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Mona M. Lindstrom, Fatima Pedrosa-Domellöf; Pax7 positive/Satellite Cells Evaluated with Multiple Marker Method in Human EOMs. Invest. Ophthalmol. Vis. Sci. 2011;52(14):1559.
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© ARVO (1962-2015); The Authors (2016-present)
We have recently developed and evaluated a more reliable multiple marker (MM) method for satellite cell identification and quantification, in human skeletal muscle. In this study the MM method was applied to cross-sections of human extraocular muscles (EOMs).
The MM method allows simultaneous evaluation of two satellite cell markers (Pax7, NCAM), the position of the identified cell in relation to the myofiber basal lamina and the presence of a nucleus stained by DAPI. Signs of satellite cell activation were analysed on serial cross-sections stained for MyoD, myogenin or Ki-67 co-stained for laminin and DAPI.
Many satellite cells were stained for both Pax7 and NCAM. However, staining for NCAM was more difficult to evaluate in EOMs compared to limb muscles. Many Pax7 positive cells were identified in positions other than the classical satellite cell niche, either surrounded by a basal lamina or not. Some Pax7 positive cells were also observed close to vessels. Therefore, the proportion of all Pax7 positive cells per myofiber cross-section (Pax7/F) was determined. Preliminary data (4 subjects, 21000 muscle fibers) showed that the proportions of Pax7/F in the middle portion of different EOMs were similar in adult and aged individuals (mean 0,024±0,0009). A similar proportion was found in the posterior part of the EOMs whereas more Pax7 positive cells were found in the anterior portion (0,087 Pax7/F). Staining for both MyoD and myogenin was negative. Co-staining for Pax7 and Ki-67 was not observed.
The proportion of Pax7 positive cells differed along the length of the EOMs. In the midbelly and posterior parts the proportion of Pax7 positive cells was lower than previously reported in human EOMs (0,07 Pax7/F) and limb muscles (0,07-0,19 SC/F) and similar to that observed in limb muscle from children (0,032 SC/F). These data are in line with our previous results from limb muscles showing a positive correlation between the number of satellite cells per myofiber and the mean myofiber cross-section area.
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