONCLUSIONS: Donor mesenchymal stem cells are not detectable in the neonate after intraamniotic injection in a normal syngeneic rodent model. This finding suggests that clinical trials of transamniotic stem cell therapy may be amenable to regulatory approval. LEVEL OF EVIDENCE: N/A (animal and laboratory study).