A preliminary study on the interaction between Asn-Gly-Arg (NGR)-modified multifunctional nanoparticles and vascular epithelial cells

Liu, Chunxi; Liu, Tingxian; Yu, Xiaoyue; Gu, Yizhu

In this section, we tried to examine whether TPIC could change the distribution of CD13 in a manner similar to anti-CD13 antibody and to examine the behavior of CD13 after cells treated by TPIC. HUVEC were incubated with TPIC using the same procedure with anti-CD13 antibody for 0-4 h at 37 1C. As shown in Fig. 4 , we found the distribution of CD13 on the HUVEC surface was no longer uniform punctuate but was randomly distributed dots at 0 h, which was different with that after treating with antibody. Moreover, when HUVEC were incubated with TPIC and fixed without warming (0 h), the co-localization of CD13 and CAV1 in small clusters had been already observed (Fig. 4 , the top row, white arrows), which was 30 min earlier than that treating with antibody. With the extension of the incubation time at 37 1C, the distribution of CD13 on the HUVEC surface gathered into clusters and extensive co-localization of CD13 and CAV1 occurred at 2 h. However, compared with the colocalization result after anti-CD13 antibody treatment at 2 h, the co-localization result at 2 h after TPIC treatment was much more extensive. These results indicate that TPIC could change the distribution of CD13 in a different manner to antibody, because TPIC could accelerate the speed and enhance the extent of colocalization compared with the anti-CD13 antibody. Additionally, the co-localization also appeared in the cytoplasm, suggesting that after TPIC treatment, CD13 could enter into cell from membrane and co-localize with CAV1 in the cytoplasm for a period of time.