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Scintigraphic imaging of malignant glioblastoma (MG) continues to be challenging. We hypothesized that VPAC1 cell surface receptors can be targeted for positron emission tomography (PET) imaging of orthotopically implanted MG in a mouse model, using a VPAC1-specific peptide [64Cu]TP3805. The expression of VPAC1 in mouse GL261 and human U87 glioma cell lines was determined by western blot. The ability of [64Cu]TP3805 to bind to GL261 and U87 cells was studied by cell-binding. Receptor-blocking studies were performed to validate receptor specificity. GL261 tumors were implanted orthotopically in syngeneic T-bet knockout C57BL/6 mouse brain (N = 15) and allowed to grow for 2–3 weeks. Mice were injected i.v., first with ~ 150 μCi of 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) then 24 h later with ~ 200 μCi of [64Cu]TP3805. In another set of tumor-bearing mice, (N = 5), ionic [64Cu]Cl2 was injected as a control. Mice were imaged at a 2-h post-injection using an Inveon micro-PET/CT, sacrificed and % ID/g of [64Cu]TP3805 and [64Cu]Cl2 were calculated in a tumor, normal brain, and other tissues. For histologic tissue examination, 3-μm thick sections of the tumors and normal brain were prepared, digital autoradiography (DAR) was performed, and then the sections were H&E stained for histologic examination. Western blots showed a strong signal for VPAC1 on both cell lines. [64Cu]TP3805 cell-binding was 87 ± 1.5 %. Receptor-blocking reduced cell-binding to 24.3 ± 1.5 % (P

The αvβ3 integrin has been shown to promote aggressive phenotypes in many types of cancers, including prostate cancer. We show that GFP-labeled αvβ3 derived from cancer cells circulates in the blood and is detected in distant lesions in NOD scid gamma (NSG) mice. We, therefore, hypothesized that αvβ3 travels through exosomes and tested its levels in pools of vesicles, which we designate extracellular vesicles highly enriched in exosomes (ExVs), and in exosomes isolated from the plasma of prostate cancer patients. Here, we show that the αvβ3 integrin is found in patient blood exosomes purified by sucrose or iodixanol density gradients. In addition, we provide evidence that the αvβ3 integrin is transferred through ExVs isolated from prostate cancer patient plasma to β3-negative recipient cells. We also demonstrate the intracellular localization of β3-GFP transferred via cancer cell-derived ExVs. We show that the ExVs present in plasma from prostate cancer patients contain higher levels of αvβ3 and CD9 as compared to plasma ExVs from age-matched subjects who are not affected by cancer. Furthermore, using PSMA antibody-bead mediated immunocapture, we show that the αvβ3 integrin is expressed in a subset of exosomes characterized by PSMA, CD9, CD63, and an epithelial-specific marker, Trop-2. Finally, we present evidence that the levels of αvβ3, CD63, and CD9 remain unaltered in ExVs isolated from the blood of prostate cancer patients treated with enzalutamide. Our results suggest that detecting exosomal αvβ3 integrin in prostate cancer patients could be a clinically useful and non-invasive biomarker to follow prostate cancer progression. Moreover, the ability of αvβ3 integrin to be transferred from ExVs to recipient cells provides a strong rationale for further investigating the role of αvβ3 integrin in the pathogenesis of prostate cancer and as a potential therapeutic target.

INTRODUCTION Accurate staging of urothelial bladder cancer (UBC) with imaging, which guides effective bladder cancer treatment, remains challenging. This investigation is to validate a hypothesis that targeting Vasoactive intestinal and pituitary adenylate cyclase activating peptide (VPAC) receptors using ⁶⁴Cu-TP3805 can PET image UBC efficiently.Nineteen patients (44-84 years of age) scheduled for radical cystectomy, underwent VPAC positron emission tomography (PET) imaging prior to surgery. Sixteen had completed neoadjuvant chemotherapy prior to imaging. All 19 received ⁶⁴Cu-TP3805 (148 % ± 10% MBq) intravenously, and were imaged 60 to 90 minutes later. Standard uptake value (SUV)max for malignant lesions and SUVmean for normal tissues were determined and mean +/-SEM recorded. Following radical cystoprostatectomy, pelvic lymphadenectomy and urinary diversion imaging, results were compared with final surgical pathology.⁶⁴Cu-TP3805 had no adverse events, negligible urinary excretion and rapid blood clearance. UBC PET images for residual disease were true positive in 11 patients and true negative in four. Of remaining 4, one had false positive and 3 had false negative scans, equating to 79% sensitivity (95%, CI 49%-95%), 80% specificity (95%, CI 28%-100%), 92% positive predictive value (95%, CI 62%-100%) and 57% negative predictive value (95%, CI 18%-90%).These first in man results, in a group, heavily pretreated with neoadjuvant chemotherapy, indicate that VPAC PET imaging can identify UBC effeiciently and suggest, that VPAC PET can diagnose UBC in a treatment naïve cohort for accurate staging, guide biopsy and treatment in patients with suspected metastasis and determine response to therapy. Further investigation of this molecular imaging approach is warranted.

Conjugation through primary amines is one of the most commonly used methods to modify cationic vectors for efficient gene delivery. Here, dimethyl suberimidate, a commercially available homobifunctional reagent bearing imidoesters at the termini, has been used to crosslink branched polyethylenimine (bPEI) into its nanoparticles (crosslinked PEI nanoparticles, CLP NPs) specifically through primary amines without altering the total charge on the resulting NPs for interaction with biomolecules and cell membranes. By varying the degree of crosslinking, a small series of CLP NPs was prepared and evaluated for their capability to deliver nucleic acids in vitro and in vivo. Physico-chemical characterization revealed the size of the NPs in the range of ∼152 to 210 nm with zeta potential ∼+35 to +38 mV. The plasmid DNA binding ability of these nanoparticles was examined by mobility shift assay, where the pDNA migration was found to be completely retarded by these NPs at an N/P ratio of 4 (cf. bPEI at N/P 3). In various mammalian cells, CLP/pDNA nanoplexes were not only found to be non-toxic but also exhibited significantly enhanced gene expression with one of the formulations, the CLP3/pDNA nanoplex, displaying the highest transfection efficiency, outperforming native bPEI and the selected commercial transfection reagents both in the presence and absence of serum. Further, the versatility of the vector, CLP3, was demonstrated by sequential delivery of GFP-specific siRNA to HEK293 cells, which resulted in ∼79% suppression of the target gene. Intracellular localization studies showed a significant population of the dual labeled nanoplex (CLP3/pDNA) in the nucleus in just 60 min of incubation. Luciferase reporter gene analysis in Balb/c mice post-intravenous administration of the CLP3/pDNA nanoplex showed the highest gene expression in their spleen. The study suggests that CLP NPs could be used as efficient gene delivery vectors for future gene therapy applications.

