TGF-β, active MMP-9, and VEGF levels in the CM from normal and IMF cell cultures. The levels of TGF-β, active MMP-9, and VEGF were quantified in the CM after 15 days of primary cultures and 3 days of secondary cultures by ELISA. Each point represents the concentration of a growth factor or protease in the CM. The bars represent the mean values for each group. (A,B) represent the levels of TGF-β in the CM from normal, IMF, and PV samples at the 2 time points mentioned above. Significantly greater levels of TGF-β were found in the IMF CM from secondary cultures (B) (P < .01). (C,D) represent the levels of active MMP-9 in the CM from normal, IMF, and PV cultures in primary and secondary cultures. Significantly greater levels of active MMP-9 were found in the IMF CM both after 15 days of primary cultures and 3 days of secondary cultures compared with normal samples (P < .05). (E-F) VEGF levels were also measured in the CM from these cultures. In contrast to TGF-β or active MMP-9, the levels of VEGF were not found to be elevated in the IMF CM after 3 days of secondary cultures (F), however, greater levels of VEGF were found in the IMF CM from primary cultures (E) (P < .05), probably related to the greater numbers of MKs found in these cultures.