Fig. 2: GFP-labeled BMSCs specifically engraft into NTD-lesions.

a A schematic picture of transamniotic BMSC microinjection of an E10 embryo. The microinjection pipette (blue) traversed the visceral yolk sac (vys, orange), exocoelomic cavity (ec) and finally the amnion (green) before entering the amniotic cavity (ac). b GFP⁺ BMSCs (green) distributed specifically at defective regions of the neural tube after transamniotic BMSCs transplantation. The arrowhead indicates a closed neural tube region. Inset: transverse section along the blue dotted line. Nuclei were stained blue with DAPI. c Representative fluorescent stereomicroscopic and microscopic images of embryos with BMSCs engraftment and their transverse sections. Scale bars: 500 μm (fluorescent stereomicroscopic images) and 50 μm (cryosection images). d Normal embryo with a closed neural tube after BMSCs transplantation. e GFP⁺ BMSCs detected in the abnormal regions of embryos with other deformities. Arrowheads indicate typical deformities where BMSCs were engrafted. Scale bars: 500 μm. cf craniofacial, hb hindbrain, H heart, md mandible, mx maxilla. f Evaluation of the BMSC engraftment rate in different types of NTDs (Controls, n = 12; atRA-treated embryos without NTDs, n = 11; Spina bifida, n = 11; Exencephaly, n = 9; Exencephaly+ spina bifida, n = 9). Engraftment rates were determined by the total number of GFP⁺ BMSCs in continuous frozen sections/ the number of transplanted BMSCs at 48 h after transplantation. * indicate significant difference compare with those in normally developed embryos, P < 0.05.