Introduction Previously, our laboratory has shown that 64Cu-TP3805 can specifically target VPAC1 receptors and be used for positron emission tomography (PET) imaging of breast (BC) and prostate cancer (PC) in humans. Present work is aimed at the formulation of a freeze-dried diaminedithiol-peptide (N2S2-TP3805) kit and it's evaluation for the preparation of 64Cu labeled TP3805. Parameters such as pH, temperature and incubation time were examined that influenced the radiolabeling efficiency and stability of the product. Methods Kits were prepared under different conditions and radiolabeling efficiency of TP3805 kit was evaluated for a range of pH 3.5–8.5, after addition of 64Cu in 30 μl, 0.1 M HCl. Incubation temperature (37-90 °C) and time (30-120 min.) were also investigated. Kits were stored at −10 °C and their long term stability was determined as a function of their radiolabeling efficiency. Further, stability of 64Cu-TP3805 complex was evaluated in presence of fetal bovine serum and bovine serum albumin by using SDS polyacrylamide gel electrophoresis. Kits were then used for PET imaging of BC and PC following eIND (101550) and institutional approvals. Specificity of 64Cu-TP3805 for VPAC1 was examined with digital autoradiography (DAR) of prostate tissues obtained after prostatectomy, benign prostatic hyperplasia (BPH) tissue, and benign and malignant lymph nodes. Results were compared with corresponding tissue histology. Results Radiolabeling efficiency was ≥95% at final pH ~7.2 when incubated at 50 °C for 90 min. Kits were stable up to 18 months when stored at −10 °C, and 64Cu-TP3805 complex exhibited excellent stability for up to 4 h at room temperature. 64Cu-TP3805 complex did not show any transchelation even after 2 h incubation at 37 °C in 10% FBS as well as in BSA as determined by SDS PAGE analysis. DAR identified ≥95% of malignant lesions 11 new PC lesions, 20 high grade prostatic intraepithelial neoplasia, 2/2 ejaculatory ducts and 5/5 urethra verumontanum not previously identified The malignant lymph nodes were correctly identified by DAR and for 3/3 BPH patients, and 5/5 cysts, DAR was negative. In human BC (n = 19) and PC (n = 26) were imaged with 100% sensitivity. Conclusion Availability of ready to use N2S2-peptide kits for 64Cu labeling is convenient and eliminates possible day to day variation during its routine preparation for clinical use.

Objective To validate a hypothesis that prostate cancer can be detected non-invasively by a simple and reliable assay by targeting genomic VPAC receptors expressed on malignant prostate cancer cells shed in voided urine. Patients/Subjects and Methods VPAC receptors were targeted with a specific biomolecule, TP4303, developed in our laboratory. With an Institutional Review Board exempt approval of use of de-identified discarded samples, an aliquot of urine collected as a standard of care, from patients presenting to the urology clinic (207 patients, 176 men and 31 women, aged ≥21 years) was cytospun. The cells were fixed and treated with TP4303 and 4,6-diamidino-2-phenylindole (DAPI). The cells were then observed under a microscope and cells with TP4303 orange fluorescence around the blue (DAPI) nucleus were considered ‘malignant’ and those only with a blue nucleus were regarded as ‘normal’. VPAC presence was validated using receptor blocking assay and cell malignancy was confirmed by prostate cancer gene profile examination. Results The urine specimens were labelled only with gender and presenting diagnosis, with no personal health identifiers or other clinical data. The assay detected VPAC positive cells in 98.6% of the men with a prostate cancer diagnosis (141), and none of the 10 men with benign prostatic hyperplasia. Of the 56 ‘normal’ patients, 62.5% (35 patients, 10 men and 25 women) were negative for VPAC cells; 19.6% (11, 11 men and no women) had VPAC positive cells; and 17.8% (10, four men and six women) were uninterpretable due to excessive crystals in the urine. Although data are limited, the sensitivity of the assay was 99.3% with a confidence interval (CI) of 96.1–100% and the specificity was 100% with a CI of 69.2–100%. Receptor blocking assay and fluorescence-activated cell sorting (FACS) analyses demonstrated the presence of VPAC receptors and gene profiling examinations confirmed that the cells expressing VPAC receptors were malignant prostate cancer cells. Conclusion These preliminary data are highly encouraging and warrant further evaluation of the assay to serve as a simple and reliable tool to detect prostate cancer non-invasively.

The main aim of the current study is to compare the physicochemical properties, cytotoxicity and gene-transfer ability of electrostatically and covalently linked nanocomposites of polyethylenimine (PEI) and polyacrylic acid (PAA) on mammalian cells. Two series of nanocomposites, ionic PEI-PAA (iPP) and covalent PEI-PAA (cPP), were synthesized by varying the amounts of polyacrylic acid (PAA). Physicochemical characterization revealed that iPP nanopcomposites were of bigger sized than cPP nanocomposites with zeta potential almost comparable. Nucleic acid binding assay displayed that iPP and cPP nanocomposites, having sufficient cationic charge, efficiently interacted with plasmid DNA and completely retarded its electrophoretic mobility on agarose gel. In vitro MTT assay showed slightly higher cell viability of cPP/pDNA complexes over their ionic counterparts. Both the series of nanocomposite/pDNA complexes exhibited considerably higher transfection efficacy compared to pDNA complexes of native bPEI and the standard transfection reagent, Lipofectamine, with cPP/pDNA complexes performed much better than iPP/pDNA complexes. Flow cytometry further confirmed these findings where cPP-4/pDNA complex showed transfection in ∼ 85% HEK293 cells, while iPP-2/pDNA complex transfected ∼ 67% HEK293 cells. Lipofectamine/pDNA and bPEI/pDNA complexes could transfect just ∼ 35% and ∼ 26% HEK293 cells. All these results demonstrate the superiority of covalently linked nanocomposites (cPP) which could be used as efficient carriers for nucleic acids in future gene delivery applications.

Highly pathogenic avian influenza (H5N8) viruses were detected in waterfowl at 2 zoos in India in October 2016. Both viruses were different 7:1 reassortants of H5N8 viruses isolated in May 2016 from wild birds in the Russian Federation and China, suggesting virus spread during southward winter migration of birds.

