Static Osteogenesis versus Dynamic Osteogenesis: A Comparison between Two Different Types of Bone Formation

In contrary to what has traditionally been believed, bone formation can occur through two different types of osteogenesis: static (SO) and dynamic (DO) osteogenesis, which are thus named because the former is characterized by pluristratified cords of unexpectedly stationary osteoblasts which differentiate at a fairly constant distance from the blood capillaries and transform into osteocytes without moving from the onset site, while the latter is distinguished by the well-known typical monostratified laminae of movable osteoblasts. The two types of osteogenesis differ in multiple aspects from both structural and functional viewpoints. Besides osteoblast arrangement, polarization, and motion, SO and DO differ in terms of time of occurrence (first SO and later DO), conditioning factors to which they are sensitive (endothelial-derived cytokines or mechanical loading, respectively), distribution of osteocytes to which they give rise (haphazard or ordered in planes, respectively), the collagen texture resulting from the different deposition types (woven or lamellar, respectively), the mechanical properties of the bone they form (poor for SO due to the high cellularity and woven texture and good for DO since osteocytes are located in more suitable conditions to perceive loading), and finally the functions of each, i.e., SO provides a preliminary rigid scaffold on which DO can take place, while DO produces bone tissue according to mechanical/metabolic needs

CAM Model: Intriguing Natural Bioreactor for Sustainable Research and Reliable/Versatile Testing

We are witnessing the revival of the CAM model, which has already used been in the past by several researchers studying angiogenesis and anti-cancer drugs and now offers a refined model to fill, in the translational meaning, the gap between in vitro and in vivo studies. It can be used for a wide range of purposes, from testing cytotoxicity, pharmacokinetics, tumorigenesis, and invasion to the action mechanisms of molecules and validation of new materials from tissue engineering research. The CAM model is easy to use, with a fast outcome, and makes experimental research more sustainable since it allows us to replace, reduce, and refine pre-clinical experimentation (“3Rs” rules). This review aims to highlight some unique potential that the CAM-assay presents; in particular, the authors intend to use the CAM model in the future to verify, in a microenvironment comparable to in vivo conditions, albeit simplified, the angiogenic ability of functionalized 3D constructs to be used in regenerative medicine strategies in the recovery of skeletal injuries of critical size (CSD) that do not repair spontaneously. For this purpose, organotypic cultures will be planned on several CAMs set up in temporal sequences, and a sort of organ model for assessing CSD will be utilized in the CAM bioreactor rather than in vivo

Role of Phytoestrogen Ferutinin in Preventing/Recovering Bone Loss: Results from Experimental Ovariectomized Rat Models

In the Chapter 35 of the book are reported observations of recent pubblications on the effect of ferutinin in preventing/recovering severe osteoporosis secondary to ovariectomy in rats. On the basis of the results so far obtained, the authors suggest to enumerate ferutinin among the osteoprotective substances. This fact acquires a more relevant importance in the light of recent tenable evidences reported from various authors concerning the absence of negative side effects by some phytoestrogens (particularly genistein, 8-prenylnaringenin, reveratrol and red clover extract) on the tropism of various organs commonly targeted by estrogens. In conclusion, the results reported not only provide evidence that ferutinin can significantly prevent/recover ovariectomy-induced bone loss in rats, but also that it could protect against the onset of uterus cancer. Although the putative undesired estrogenic-like side effects on uterus of such phytoestrogen have not yet been fully investigated, ferutinin could be an interesting safer alternative new candidate for HRT in treatment of post-menopausal symptoms, since it seems to protect from bone loss induced by ovariectomy (Palumbo et al., 2009; Ferretti et al., 2010) and in part to mime the ovarian endocrine function during menopause

Bone texture modifications during bone regeneration and osteocyte cell-signaling changes in response to treatment with Teriparatide

Bone texture modifications during bone regeneration and osteocyte cell-signaling changes in response to treatment with Teriparatid

The Enactive Didactics for Enactive Mind:The Evolution of a Learning Model

The term "enactive mind " comes from the Varela work and the concept of "activation " underlines. Approach you enactive involves two concepts: from a side than the perception he consists in an action to his time driven by the perception coming from that action date and from the other but the cognitive structures they emerge from the recurring sensory- motor schemes which allow the action to be perceptively driven. In the specific one, approach him EM places like a frame to frame a series of phenomena considered essential for the comprehension of the concept of adaptation as social as the necessity of considering the relation world complexity as, the importing time constraints present in it, the nature and the modes in which mechanisms of this adaptation allow the formation of the social knowledge. In the EM approach the child "activates the social world " selectively perceiving it in the terms of what which is immediately essential for a social action, while the mental representations (the social knowledge) of this individualized world build themselves based on the repeated experiences ripened by these actions driven by the perception, become then deeply you root in the history of relational actions of the child to be tools for the adaptation to the world in which alive. The enactive vision, although it recalls in the meaning the concept of representation as mode to know, tries to exceed it in favor of the corporeality, that is an incorporate mind (embodied mind). A corollary of this theory is that subject

