length and cell division or cell replicative senescence has been examined. Much effort has centered on whether the telomere can be used as a biologic timing device for ageing (Cawthon et al. 2003; Thomas et al. 2008). Evidence from kidneys, lens epithelium, and trabecular meshwork cells supporting this perspective has grown substantially in last few years (Melk et al. 2000; Pendergrass et al. 2001; Yamazaki et al. 2007). While others (Bodnar et al. 1998; van Steensel et al. 1998) found an association between telomere length and apoptosis; when the telomere length decreased to Hayflick limits, cells lost their ability to be susceptible to chromosomal fusion and their potential for division, going into replicative senescence and apoptosis or cancer.

Some researchers gradually realized that the ageing process is not simply a time problem, but is accompanied by or involves the accumulative effects from various environmental factors such as oxidation and radiation (Goytisolo et al. 2000). Hence research has been initiated to identify the bridge between the gene and the environment by using the telomere (Huda et al. 2007; Starr et al. 2008). The current study was initiated to examine the association among oxidation factors, telomeres, ageing, and apoptosis and to determine whether the sensitivity or susceptibility to apoptosis can be expressed by mean telomere length (MTL).

6.2 Methods

6.2.1The Culture of HUVEC and the Construction of Cell Division Model

We used culture time to reflect both the amounts of cell division and telomere length according to our working hypothesis. For example HUVEC cultured for 1 month represented the less cell division group (long telomere length) and HUVEC cultured for 3 months represented the more cell division group (short telomere length).

6.2.2Construction of an Apoptosis Model of HUVEC with Free Hydroxyl Radicals

The Fenton reaction (Fe2+ + H2O2 =Fe3+ + OH– +.OH) was used to produce free hydroxyl radicals as the oxidative factor to induce apoptosis in HUVEC. The reaction system comprising 0.2 mmol/l FeSO4 and 0.1, 0.05, 0.01, 0.005, or 0.0001 mmol/l H2O2 was tested to find the appropriate concentration of free radicals for inducing the apoptosis of HUVEC. Apoptosis was induced in HUVEC at 0.2 mmol/l FeSO4/0.0001 mmol/l H2O2 and 0.2 mmol/l FeSO4/0.005 mmol H2O2; and necrosis of HUVEC was found at the other concentrations. Thus, 0.2 mmol/l FeSO4/0.0001 mmol/l H2O2 was added to 1-month-cultured HUVEC and 0.2 mmol/l FeSO4/0.005 mmol H2O2 was added to 3-month-cultured HUVEC. Apoptosis of HUVEC was detected with HE stain, Hoechst 33,258 fluorescent stain, and apoptotic DNA ladder.