Human Chorionic Gonadotropin Improves the Proliferation and Regenerative Potential of Bone Marrow Adherent Stem Cells and the Immune Tolerance of Fetal Microchimeric Stem Cells In Vitro

Synergistic Effect of Human Chorionic Gonadotropin and Granulocyte Colony Stimulating Factor in the Mobilization of HSPCs Improves Overall Survival After PBSCT in a Preclinical Murine Model. Are We Far Enough for Therapy?

Strategies to improve hematopoietic stem and progenitor cell (HSPC) mobilization from the bone marrow can have a pivotal role in addressing iatrogenic bone-marrow insufficiency from chemo(radio)therapy and overcoming peripheral blood stem cell transplantation (PBSCT) limitations such as insufficient mobilization. Granulocyte-colony stimulating factor (G-CSF) represents the standard mobilization strategy for HSPC and has done so for more than three decades since its FDA approval. Its association with non-G-CSF agents is often employed for difficult HSPC mobilization. However, obtaining a synergistic effect between the two classes is limited by different timing and mechanisms of action. Based on our previous in vitro results, we tested the mobilization potential of human chorionic gonadotropin (HCG), alone and in combination with G-CSF in vivo in a murine study. Our results show an improved mobilization capability of the combination, which seems to act synergistically in stimulating hematopoiesis. With the current understanding of the dynamics of HSPCs and their origins in more primitive cells related to the germline, new strategies to employ the mobilization of hematopoietic progenitors using chorionic gonadotropins could soon become clinical practice.

Fetal microchimerism and the two-stage model of preeclampsia

Fetal cells cross the placenta during pregnancy and some have the ability to persist in maternal organs and circulation long-term, a phenomenon termed fetal microchimerism. These cells often belong to stem cell or immune cell lineages. The long-term effects of fetal microchimerism are likely mixed, potentially depending on the amount of fetal cells transferred, fetal-maternal histocompatibility and fetal cell-specific properties. Both human and animal data indicate that fetal-origin cells partake in tissue repair and may benefit maternal health overall. On the other hand, these cells have been implicated in inflammatory diseases by studies showing increased fetal microchimerism in women with autoimmune diseases such as systemic lupus erythematosus and rheumatoid arthritis. During pregnancy, preeclampsia is associated with increased cell-transfer between the mother and fetus, and an increase in immune cell subsets. In the current review, we discuss potential mechanisms of transplacental transfer, including passive leakage across the compromised diffusion barrier and active recruitment of cells residing in the placenta or fetal circulation. Within the conceptual framework of the two-stage model of preeclampsia, where syncytiotrophoblast stress is a common pathophysiological pathway to maternal and fetal clinical features of preeclampsia, we argue that microchimerism may represent a mechanistic link between stage 1 placental dysfunction and stage 2 maternal cardiovascular inflammation and endothelial dysfunction. Finally, we postulate that fetal microchimerism may contribute to the known association between placental syndromes and increased long-term maternal cardiovascular disease risk. Fetal microchimerism research represents an exciting opportunity for developing new disease biomarkers and targeted prophylaxis against maternal diseases.

Stem Cells in the Tumor Immune Microenvironment -Part of the Cure or Part of the Disease? Ontogeny and Dichotomy of Stem and Immune Cells has Led to better Understanding

Stem cells are at the basis of tissue homeostasis, hematopoiesis and various regenerative processes. Epigenetic changes in their somatically imprinted genes, prolonged exposure to mutagens/carcinogens or alteration of their niche can lead to the development of an enabling environment for tumor growth and progression. The involvement of stem cells in both health and disease becomes even more compelling with ontogeny as embryonic and extraembryonic stem cells which persist into adulthood in well established and specific niche may have distinct implications in tumorigenesis. Immune surveillance plays an important role in this interplay since the response of immune cells toward the oncogenic process can range from reactivity to placidity and even complicity, being orchestrated by intercellular molecular dialogues with the other key players of the tumor microenvironment. With the current understanding that every developing and adult tissue contains inherent stem and progenitor cells, in this manuscript we review the most relevant interactions carried out between the stem cells, tumor cells and immune cells in a bottom-up incursion through the tumor microenvironment beginning from the perivascular niche and going through the tumoral parenchyma and the related stroma. With the exploitation of various factors that influence the behavior of immune effectors toward stem cells and other resting cells in their niche, new therapeutic strategies to tackle the polarization of immune effectors toward a more immunogenic phenotype may arise.