Real time evaluation of tissue optical properties during thermal ablation of ex vivo liver tissues.

Complete ablation of liver tumors is vital for minimizing the risk of local tumor recurrence. Accurately identifying the hallmarks of tissue necrosis during thermal ablative therapies may significantly increase the efficacy of ablation, while minimizing unnecessary damage to the surrounding normal tissues or critical structures. Light propagation in biological tissues is sensitive to the tissue microstructure and chromophore concentrations. In our previous studies, we found that the wavelength (λ) averaged liver tissue absorption coefficient (µa) and reduced scattering coefficient (µs') change significantly upon heating which may be used for assessment of tissue damage during thermal ablation of solid tumors. Here, we seek to demonstrate the use of an integrated fiber-optic probe for continuous monitoring of the local tissue temperature (T), µa(λ) and µs'(λ) during thermal ablation of ex vivo porcine livers. The wavelength-averaged (435-630 nm) tissue absorption and scattering (µa and µs' ) increased rapidly at 45 °C and plateaued at 67 °C. The mean µa and µs' for liver tissue at 37 °C (n = 10) were 8.5 ± 3.7 and 2.8 ± 1.1 cm-1, respectively. The relative changes in µa and µs' at 37, 55, and 65 °C were significantly different (p < .02) from each other. A relationship between the relative changes in µa and µs' and the degree of tissue damage estimated using the temperature-based Arrhenius model for porcine liver tissues was established and studied.

Early Immunologic Response of Irreversible Electroporation versus Cryoablation in a Rodent Model of Pancreatic Cancer.

PURPOSE: To investigate the differences in immune responses between cryoablation and irreversible electroporation (IRE) in a preclinical mouse model. MATERIAL AND METHODS: A mouse pancreatic cancer cell line (PANC-2) was implanted in the bilateral flanks of mice, and tumor-bearing mice were divided into 6 groups. One of the tumors was ablated either with contact cryoablation using an argon-cooled cryoablation probe for 1 minute at 5% power or by IRE for a total of 64 100-µs-duration, 1250-V/cm2 pulses with 100-ms spacing. The contralateral tumors in the same animal served as controls. At immediate, 6, 12, and 24 hours after ablation, the tumors were processed for immunostaining with F480 (macrophages), CD3 (T cells), and CD-56 (natural killer cells) antibodies. RESULTS: CD3 staining demonstrated significantly more T cells in the IRE group than in the cryoablation group at 6 hours (45 vs 16; P = .027), 12 hours (67 vs 33; P = .020), and 24 hours (161 vs 94; p = .003), with almost a 2-fold increase at every time point. Although the mean number of natural killer cells in the treated tumors was higher, no significant differences were observed between the 2 groups at any of the time points. A significant difference was observed in F480 positivity between the cryoablation group and the IRE group at 12 hours (210 vs 356; P = .0004) and 24 hours (220 vs 328; P = .04), respectively. CONCLUSIONS: In a mouse model of pancreatic cancer, IRE evokes a more robust infiltration of macrophages and T cells than cryoablation within 24 hours.

Biofunctionalized Hybrid Magnetic Gold Nanoparticles as Catalysts for Photothermal Ablation of Colorectal Liver Metastases.

Purpose To demonstrate that anti-MG1 conjugated hybrid magnetic gold nanoparticles (HNPs) act as a catalyst during photothermal ablation (PTA) of colorectal liver metastases, and thus increase ablation zones. Materials and Methods All experiments were performed with approval of the institutional animal care and use committee. Therapeutic and diagnostic multifunctional HNPs conjugated with anti-MG1 monoclonal antibodies were synthesized, and the coupling efficiency was determined. Livers of 19 Wistar rats were implanted with 5 × 106 rat colorectal liver metastasis cell line cells. The rats were divided into three groups according to injection: anti-MG1-coupled HNPs (n = 6), HNPs only (n = 6), and cells only (control group, n = 7). Voxel-wise R2 and R2* magnetic resonance (MR) imaging measurements were obtained before, immediately after, and 24 hours after injection. PTA was then performed with a fiber-coupled near-infrared (808 nm) diode laser with laser power of 0.56 W/cm2 for 3 minutes, while temperature changes were measured. Tumors were assessed for necrosis with hematoxylin-eosin staining. Organs were analyzed with inductively coupled plasma mass spectrometry to assess biodistribution. Therapeutic efficacy and tumor necrosis area were compared by using a one-way analysis of variance with post hoc analysis for statistically significant differences. Results The coupling efficiency was 22 µg/mg (55%). Significant differences were found between preinfusion and 24-hour postinfusion measurements of both T2 (repeated measures analysis of variance, P = .025) and T2* (P < .001). Significant differences also existed for T2* measurements between the anti-MG1 HNP and HNP-only groups (P = .034). Mean temperature ± standard deviation with PTA in the anti-MG1-coated HNP, HNP, and control groups was 50.2°C ± 7.8, 51°C ± 4.4, and 39.5°C ± 2.0, respectively. Inductively coupled plasma mass spectrometry revealed significant tumor targeting and splenic sequestration. Mean percentages of tumor necrosis in the anti-MG1-coated HNP, HNP, and control groups were 38% ± 29, 14% ± 17, and 7% ± 8, respectively (P = .043). Conclusion Targeted monoclonal antibody-conjugated HNPs can serve as a catalyst for photothermal ablation of colorectal liver metastases by increasing ablation zones. © RSNA, 2017.

