The Effects of Negative Pressure Therapy on Hair Growth of Mouse Models.

Negative pressure therapy (NPT) has been shown to facilitate wound healing and promote hair growth in a porcine model. However, there is a paucity of research on the impact of negative pressure on hair growth in murine models. Despite the ability of nude mice to develop hair follicles, the hair they produce is often flawed towing to genetically induced keratin disorders, rendering them a pertinent animal model for assessing hair regeneration. Therefore, this study aims to investigate the effects of negative pressure on hair follicle growth in a nude mouse model. To achieve this, a customized external tissue expansion device was developed to apply negative pressure to the dorsum of nude mice. The mice were subjected to several treatment courses consisting of 15 and 30 min of continuous negative pressure at 10 mmHg, which were repeated 5 and 10 times every other day until sacrifice. Dorsal skin samples were subsequently extracted from the suction and nonsuction areas. The sections were stained with various antibodies to assess the expression of SOX-9, LHX-2, Keratin-15, ß-catenin, CD31, and vascular endothelial growth factor-A, and a TUNEL assay was used to analyze cell apoptosis. The results showed that the number of hair follicles and angiogenesis were significantly higher in the suction area than in the nonsuction area in all groups. Moreover, mice that received NPT for 15 min for 10 times had a higher hair follicle density than the other three groups. Immunofluorescence staining for LHX-2 and Keratin 15 further validated the results of these findings. In conclusion, this study demonstrated that negative pressure effectively promotes hair follicle growth and angiogenesis in nude mice through SOX-9- and LHX-2-mediated follicular regeneration and ß-catenin-mediated hair follicle morphogenesis.

Enhanced cancer therapeutic efficiency of NO combined with siRNA by caspase-3 responsive polymers.

The combination of nitric oxide (NO) and siRNA is highly desirable for cancer therapy. Here, the furoxans-grafted PEI polymer (FDP) with caspase-3 responsive cleavable DEVD linker was synthesized, and used to bind siRNAs via electrostatic interaction and self-assembled into FDP/siRNA nanoplexes by hydrophobic force. After cellular uptake and lysosomal escape, the FDP/siRNA nanoplexes could achieve GSH-triggered NO release, and then increase the activity of caspase-3. The activated caspase-3 could specifically cleave the DEVD peptide sequence and enhance cell apoptosis. With the cleavage of DEVD peptide sequence, the disassembly of FDP/siRNA nanoplexes was further promoted, thereby resulting in increased siRNAs of ~40% were released at 48 h compared with the caspase-3 non-responsive FDnP/siRNA nanoplexes. By this way, cell apoptosis promotion and cell proliferation inhibition was achieved by siRNA-based downregulation of EGFR protein and the upregulated activity of caspase-3, followed by the enhanced cascade release of NO from FDP/siRNA nanoplexes. Furthermore, in vivo results demonstrated the improved anti-cancer efficiency of FDP/siEGFR nanoplexes without any detectable side effects. Therefore, it is believed that the caspase-3 responsive cleavable furoxans-grafted PEI polymers could provide a potential and efficient enhancement for cancer therapeutic efficiency by the co-delivery of nitric oxide and siRNA.

Biological activities of siRNA-loaded lanthanum phosphate nanoparticles on colorectal cancer.

Lanthanum can reduce absorption of phosphate by forming lanthanum phosphate complexes after oral administration of lanthanum carbonate tablets (FOSRENOL®) in patients. Based on the pH-responsive interaction of phosphate and lanthanum ions, the chitosan coated siRNA-loaded lanthanum phosphate nanoparticles (CS/LaP/siRNA NPs) were prepared for improving cancer treatment, in which polysaccharide chitosan was used as the outer shell to control the excessive growth of lanthanum phosphate complexes, and enable intestinal mucoadhesion. The CS/LaP/siEGFR NPs exhibited significant biological activities in human colorectal cancer HT-29 cells by the synergistic effects of siEGFRs and lanthanum ions, such as downregulation of EGFR and upregulation of miR-34a. Furthermore, significant tumor growth inhibition was observed in both transgenic C57BL/6-ApcMinC/Nju cancer mouse model and AOM/DSS chemically induced orthotopic colorectal cancer mouse model after intestinal instillation administration of CS/LaP/siEGFR NPs. Therefore, the lanthanum-based siRNA delivery system would provide a potential and efficient strategy for the treatment of colorectal cancers.

Encapsulated microRNA by gemcitabine prodrug for cancer treatment.

Although microRNAs (miRNAs) function as the important tumor gene regulators, they still confront with many challenges in systemic delivery. Here, the amphiphilic gemcitabine-oleic acid prodrugs (GOA) binding miRNAs with hydrogen bond are assembled into nanoparticles (GOA/miR NPs) through hydrophobic interaction via denaturation-annealing processes and nano-precipitation technique. The non-cationic GOA/miR NPs with an average size of ~150 nm and a zeta potential of ~ - 15 mV exhibit a stable encapsulation of miRNAs with non-sequence selectivity. Either miR-122 or miR-34a encapsulated in the GOA/miR NPs is efficiently delivered into HepG2 cells and significantly downregulate the expression levels of target gene after lysosome escape and pH-responsive disassembly. Moreover, in vivo experiments demonstrate that the GOA/miR-122 NPs exhibit higher tumor accumulation. Compared to GOA micelles, GOA/miR-122 NPs displayed stronger tumor inhibition (73% regression) after intravenous injection in nude mice xenografted with HCC, along with rapid clearance in normal liver tissues. Furthermore, there is no significant influence on biochemical indicators and immune factors during the systematic administration of GOA/miR-122 NPs. The non-cationic GOA/miR NPs engineered by hydrogen bond interaction and hydrophobic forces show the enhanced synergistic antitumor efficacy and good biosafety, which will provide a potential nanomedcine for HCC treatment.

Improved Cell Transfection of siRNA by pH-Responsive Nanomicelles Self-Assembled with mPEG- b-PHis- b-PEI Copolymers.

Here, the novel pH-responsive nanomicelles self-assembled with amphipathic meo-poly(ethylene glycol)- b-poly(l-histidine)- b-polyethylenimine (mPEG- b-PHis- b-PEI, EHE) copolymers based on hydrophobic interaction of PHis with deprotonation of imidazoles were developed for siRNA transfection. The cationic nanomicelles could electrostatically compact siRNA into stable EHE/siRNA nanoplexes with a hydrodynamic diameter of ∼190 nm and present a low toxicity in normal physiological condition (pH ∼ 7.4). Different from pH-irresponsive ECE/siRNA nanoplexes based on mPEG- b-poly(ε-caprolactone)- b-PEI (ECE), the EHE/siRNA nanoplexes exhibited a higher cellular uptake along with an increased ζ-potential (from +18 to +32 mV) when the pH changed from 7.4 to 6.8 (extracellular acidic microenvironments). After cell internalization, the EHE/siRNA nanoplexes also exhibited an enhanced nanostructural disassembling and release of siRNA from lysosomal acidic microenvironments (pH ∼ 5.5). Furthermore, it was demonstrated that the EHE/siEGFR nanoplexes downregulated the expression levels of the corresponding mRNA and protein more efficiently than ECE/siEGFR in HeLa cells. The improved siRNA silencing effects of EHE/siEGFR nanoplexes resulted from the higher cellular uptake and enhanced endosomal/lysosomal escape, which is associated with the pH-responsive disassembly of nanostructure as well as the synergistic "proton sponge" effects of PHis and PEI in EHE copolymers. Therefore, the pH-responsive EHE nanomicelles would be promising and potential carriers for cell transfection of siRNA.