BIOPHYSICAL INHIBITION OF OSTEOCLAST FORMATION

生理负荷会产生一系列的物理力 力阻止骨吸收还没有被很好地理解。在 在过去的资助期内，我们证明了一个外生电场 类似于在骨骼负荷期间产生的 抑制破骨细胞的生成。我们已经证明了另外两个 负荷产生的力量也会影响破骨细胞的招募。 持续施加1.37(或2atm)压力抑制 破骨细胞形成率为33±5%。由产生的机械应变 拉伸细胞可抑制破骨细胞形成60%+5%。这 这项工作提出了一个范例--力量通过以下方式限制骨吸收 破骨细胞数量减少。 我们已经开始开发关于细胞的信息 以及破骨细胞募集过程中的分子靶标。 压力和拉伸都是有效的，如果在 破骨细胞处于增殖前和晚期的培养时期 分化发生了。巨噬细胞集落刺激因子 (MCSF)对文化中的这些早期事件至关重要。使用RT- 我们已经证明，压力和拉伸会降低这种水平。 编码mcsf的膜结合亚型的mrna， 它由成骨细胞表达。因为成骨细胞和 巨噬细胞集落刺激因子是破骨细胞形成所必需的，有可能 外力诱导成骨细胞膜表达下降 结合的MCSF可能是破骨细胞减少的原因 队形。 因此，我们提出生物物理刺激抑制破骨细胞。 通过调节成骨细胞旁分泌信号进行募集。 我们推测，在限制骨吸收方面，生物物理学 力量直接瞄准成骨细胞。成骨细胞对 通过发出信号强制减少核扩散 破骨细胞前体或减少这些前体进入 破骨细胞谱系。这些效应可以通过以下方式传递 成骨细胞MCSF表达减少。为了澄清 在这个系统中的力机制我们将1)量化一个 抑制剂量--对压力和拉伸的反应，并将 限制可能的目标的“力敏感性”的最小窗口 及时施力。2)我们将定义哪个单元格是关键直接 有效力量的靶点-破骨细胞前体和/或 成骨细胞前体。3)然后我们将澄清远端是否 武力的目标是增殖或早期分化 破骨细胞前体。最后，我们希望至少区分 参与这一过程的一种分子机制，并将 追寻力在膜中引起减缩的观点 结合MCSF可抑制破骨细胞的形成。

Physiologic loading generates a host of physical forces which force prevents bone resorption are not well understood. In the past funding period we proved that an exogenous electrical field similar to that generated during skeletal loading is capable of inhibiting osteoclastogenesis. We have shown that two other load-generated forces inhigit osteoclast recruitment as well. Continuous application of 1.37 (or 2 atm) of pressure inhibits osteoclast formation by 33+5%. Mechanical strain created by stretching cells inhibits osteoclast formation by 60+5%. This work suggested a paradigm - that force limits bone resorptio by decreasing osteoclast numbers. We have begun to develop information regarding the cellular and molecular targets of force during osteoclast recruitment. Both pressure and stretch are effective if dosed during the period of culture when osteoclast precusor proliferation and erly differentiation occur. Macrophage colony stimulating factor (MCSF) is crtical for these early events in culture. Using RT- PCR we have shown that presure and stretch decrease the level of mRNA encoding the membrane-bound isoform of MCSF, which is expressed by osteoblasts. Since both osteoblasts and MCSF are necessary for osteoclastogenesis, it is possible that a force-induced decrease in osteoblast expression of membrane bound MCSF could be responsible for decreased osteoclast formation. We therefore propose that biiphysical stimuli inhibit osteoclast recruitment through modulation of osteoblast paracrine signals. We postulate that in limiting bone resorption, biopphysical forces directly target the osteoblast. The osteoblast responds to force by signalling for either decreased proliferation of osteoclast precursors or decreased entry of these precursors into the osteoclast lineage. These effects may be transduced by decreases in osteoblast MCSF expression. To elucidate the mechanisms of force in this system we will 1) quantify an inhibitory dose-response to pressure and stretch and assign a minimal window of "force sensitivity" to limit possible targets of force in time. 2) We will define which cell is the critical direct target of effective forces - the osteoclast precursors and/or osteoblast precursor. 3) We will then clarify whether the distal target of force is the proliferation or eraly differentiation of osteoclast precursors. Finally, we hope to 4) distinguish at least one molecular mechanism involved in this process, and will pursue the idea that force induced decrements in membrane bound MCSF lead to an inhibition of osteoclast formation.