Kinetics of mesenchymal and hematopoietic stem cells mobilization by G-CSF and its impact on the cytokine microenvironment in primary cultures

G-CSF treatment of healthy pediatric donors affects their hematopoietic microenvironment through changes in bone marrow plasma cytokines and stromal cells

Although G-CSF mobilized peripheral blood stem cell (PBSC) transplantation is commonly used in adults, bone marrow (BM) is still the preferred stem cell source in pediatric stem cell transplantation. Despite the fact that G-CSF is increasingly being used to enhance the hematopoietic stem/progenitor cell (HSPC) yield in BM transplantation (G-BM), the direct effects of G-CSF on the pediatric BM microenvironment have never been investigated. The BM hematopoietic niche provides the physical space where the HSPCs reside. This BM niche regulates HSPC quiescence and proliferation through direct interactions with other niche cells, including Mesenchymal Stromal Cells (MSCs). These cells have been shown to secrete a wide range of hematopoietic cytokines (CKs) and growth factors (GFs) involved in differentiation, retention and homing of hematopoietic cells. Here, we assessed changes in the BM microenvironment by measuring levels of 48 different CKs and GFs in G-BM and control BM (C-BM) plasma from pediatric donors. In addition, the effect of G-CSF on cell numbers and characteristics of HSPCs and MSCs was assessed. IL-16, SCGF-b, MIP-1b (all >1000 pg/mL) and RANTES (>10.000 pg/mL) were highly expressed in healthy donor pediatric BM plasma. Levels of IL-3, IL-18, GROa, MCP-3 (p<0.05) were increased in G-BM, whereas levels of RANTES (p<0.001) decreased after G-CSF treatment. We found a negative correlation with increasing age for IL2-Ra and LIF (p<0.05). In addition, a concomitant increase in the number of both hematopoietic and fibroblast colony forming units was observed, indicating that G-CSF affects both HSPC and MSC numbers. In conclusion, G-CSF treatment of healthy pediatric donors affects the hematopoietic BM microenvironment by expansion of HSPC and MSC numbers and modifying local CK and GF levels.

Mesenchymal stem cells and the embryonic reawakening theory of BPH

The prostate is the only organ in a man that continues to grow with age. John McNeal proposed, 40 years ago, that this BPH is characterized by an age-related reinitiation of benign neoplastic growth selectively in developmentally abortive distal ducts within the prostate transition-periurethral zone (TPZ), owing to a reawakening of inductive stroma selectively within these zones. An innovative variant of this hypothesis is that, owing to its location, the TPZ is continuously exposed to urinary components and/or autoantigens, which produces an inflammatory TPZ microenvironment that promotes recruitment of bone marrow-derived mesenchymal stem cells (MSCs) and generates a paracrine-inductive stroma that reinitiates benign neoplastic nodular growth. In support of this hypothesis, MSCs infiltrate human BPH tissue and have the ability to stimulate epithelial stem cell growth. These results provide a framework for defining both the aetiology of BPH in ageing men and insights into new therapeutic approaches.