PRELIMINARY FINDINGS OF A POTENZIATED PIEZOSURGERGICAL DEVICE AT THE RABBIT SKULL

The number of available ultrasonic osteotomes has remarkably increased. In vitro and in vivo studies have revealed differences between conventional osteotomes, such as rotating or sawing devices, and ultrasound-supported osteotomes (Piezosurgery®) regarding the micromorphology and roughness values of osteotomized bone surfaces. Objective: the present study compares the micro-morphologies and roughness values of osteotomized bone surfaces after the application of rotating and sawing devices, Piezosurgery Medical® and Piezosurgery Medical New Generation Powerful Handpiece. Methods: Fresh, standard-sized bony samples were taken from a rabbit skull using the following osteotomes: rotating and sawing devices, Piezosurgery Medical® and a Piezosurgery Medical New Generation Powerful Handpiece. The required duration of time for each osteotomy was recorded. Micromorphologies and roughness values to characterize the bone surfaces following the different osteotomy methods were described. The prepared surfaces were examined via light microscopy, environmental surface electron microscopy (ESEM), transmission electron microscopy (TEM), confocal laser scanning microscopy (CLSM) and atomic force microscopy. The selective cutting of mineralized tissues while preserving adjacent soft tissue (dura mater and nervous tissue) was studied. Bone necrosis of the osteotomy sites and the vitality of the osteocytes near the sectional plane were investigated, as well as the proportion of apoptosis or cell degeneration. Results and Conclusions: The potential positive effects on bone healing and reossification associated with different devices were evaluated and the comparative analysis among the different devices used was performed, in order to determine the best osteotomes to be employed during cranio-facial surgery

Effects of PTH(1-34) during fracture healing after experimental bone drilling in rat femur: novel aspects

The study concerns the role of PTH(1-34) during bone lesion repair. 3-month-old male Sprague-Dawley rats, in which trans-cortical holes were drilled at femur middiaphysis, were divided in groups with/without Teriparatide administration (40g/ Kg/day), and sacrificed at different times (10, 28, 45 days). In 2002 (1) we demonstrated the occurrence of two successive bone forming processes during both skeletal organogenesis and bone repair, i.e. static (SO) and dynamic (DO) osteogenesis: the former (due to stationary osteoblasts, haphazardly grouped in cords) producing preliminary bad quality trabecular bone, the latter (due to typical polarized osteoblasts organized in ordered movable laminae) producing mechanically valid bone tissue. In brief, the primary function of SO is to provide a rigid scaffold, containing osteocytes (i.e. mechano-sensors), to DO-osteoblastic laminae; therefore, in DO mechanical factors can play a crucial role in transduction of mechanical stresses into biological signals. In the present work, histomorphometric analysis showed that, already after 10 days from drilling, notwithstanding the holes are temporarily filled by the same amount of newly-formed trabecular bone (produced by SO) independently from the treatment, the number of movable osteoblast laminae (typical of DO), covering the trabecular surface, is statistically higher in animals submitted to PTH(1-34) administration than in the control ones; this suggests that the mere effect of Teriparatide is to anticipate the occurrence of dynamic osteogenesis involved in the production of good quality bone more suitable to loading. These findings are also supported by the higher values of microhardness as well as the more ordered-fibered texture (observed by polarized light) in treated animals with respect to control ones that strongly indicates the qualitative (instead of quantitative) effect of PTH (1-34) in improving bone healing. The present investigation could be of crucial importance in further translational clinical research in humans to define the best therapeutic strategies in recovering skeletal lesions, particularly in terms of time of administration of PTH(1-34)

Induced Biochemical osteoporosis: Effects of 1-month calcium–deprived diet on rat bone remodelling with/without contemporary administration of PTH(1-34)

It is known that rats fed calcium-deprived diet develop osteoporosis due to en-hanced bone resorption secondary to parathyroid overactivity resulting from nutritional hypocalcemia. Therefore, rats provide a good experimental animal model for studying bone remodelling alterations during biochemical osteoporosis. This preliminary study is performed in 3 month-old Sprague Dawley male rats, divided into 4 groups (5 rats each): 1) base line, 2) normal diet for 4 weeks, 3) calcium-deprived diet for 4 weeks; 4) calcium-deprived diet for 4 weeks plus contemporary administration of PTH(1-34) 40µg/kg/day. Three labels of osteogenesis were performed at 1st , 20th and 27th day of experimental period in order to evaluate bone formation during animal treatment. His-tomorphometrical analyses were performed on cortical bone of femoral diaphyses, as well as on trabecular bone of distal femoral metaphyses, both transversely sectioned. The preliminary results showed that at femur mid-diaphyseal level the diet induced a reduction of cortical bone area (even if not significant) with enlargement of the medul-lary canal due to endosteal resorption, while periosteal neo-deposition is similar in all groups and particularly abundant in those periosteal regions mainly devoted in answering the mechanical demands. PTH(1-34) treatment seems to reduce endosteal resorption only in those surfaces where periosteal mechanical loading are less consistent. Conversely, PTH(1-34) treatment doesn't seem to affect osteoblast activity. Moreover, in distal femoral metaphyses, diet induced osteoclast activity, with a decrease in the amount of trabecular bone volume, confirming that this architecture is mainly devoted in answering the metabolic demands. The novelty of the proposed model Is the contemporary administration of PTH(1-34) together with calcium deprived diet to evaluate induced-biochemical osteoporosis. This model seems a good starting point for successive studies in order to study bone alterations during unbalanced calcium metabolism frequently occurring in aging and to define time and manner of bone mass recovery