Communications between bone cells and hematopoietic stem cells

Abstract

The skeletal system, while characterized by a hard tissue component, is in fact an extraordinarily dynamic system, with disparate functions ranging from structural support, movement and locomotion and soft-organ protection, to the maintenance of calcium homeostasis. Amongst these functions, it has long been known that mammalian bones house definitive hematopoiesis. In fact, several data demonstrate that the bone microenvironment provides essential regulatory cues to the hematopoietic system. In particular, interactions between the bone forming cells, or osteoblasts, and the most primitive hematopoietic stem cells (HSC) have recently been defined. This review will focus mainly on the role of osteoblasts as HSC regulatory cells, discussing the signaling mechanisms and molecules currently thought to be involved in their modulation of HSC behavior. We will then review additional cellular components of the HSC niche, including endothelial cells and osteoclasts. Finally, we will discuss the potential clinical implications of our emerging understanding of the complex HSC microenvironment.

Adhesion to osteopontin in the bone marrow niche regulates lymphoblastic leukemia cell dormancy

“…5 In the basal state, interactions between HSCs and specific cells and molecules within these niches modulate HSC transit and self-renewal. 6,7 Although the anatomic and molecular distinctions between these niches are controversial, evidence suggests that the endosteal niche maintains a population of quiescent HSCs with high reconstitution potential, whereas the perivascular niche harbors more activated HSCs. 8,9 Stromal cell-derived factors, including cytokines and extracellular matrix proteins (ECMs), play a significant role in niche regulation of the benign HSC population.…”

The combination method using magnetic beads and a magnet helps sustain the number of donor BM cells after intra-BM injection, resulting in rapid hematopoietic recovery

“…22,23 It has also been reported that the niche cells and the HSCs exist at the margins of the BM. 22,23 It was therefore plausible to draw the HSCs to the margins of the BM using the combination of magnetic beads and magnet.…”

“…22,23 It has also been reported that the niche cells and the HSCs exist at the margins of the BM. 22,23 It was therefore plausible to draw the HSCs to the margins of the BM using the combination of magnetic beads and magnet. As it has been reported that both HSCs/IHPCs and MSCs express Sca-1 Ag, the magnetic beads should be able to attach not only to HSCs/ IHPCs but also to MSCs, thereby helping the interaction between HSCs/IHPCs and MSCs.…”

Kemik İliği Stroması: Hücreleri ve Mikroçevresi

“…Adventif retiküler hücreler VCAM-1, alkalin fosfataz ve alfa aktini ifade eder ve CXC kemokin ligandı 12 (CXCL), IL-7 ve SCF'yi üretirler. CXCL12 adventif retiküler hücreler tarafından sağlanan destekleyici nişler içerisinde HKH'yi tutmada rol alan bir kemokindir (reseptörü (CXCR) 4 ile birlikte) (Porter and Calvi, 2008). Adventif retiküler hücreler aynı zamanda vaskülogenezi yönlendirir ve kemik iliğindeki kan damarlarını stabilize eder (Moore and Lemischka, 2006).…”