Antunes-Foschini Rosalia S, Miyashita Denise, Bicas Harley E A, McLoon Linda K
Department of Ophthalmology, Faculty of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil.
Invest Ophthalmol Vis Sci. 2008 Jan;49(1):215-20. doi: 10.1167/iovs.07-0507.
The goal of this study was to determine whether the medial rectus muscles of patients with a history of medial rectus underaction or overaction show alterations in the process of satellite cell activation when compared with normal age-matched control muscles.
Medial rectus muscles were obtained with consent from adult patients undergoing surgical resection due to medial rectus underaction or overaction and were prepared for histologic examination by fixation and paraffin embedding. Control muscles were obtained from cornea donor eyes of adults who had no history of strabismus or neuromuscular disease. Cross sections were obtained and stained immunohistochemically for the presence of activated satellite cells, as identified by MyoD immunoreactivity, and the presence of the total satellite cell population, as identified by Pax7 immunoreactivity. The percentages of MyoD- and Pax7-positive satellite cells per 100 myofibers in cross section were calculated.
As predicted from results in the literature, MyoD-positive satellite cells, indicative of activation, were present in both the control and resected muscles. In the underacting medial rectus muscles, the percentages of MyoD- and Pax7-positive satellite cells, based on the number of myofibers, were approximately twofold higher than the percentages in the control muscles. In the overacting medial rectus muscles, the percentage of MyoD-positive satellite cells was twofold less than in the control muscles, whereas the percentage of Pax7-positive satellite cells significantly increased compared with that in the control specimens.
The presence of an increased number of activated satellite cells in the resected underacting medial rectus muscles and the decreased numbers of activated satellite cells in the overacting muscles was unexpected. The upregulation in the number of MyoD-positive satellite cells in underacting muscles suggests that there is potential for successful upregulation of size in these muscles, as the cellular machinery for muscle repair and regeneration, the satellite cells, is retained and active in patients with medial rectus underaction. The decreased number of activated satellite cells in overacting MR muscle suggests that factors as yet unknown in these overacting muscles are able to affect the number of satellite cells and/or their responsiveness compared with normal age-matched control muscles. These hypotheses are currently being tested.
本研究的目的是确定与年龄匹配的正常对照肌肉相比，有内直肌作用不足或过强病史的患者的内直肌在卫星细胞激活过程中是否显示出改变。
经同意，从因内直肌作用不足或过强而接受手术切除的成年患者身上获取内直肌，并通过固定和石蜡包埋制备用于组织学检查。对照肌肉取自无斜视或神经肌肉疾病病史的成年角膜供体眼。获取横切片并进行免疫组织化学染色，以检测由MyoD免疫反应性鉴定的活化卫星细胞的存在，以及由Pax7免疫反应性鉴定的卫星细胞总数的存在。计算横切片中每100条肌纤维中MyoD和Pax7阳性卫星细胞的百分比。
正如文献结果所预测的，指示激活的MyoD阳性卫星细胞在对照肌肉和切除的肌肉中均存在。在作用不足的内直肌中，基于肌纤维数量的MyoD和Pax7阳性卫星细胞的百分比比对照肌肉中的百分比高约两倍。在作用过强的内直肌中，MyoD阳性卫星细胞的百分比比对照肌肉中少两倍，而Pax7阳性卫星细胞的百分比与对照标本相比显著增加。
在切除的作用不足的内直肌中活化卫星细胞数量增加，而在作用过强的肌肉中活化卫星细胞数量减少，这是出乎意料的。作用不足的肌肉中MyoD阳性卫星细胞数量的上调表明这些肌肉有成功上调大小的潜力，因为作为肌肉修复和再生的细胞机制的卫星细胞在有内直肌作用不足的患者中保留并活跃。作用过强的内直肌中活化卫星细胞数量的减少表明，与年龄匹配的正常对照肌肉相比，这些作用过强的肌肉中尚未知晓的因素能够影响卫星细胞的数量和/或它们的反应性。这些假设目前正在进行测试。
