Erythropoietin Couples Hematopoiesis with Bone Formation

It is well established that bleeding activates the hematopoietic system to regenerate the loss of mature blood elements. We have shown that hematopoietic stem cells (HSCs) isolated from animals challenged with an acute bleed regulate osteoblast differentiation from marrow stromal cells. This suggests that HSCs participate in bone formation where the molecular basis for this activity is the production of BMP2 and BMP6 by HSCs. Yet, what stimulates HSCs to produce BMPs is unclear.In this study, we demonstrate that erythropoietin (Epo) activates Jak-Stat signaling pathways in HSCs which leads to the production of BMPs. Critically, Epo also directly activates mesenchymal cells to form osteoblasts in vitro, which in vivo leads to bone formation. Importantly, Epo first activates osteoclastogenesis which is later followed by osteoblastogenesis that is induced by either Epo directly or the expression of BMPs by HSCs to form bone.These data for the first time demonstrate that Epo regulates the formation of bone by both direct and indirect pathways, and further demonstrates the exquisite coupling between hematopoiesis and osteopoiesis in the marrow

A review of potential new diagnostic modalities for caries lesions

This paper aims to present a simple overview of potential new diagnostic methods for dental caries. There are several novel methods of caries detection (with potential application to diagnosis) which have been proposed in the last few years, in addition to those that are gaining some commercial exposure and clinical acceptance. For the most part, these methods have been demonstrated in laboratories and are generally many years away from routine clinical application. They include multi-photon imaging, infrared thermography and infrared fluorescence, optical coherence tomography, ultrasound, and terahertz imaging

Distraction Osteogenesis Enhances Remodeling of Remote Bones of the Skeleton: A Pilot Study

Bone injuries have a systemic influence on the remodeling of bone. This effect has not been examined concerning its extent and duration. We measured the systemic effect of distraction osteogenesis on the remodeling of bones of the axial skeleton by means of the mineral apposition rate and bone formation rate in an animal experiment. Distraction osteogenesis was performed on the tibiae of 24 mature Yucatan minipigs. After a 4-day latency period, the tibiae were distracted 2 mm/day for 10 days. The ensuing consolidation phase lasted 10 days. Three fluorescent labeling substances were applied intravenously: calcein green at the second postoperative day, tetracycline 1 day after the end of the distraction phase, and xylene orange 2 days before sacrifice. We prepared ground sections from the ninth right ribs. The mineral apposition rate and bone formation rate were measured histomorphometrically on labeled osteons. The median mineral apposition rate during distraction was 2.39 μm/day (2.12–2.62 μm/day), which was higher than the rate during consolidation (median, 1.62 μm/day; 1.54–1.84 μm/day). The median bone formation rate confirmed this result and was 840.51 μm2/day (744.20–1148.26 μm2/day) during distraction and 384.25 μm2/day (330.84–467.71 μm2/day) during consolidation. Thus, a short period of distraction osteogenesis appears to have an anabolic effect on the mineral apposition rate of remote cortical bone