PURPOSE: In recent years, considerable progress has been made in the use of gallium-68 labeled receptor-specific peptides for imaging oncologic diseases. The objective was to examine the stability and pharmacokinetics of [(68)Ga]NODAGA and DOTA-peptide conjugate targeting VPAC [combined for vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating peptide (PACAP)] receptors on tumor cells. PROCEDURES: A VPAC receptor-specific peptide was chosen as a model peptide and conjugated to NODAGA and DOTA via solid-phase synthesis. The conjugates were characterized by HPLC and MALDI-TOF. Following Ga-68 chelation, the radiochemical purity of Ga-68 labeled peptide conjugate was determined by radio-HPLC. The stability was tested against transmetallation using 100 nM Fe(3+)/Zn(2+)/Ca(2+) ionic solution and against transchelation using 200 μM DTPA solution. The ex vivo and in vivo stability of the Ga-68 labeled peptide conjugate was tested in mouse plasma and urine. Receptor specificity was determined ex vivo by cell binding assays using human breast cancer BT474 cells. Positron emission tomography (PET)/X-ray computed tomography (CT) imaging, tissue distribution, and blocking studies were performed in mice bearing BT474 xenografts. RESULTS: The chemical and radiochemical purity was greater than 95 % and both conjugates were stable against transchelation and transmetallation. Ex vivo stability at 60 min showed that the NODAGA-peptide-bound Ga-68 reduced to 42.1 ± 3.7 % (in plasma) and 37.4 ± 2.9 % (in urine), whereas the DOTA-peptide-bound Ga-68 was reduced to 1.2 ± 0.3 % (in plasma) and 4.2 ± 0.4 % (in urine) at 60 min. Similarly, the in vivo stability for [(68)Ga]NODAGA-peptide was decreased to 2.1 ± 0.2 % (in plasma) and 2.2 ± 0.4 % (in urine). For [(68)Ga]DOTA-peptide, it was decreased to 1.4 ± 0.3 % (in plasma) and 1.2 ± 0.4 % (in urine) at 60 min. The specific BT474 cell binding was 53.9 ± 0.8 % for [(68)Ga]NODAGA-peptide, 25.8 ± 1.4 % for [(68)Ga]-DOTA-peptide, and 18.8 ± 2.5 % for [(68)Ga]GaCl(3) at 60 min. Inveon microPET/CT imaging at 1 h post-injection showed significantly (p < 0.05) higher tumor to muscle (T/M) ratio for [(68)Ga]NODAGA-peptide (3.4 ± 0.3) as compared to [(68)Ga]DOTA-peptide (1.8 ± 0.6). For [(68)Ga]GaCl(3) and blocked mice, their ratios were 1.5 ± 0.6 and 1.5 ± 0.3 respectively. The tissue distributions data were similar to the PET imaging data. CONCLUSION: NODAGA is superior to DOTA in terms of radiolabeling kinetics. The method of radiolabeling was reproducible and yielded higher specific activity. Although both agents have relatively low in vivo stability, PET/CT imaging studies delineated BC tumors with [(68)Ga]NODAGA-peptide, but not with [(68)Ga]DOTA-peptide.

Though congenital hydrocephalus is heritable, it has been linked only to eight genes, one of which isMPDZ. Humans and mice that carry a truncated version of MPDZ incur severe hydrocephalus resulting in acute morbidity and lethality. We show by magnetic resonance imaging that contrast-medium penetrates into the brain ventricles of mice carrying aMpdzloss-of-function mutation, whereas none is detected in the ventricles of normal mice, implying that the permeability of the choroid plexus epithelial cell monolayer is abnormally high. Comparative proteomic analysis of the cerebrospinal fluid of normal and hydrocephalic mice revealed up to a 53-fold increase in protein concentration, suggesting that transcytosis through the choroid plexus epithelial cells ofMpdzKO mice is substantially higher than in normal mice. These conclusions are supported by ultrastructural evidence, and by immunohistochemistry and cytology data. Our results provide a straight-forward and concise explanation for the pathophysiology ofMpdz-linked hydrocephalus.

Objective To evaluate 64 Cu-TP3805 as a novel biomolecule, to positron emission tomography (PET) image prostate cancer (PC), at the onset of which VPAC1, the superfamily of G protein-coupled receptors, is expressed in high density on PC cells, but not on normal cells. Materials and Methods Twenty-five patients undergoing radical prostatectomy were PET/X-ray computerized tomography imaged preoperatively with 64 Cu-TP3805. Standardized maximum uptake (SUVmax) values were determined and malignant lesions (standardized uptake value > 1.0) counted, and compared with histologic findings. Whole-mount pathology slides from 6 VPAC1 PET imaged patients, 3 benign prostatic hyperplasia patients, 1 malignant and 1 benign lymph node underwent digital autoradiography (DAR) after 64 Cu-TP3805 incubation and were compared to hematoxylin- and eosin-stained slides. Results In 25 patients who underwent PET imaging, 212 prostate gland lesions had SUVmax > 1.0 vs 127 lesions identified by histology of biopsy tissues. The status of the additional 85 PET identified prostate lesions remains to be determined. In 68 histologic slides from 6 PET imaged patients, DAR identified 105 of 107 PC foci, 19 of 19 high-grade prostatic intraepithelial neoplasias, and ejaculatory ducts and verumontanum involved with cancer. Additionally, DAR found 9 PC lesions not previously identified histologically. The positive and negative lymph nodes were correctly identified, and in 3 of 3 benign prostatic hyperplasia patients and 5 of 5 cysts, DAR was negative. Conclusion This feasibility study demonstrated that 64 Cu-TP3805 delineates PC in vivo and ex vivo, provided normal images for benign masses, and is worthy of further studies.

443 Background: Urothelial bladder cancer (UBC) inflicts >80,000 new patients annually. Since treatment is stage-dependent, accurate staging is crucial. Conventional imaging and biopsy are often unreliable. A large number of PET tracers, developed to improve imaging, have limitations e.g. urinary excretion compromising their ability to assess the bladder lumen and invasive tumors. This study is to validate a hypothesis that high density VPAC receptors expression on UBC cell surface, can be targeted to PET image UBC, to determine loco-regional disease and metastatic lesions. Methods: Cu-64-TP3805 (4±10% mCi), with its high affinity (3.1 x 10−9M) for VPAC, was given IV to 19 UBC patients (44-80 yrs), scheduled for radical cystectomy. Those eligible for neoadjuvant chemotherapy were treated as such. Urine and blood samples were collected on the day of scan. Whole body PET/CT images acquired 60 to 90 min later and read by two physicians. Surgery was performed 1 to 4 weeks later. Imaging results were correlated with histology. Results: There were no adverse events. Urinary excretion of Cu-64-TP3805 was negligible. Blood clearance was biphasic (t ½ a = 22.3 ±2.7 min ~ 85% and t ½ β = 118.2 ± 4.9 min ~ 15%). VPAC PET bladder images were true positive (TP) in 11, true negative (TN) in 4, false positive (FP) in 1 and false negative (FN) in 3 patients with 79% sensitivity (95% CI 49%-95%), 80% specificity (95% CI 28%-100%), 92% PPV (95% CI 62%-100%), and 57% NPV (95% CI 18%-90%). Prostate images were TP in 8, TN in 6, and FP in 5 patients, with 100% sensitivity (95% CI 63%-100%), 55% specificity (95% CI 23%-83%), 62% PPV (95% CI 32%-86%), and 100% NPV (95% CI 54%-100%). The 5 FP images revealed HGPIN on re-analysis. For lymph nodes, images were TP in 1, TN in 14 and FN in 4 patients, with 25% sensitivity (95% CI 1%-81%), 100% specificity (95% CI 78%-100%), 100% PPV (95% CI 3%-100%), and 83% NPV (95% CI 59%-96%). In one patient, several lesions were seen in the spine and iliac crest. Biopsy was positive for metastasis. In smokers (N=12) there was diffused or focal tracer uptake in the lungs. In 7 non-smokers, 3 with CT depicted abnormality had tracer lung uptake and 4 did not. Conclusions: These first in human pilot study data depict Cu-64-TP3805 VPAC targeting to image UBC as worthy of further investigation.

