Skeletal disuse can cause an accumulation of bone marrow adipose tissue (MAT) characterized by a combination of marrow adipocyte hyperplasia and/or hypertrophy. The malleability of MAT accumulation and of the hyperplasia and hypertrophy upon remobilization is unknown. In this study, we showed extensive hyperplasia and accelerated hypertrophy of bone marrow adipocytes in the proximal tibia epiphysis of rat knees immobilized for durations between 1 and 32 weeks. Similar histomorphometric measures of adipocytes carried out in unoperated controls allowed distinguishing the effects of immobilization from the effects of aging. While both knee immobilization and aging led to adipocyte hypertrophy, adipocyte hyperplasia was the hallmark signature effect of immobilization on MAT. Both bone marrow adipocyte hyperplasia and hypertrophy were sustained despite knee remobilization for durations up to 4 times the duration of immobilization. These results suggest that adipocyte hyperplasia is the predominant mechanism explaining MAT accumulation in skeletal disuse. In this model, the changes were unremitting for the investigated time points. Investigating the cellular and molecular mechanisms of marrow adipocyte mechanoregulation will be important to better understand how adipocytes adapt to changes in mechanical environments.

中文翻译：

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尽管进行了固定，但通过膝关节固定仍可维持骨髓脂肪细胞的增生和加速肥大。

骨骼废止可导致以脂肪细胞增生和/或肥大为特征的骨髓脂肪组织（MAT）积累。MAT累积的可塑性以及动员后的增生和肥大的可塑性是未知的。在这项研究中，我们显示了固定的大鼠膝关节胫骨近端骨epi附近广泛的增生和加速的骨髓脂肪细胞肥大，持续时间为1至32周。在未操作的对照中进行的脂肪细胞类似的组织形态计量学测量可以区分固定化的作用和衰老的作用。虽然膝盖固定和衰老都会导致脂肪细胞肥大，但脂肪细胞增生是MAT固定的标志性作用。尽管膝关节固定，但骨髓脂肪细胞增生和肥大均持续，其持续时间最多为固定时间的4倍。这些结果表明，脂肪细胞增生是解释骨骼废用中MAT积累的主要机制。在此模型中，对于所调查的时间点，变化是不懈的。研究骨髓脂肪细胞机械调节的细胞和分子机制对于更好地了解脂肪细胞如何适应机械环境的变化非常重要。