Sterically Polymer-Based Liposomal Complexes with Dual-Shell Structure for Enhancing the siRNA Delivery

The sterically polymer-based liposomal complexes (SPLexes) were formed by cationic polymeric liposomes and pH-sensitive diblock copolymer were studied for their capabilities in improving the stability with high efficiency of siRNA delivery. The SPLexes were formed a dual-shelled structure and uniform size distribution. The PEGylated outer shell could mitigate the phagocytosis and reduce the cytotoxicity. Moreover, the folated SPLexes improved 42.9× accumulation in vitro and 1.7× tumor uptake in vivo in contrast with nonfolated SPLexes. The protonated copolymer at low pH would improve the siRNA released into cytoplasm following SPLexes fusion with the endo/lysosome membrane and inhibited the protein expression to 75.6 ± 4.5% efficiently. Results of this study significantly contribute to efforts to develop lipoplexes based siRNA delivery systems

The external photos of control, 20 wt % ECE hydrogel (A, top row), Matrigel, and Pluronic F127 at two weeks after injection (from L to R).

<p><b>(B, middle row):</b> The fundus oculi of control, 20 wt % ECE hydrogel, Matrigel, and Pluronic F127 at two weeks after injection (from L to R). (C, bottom row) The external color photos of control, 20 wt % ECE hydrogel, Matrigel, and Pluronic F127 for ocular media at one month after injection (from L to R). The red arrows indicate the cataract formation. The black arrow indicates the ECE <i>in situ</i> hydrogel formation. The inset photo of Matrigel is at two months after injection, which had a denser cataract formation and perilimbal ciliary injection. The inset photo of Pluronic F127 is the high magnification of cataract.</p

The optical coherent tomography (OCT) images after 2 months of injection.

<p>(A) control, (B) 20 wt % ECE hydrogel, (C) Matrigel, (D) Pluronic F127. The red lines in color photos indicate the unusual points. The retinal thickness of Matrigel and Pluronic F127 eyes were atrophic, whereas the ECE eye had a similar retinal thickness as control.</p

TEM micrographs of the outer retina, which demonstrates the morphology of outer nuclear layer (cell body of rod and cone cells).

<p>The control eyes (A), the 20 wt % ECE hydrogel (B), Matrigel (C), Pluronic F127 (D) after two months of injection. (C) and (D) demonstrate more cell loss than ECE and control eyes. (scale bar is 6.1 µm).</p

Histology of retinal sections of BSS-injected control eyes (A), 20 wt % ECE hydrogel (B), Matrigel (C, white arrow indicates the disrupted photoreceptor outer segments), and Pluronic F127 (D, black arrow indicates the disrupted photoreceptor outer segments) injected eyes after two months. (Hematoxylin and eosin stain, 400×).

<p>Histology of retinal sections of BSS-injected control eyes (A), 20 wt % ECE hydrogel (B), Matrigel (C, white arrow indicates the disrupted photoreceptor outer segments), and Pluronic F127 (D, black arrow indicates the disrupted photoreceptor outer segments) injected eyes after two months. (Hematoxylin and eosin stain, 400×).</p

The morphology of inner retinal layer (nuclei and surrounding cell bodies of the bipolar cells) with TEM technique.

<p>The control eyes (A), 20 wt % ECE hydrogel (B), Matrigel (C), and Pluronic F127 (D) after two months of injection. (scale bar is 6.1 µm).</p