Previously, our laboratory has shown thatKits were prepared under different conditions and radiolabeling efficiency of TP3805 kit was evaluated for a range of pH3.5-8.5, after addition ofRadiolabeling efficiency was ≥95% at final pH ~7.2 when incubated at 50°C for 90min. Kits were stable up to 18months when stored at -10°C, andAvailability of ready to use N

We report a simple preparation of linear polyethylenimine-grafted graphene oxide (LP-GO) conjugates and their efficacy to transfer nucleic acids into the mammalian cells. Graphene oxide (GO), with epoxy functions on its surface, was reacted with different amounts of linear polyethylenimine (lPEI), a non-toxic polymer, to obtain three different positively charged LP-GO conjugates (LP-GO-1 to LP-GO-3), capable of interacting with negatively charged nucleic acids (gel retardation assay) and transporting them efficiently into the cells. The results show that these conjugates not only exhibited considerably higher transfection efficiency but also possessed even better cell viability than lPEI. LP-GO-2, the best system in terms of transfection efficiency, showed improved buffering capacity compared to lPEI and provided sufficient stability to bound DNA against DNase I. Further, LP-GO-2 was used for the sequential delivery of GFP specific siRNA, which resulted in ∼70% suppression of the target gene expression. Intracellular trafficking using fluorescence microscopy revealed that LP-GO-2 conjugate delivered pDNA in the nucleus within 1 h of exposure. The results indicate the prospect of using these conjugates as efficient carriers of nucleic acids for future gene therapy applications.

Development of efficient and safe nucleic acid carriers (vectors) is one of the essential requirements for the success of gene therapy. Here, we have evaluated the gene transfer capability of chitosan-PEI (CP) conjugates prepared by conjugating low molecular weight branched polyethylenimine (LMWP) with depolymerized chitosans (7 and 10 kDa) via their terminal aldehyde/keto groups. The CP conjugates interacted efficiently with nucleic acids and also showed higher cellular uptake. These conjugates on complexation with DNA yielded nanoparticles in the size range of 100–130 nm (in case of C7P) and 115–160 nm (in case of C10P), which exhibited significantly higher transfection efficiency (∼2–42 folds) in vitro compared to chitosans (high and low mol. wt.) and the commercially available transfection reagents retaining cell viability almost comparable to the native chitosan. Of the two CP conjugates, chitosan 7 kDa-LMWP (C7P) displayed higher gene transfer ability in the presence and absence of serum. Luciferase reporter gene analysis in male Balb/c mice receiving intravenous administration of C7P3/DNA polyplex showed the maximum expression in their spleen. Further, tuftsin, a known macrophage targeting molecule, was tethered to C7P3 and the resulting complex, i.e., C7P3-T/DNA, exhibited significantly higher gene expression in cultured mouse peritoneal macrophages as compared to unmodified C7P3/DNA complex without any cytotoxicity demonstrating the suitability of the conjugate for targeted applications. Conclusively, the study demonstrates the potential of the projected conjugates for gene delivery for wider biomedical applications.

Use of cationic polymers as nonviral gene vectors has several limitations such as low transfection efficiency, high toxicity, and inactivation by serum. In this study, varying amounts of low molecular weight branched polyethylenimine 1.8 kDa (bPEI 1.8) were introduced on to a neutral polymer, poly(vinyl alcohol) (PVA), to bring in cationic charge on the resulting PVA-PEI (PP) nanocomposites. We rationalized that by introducing bPEI 1.8, buffering and condensation properties of the proposed nanocomposites would result in improved gene transfer capability. A series of PVA-PEI (PP) nanocomposites was synthesized using well-established epoxide chemistry and characterized by IR and NMR. Particle size of the PP/DNA complexes ranged between 120 to 135 nm, as determined by dynamic light scattering (DLS), and DNA retardation assay revealed efficient binding capability of PP nanocomposites to negatively charged nucleic acids. In vitro transfection of PP/DNA complexes in HEK293, HeLa, and CHO cells revealed that the best working formulation in the synthesized series, PP-3/DNA complex, displayed ~2-50-fold higher transfection efficiency than bPEIs (1.8 and 25 kDa) and commercial transfection reagents. More importantly, the PP/DNA complexes were stable over a period of time, along with their superior transfection efficiency in the presence of serum compared to serum-free conditions, retaining the nontoxic property of low molecular weight bPEI. The in vivo administration of PP-3/DNA complex in Balb/c mice showed maximum gene expression in their spleen. The study demonstrates the potential of PP nanocomposites as promising nonviral gene vectors for in vivo applications.

A series of polyethylenimine (PEI) and γ-polyglutamic acid (PGA) nanocomposites (PPGA) was prepared and evaluated in terms of their cell viability and transfection efficiency in vitro and in vivo. On complexion with pDNA, the positively charged PPGA/DNA nanocomposites resulted in a higher level of in vitro reporter gene transfection (2.7-7.9-fold) as compared to native PEI, and selected commercial reagents and >95% cell viability in HEK293, HeLa and HepG2 cell lines. Further, PPGA-5 nanocomposite (the best working system in terms of transfection efficiency among the series) was found to efficiently transfect primary mouse keratinocytes up to 22% above the control level. PPGA-5, when tested for in vivo cytotoxicity in Drosophila, did not induce any stress in the exposed larvae in comparison with control. In vivo gene expression using PPGA-5 showed the highest transfection efficiency in spleen of mouse closely followed by heart tissues after intravenous injection through tail vein. Besides, these nanocomposites also delivered siRNA efficiently into mammalian cells, resulting in ∼ 80% suppression of EGFP expression. These results together demonstrated the potential of the projected nanocomposites for in vivo gene delivery.

Branched Polyethylenimine, 25 kDa (PEI), was blended with gellan gum, an anionic heteropolysaccharide, for partial neutralization of its excess positive charge to form gellan gum-polyethylenimine (GP) nanocomposites (NCs). Subsequently, we manipulated the amount of gellan gum for obtaining a series of NCs and characterized them for their size, charge and morphology. Among all the NCs, one member, named GP3, showed the best transfection efficiency in tested cell lines in comparison with the rest of the series, PEI, Lipofectamine and other commercial transfection agents and also exhibited minimum cytotoxicity. It was found to transfect primary cells of mouse skin with better efficiency than PEI and Lipofectamine and was able to protect the plasmid DNA from nucleases and serum proteins present in the blood. GP3 exhibited efficient intracellular delivery of plasmid as revealed by confocal studies while its intracellular presence was also confirmed by the knockdown of GFP expression (using GFP specific siRNA) and JNKII by quantifying proteins in cell lysates and by western blotting and hybridization, respectively. In vivo cytotoxicity studies in Drosophila showed lack of induction of stress response in the exposed organisms. Further, exposed organisms did not show any developmental delay or mortality and no morphological defects were observed in the emerged flies. In vivo gene expression studies in Balb/c mice revealed maximum expression of luciferase enzyme in spleen. The study suggests that GP3 may act as an efficient non-viral gene carrier with diverse biomedical applications.

