Second harmonic generation analysis of early Achilles tendinosis in response to in vivo mechanical loading
Second harmonic generation analysis of early Achilles tendinosis in response to in vivo mechanical loading
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DOI：
10.1186/1471-2474-12-26
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发表时间：
2011-01-26
影响因子：
2.3
通讯作者：
Scott, Alex
中科院分区：
文献类型：
--
作者：
Abraham, Thomas;Fong, Gloria;Scott, Alex
背景：肌腱细胞与肌腱病的发生有关，肌腱病是一种常见于肌肉骨骼过度使用综合征的慢性疾病。然而，肌腱细胞形态异常与胶原纤维基质早期变化之间的关系尚未在活体中得到密切研究。二次谐波显微镜(SHG)是一种新发展起来的技术，它能够以高度的特异性和分辨率检查胶原纤维结构。本研究的目的是检测SHG和多光子激发荧光(MPEF)显微镜在了解早期肌腱过度损伤时腱细胞与其周围胶原基质之间关系的潜在应用价值。方法：肌腱的组织学准备来自成年雄性SD大鼠(大鼠-A-PED)，或来自久坐不动的笼养对照组。在至少三个不同区域对这些组织切片同时进行二次谐波产生和多光子激发荧光。结果：SHG显微镜显示机械负荷跟腱的肌腱细胞形态异常与胶原纤维基质的形态变化有关。在机械负荷的肌腱局部微区，胶原密度和组织明显减少。这些病理改变与腱细胞形态的改变有关。正常肌腱呈规则分布的纤维束，经高斯分析，这些纤维束的平均大小为0.47µm+/-0.02。与之相比，肌腱异常细胞附近肌腱区域的纤维束测量无法量化，因为它们的分布和方向的规律性降低。结论：SHG显微镜可以高分辨率检测影响纤维胶原基质的肌腱局灶性异常。随着持续的重复加载，这些与腱细胞相关的局灶性胶原缺失可能容易导致过度使用病理的进展。
Background: Tenocytes have been implicated in the development of tendinosis, a chronic condition commonly seen in musculoskeletal overuse syndromes. However, the relation between abnormal tenocyte morphology and early changes in the fibrillar collagen matrix has not been closely examined in vivo. Second harmonic generation (SHG) microscopy is a recently developed technique which allows examination of fibrillar collagen structures with a high degree of specificity and resolution. The goal of this study was to examine the potential utility of SHG and multiphoton excitation fluorescence (MPEF) microscopy in understanding the relation between tenocytes and their surrounding collagenous matrix in early tendon overuse lesions.Methods: Histological preparations of tendon were prepared from adult male Sprague-Dawley rats subjected to an Achilles tendon loading protocol for 12 weeks (Rat-A-PED), or from sedentary age-matched cage controls. Second harmonic generation and multiphoton excitation fluorescence were performed simultaneously on these tissue sections in at least three different areas.Results: SHG microscopy revealed an association between abnormal tenocyte morphology and morphological changes in the fibrillar collagen matrix of mechanically loaded Achilles tendons. Collagen density and organization was significantly reduced in focal micro-regions of mechanically loaded tendons. These pathological changes occurred specifically in association with altered tenocyte morphology. Normal tendons displayed a regular distribution of fibre bundles, and the average size of these bundles as determined by Gaussian analysis was 0.47 mu m +/- 0.02. In comparison, fibre bundle measures from tendon regions in the vicinity of abnormal tenocytes could not be quantified due to a reduction in their regularity of distribution and orientation.Conclusions: SHG microscopy allowed high resolution detection of focal tendon abnormalities affecting the fibrillar collagen matrix. With ongoing repetitive loading, these tenocyte-associated focal collagen defects could predispose to the progression of overuse pathology.