Figure 6From: Increased microenvironment stiffness in damaged myofibers promotes myogenic progenitor cell proliferation Collapse of myofibers increases the myogenic progenitor cell microenvironment stiffness and maintains cell proliferation. (A) Representative phase contrast photomicrographs of freshly isolated intact and collapsed myofibers from 3 WT mice in differentiation medium during AFM measurements. The triangular cantilever is shown. (B) Histograms showing the stiffness of isolated intact myofibers (n = 27), collapsed myofibers after 0 days of culture (n = 26), and collapsed myofibers after 6 days of culture (n = 22). The myofiber stiffness values (average of 3 measurements/myofiber) from 3 independent experiments are expressed as kPa. ***P < 0.0001 versus intact myofibers on day 0. (C) Scatter dot plot showing the number of myogenic progenitor cells (MPCs or myoblasts)/ cm2 after 3 days of culture in proliferative medium on the 0.5- and 2-kPa substrates. The results were obtained by counting eight fields/well and three wells/substrate (n = 3). (D) Scatter dot plot showing the number of MPCs/cm2 after 3 days of culture in proliferative medium on the 0.5- or 2-kPa substrates following treatment with mitomycin. Results were obtained by counting 15 fields/well and 4 wells/substrate (n = 2). (E) Scatter dot plot showing the percentage of Ki67+ MPCs after 3 days of culture in proliferative medium on the 0.5- or 2-kPa substrates. Results were obtained by counting eight fields/well and three wells/substrate (n = 3). (F) Scatter dot plot showing the percentage of Myog+ MPCs after 3 days of culture in proliferative medium on the 0.5- and 2-kPa substrates. Results were obtained by counting eight fields/well and three wells/ substrate (n = 3). The primary MPC lines were isolated from 3 different mice. Percentages are expressed as relative values of the 0.5-kPa substrate values. *P < 0.05; **P < 0.01; ***P < 0.0001 versus 0.5 kPa. Results are expressed as means ± SEM.Back to article page