Exosomes are the best options for gene targeting, because of their natural, nontoxic, non-immunogenic, biodegradable, and targetable properties. By engineering exosome-producing cells, ligands can be expressed fusing with exosomal surface proteins for targeting cancer cell receptors. In the present study, HER2-positive breast cancer cells were targeted with a modified exosome producing engineered HEK293T cell. For this purpose, the HEK293T cells were transduced by a lentiviral vector bearing-LAMP2b-DARPin G3 chimeric gene. Stable cells expressing the fusion protein were selected, and the exosomes produced by these cells were isolated from the culture medium, characterized, and then loaded with siRNA for subsequent delivery to the SKBR3 cells. Our results showed that stable HEK293T cells produced DARPin G3 on the surface of exosomes. These exosomes can bind specifically to HER2/Neu and are capable of delivering siRNA molecules against TPD52 gene into SKBR3 cell line down-regulating the gene expression up to 70%. Present approach is envisaged to facilitate genes and drugs transfer to HER2 cancer cells providing additional option for gene therapy and drug delivery.

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HER2 is a member of epidermal factor receptor (EGFR) family which is overexpressed in breast cancer, ovarian cancer and gastric cancer. Development of new binders for cancer cell surface receptors and expressing them at the surface of exosomes would be a great approach in targeted cancer therapy. We found a high affinity scFv against HER2 using ribosome display with the approach of applying it as a targeting moiety at the surface of exosomes by fusion to lysosomal associated membrane protein 2B (LAMP2B). We also provide some structural information about the ribosome display selected scFv (scFv HFS2) through modeling the 3D structure of scFv HFS2 using RosettaAntibody and docked it at the extracellular domain of HER2. We also evaluated the structure of scFv HFS2 and its binding to HER2 after fusion to LAMP2B. Our results showed no significant change in 3D structure of scFv HFS2 when fused to LAMP2B (RMSD 1.3) and interaction analysis represented that scFv HFS2 binds HER2 domain III before and after fusion to LAMP2B. Although binding domain of scFv HFS2 on HER2 was the same at both state, residues involved in their interactions showed significant differences as it was probably due to the spatial hindrance of scFv HFS2 when fused to LAMP2B through a short linker and it should be considered before proceeding to experiment.

Background: Multi-drug resistant Pseudomonas aeruginosa causes serious complications in burn patients. One of the most important mechanisms of resistance to β-lactam antibiotics is hydrolysis of antibiotics by various β-lactamases. In recent years, Carbapenems have been widely used for treatment of P. aeruginosa infections. However, the organisms have become resistant to Carbapenems mostly by producing metallo β-lactamases. Objectives: The aim of this study was to determine antibiotic susceptibility, production of extended spectrum and AmpC β-lactamases in metallo β-lactamase producing P. aeruginosa burn isolates. Materials and Methods: Antibiotic susceptibility of 135 P. aeruginosa burn isolates was determined by disc diffusion. Metallo β-lactamase production was screened by the double disc synergy test. Metallo β-lactamase producing bacteria were then tested for extended spectrum β-lactamase production by the combined disc diffusion method. AmpC production was carried out using AmpC disc test. Results: There was 99% resistance to Carbenicillin, and Ticarcillin, 98% to Cotrimoxazole, 96% to Ciprofloxacin, and Aztreonam, 95% to Imipenem, and Meropenem, 94% to Pperacillin, 93% to Tobramycin, 92% to Cefepime, 90% to Amikacin, 89% to Ceftazidime, and 87% to Piperacillin-tazobactam. Among the 128 Imipenem resistant isolates, 32 (25%) were capable of producing metallo β-lactamases of which, 4 (12.5%) produced extended spectrum and 26 (81%) produced AmpC β-lactamases. Four isolates (12.5%) produced all 3 types. Conclusions: This study showed that multiple β-lactamases can be produced in burn isolates. This suggests that use of Cephalosporins and Carbapenems should be restricted in burn isolates to minimize the development and spread of these multidrug resistant pathogens.