To identify the direct destruction of bone by neutrophils in collagen-induced arthritis treated with powerful anti-osteoclastic bone resorptive agents, bisphosphonates, we designed the experiments to examine whether the bone destruction induced by collagen-induced arthritis (CIA) was inhibited by nitrogen-containing bisphosphonates (NBPs) or not, and examined histologically and ultrastructually to detect the cells directly related to bone destruction. One of the representative NBPs, alendronate (1.6 µmol/kg), was injected once a week from one week before the onset of the first sensitization with type II collagen. Flow cytometric analysis indicated the enhanced granulopoiesis in both BP-treated and non-treated CIA mice. Severe bone destruction was detected in both saline-group and alendronate-group. Although many active osteoclasts were developed on the destructive bone in saline-group, almost no active osteoclasts were detected in alendronate-group, where many neutrophils were accumulated. Some of neutrophils accumulated on the destructive bone were ruptured and cytoplasmic granules were scattered extracellularly, where collagen fibers were no longer detected. These results indicated that the bone destruction in CIA mice was not prevented by the injection of NBP and suggested that neutrophils in addition to osteoclasts might directly have the capacity for the bone destruction.
It is well known that the body skeleton is formed by two different types of ossification systems, endochondoral and intramembranous ossification. Bone marrow is the main site of active hematopoiesis after the formation of the bone marrow cavities. However, it is unclear whether the hematopoiesis in the bone marrow of two types of ossification is regulated by the same system or not. In this study, we focused on the ontogenic development of bone marrow hematopoiesis in two different ossification systems using mouse humeral bones and palatal process of maxillary bones. Immunohistochemical and RT-PCR analyses were performed to examine the development of hematopoiesis and the expression of cytokines related to hematopoiesis in the forming bone marrow (16-days gestation stage to 1-day postnatal stage). Immunohistochemical studies showed the sequential difference of hematopoiesis between two different ossification systems. In humeral bone marrow, granulopoiesis appeared first at E16, followed by erythropoiesis from E17. On the contrary, erythropoiesis preceded one day in the maxillary bone marrow at E18, one day before the detection of granulopoiesis. G-SCF and GM-CSF were expressed at every examined stage in both types of bones while M-CSF was not expressed in the humeral bone marrow at E16. Erythropoietin was detetcted in the endothelial cells and its expression was coincident with the onset of erythopoiesis. These results suggest the time kinetic and sequential differences of hematopoiesis in two different ossification systems, which might relate to the differences of hematopoietic microenvironment.
Narrow band imaging (NBI) enhances the diagnostic capability of endoscopy for tissue characterization. The procedure uses using narrow-bandwidth filters in a sequential red-green-blue illumination system. The blue filter corresponds to the peak absorption spectrum of hemoglobin and thus emphasizes images of capillary vessels on the surface mucosa. Here, we examined the applicability of the NBI system to evaluate oral mucosa, and the status of 6 patients with oral squamous cell carcinoma and 5 with oral pre-cancerous lesions. Regular, orderly, thin-caliber vessels in the tongue, floor of the mouth, buccal mucosa, soft palate and lip were clearly distinguished by NBI. However, small vessel branches are difficult to evaluate in the gingival and hard palate mucosa. Adding the patterns of capillary branches to find mucosal patterns appeared to improve the diagnostic value for detecting the borders of oral cancer or pre-cancerous lesions by NBI. The vascular pattern revealed by NBI defined the margin of hyperkeratotic lesions. Although appropriate criteria for oral cancer lesions remain to be established, the NBI system should be useful in the diagnosis of patients with oral cancer and pre-cancerous lesions.