Branched polyethylenimine, (b PEI, 25 kDa), was converted into nanoparticles by using three different crosslinkers, 1,6-hexanebisphosphate (HP), adipic acid (AA), and 1,4-butane dialdehyde (BA), having same carbon chain length (C-6), and the effect of ionic and covalent crosslinking on the transfection efficiency was studied. The synthesized nanoparticles were characterized by 1H-NMR, IR, DLS, AFM, and TEM. The entire series of nanoparticles was tested for their toxicity and ability to deliver genes in COS-1 and CHO cell lines. It was observed that, AAP-3 nanoparticle/DNA complex exhibited highest transfection efficiency (~2.1–10.7 folds) than the native PEI and commercially available transfection reagents, such as GenePORTER 2TM, LipofectamineTM, and SuperfectTM, with cell viability >80%. Among the series, the highest cell viability was observed with BAP nanoparticles (>96%). These nanoparticles were able to deliver GFP-siRNA very efficiently inside the cells with ~76%–90% suppression of EGFP expression. Cellular trafficking studies showed that these nanoparticles carry pDNA inside the nucleus of the cells within 2 h of the addition to the cells.

The authors have conjugated chelating agents (DOTA and NODAGA) with a peptide (pituitary adenylate cyclase-activating peptide [PACAP] analogue) that has a high affinity for VPAC1 receptors expressed on cancer cells. To determine a suitable chelating agent for labeling with (68)Ga, they have compared the labeling kinetics and stability of these peptide conjugates.For labeling, (68)GaCl3 was eluted in 0.1 M HCl from a [(68)Ge-(68)Ga] generator. The influences of peptide concentration, pH, and temperature on the radiolabeling efficiency were studied. The stability was evaluated in saline, human serum, DTPA, transferrin, and metallic ions (FeCl3, CaCl2, and ZnCl2). Cell binding assay was performed using human breast cancer cells (T47D). Tissue biodistribution was studied in normal athymic nude mice.Optimal radiolabeling (95.0%) of the DOTA-peptide conjugates required a higher (50°C-90°C) temperature and 10 minutes of incubation at pH 2-5. The NODAGA-peptide conjugate needed incubation only at 25°C for 10 minutes. Both radiocomplexes were stable in saline, serum, as well as against transchelation and transmetallation. Cell binding at 37°C for 15 minutes of incubation with (68)Ga-NODAGA-peptide was 34.0% compared to 24.5% for (68)Ga-DOTA-peptide. Tissue biodistribution at 1 hour postinjection of both (68)Ga-labeled peptide conjugates showed clearance through the kidneys.NODAGA-peptide showed more convenient radiolabeling features than that of DOTA-peptide.

INTRODUCTION AND OBJECTIVES: Prostate cancer (CaP) overexpresses VPAC1, representing a highly suitable target for imaging and treatment. VPAC1 is over-expressed at the onset of the malignancy, which may be prior to elevation of PSA, and before cell morphology is altered. We have successfully used VPAC1 receptor-specific peptide constructs to image breast cancer in experimental animal models, and in humans. We hypothesized that VPAC1 expressed in high density on PC can be targeted for detection of intraprostatic tumor foci on whole mount radical prostatectomy specimens, using TP3805, a VPAC1 specific biomolecule labeled with Cu-64 a PET imaging radionuclide. METHODS: As part of a PET imaging protocol targeting VPAC1, men (N1⁄425) with prostate cancer undergoing radical prostatectomy were imaged preoperatively, and compared to whole mount radical prostatectomy pathologic analysis. De-paraffinized slides from whole mount pathology from two patients who participated the protocol, as well as one malignant lymph node and one benign lymph node specimens and 3 BPH negative controls underwent digital autoradiography with Cu-64, and then were H&E stained. Autoradiography images were compared with prostate H&E staining in which tumor foci were delineated. RESULTS: Prostate cancer foci (n1⁄430/31) were identified by autoradiography imaging (Figure 1). Autoradiography missed one malignant lesion due to technical artifact. Additionally, 6 small cancerous lesions were identified by autoradiography that were not previously noted by histologic examinations. A total of 7 additional lesions seen by autoradiography corresponded with HGPIN. The positive lymph node and the benign lymph node were correctly identified by auto radiography (Fig.2). For the 3 BPH patients, no cancer foci were noted by autoradiography. CONCLUSIONS: VPAC1 peptide analog constructs accurately identified foci of prostate cancer on whole mount radical prostatectomy specimens. Several additional lesions were also identified. Detection of HGPIN is consistent with the early expression of VPAC1 prior to the modulations in cell morphology. The PPV (97%) and NPV(100%) were excellent, validating VPAC1 as a potential theragnostic target for prostate cancer imaging and treatment.

Recently, polyethylenimines (PEIs) have emerged as efficient vectors for nucleic acids delivery. However, inherent cytotoxicity has limited their in vivo applications. To address this concern as well as to incorporate hydrophobic domains for improving interactions with the lipid bilayers in the cell membranes, we have tethered varying amounts of amphiphilic pyridoxyl moieties onto bPEI to generate a small series of pyridoxyl-PEI (PyP) polymers. Spectroscopic characterization confirms the formation of PyP polymers, which subsequently form stable complexes with pDNA in nanometric range with positive surface charge. The projected modification not only accounts for a decrease in the density of 1° amines but also allows formation of relatively loose complexes with pDNA (cf. bPEI). Alleviation of the cytotoxicity, efficient interaction with cell membranes and easy disassembly of the pDNA complexes have led to the remarkable enhancement in the transfection efficiency of PyP/pDNA complexes in mammalian cells with one of the formulations, PyP-3/pDNA complex, showing transfection in ∼68% cells compared to ∼16% cells by Lipofectamine/pDNA complex. Further, the efficacy of PyP-3 vector has been established by delivering GFP-specific siRNA resulting in ∼88% suppression of the target gene expression. These results demonstrate the efficacy of the projected carriers that can be used in future gene therapy applications.

