Enhanced Hematovascular Contribution of SCL 3′ Enhancer Expressing Fetal Liver Cells Uncovers Their Potential to Integrate in Extramedullary Adult Niches  

Abstract

Fetal liver (FL) hematopoietic progenitors have superior blood engraftment competence compared with adult bone marrow (BM), however less is known about FL in vivo vascular capacity. Here we show in transplantation assays that FL cells possess enhanced vascular endothelial potential compared with adult bone marrow. We generated high-level hematopoietic chimeras using donor cells from mice transgenic for the stem cell leukaemia 3 0 enhancer human placental alkaline phosphatase (SCL3 0 Enh-PLAP) reporter construct, active in vascular endothelium, and blood progenitor and stem cells. Long-term lineage tracing analysis revealed PLAP 1 vascular-like patches in FL-derived chimeras, whereas adult BM-derived chimeras presented only rare and scattered PLAP 1 cells. PLAP 1 vascular-like patches were formed following transplantation into both newborn and adult recipient mice, although their frequency was reduced in adult recipients. Confocal analysis of multiple labeled tissues revealed that whereas most liver and heart PLAP 1 vascular patch-associated cells were endothelial, PLAP 1 vascular patches in the kidney contained endothelial, hematopoietic, and putative hemangioblastic cells. Moreover, fluorescenceactivated cell sorting assays showed that only FL PLAP bright1 donor cells can generate PLAP 1 vascular patches upon transplantation. Taken together, these data demonstrate superior vascular contribution potential of FL cells, and not only provide new insights into the developmental pathways controlling endothelial development but also may prove informative when addressing the mechanisms involved in vascular regeneration and hemangiogenic recovery in a clinical context.

A population of hematopoietic stem cells derives from GATA4-expressing progenitors located in the placenta and lateral mesoderm of mice

“…10,11 Pregnant females are injected by intraperitoneal (i.p.) injection on days 17 and 18 of gestation with a 15 mg busulfan/Kg dose.…”

Characterization of a Fetal Liver Cell Population Endowed with Long-Term Multiorgan Endothelial Reconstitution Potential

“…Animals were maintained in the CABD animal care facility and procedures performed under the guidance of the European Community Legislation with the approval of ethical committee of CSIC and Universidad Pablo de Olavide. Transgenic lines for transplantation assays include the SCL3′Enh‐hPLAP mice, expressing the human placental alkaline phosphatase (PLAP) reporter gene , the SCL‐3′Enh‐Lacz mice expressing the β‐galactosidase reporter gene and the actin‐DsRed mice expressing the DsRed‐MST reporter gene under the actin regulatory elements (Jackson Laboratories, stock 005441) .…”

“…Fetuses were obtained from day 10 (E10) to day 14 (E14) of gestation. Cell preparation procedures from embryonic/fetal and adult hematopoietic tissues were previously published , (Supporting Information). A fragment of yolk sac (YS) was used for embryo typing by staining with the PLAP substrate, nitroblue tetrazolium (NBT) (Roche, Mannheim, Germany, http://www.lifescience.roche.com) as described .…”

“…Cell suspensions were stained, analyzed and separated by flow cytometry as previously described (Sup. Information).…”

“…Using intravenous cell transfer into myelo‐ablated newborn‐mice, we found that cells from the FL, a predominant hematopoietic organ at this stage, had a much superior contribution potential to the endothelium of different organs than postnatal BM cells . Newborns present an active organ growth and neovascularization activity, thereby it was proposed that this might facilitate the engraftment of transferred EC/EPCs in different locations . The FL multiorgan EC engraftment potential is hence referred as long‐term reconstituting EC (LTR‐EC) activity, involving cell homing/lodging, differentiation to organ‐associated endothelial types and long term stabilization of the donor‐derived vascular beds.…”