Figure 4

Survival and proliferation of HUVECs. HUVECs were cultured on both films for 6, 12, 24, and 36 h. DNA damage, apoptosis, and cell proliferation of HUVECs plated on the collagen-treated film were analyzed using flow cytometry to investigate their survival and proliferation. Comparison of histograms of H2AX-negative cells [(A) and (B), non-DNA damage] and PARP-negative cells [(C) and (D), non-apoptosis] on the normal collagen film (non-treatment group) and denatured collagen film (treatment group). Cell death by DNA damage (positive population of H2AX) and apoptosis (positive population of PARP) was not detected. (E–L) Comparison of HUVECs on the collagenase-treated collagen film showed enhanced proliferation rates.