1195 10.2217/FON.13.82 © 2013 Future Medicine Ltd ISSN 1479-6694 Future Oncol. (2013) 9(8), 1195–1206 Future Oncology part of Cancer gene therapy is the treatment of diseases by transferring DNA, RNA, siRNA or antisense oligonucleotides to the site of the tumor [1]. The host immune system has a major role in recogni- tion and eradication of cancer cells [2]. Cancer gene immunotherapy via delivery of cytokine genes to cancerous cells alters the local tumor environment in order to induce anti-tumor immune responses [3,4]. IL-12 is a heterodimeric cytokine composed of subunits of a- (35 kD) and b-chain (40 kD), which are linked by a disulfide bridge [5]. Studies have revealed that IL-12 possesses superior anti- tumor activity compared with other cytokines [6–8]. However, the application of recombinant IL-12 in humans has been limited owing to its toxicity [9]. On the other hand, delivery of IL-12 protein requires frequent injections owing to its instability and short half-life subsequent to bolus administration [10,11]. Therefore, the local administration of the gene encoding IL-12 might produce less toxicicity in comparison with sys- temic delivery of this cytokine as a recombinant protein. On the whole, the cellular uptake of naked DNA molecules is an extremely inefficient process due to several inherent factors, such as DNA’s negative charge, size and poor sta- bility. In addition, naked DNA has extremely low in vivo stability and is rapidly degraded by hydrolytic endo- and exo-nucleases [12]. Furthermore, naked plasmid DNA delivery is ineffective if delivery to anatomically inacces- sible sites (e.g., solid tumors in organs) is desired. Therefore, there is an acute need for a delivery system for cancer gene therapy [13]. The Encyclopedia of Pharmaceutical Technology defines nanoparticles as solid colloi- dal particles ranging in size from 1 to 1000 nm (1 μm) [14]. Indeed, nanosized particles are of numerous advantages for pharmaceutical pur- poses: they are able to interact with and cross mucosal surfaces, cross the blood–brain barrier, enhance cellular uptake, escape endolysosomal compartments and release genes continuously within the cell [15]. Gelatin is a natural macromolecule that is obtained by the partial hydrolysis of collagen Preparation and characterization of gelatin nanoparticles containing pDNA encoding IL-12 and their expression in CT-26 carcinoma cells Somayeh Hallaj-Nezhadi 1 , Hadi Valizadeh 1 , Behzad Baradaran 2 , Faramarz Dobakhti 3 & Farzaneh Lotfipour* 4 1 Drug Applied Research Center & Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran 2 Immunology Research Center & Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran 3 Faculty of Pharmacy, Zanjan University of Medical Sciences, Zanjan, Iran 4 Hematology Oncology Research Center & Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran *Author for correspondence: Tel.: +98 411 339 2580 n Fax: +98 411 334 4798 n lotfipoor@tbzmed.ac.ir Aim: Gelatin as a biodegradable, nontoxic and biocompatible natural protein is a good candidate for gene delivery. In this study, pDNA-loaded gelatin nanoparticles were prepared and characterized for the expression of the cytokine IL-12 and anti-tumor effects. Materials & methods: Gelatin–pUMVC3–hIL-12 nanoparticles were prepared by the ethanol precipitation technique and evaluated for physicochemical characteristics, cytotoxiciy and transfection efficiency. Results: The prepared particles were spherical in shape with sizes varying from 344.27 to 826.23 nm, z -potentials between -944 and -165 mV, and greater than 97% encapsulation efficiency. The particles were nontoxic to CT-26 carcinoma cells. The nanoparticles prepared using 0.5% gelatin solution (G14) with a mean particle size of 816.87 nm (polydispersity index = 0.56 ± 0.01) demonstrated maximum transfection efficiency with 2.5-times higher expression compared with the naked plasmid. Conclusion: Gelatin–DNA nanoparticles using 0.5% gelatin solution had minimal cytotoxicity and can be used as a suitable candidate for further gene delivery studies and applications. Keywords n gelatin n gene delivery n IL-12 n nanoparticle n plasmid DNA Research Article For reprint orders, please contact: reprints@futuremedicine.com