Research Projects

• Amniotic Epithelial Stem cells: Isolation, characterization and experimental evaluation of its clinical utility.  (Julieta Maymó, PhD and Rodrigo Nicolas Riedel, Doctoral Student) 

The placenta and its membranes are of a great interest as a source of cells for regenerative medicine due to the phenotypic plasticity of many cell types isolated from this tissue. Placental tissues are easy to obtain without invasive procedures, they proliferate fast, they are obtained in high mass and their use does not generate ethical debates, as with embryonic stem cells (hESC).

Recent publications indicate that there are several types of potential stem cells derived from human placenta, including the amnion epithelial cells (HAEC). The HAECs express stem cell markers and have the ability to differentiate into the three germ layers types: endoderm, mesoderm and ectoderm. Unlike hESCs, the HAECs not express telomerase and are not tumorigenic. These properties, the simple isolation and easy availability of the placenta, turn the amnions as useful and non-controversial source of cells for transplantation and regenerative medicine.

The overall objective of our new research project is the study of human placenta as a novel source of great interest, of stem cells with regenerative capacity of tissues with different pathologies. In particular the objectives for our research topic are:

-Isolation and characterization of human amniotic epithelial cells

-Study of the cellular mechanisms involved in the differentiation of HAECs respect to cell proliferation and apoptosis. Study of the transduction pathways activated signals.

-As future clinical application, develop an alternative strategy to liver transplantation in patients with chronic liver disease

• Mechanisms of leptin action on migration and invasion of trophoblast cells. (Ayelén R. Toro, PhD) 

During embryo implantation embryo is anchored in the endometrium in order to form the placenta, which consists of a transitional and highly specialized body that maintains normal growth and development of the fetus during pregnancy. In a first stage of embryo implantation the blastocyst attaches unstable to the uterine wall form, then a physical contact between the blastocyst and the uterine epithelium and finally trophoblast cells (constituting the outermost layer of the blastocyst is established and will rise to the placenta) invade the entire endometrium, myometrium and part of uterine vasculature. The invasiveness of trophoblasts into the uterine wall is a determinant of pregnancy outcome for this reason it is highly regulated. Various pathologies associated with pregnancy are caused excessive invasion (placenta accreta, hydatidiform mole, choriocarcinoma) or poor (preeclampsia, hypertension, poor fetal growth).

In our research group we have studied the role of leptin on the proliferation of trophoblast cells and found that treatment with recombinant leptin leads to an increase in cell proliferation so time and dose dependent. During the course of my PhD thesis we focus on the study of the action of leptin on apoptosis of trophoblast cells. We showed that leptin decreases apoptosis induced by the absence of serum and exercises that function primarily through MAPK and PI3K / Akt pathways. We noted that leptin reduces expression and activity  levels of the transcription factor p53 and increases its degradation generating decreasing its half-life. When analyzing later phases of apoptosis, we found that leptin reduces activation of caspase-3, PARP-1, DNA fragmentation and the proportion of apoptotic nuclei. We observed similar effects by inducing UV irradiation damage.

Recently we showed that leptin upregulates the expression of HLA-G, a protein involved in trophoblast invasion. For proper embryo implantation are critical not only the processes of proliferation and apoptosis of trophoblast cells but also migration and invasion.

Based on background information provided by the literature and our preliminary results we suggest that leptin, as placental cytokine, is a key regulatory of the molecule implantational process, promoting the invasion of trophoblastic cells.

Thus, the overall objective of this project is the study of a possible role of leptin during trophoblast invasion, which is a key process during implantation and pacentation. For this aim we will investigate leptin effect on molecular and cellular mechanisms involved in migration and invasion of human first trimester trophoblasts.

• Transcriptional factors involved on leptin induction by estradiol on  normal and patological humans placenta. (Lic. Schanton Malena)

In pregnancy, maternal-fetal dialogue is essential for implantation. Implantation involves a series of steps leading to a reciprocal signaling between the blastocyst and the uterus in wich leptin is involved. In particular we study the regulation of expression of leptin by estradiol. We also want to identify whether this process is altered in various diseases such as preeclampsia, gestational diabetes and IUGR (intrauterine growth retardation)

The objectives for this project are:

- Study of transcription factors involved in the regulation exerted by estradiol on leptin expression in placental cells. Analyze leptin promoter.

- Study of the signal transduction pathways involved.

- Determination of the effects of estradiol on leptin expression in pathological placentas.

• Mechanisms of leptin action on trophoblast cell proliferation and apoptosis under hypoxia. (Student Paula Balestrini)

Currently leptin is considered as a new placental hormone that regulates embryo-endometrium connection. Previous results from our laboratory indicate that leptin increases proliferation of trophoblast cells time and dose dependent manner and also has an anti-apoptotic action.

Previously we have demonstrated that leptin is able to regulate mRNA and proteins levels of p53 in serum deprivation conditions. In this project we are interested in evaluating leptin action under different stress conditions like hypoxia. Currently we are deepening the study of this factor, including the research of target genes involved in cell cycle regulation and apoptosis. 

The main objectives of this project are:

- The study of the cellular mechanisms involved in the action of leptin on cell proliferation and apoptosis in trophoblast cells under hypoxia.

- The study of signal transduction pathways involved in the action of leptin on the survival of trophoblast cells under hypoxia.

• Study immunomodulatory function of leptin in gestation.

Leptin, through its interaction with Lep-R expressed in different leucocyte populations, is able to modulate the innate and adaptive immune responses in different pathophysiological contexts. Since is expressed by the placenta from the early stages and is released into the maternal circulation throughout gestation, this molecule may either modulate the function of immune cells to locally and systemically favoring the maintenance of pregnancy. There is little evidence about the possible immunomodulatory function of leptin during normal gestation and their relationship with pathogenesis mechanisms underlying the different reproductive disorders in which abnormalities occur in leptin levels is unknown.

As part of our project we investigate the role of leptin as an immunomodulatory molecule in the context of pregnancy, identifying and characterizing its effects at local and systemic level in the maternal-fetal interface. The problem is addressed by in vitro tests using trophoblast cell lines and placental explants and immune cells isolated from peripheral blood samples.

In particular, the specific objectives include:

- To determine the effect of leptin on the expression of HLA-G isoforms in trophoblast cells

- To characterize the effect of leptin on the phenotype and function of dendritic cells and NK cells during pregnancy

- To characterize the mechanism of action of leptin in its immunomodulatory function and signal transduction pathways involved.