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Purpose/Aim of the studymice are the most often used pre-clinical lab models for studying the pathologies of bone mineralization. However, recent evidence suggests that two of the most often used mice strains (C57BL/6J and CD-1) might show differences in the bone mineralization process. This study sought to investigate the main compositional properties of bone tissue between nonpathological C57BL/6J and CD-1 murine knee joints. Materials and Methods: to this end, medial and lateral condylar subchondral bones and the adjacent diaphyseal cortical bone of 13 murine femurs (n = 7 C57BL/6J and n = 6 CD-1 at eight weeks old, just after sexual maturation) were analyzed with ex vivo Raman spectroscopy. Results: regardless of the bone tissue analyzed, our results showed that CD-1 laboratory mice present a more mature mineral phase than C57BL/6J laboratory mice, but present no difference in maturity of the collagen phase. For both strains, the subchondral bone of the medial condylar and cortical bone from the diaphysis have similar compositional properties, and CD-1 presents less variation than C57BL/6J. Furthermore, we depict a novel parametric relationship between the crystallinity and carbonate-to-amide-I ratio that might help in deciphering the mineral maturation process that occurs during bone's mineralization. Conclusions: Our results suggest that the timing of bone maturation might be different between non-pathological C57BL/6J and CD-1 murine knee femurs. [ABSTRACT FROM AUTHOR]

Bone is a hard-soft biomaterial built through a self-assembly process under genetic regulatory network (GRN) monitoring. This paper aims to capture the behavior of the bone GRN part that controls mineralization by using a mathematical model. Here, we provide an advanced review of empirical evidence about interactions between gene coding (i) transcription factors and (ii) bone proteins. These interactions are modeled with nonlinear differential equations using Michaelis-Menten and Hill functions. Compared to empirical evidence - coming from osteoblasts culture -, the two best systems (among 12 6 = 2 , 985 , 984 possibilities) use factors of inhibition from the start of the activation of each gene. It reveals negative indirect interactions coming from either negative feedback loops or the recently depicted micro-RNAs. The difference between the two systems also lies in the BSP equation and two ways for activating and reducing its production. Thus, it highlights the critical role of BSP in the bone GRN that acts on bone mineralization. Our study provides the first theoretical evidence of osteoblast self-inhibition after activation of the genetic regulatory network controlling mineralization with this work. [ABSTRACT FROM AUTHOR]