Analysis of Minor Elements in the Developing Human Endochondral Bone by Energy Dispersive Spectroscopic Imaging Method

Abstract Background: Bones, as a matrix, are rather complicated, and trace/minor elements can disrupt the growth, development, and maintenance of bones. Therefore, the concentration of various minor elements must be determined carefully. However, there are no quantitative data on the variations in bone composition across the growth period of fetal bone to gain better insight into bone mechanobehavior and bone disorders of fetal origin and adult life. This study analyzed the trace element contents of the developing humerus bone in different trimesters of pregnancy. Methodology: Stillborn or medically terminated human fetal samples ranging from 10 to 36 weeks of gestation were obtained after institutional ethical committee clearance. The transverse section of each humerus at the mid-diaphysis was subjected to scanning electron microscopy imaging and energy dispersive spectroscopy techniques. Results: The weight percentage (wt.%) of carbon (C) was greater at 10 weeks of gestation and was reduced to half at 36 weeks of gestation. The content of oxygen (O) was consistently the same throughout pregnancy. The sulfur (S) content was greater in the first trimester, especially at 12 weeks. The wt.% of magnesium (Mg) was lowest throughout pregnancy, except at 20 and 36 weeks. The wt.% of manganese (Mn) was highest at 10 and 12 weeks of pregnancy and lowest at 36 weeks of pregnancy. The wt.% zinc (Zn) content appeared to be greater at the beginning of each trimester. In contrast, the wt.% of iron (Fe) appeared to follow a reverse pattern (wt.%) and was found to be greater in the later part of each trimester. Conclusions: Trace elements play crucial roles in bone metabolism. Some trace elements are beneficial, whereas others are detrimental to the normal function of the bone. Knowledge of the roles played by both groups of elements can be correlated with the mechanical behavior of the bone. This helps to gain insight into advanced interventions to treat more significant bone defects, design biomimetic implants, or treat congenital bone diseases through therapeutic supplementation with specific trace elements.