Branched polyethylenimine (bPEI, 25 kDa) has been widely used as an efficient delivery vector for nucleic acids in vitro. However, its charge-associated toxicity has limited its in vivo applications. In an attempt to control its toxicity, it was reacted with varying amounts of glycidol (2,3-epoxy-1-propanol) to obtain a small series of hydrophilic polymers, 2,3-dihydroxypropyl-grafted-polyethylenimines (DHP-g-P). The resulting polymers were characterized by (1)H-NMR and subjected to interaction with negatively charged pDNA, which yielded complexes in the size range of ~171-190 nm with a zeta potential of ∼+33-39 mV. Acid-base titration revealed no effect of substitution on the buffering capacity of the modified polymers. Grafting of 2,3-dihydroxypropyl groups on bPEI significantly improved the cell viability (i.e. almost non-toxic) as well as the DNA release properties of these modified polymers compared to native bPEI. Formation of a relatively loose DHP-g-P25/pDNA complex (the best working system in terms of transfection efficiency) resulted in the efficient nuclear release of pDNA for transcription, a prerequisite for efficient transfection. Subsequently, upon evaluation of their ability to transfer nucleic acids in vitro, the DHP-g-P/pDNA complexes exhibited higher gene transfection efficiency with one of the formulations, DHP-g-P25/DNA complex, displaying ~2.7 folds higher GFP expression than bPEI and ~2.3-3.5 folds higher than the selected commercial transfection reagents used in this study. Further to quantify the extent of GFP positive cells, FACS analysis was performed, which revealed DHP-g-P25/DNA mediated gene expression in ~51% cells outcompeting bPEI, Superfect™, Fugene™ and Lipofectamine™. Sequential delivery of GFP-specific siRNA resulted in ~78% suppression of the target gene compared to ~49% achieved by Fugene™. All these results demonstrate the potential of these polymers for in vivo gene delivery.

Of the non-viral vectors, a cationic polymer like PEI is an attractive candidate which however, has been negatively impacted due to its marked toxicity. An anionic sugar polymer gelan gum (GG) has been introduced into PEI system to increase transfection efficiency with minimal toxicity. We showed that one of the synthesized (GP1-GP6) GG-PEI nanocomposites (NCs), GP3, exhibited negligible toxicity in in vitro (primary keratinocytes, HEK293, HeLa and HepG2 cells) and in vivo (Drosophila melanogaster) as compared to PEI or lipofectamin. GP3-pDNA complex was found to be transfected efficiently in the above cells as confirmed by FACS analysis (72.0 + 5.5%) while lipofectamine showed only 12.4 + 3.5% efficiency. GP3 mediated GFP specific siRNA delivery resulted in the knockdown of the GFP expression by approximately 77% and JNK (60%). In vivo gene expression studies in mice revealed reporter gene expression in spleen. The study demonstrates that GG blended PEI NCs hold promise for future applications in gene delivery both in vitro and in vivo.

Chitosan was partially converted to its chlorohydrin derivative by the reaction with epichlohydrin, which was subsequently reacted with varying amounts of lPEI(2.5 kD) to obtain a series of chitosan-lPEI(2.5 kD) copolymers (CP). These copolymers were then characterized and evaluated in terms of transfection efficiency (in vitro and in vivo), cell viability, DNA release and buffering capacity. The CP-4 copolymer (the best among the CP series) showed enhanced transfection (-2 - 24 folds) in comparison with chitosan, lPEI(2.5 kD), bPEI(25 kD) and Lipofectamine in HEK293, HeLa and CHO cells. The buffering capacity (in the pH range of 3 - 7.5), as shown by confocal microscopy, and DNA-release capability of the CP copolymers, was found to be significantly enhanced over chitosan. Intravenous administration of CP-4/DNA polyplex in mice followed by the reporter gene analysis showed the highest gene expression in spleen. Collectively, these results demonstrate the potential of CP-4 copolymer as a safe and efficient nonviral vector. From the Clinical Editor: Chitosan -PEI (2.5 kD) copolymers (CP) were characterized and their transfection efficiency, DNA release and buffering capacity were studied. The CP-4 copolymer significantly enhanced buffering capacity and provided the highest gene expression levels. The method may be used to enhance DNA transfection.

Linear polyethylenimine (lPEI, 25 kDa) nanoparticles' (LPN) series was synthesized by varying percentage of cross-linking with 1,4-butanediol diglycidyl ether (BDE) and their size, surface charge, morphology, pDNA protection/release, cytotoxicity and transfection efficiency were evaluated. Synthesized nanoparticles (NPs) were spherical in shape (size: ∼109 – 235 nm; zeta potential: +38 to +16 mV). These NPs showed increased buffering capacity with increasing percent cross-linking and also exhibited excellent transfection efficiency (i.e., ∼1.3 – 14.7 folds in case of LPN-5) in comparison with lPEI and the commercial transfection agents used in this study. LPN-5 based GFP-specific siRNA delivery resulted in ∼86% suppression of targeted gene expression. These particles were relatively nontoxic in vitro (in cell lines) and in vivo (in Drosophila ). In vivo gene expression studies using LPN-5 in Balb/c mice through intravenous injection showed maximum expression of the reporter gene in the spleen. These results together demonstrate the potential of these particles as efficient transfection reagents. From the Clinical Editor The authors demonstrate a novel method of synthesizing linear PEI nanoparticles to utilize these as transfection agents.

Polyethylenimine (PEI), a widely used cationic polymeric vector with high transfection efficiency, was converted into nanoparticles by introducing ionic and covalent crosslinkers with varying proportion of 1,6-hexanebisphosphate (HP), adipic acid (AA) and 1,4-butane dialdehyde (BA) to obtain a small library of HP-PEI (HPP), AA-PEI (AAP) and BA-PEI (BAP) nanoparticles, respectively. Particles were characterized by spectroscopic technique as well as physicochemical parameters such as size, morphology, surface charge, effect of crosslinking on buffering capacity and DNA binding ability. The entire series of nanoparticles were compared for their cytoxicity and ability to deliver genes in various cell lines. Among various nanoparticles, AAP-3 nanoparticle/DNA complex exhibited higher transfection efficiency (1.5-7.8 folds) than the native PEI (25kDa) and commercially available transfection reagents, such as GenePorter, GenePorter2, Fugene and Superfect, with cell viability >85%. The highest cell viability was observed with BAP nanoparticles (>95%). Importantly, the transfection activity of nanoparticle/DNA complexes was preserved in the presence of serum. Transfection with GFP-siRNA inhibited expression of transfected GFP gene by approximately 81-92%. All nanoparticle types (HPP, AAP and BAP) required a comparable time for entry into cells and subsequent intracellular passage from the cytoplasm to the nucleus. Intravenous delivery of (99)Tc labeled BAP-2/DNA complex to female Balb/c mice revealed the presence of the complex in most of the organs with the highest retention in liver. In conclusion, HPP, AAP and BAP nanoparticles are safe for efficient gene delivery.

