Osteoblasts and Bone Marrow Mesenchymal Stromal Cells Control Hematopoietic Stem Cell Migration and Proliferation in 3D In Vitro Model

Abstract

BackgroundMigration, proliferation, and differentiation of hematopoietic stem cells (HSCs) are dependent upon a complex three-dimensional (3D) bone marrow microenvironment. Although osteoblasts control the HSC pool, the subendosteal niche is complex and its cellular composition and the role of each cell population in HSC fate have not been established. In vivo models are complex and involve subtle species-specific differences, while bidimensional cultures do not reflect the 3D tissue organization. The aim of this study was to investigate in vitro the role of human bone marrow–derived mesenchymal stromal cells (BMSC) and active osteoblasts in control of migration, lodgment, and proliferation of HSCs.Methodology/Principal FindingsA complex mixed multicellular spheroid in vitro model was developed with human BMSC, undifferentiated or induced for one week into osteoblasts. A clear limit between the two stromal cells was established, and deposition of extracellular matrix proteins fibronectin, collagens I and IV, laminin, and osteopontin was similar to the observed in vivo. Noninduced BMSC cultured as spheroid expressed higher levels of mRNA for the chemokine CXCL12, and the growth factors Wnt5a and Kit ligand. Cord blood and bone marrow CD34+ cells moved in and out the spheroids, and some lodged at the interface of the two stromal cells. Myeloid colony-forming cells were maintained after seven days of coculture with mixed spheroids, and the frequency of cycling CD34+ cells was decreased.Conclusions/SignificanceUndifferentiated and one-week osteo-induced BMSC self-assembled in a 3D spheroid and formed a microenvironment that is informative for hematopoietic progenitor cells, allowing their lodgment and controlling their proliferation.

Wnt3a Reestablishes Osteogenic Capacity to Bone Grafts from Aged Animals

“…A patient's own bone and marrow is considered the ''gold standard, '' 15 but these autografts are oftentimes inadequate when the patient is elderly 16 . There are multiple, distinct stem-cell and/or progenitor cell populations, including mesenchymal stem cells, that reside in the bone marrow [17][18][19][20][21] . Although mesenchymal stem cells can give rise to cartilage, bone, fat, and muscle cells when cultured in vitro, mesenchymal stem cells residing in the marrow cavity itself only differentiate into an osteogenic or an adipogenic lineage 22 , and growing evidence indicates that this adipogenicosteogenic fate decision is regulated by beta-catenin-dependent Wnt signaling 23 .…”

Prostate cancer cells metastasize to the hematopoietic stem cell niche in bone

“…3 However, the osteoblast has risen as a key cellular component of the HSC niche. 4 Several studies have provided strong support to the importance of the osteoblast in maintaining the HSC population including the observations that decreasing osteoblasts results in contraction of the HSC population, 5 whereas increasing osteoblasts results in expansion of the HSC population. 6 Osteoblasts regulate the HSC through several mechanisms.…”

Structural-functional organisation of the bone marrow hematopoietic stem cells niches

“…It is worth noting that HSCs, adhering to osteo-induced MSCs, show significant decrease proliferative activity that is also observed in the niches of HSCs in vivo. [134].…”

“…Depletion of the BM by resident macrophages enhances HSCs proliferation and increases the pool of dormant HSCs [134]. The macrophages were attributed to the pool of cells with regulation properties, owing to their humoral effects via non-identified cytokines on nestin + cells inducing them for CXCL12 secretion and thus maintaining HSCs in the niche [251,252].…”