Open-source cell extension system assembled from laser-cut plates

Biological response of cells to mechanical stimulation plays an important role in regulation of cell activity, and thus has been an attracting topic for researchers in the field of biomechanics for many years. Stretching is the most common type of the mechanical stimulus that has been used for in vitro experiments. The device for application of stretching to cells has commercially been available for more than three decades. Although these ready-made devices will bring a smooth start of research work, they cost several thousands to tens of thousands dollars for introduction. Therefore, this study proposes an open-source self-made cell extension system which can be built at one tenth to one hundredth of the price of commercial devices. To reduce the difficulty of machining, the device was designed to be assembled from acrylic plates fabricated only by using a laser cutter without machining such as drilling or screw thread cutting. All other mechanical elements and electrical components are purchased from web shops. The accuracy of the reciprocating motion was verified with the fabricated device and an elastic silicone container for cell culture. Keywords: Cell culture, Mechanical loading, Elastic silicone container, Laser cutting, Mortise and tenon, Raspberry P

機械的刺激に対する骨および骨系細胞の応答に関する実験的研究

目次 第1章 緒論 第2章 骨粗鬆症モデルラット長管骨の適応モデリング 第3章 ラット尾椎形態リモデリングの非侵襲計測と二次元応力解析 第4章 ラット尾椎形態リモデリングの三次元応力解析 第5章 機械的刺激に対する単離破骨細胞の応答 第6章 超微小押込み試験による骨組織の局所的物性評価 第7章 結論 参考文献関連論文および発表 謝辞主1-参1工学_機械科学_知能機

Osteocyte: a cellular basis for mechanotransduction in bone

Osteocyte is the most abundant cell type in bone, and the only cell type located inside the mineralized matrix. The striking structural design of bone predicts an important role for osteocytes in determining bone structure and function. Osteocytes are connected with each other via gap junctions and form a three dimensional cellular network in mineralized bone matrix. Recently, it has been shown that osteocytes are not only passive bystanders, but also have an active regulatory role in whole body phosphate and calcium metabolism. Osteocytes are cells which sense mechanical loading in bone. They respond to mechanical stimuli by producing and secreting several bioactive substances including nitric oxide and prostaglandins and thus transmit messages of loading to effector cells, like osteoblasts and osteoclasts. Present data suggest that osteocytes actively inhibit osteoclastic bone resorption. Whenever osteocytes die, this inhibitory effect is turned off and osteoclasts are activated. This mechanism of action could explain targeted remodeling in the region of stress induced microcracks happened. Osteocytes can also modulate osteoblasts function. In conclusion, osteocytes sense mechanical stimuli, transmit signals through cellular network and regulate osteoblast and osteoclast function during bone remodeling

Effect of Hyperthermal Treatment on the Viability of Bone-Derived Cells

Polymethylmethacrylate (PMMA) bone cement has been widely used in orthopedic surgery for fixing prostheses and stabilizing collapsed vertebral fractures. Although it is the most popular biomaterials in orthopedics, heat generation during polymerization may cause thermal injury to the surrounding cells. Bone cells exposed to the thermal injury would secret a number of biological factors, and then locally influence a balance of bone remodeling. However, thermal tolerance of bone cells is not well understood. The aim of this study was therefore to quantify in vitro thermal injury of bone-derived cells and to establish a model to predict accumulation of the cell damage. Osteocyte, osteoblast, and fibroblast cell lines were exposed to steady supraphysiological temperatures ranging 40-75°C, and change of cell mortality depending on heating time and temperature was determined by using a dye, propidium iodide. When the cells were exposed to thermal treatment, all cell lines exhibited approximately exponential increase of cell injury at the initial phase, and then gradual decline of the increasing rate as the cell mortality approached 1. This kinetics of cell injury was described well by a logistic curve with high correlation coefficient. By comparing the slope of the logistic curves and the time to reach 50% of cell mortality, it is found that thermal tolerance of osteocytes was significantly low among three cell lines. This result indicates that thermal injury of osteocytes would be induced by the heating at a temperature that is harmless to other cell types, and both necrotic and apoptotic responses of thermally injured osteocytes might stimulate osteoclastic bone resorption