Trophoblast Stem Cells Rescue Placental Defect in SOCS3-deficient Mice

Abstract

Stem cells have important clinical and experimental potentials. Trophoblast stem (TS) cells possess the ability to differentiate into trophoblast subtypes in vitro and contribute to the trophoblast lineage in vivo.Suppressor of cytokine signaling 3 (SOCS3) is a negative regulator of cytokine signaling. Targeted disruption of SOCS3 revealed embryonic lethality on E12.5; it was caused by placental defect with enhanced leukemia inhibitory factor receptor signaling. A complementation of the wild-type (WT) placenta by using tetraploid rescue technique showed that the embryonic lethality in SOCS3-deficient embryo was due to the placental defect. Here we demonstrate that TS cells supplementation rescues placental defect in SOCS3-deficient embryos. In the rescued placenta, TS cells were integrated into the placental structure, and a substantial structural improvement was observed in the labyrinthine layer that was disrupted in the SOCS3-deficient placenta. Importantly, by supplying TS cells, living SOCS3-deficient embryos were detected at term. These results indicate a functional contribution of TS cells in the placenta and their potential application.In mammals, trophoblast cells in the placenta are essential for the growth and survival of the embryo. Trophoblast stem (TS) 3 cells have been established from either blastocysts or early postimplantation trophoblasts in the presence of fibroblast growth factor 4 (FGF4) (1). These cell lines differentiated into trophoblast subtypes in vitro and have the potential to contribute to the placenta in chimeras in vivo. However, it remains to be clarified whether the in vivo differentiated trophoblasts from TS cells are functional.SOCS3 is an essential negative regulator of leukemia inhibitory factor receptor signaling in trophoblast differentiation (2). Targeted disruption of SOCS3 demonstrates embryonic lethality with placental defect (2, 3). In the SOCS3-deficient placenta, an excess status of trophoblast giant cell differentiation is observed. The embryonic lethality in SOCS3Ϫ/Ϫ embryos is rescued by the complementation of wild-type tetraploid embryos, thus demonstrating an essential role of SOCS3 in placental development and a non-essential role in embryo development (2). To explore the potential of TS cells in rescuing the placental defect in SOCS3-deficient mice, we attempted to prepare a chimera by using SOCS3Ϫ/Ϫ embryo and WT TS cells. MATERIALS AND METHODSMice-The generation of SOCS3-disrupted mice was as described in a previous study (2). Using tail biopsies, genotyping was performed by PCR as described. Mutant phenotypes were analyzed in a mixed 129/Sve, C57Bl/6 background.TS Cell Injections-TS cell lines were derived from B5/enhanced green florescent protein (EGFP) transgenic mice (4) (kindly supplied by Dr. J. Rossant) that ubiquitously express EGFP. These cells had already been cultured for more than 30 passages and showed a typical colony (Fig. 1, left). TS cells were maintained in the presence of FGF4 and conditioned medium from mouse embryonic fibroblast cells...

Blastocyst-Derived Trophoblast Stem Cells from the Rhesus Monkey

“…First, the cells offer researchers an ideal model system to study the regulation of trophoblast differentiation and growth. Second, as has been demonstrated in the mouse (57), TS cells offer the means to develop novel intervention strategies to treat placental dysfunction. Because of the many similarities between rhesus monkey and human placentas, the cells described here could be used to test new intervention strategies before translation to human clinical trials.…”

LIF-STAT signaling and trophoblast biology

“…In the SOCS3-null placenta, chorio-allantoic fusion occurred normally, but the labyrinthine and spongiotrophoblast layers of the mouse placenta were poorly formed, while trophoblast giant cells were increased in number and in size. To emphasize the fact that embryonic lethality associated with absence of SOCS3 is due to compromised placental differentiation, use of wild-type extraembryonic tissues, either in complementation via aggregation with tetraploid embryos (which contribute to extraembryonic tissues but not to embryo proper) or generation of chimeras composed of SOCS3-null embryos and wild-type trophoblast stem cells rescued the lethal phenotype 95 , 96 . Genetic crosses between mice heterozygous for deletion of SOCS3 and LIFRα (null mutants for each is lethal) revealed that the phenotype is due to dysregulation of signaling downstream of the LIFR and that the ligand responsible for this, LIF, is produced by embryonic tissues and acts in a paracrine fashion 28 , 95 .…”

Socs3

“…Interestingly, a recent study in which Socs3 was deleted specifically in cardiomyocytes found that SOCS3 deficiency in the heart leads to death by 33 weeks of age from cardiomyopathy 68 67 , 69 , 70 …”