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

NGR peptide showed highly specific recognition of CD13. It was also reported that aggregated labelling of CD13 co-localized with CAV1 in most cells. Based on these findings and the previously obtained conclusion, we hypothesized that NGR might be able to mediate the TPIC into CD13 positive cells via the CvME. In the present study, it was verified that there was no colocalization between CD13 and CAV1 without treatment (Fig. 3, Figure 7 The TPIC uptake and surface accessible CD13 after HUVEC incubated with TPIC at (A) 4 1C or (B) 37 1C at various time points. 0 min). However, when cells were incubated with an anti-CD13 antibody, co-localization between CD13 and CAV1 was observed (Fig. 3, 10 min to 3 h) . These exciting results imply that targeting CD13 could initiate a subsequent interaction with CAV1. When HUVEC were treated with TPIC, a greater degree of colocalization of CD13 and CAV1 was found. It was shown that TPIC could accelerate the speed and enhance the degree of the colocalization of CD13 and CAV1 to a greater degree than anti-CD13 antibody. This difference could be attributed to the differences in the cross-linking degree and size between ligands and antibodies. Compared with antibodies, the NGR-modified nanocarrier was supposed to be a polyvalent ligand for CD13. Therefore, after treating with TPIC, both the speed and the extent of co-localization were enhanced compared with antibody. Notably, although the pattern was less conspicuous, cross-linked CD13 molecules after TPIC treatment showed a streaky distribution along longitudinal lines (Fig. 3, 2h; Fig. 3, 3h) . This phenomenon was probably because the cross-linking of CD13 by TPIC would induce binding to actin filaments, either directly or indirectly, and further cause the longitudinal alignment. This similar distribution was also reported for cross-linked β2-microglobulin 44 and HCoV-229E 45 and both were eventually internalized by the CvME.