Introduction: Vasoactive Intestinal Peptide and Pituitary Adenylate Cyclase Activating Peptide Receptor 1 (VPAC1) is over-expressed in prostate cancer (PC), representing a highly suitable target for imaging and treatment. VPAC1 expression occurs at the onset of the malignancy, before alterations of cell morphology, which may be prior to elevation of serum PSA. We have successfully used VPAC1 receptor-specific peptide constructs to image breast cancer in experimental animal models, and in humans. We hypothesized that VPAC1 expressed in high density on PC can be targeted for detection of intraprostatic tumor foci, as correlated with whole mount radical prostatectomy specimens, using TP3805, a VPAC1 specific biomolecule labeled with Cu-64 a PET imaging radionuclide. Methods: Twenty five men with prostate cancer undergoing radical prostatectomy were imaged preoperatively as part of a PET imaging protocol targeting VPAC1. The PET images were compared to whole mount radical prostatectomy pathologic analysis. De-paraffinized whole mount pathology slides from two patients who participated in VPAC1 PET imaging protocol, as well as slides from 3 BPH patients, one malignant lymph node and one benign lymph node were incubated with Cu-64-TP3805, washed thoroughly with PBS, dried and subjected to 15 second digital autoradiography. Slides were then H&E stained and autoradiography images were compared with prostate H&E staining in which tumor foci were delineated. Results: Prostate cancer foci (n = 30/31) were identified by autoradiography imaging. Autoradiography missed one malignant lesion due to technical artifact. Additionally 6 small cancerous lesions were identified by autoradiography that were not previously noted by histologic examinations. A total of 7 additional lesions seen by autoradiography in areas without prostate cancer foci corresponded to areas of high grade prostatic intraepithelial neoplasia (HGPIN). The positive lymph node and the benign lymph node were correctly identified by autoradiography. For the three BPH patients without any cancer, no lesions were noted by autoradiography. Conclusion: VPAC1 peptide analog constructs accurately identified foci of prostate cancer on whole mount radical prostatectomy specimens. Several additional lesions were also identified. Detection of HGPIN is consistent with the early expression of VPAC1 prior to the modulations in cell morphology. The PPV (97%) and NPV(100%) were excellent, validating VPAC1 as a potential theranostic target for prostate cancer imaging and treatment. Support: NIH R01 CA157372-01 and by NuView, Inc. (MLT). Citation Format: Edouard J. Trabulsi, Pradeep Kumar, Sushil Tripathi, Ruth Birbe, Peter McCue, Eric Wickstrom, Charles Intenzo, Sung Kim, Robert Den, Leonard Gomella, Mathew L. Thakur. Pilot study of VPAC1 targeted PET imaging of prostate cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1485. doi:10.1158/1538-7445.AM2015-1485

bPEI (polyethylenimine, 25 kDa, gold standard) is highly effective in transfection efficiency owing to its high buffering capacity, however, cytotoxicity limits its use in in vivo applications. We hypothesized that partial conversion of secondary amines in IPEI to tertiary amines, while preserving the overall number of amines, would result in improved buffering capacity, which may, in turn, improve transfection efficiency of the resulting nanoparticles with cell viability comparable to that of native IPEI. IPEI was crosslinked with BDE to obtain a series of IPEI nanoparticles (LPN-1 to LPN-8) which were obtained in approximately 80-85% yield. These particles were relatively non-toxic in vitro and in vivo. In vivo gene expression studies using LPN-5 in Balb/c mice through i.v. injection showed maximum expression of the reporter gene in the spleen. These results demonstrate the potential of these particles as efficient transfection reagents.

Activating mutations in KRAS2 oncogene lead to constitutive K-Ras-GTP signals regardless of EGFR signaling, enabling resistance to EGFR-targeted therapies. Some cancers are activated by mutation of the KRAS2 12th codon from the wild type GGU that encodes glycine (G) to a mutant GAU that encodes aspartate (D) or a mutant GUU that encodes valine (V). For this reason, we hypothesize that determining multiple KRAS2 mutations in vivo by external mRNA PET imaging will enable physicians to decide on alternatives to EGFR-directed therapy. We previously pioneered tumor mRNA PET imaging in pancreatic cancer and breast cancer xenografts [Paudyal, et al. (2013) Nuclear Medicine and Biology 40(8):994-9] with peptide nucleic acid (PNA) 12-mers coupled to receptor-targeting peptides and imaging reporter moieties, showing single mismatch specificity. Thus, we designed and synthesized a 12-mer PNA hybridization agent with a hypoxanthine wobble base opposite the middle base of the KRAS2 mRNA 12th codon. At the C-terminus, we included a cyclized tetrapeptide based on insulin-like growth factor 1 (IGF1) to enable IGF1R-mediated cellular uptake. We included an N-terminal N2S2 chelator in order to bind 64Cu. Molecular dynamics and circular dichroism analysis of the wobble base PNA H-bonded to KRAS2 RNA showed preference for mutant A or U over wild type G [Sanders, et al. (2013) Journal of Physical Chemistry B 117(39):11584-95]. We then administered 200 μCi of the [64Cu]PNA wobble base agent, or the complementary G12D agent, or the wild type agent, by tail vein into 3-month-old G12D transgenic mice that developed spontaneous lung tumors. 4 hr and 24 hr later, mice were imaged in a Siemens Inveon microPET/CT scanner. The PET standard uptake value (SUV) with the G12D agent was 1.4, while SUV was 1.3 with the G12DVA wobble base agent, vs. 0.04 with the G12 wild type sequence. The wobble base approach enables detection of three different KRAS2 mutations, G12D, G12V, or G12A, with a single agent. mRNA PET imaging also enables external monitoring of therapeutic efficacy. Supported by NIH CA148565; IP owned by EW/MLT, licensed to MTTI. Citation Format: Eric Wickstrom, Chang-Po Chen, Matthew E. Wampole, Kaijun Zhang, Bishnuhari Paudyal, Antican Wang, Sushil Tripathi, Pardeep Kumar, Edith P. Mitchell, Bo Lu, Mathew L. Thakur, Brian D. Gray, Jeffrey A. Mattis. Hypoxanthine wobble base multimutant KRAS2 mRNA PET imaging agent in G12D mice. [abstract]. In: Proceedings of the AACR Special Conference on RAS Oncogenes: From Biology to Therapy; Feb 24-27, 2014; Lake Buena Vista, FL. Philadelphia (PA): AACR; Mol Cancer Res 2014;12(12 Suppl):Abstract nr B55. doi: 10.1158/1557-3125.RASONC14-B55

Branched polyethylenimine (bPEI) was conjugated with hydrophobic pyridoxal phosphate (PLP) in the side chain via reaction with primary amines to obtain amphiphilic phosphopyridoxyl-polyethylenimine (PPyP) polymers. These polymeric amphiphiles with a defined degree of hydrophobicity self-assembled into nanostructures, which were characterized by DLS and evaluated for their capability to condense nucleic acids and carry them into cells. Further condensation of pDNA compacted the size of the self-assembled nanostructures from 421-559 nm to 134-210 nm with zeta potentials from +20-32 mV to +18-28 mV. Conjugation of PLP with bPEI not only reduced the density of the primary amines (i.e. charge density) but also improved the cell viability of the modified polymers considerably and weakened the binding of pDNA with these polymers. Efficient unpackaging of the pDNA complexes inside the cells led to a several fold enhancement in the transfection efficiency with one of the formulations, PPyP-3/pDNA complex, among the series, exhibiting ∼4.9 to 8.2 folds higher gene delivery activity than pDNA complexes of bPEI and Lipofectamine™ in HeLa and MCF-7 cells. Flow cytometry analysis revealed a very high percentage of transfected cells by PPyP/pDNA complexes compared to pDNA complexes of bPEI and Lipofectamine™. Further, GFP-specific siRNA delivery using PPyP-3 as a vector resulted in ∼84% knockdown of the target gene expression (cf.∼54% by Lipofectamine™/pDNA/siRNA complex). Moreover, the PPyP-3/pDNA complex displayed ∼6.7 fold higher transfection efficiency than the bPEI/pDNA complex in human peripheral blood dendritic cells. Intravenous administration of PPyP-3/pGL3 complex showed the highest gene expression in spleen tissue, advocating the potential of these vectors in future gene delivery applications.

