 Studies that have increased or decreased osteoblasts have shown a similar increase or decrease, respectively, in the number of HSCs.Coculturing endosteal cells with HSCs was also found to be sufficient in maintaining their differentiation potential long-term, presumably through the secretion of the cell signaling molecules previously mentioned.These HSCs that interact with the endosteal osteoblasts display a quiescent phenotype, as shown in both "ex vivo" and "in vivo" imaging studies, whereas HSCs that are more actively dividing show less interaction.