Localized and triggered release of oxaliplatin for the treatment of colorectal liver metastasis.

Purpose: The aim of this study was to develop and evaluate a liposome formulation that deliver oxaliplatin under magnetic field stimulus in high concentration to alleviate the off-target effects in a rat model of colorectal liver metastases (CRLM). Materials and Methods: Hybrid liposome-magnetic nanoparticles loaded with Cy5.5 dye and oxaliplatin (L-NIR- Fe3O4/OX) were synthesized by using thermal decomposition method. CRLM (CC-531) cell viability was assessed and rats orthotopically implanted with CC-531 cells were treated with L-NIR-Fe3O4/OX or by drug alone via different routes, up to 3 cycles of alternating magnetic field (AMF). Optical and MR imaging was performed to assess the targeted delivery. Biodistribution and histology was performed to determine the distribution of oxaliplatin. Results: L-NIR-Fe3O4/OX presented a significant increase of oxaliplatin release (~18%) and lower cell viability after AMF exposure (p<0.001). Optical imaging showed a significant release of oxaliplatin among mesenteric vein injected (MV) group of animals. MR imaging on MV injected animals showed R2* changes in the tumor regions at the same regions immediately after infusion compared to the surrounding liver (p<0.001). Biodistribution analysis showed significantly higher levels of oxaliplatin in liver tissues compared to lungs (p<0.001) and intestines (p<0.001) in the MV animals that received AMF after L-NIR- Fe3O4/OX administration. Large tumor necrotic zones and significant improvement in the survival rates were noted in the MV animals treated with AMF. Conclusion: AMF triggers site selective delivery of oxaliplatin at high concentrations and improves survival outcomes in colorectal liver metastasis tumor bearing rats.

Heritable modifiers of the tumor microenvironment influence nanoparticle uptake, distribution and response to photothermal therapy.

We report the impact of notch-DLL4-based hereditary vascular heterogeneities on the enhanced permeation and retention (EPR) effect and plasmonic photothermal therapy response in tumors. Methods: We generated two consomic rat strains with differing DLL4 expression on 3rd chromosome. These strains were based on immunocompromised Salt-sensitive or SSIL2Rγ- (DLL4-high) and SS.BN3IL2Rγ- (DLL4-low) rats with 3rd chromosome substituted from Brown Norway rat. We further constructed three novel SS.BN3IL2Rγ- congenic strains by introgressing varying segments of BN chromosome 3 into the parental SSIL2Rγ- strain to localize the role of SSIL2Rγ- DLL4 on tumor EPR effect with precision. We synthesized multimodal theranostic nanoparticles (TNPs) based on Au-nanorods which provide magnetic resonance imaging (MRI), X-ray, and optical contrasts to assess image guided PTT response and quantify host specific therapy response differences in tumors orthotopically xenografted in DLL4-high and -low strains. We tested recovery of therapy sensitivity of PTT resistant strains by employing anti-DLL4 conjugated TNPs in two triple negative breast cancer tumor xenografts. Results: Host strains with high DLL4 allele demonstrated slightly increased tumor nanoparticle uptake but consistently developed photothermal therapy resistance compared to tumors in host strains with low DLL4 allele. Tumor micro-environment with low DLL4 expression altered the geographic distribution of nanoparticles towards closer proximity with vasculature which improved efficacy of PTT in spite of lower overall TNP uptake. Targeting TNPs to tumor endothelium via anti-DLL4 antibody conjugation improved therapy sensitivity in high DLL4 allele hosts for two triple negative human breast cancer xenografts. Conclusions: Inherited DLL4 expression modulates EPR effects in tumors, and molecular targeting of endothelial DLL4 via nanoparticles is an effective personalized nanomedicine strategy.

Induction of apoptosis in glioma cells requires cell-to-cell contact with human umbilical cord blood stem cells.

We have previously demonstrated the multipotent nature of human umbilical cord blood stem cells (hUCB). In this study, we have attempted to show the use of hUCB in glioma therapy. We used hUCB enriched in CD44 and CD133 cells for our studies and observed that glioma cells co-cultured with hUCB undergo apoptosis. To prove the role of cell-to-cell contact in the induction of apoptotic events, we used a modified 0.22 microm Boyden's chamber where the upper surface was used to culture glioma cells (SNB19 or U87) or xenografts (4910 or 5310) and the lower surface to culture hUCB. TUNEL assay was carried out to determine the degree of apoptotic induction and we observed that glioma or xenograft cells co-cultured with hUCB had a higher number of TUNEL-positive characteristics (63+/-6%) compared to the controls. Further, we co-cultured glioma cells labeled with lipophilic green fluorescent dye and hUCB labeled with lipophilic red fluorescent dye. FACS analysis of cells collected from the upper and lower surfaces revealed that glioma cells had taken up red fluorescent dye from the stem cells (70+/-3%) when compared to glioma cells co-cultured with fibroblast cells (15+/-4%). The apoptotic events in the glioma and xenograft cells co-cultured with hUCB were also confirmed by Western blot analysis for the cleavage of PARP and activation of caspase 8. In addition, elevated levels of CHK-2 levels and downregulation of MAP2K1 were observed in glioma cells co-cultured with hUCB indicating the DNA damage and decrease in cell survival. Nude mice, intracranially implanted with luciferase-expressing U87 cells followed by implantation of hUCB or human fibroblast cells showed retardation of intracranial tumors in hUCB-implanted mice. Taken together, these results demonstrate that hUCB have therapeutic potential with possible clinical implications.