In the present study, biodegradable hyaluronic acid-low molecular weight branched polyethylenimine (HP) based delivery systems have been developed to address the limitations of the existing high molecular weight branched polyethylenimine (bPEI)–HA conjugates. To elucidate the influence of the degree of substitution of HA on to low molecular weight branched polyethylenimine (LMWP, 1.8 kDa), a small series of covalently linked HA–PEI (HP) conjugates was prepared by carbodiimide chemistry varying the amount of HA and the resulting conjugates were critically evaluated for their zeta potential, size, cytotoxicity and transfection efficiency. Gel retardation assay confirmed the formation of stable nanoplexes that retarded the mobility of pDNA at a conjugate to pDNA weight ratio of 1.66 [cf. 0.5 in case of bPEIs (1.8 and 25 kDa)/pDNA complexes]. MTT assay further revealed that the resulting formulations were non-toxic to cells in vitro. It was also observed that the degree of substitution of HA on to LMWP significantly affected the gene carrying capacity of the projected conjugates with one of the nanoplexes, HP2–pDNA complex, exhibited the highest transfection efficiency (∼32–38 folds as compared to LMWP) in mammalian cells. Heparin-mediated pDNA release studies showed that HP2 released >90% of bound pDNA upon exposure to 10 U of heparin. The versatility of the delivery vector, HP2, was demonstrated by delivering GFP-specific siRNA, which resulted in ∼83% suppression of the expression of the target gene (cf. ∼ 46% by Superfect™). These results advocate that hyaluronan-LMWP conjugates could be used as efficient carriers for future gene therapy applications, particularly, for targeted gene delivery to CD44 over-expressing tumors.

Synthetic chemical vectors have recently provided a versatile and robust platform for the safe and efficient delivery of exogenous genes. Here, for the first time, a small series of N-butyltriphenylphosphonium bromide-grafted-linear polyethylenimine (BTP-g-lP) polymers (N–P hybrid polymers) have been evaluated for their ability to deliver genes into mammalian cell lines, viz., MCF-7 and A549 cells. Biophysical characterization revealed that the projected polymers efficiently interacted with plasmid DNA, and the resulting complexes displayed hydrodynamic diameters in the range of 249–307 nm with relatively higher zeta potential values of +31 to +34 mV (cf. lPEI, +26 mV). The tethering of lipophilic and cationic triphenylphosphonium moieties to linear PEI (lPEI) addressed several limitations associated with lPEI, such as solubility, the stability of the pDNA complexes and the timely release of pDNA for nuclear localization as assessed by protection and release assays. Also, the lipophilic interactions between cellular membranes and the pDNA complexes mediated the efficient cellular uptake and internalization of the pDNA complexes, resulting in significantly higher transfection efficiency in these cell lines, outperforming the GenePORTER 2™, Lipofectamine™ and Superfect™ used in the study for comparison purposes. Confocal studies using dual-labeled TMR-BTP-g-lP3/YOYO-1-pDNA complex in MCF-7 cells confirmed that the complex behaved more or less like native lPEI, as the substitution of the phosphonium moiety was too small to affect the intracellular trafficking. Furthermore, the versatility of the BTP-g-lP3 vector was established by GFP specific siRNA delivery, which resulted in ∼79% suppression of targeted gene expression (cf. Lipofectamine™, ∼55%). Altogether, the study demonstrates the potential of these hybrid polymers for the efficient delivery of nucleic acids for future gene therapy applications.

Dextran–PEI grafted nanoparticles as transfection agents have been reported, however, with limited success due to their large size, poor buffering capacity and inadequate availability of charge for competent binding to DNA. To address these concerns, dextran was first crosslinked with 1,4-butanediol diglycidyl ether (BDE), a commercially available homobifunctional crosslinker, to form its nanoparticles (DN), which were then partially oxidized with sodium periodate to generate aldehyde functionalities on them. The resultant nanoparticles were grafted with branched polyethylenimine (bPEI, 25 kDa) to obtain a series of DN–PEI nanocomposites (DP), having comparatively smaller size, enhanced buffering capacity and competent binding ability with DNA. Subsequent to biophysical characterization, these nanocomposites were evaluated for their transfection efficiency in serum and serum-free environments and toxicity in various mammalian cell lines. A significantly (p < 0.05) improved transfection efficiency of these nanocomposites concurrent with their minimal cytotoxicity as compared to the selected commercial transfection agents and native PEI was observed. These results were further validated by intracellular trafficking, wherein DP4 (the best working system in the series) was able to carry the DNA inside the nucleus after 1 h of the addition of the complex. The in vivo gene expression profile of the DP4/DNA complex in male Balb/c mice exhibited maximum expression in their spleen tissue raising promise of using these nanocomposites as improved non-viral transfection agents.

In an attempt to circumvent toxic effects of branched polyethylenimine (bPEI, 25 kDa), it was crosslinked with varying proportions of a novel linker, PEG600-bis(aminoethylphosphate) (PaP), which resulted in the formation of nanoparticles (PPaP) in the range of 61–99 nm. These nanoparticles were found to have significantly lower toxicity in vitro than the native PEI. GFP expression in cells mediated by PPaP (8.1%)/DNA complex was found to be ∼1.1–4.8 folds higher compared to GenePORTER 2™, Lipofectamine™, Superfect™ and native PEI in HeLa, HEK293 and CHO cells. FACS analysis on HeLa cells revealed ∼62% transfected cells, whereas, in the case of the GenePORTER 2™ transfection reagent, transfected cells were found to be ∼36%. Intracellular trafficking in HeLa cells showed a significant population of PPaP (8.1%) nanoparticles and their DNA complex in nucleus after 1 h of treatment. Also, efficient delivery of GFP specific siRNA resulted in ∼71% suppression of the target gene. DNase protection assay revealed that ∼78% of complexed DNA was protected by PPaP(8.1%) nanoparticles even after 2 h of treatment. In vivo transgene expression studies in Balb/c mice showed significantly higher expression in the spleen. The results advocate the potential of PPaP nanoparticles as efficient carriers of nucleic acids in vivo.