In this study, lactoferrin-conjugated PEGylated liposomes (PL), a potential drug carrier for brain delivery, was loaded with radioisotope complex, ^99mTc labeled N,N-bis(2-mercaptoethyl)-N',N'-diethylethylenediamine (^99mTc-BMEDA) for in vitro and in vivo evaluations. The hydrophilicity of liposomes was enhanced by PEGylation which was not an ideal brain delivery system for crossing the blood brain barrier (BBB). With the modification of a brain-targeting ligand, lactoferrin (Lf), the PEGylated liposome (PL) might become a potential brain delivery vehicle. In order to test the hypothesis in vitro and in vivo, ^99mTc-BMEDA was loaded into the liposomes as a reporter with or without Lf-conjugation. The mouse brain endothelia cell line, bEnd.3 cells, was cultured to investigate the potential uptake of liposomes in vitro. The in vivo uptake by the mouse brain of the liposomes was detected by tissue biodistribution study. The results indicated that Lf-conjugated PEGylated liposome showed more than three times better uptake efficiency in vitro and two-fold higher of brain uptake in vivo than PEGlyated liposome. With the success of loading the potential Single Photon Emission Tomography (SPECT) imaging probe, ^99mTc-BMEDA, Lf-PL might serve as a promising brain delivery system for loading diagnostics or therapeutics of various brain disorders.

Purpose: In this study, the ¹⁸⁸Re-labeled PEGylated nanoliposome (¹⁸⁸Re-liposome) was prepared and evaluated as a therapeutic agent for glioma. Materials and methods: The reporter cell line, F98_luc was prepared via Lentivector expression kit system and used to set up the orthotopic glioma-bearing rat model for non-invasive bioluminescent imaging. The maximum tolerated dose applicable in Fischer344 rats was explored via body weight monitoring of the rats after single intravenous injection of ¹⁸⁸Re-liposome with varying dosages before the treatment study. The OLINDA/EXM 1.1 software was utilized for estimating the radiation dosimetry. To assess the therapeutic efficacy, tumor-bearing rats were intravenously administered ¹⁸⁸Re-liposome or normal saline followed by monitoring of the tumor growth and animal survival time. In addition, the histopathological examinations of tumors were conducted on the ¹⁸⁸Re-liposome-treated rats. Results: By using bioluminescent imaging, the well-established reporter cell line (F98_luc) showed a high relationship between cell number and its bioluminescent intensity (R²=0.99) in vitro; furthermore, it could also provide clear tumor imaging for monitoring tumor growth in vivo. The maximum tolerated dose of ¹⁸⁸Re-liposome in Fischer344 rats was estimated to be 333 MBq. According to the dosimetry results, higher equivalent doses were observed in spleen and kidneys while very less were in normal brain, red marrow, and thyroid. For therapeutic efficacy study, the progression of tumor growth in terms of tumor volume and/or tumor weight was significantly slower for the ¹⁸⁸Re-liposome-treated group than the control group (P<0.05). As a result, the lifespan of glioma-bearing rats treated with ¹⁸⁸Re-liposome was prolonged 10.67% compared to the control group. Conclusion: The radiotherapeutic evaluation by dosimetry and survival studies have demonstrated that passive targeting ¹⁸⁸Re-liposome via systemic administration can significantly prolong the lifespan of orthotopic glioma-bearing rats while maintaining reasonable systemic radiation safety. Therefore, ¹⁸⁸Re-liposome could be a potential therapeutic agent for glioblastoma multiforme treatment.

The ¹⁸⁸Re-labeled pegylated nanoliposome (abbreviated as ¹⁸⁸Re-Liposome) was prepared and evaluated for its potential as a theragnostic agent for glioma. ¹⁸⁸Re-BMEDA complex was loaded into the pegylated liposome core with pH 5.5 ammonium sulfate gradient to produce ¹⁸⁸Re-Liposome. Orthotopic Fischer344/F98 glioma tumor-bearing rats were prepared and intravenously injected with ¹⁸⁸Re-Liposome. Biodistribution, pharmacokinetic study, autoradiography (ARG), histopathology, and nano-SPECT/CT imaging were conducted for the animal model. The result showed that ¹⁸⁸Re-Liposome accumulated in the brain tumor of the animal model from 0.28%±0.09% injected dose (ID)/g (n=3) at 1 hour to a maximum of 1.95%±0.35% ID/g (n=3) at 24 hours postinjection. The tumor-to-normal brain uptake ratio (T/N ratio) increased from 3.5 at 1 hour to 32.5 at 24 hours. Both ARG and histopathological images clearly showed corresponding tumor regions with high T/N ratios. Nano-SPECT/CT detected a very clear tumor image from 4 hours till 48 hours. This study reveals the potential of ¹⁸⁸Re-Liposome as a theragnostic agent for brain glioma.

Radiation therapy for cancer patients works by ionizing damage to nuclear DNA, primarily by creating double-strand breaks (DSB). A major shortcoming of traditional radiation therapy is the set of side effect associated with its long-range interaction with nearby tissues. Low-energy Auger electrons have the advantage of an extremely short effective range, minimizing damage to healthy tissue. Consequently, the isotope ^99mTc, an Auger electron source, is currently being studied for its beneficial potential in cancer treatment. We examined the dose effect of a pyrene derivative ^99mTc complex on plasmid DNA by using gel electrophoresis in both aqueous and methanol solutions. In aqueous solutions, the average yield per decay for double-strand breaks is 0.011±0.005 at low dose range, decreasing to 0.0005±0.0003 in the presence of 1 M dimethyl sulfoxide (DMSO). The apparent yield per decay for single-strand breaks (SSB) is 0.04±0.02, decreasing to approximately a fifth with 1 M DMSO. In methanol, the average yield per decay of DSB is 0.54±0.06 and drops to undetectable levels in 2 M DMSO. The SSB yield per decay is 7.2±0.2, changing to 0.4±0.2 in the presence of 2 M DMSO. The 95% decrease in the yield of DSB in DMSO indicates that the main mechanism for DSB formation is through indirect effect, possibly by cooperative binding or clustering of intercalators. In the presence of non-radioactive ligands at a near saturation concentration, where radioactive Tc compounds do not form large clusters, the yield of SSB stays the same while the yield of DSB decreases to the value in DMSO. DSBs generated by ^99mTc conjugated to intercalators are primarily caused by indirect effects through clustering.

Background/Aim: An injectable chitosan-based co-cross-linking thermosensitive hydrogel combining ¹⁸⁸Re- and doxorubicin-encapsulated liposomes (C/GP/GE/¹⁸⁸Re-LIPO-DOX) was developed for the prevention of locoregional recurrence after mastectomy. Materials and Methods: The hydrogel properties, in vitro drug release characteristics, and in vivo scintigraphy imaging attributes were investigated. Results: The gelation time of the hydrogels can be controlled to be within 5 min. Results from Fourier-transform infrared spectroscopy, scanning electron microscopy, and dynamic mechanical analysis showed that a covalent cross-linking reaction between chitosan and genipin occurred and that the hydrogel's mechanical strength and chemical stability were improved. In vitro drug release studies showed that the hydrogel can prolong the release of doxorubicin by several weeks (51.5%±5.3% at 21 days). In addition, in vivo scintigraphy results suggested high retention rates (43.1%±1.0% at 48 h) of the radiopharmaceutical compound at the tumor injection site. Conclusion: The preliminary results indicated that the C/GP/GE/¹⁸⁸Re-LIPO-DOX radiopharmaceutical hydrogel is a potential candidate for further in vivo therapeutic evaluation.