FIGURE 1.
Interactions between bone cell populations considered in the Graham 2013 model24 and the added impact of Wnt-10b (labels 1-3). Pre-osteoblasts (P), osteoblasts (B), osteocytes (S), and osteoclasts (C) are tracked by differential equations. Pre-osteoclasts (PC) are assumed constant and are not explicitly modeled. The interactions include an assortment of autocrine (not depicted here) and paracrine (single dashed lines) signaling factors. Single dashed lines with arrows represent activating relationships, and single dashed lines with flat ends represent inhibitory relationships. Solid lines represent transformations: self-proliferation, differentiation, and apoptosis. Wnt-10b (Wnt) stimulates osteoblastogenesis through pre-osteoblast proliferation (1) and differentiation to osteoblasts (2). Wnt-10b inhibits osteoblast apoptosis (3). Impacts of bone cells on bone volume from a combination of bone resorption and formation are represented by double dashed lines with flat and arrow ends, respectively.