Step-by-step protocol for isolating the entire repertoire of human first trimester placental cells.

Correct placental development and function are essential for adapting the mother to the ongoing pregnancy and the wellbeing of the growing fetus; however, underlying processes are still poorly understood. Only limited structural and cellular placental features are shared among species hence requiring reliable human in-vitro models. Recently established trophoblast stem cell and organoid models significantly improved placental research; however, the human placenta constitutes a multi-cellular organ with tightly orchestrated, cellular and molecular networks between trophoblasts (TBs) and villous core cells (VCCs) vital for correct placentation. The establishment of co-culture models is accordingly the logical consequence to investigate TB and VCC interactions, but first requires efficient purification of ideally donor-matched placental cell types. We herein present a meticulously-tailored protocol based on four sequential digestion steps (d-steps) with varying enzyme compositions and digestion mode and length, gently releasing cells layer-by-layer from human first trimester placentae (8 - 9th week of gestation). Using immunofluorescence and flow cytometry, we analyzed the tissue fragments and digestion solutions after every d-step and collected data on individual digestion progress as well as cell viability, counts, and specifications. D-step 1 revealed a significantly low viability and was mainly composed of syncytial fragments, extravillous trophoblasts EVTs, and maternal leukocytes. D-step 2 and 3, comprising high viability predominantly contained TBs (90-99 %) with a significant enrichment of EVTs in d-step 2 and an almost pure villous cytotrophoblast (vCTB) population in d-step 3. D-step 4 finally enabled isolating fetal VCCs consisting of endothelial cells, fibroblasts, and Hofbauer cells. Interestingly, maternal leukocytes were detected in d-step 1 and 2 but completely absent from d-step 3 and 4 revealing pure fetal cell populations. In sum, we present a detailed guideline for stepwise isolating selected placental cell types suitable for further studies and co-culture models investigating TB and VCC interactions involved in early placental development.

Transforming growth factor-ß signaling governs the differentiation program of extravillous trophoblasts in the developing human placenta.

Abnormal placentation has been noticed in a variety of pregnancy complications such as miscarriage, early-onset preeclampsia, and fetal growth restriction. Defects in the developmental program of extravillous trophoblasts (EVTs), migrating from placental anchoring villi into the maternal decidua and its vessels, is thought to be an underlying cause. Yet, key regulatory mechanisms controlling commitment and differentiation of the invasive trophoblast lineage remain largely elusive. Herein, comparative gene expression analyses of HLA-G-purified EVTs, isolated from donor-matched placenta, decidua, and trophoblast organoids (TB-ORGs), revealed biological processes and signaling pathways governing EVT development. In particular, bioinformatics analyses and manipulations in different versatile trophoblast cell models unraveled transforming growth factor-ß (TGF-ß) signaling as a crucial pathway driving differentiation of placental EVTs into decidual EVTs, the latter showing enrichment of a secretory gene signature. Removal of Wingless signaling and subsequent activation of the TGF-ß pathway were required for the formation of human leukocyte antigen-G+ (HLA-G+) EVTs in TB-ORGs that resemble in situ EVTs at the level of global gene expression. Accordingly, TGF-ß-treated EVTs secreted enzymes, such as DAO and PAPPA2, which were predominantly expressed by decidual EVTs. Their genes were controlled by EVT-specific induction and genomic binding of the TGF-ß downstream effector SMAD3. In summary, TGF-ß signaling plays a key role in human placental development governing the differentiation program of EVTs.

Effect of L- to D-Amino Acid Substitution on Stability and Activity of Antitumor Peptide RDP215 against Human Melanoma and Glioblastoma.

The study investigates the antitumor effect of two cationic peptides, R-DIM-P-LF11-215 (RDP215) and the D-amino acid variant 9D-R-DIM-P-LF11-215 (9D-RDP215), targeting the negatively charged lipid phosphatidylserine (PS) exposed by cancer cells, such as of melanoma and glioblastoma. Model studies mimicking cancer and non-cancer membranes revealed the specificity for the cancer-mimic PS by both peptides with a slightly stronger impact by the D-peptide. Accordingly, membrane effects studied by DSC, leakage and quenching experiments were solely induced by the peptides when the cancer mimic PS was present. Circular dichroism revealed a sole increase in ß-sheet conformation in the presence of the cancer mimic for both peptides; only 9D-RDP215 showed increased structure already in the buffer. Ex vitro stability studies by SDS-PAGE as well as in vitro with melanoma A375 revealed a stabilizing effect of D-amino acids in the presence of serum, which was also confirmed in 2D and 3D in vitro experiments on glioblastoma LN-229. 9D-RDP215 was additionally able to pass a BBB model, whereupon it induced significant levels of cell death in LN-229 spheroids. Summarized, the study encourages the introduction of D-amino acids in the design of antitumor peptides for the improvement of their stable antitumor activity.