The current clinical gold standards for tissue sealing include sutures, staples, and glues, however several adverse effects limit their use. Sutures and staples inherently cause additional trauma to tissue surrounding the wound, and glues can be lacking in adhesion and are potentially inflammatory. All three also introduce risk of infection. Light-activated tissue sealing, particularly the use of near-infrared light, is an attractive alternative, as it localizes heat, thereby preventing thermal damage to the surrounding healthy tissue. Previous work identified a glutaraldehyde-crosslinked chitosan film as a lead sealant for gastrointestinal incision sealing, but in vivo testing resulted in tissue degradation in and around the wound. The suggested causes for this degradation were excess acetic acid, endotoxins in the chitosan, and thermal damage. A basic buffer wash protocol was developed to remove excess acid from the films following fabrication. UV-Vis spectroscopy demonstrated that following the wash, films had the same concentration of Indocyanine green as unwashed films, allowing them to absorb light at the same wavelength, therefore showing the wash did not affect the film’s function. However subsequent washes led to degradation of film mass of nearly 20%. Standard chitosan films had significantly greater mass gain (p = 0.028) and significantly less subsequent loss (p= 0.012) than endotoxin free chitosan-films after soaking in phosphate buffered saline for varying durations , while soaking duration had no effect (p = 0.332). Leak pressure testing of films prepared with varying numbers of buffer washes, laser temperature, and lasering time revealed no significant interaction between any of the 3 variables. As such, it was confirmed that proceeding with in vivo testing with the buffer wash, various lasering temperatures, and laser times would not affect the sealing performance of the films. Future investigation will involve characterization of additional materials that may be effective for sealing of internal wounds, as well as drug loading of agents that may hasten the healing process.
Nanoparticle (NP) based therapeutic and theranostic agents have been developed for various diseases, yet application to neural disease/injury is restricted by the blood-brain-barrier (BBB). Traumatic brain injury (TBI) results in a host of pathological alterations, including transient breakdown of the BBB, thus opening a window for NP delivery to the injured brain tissue. This study focused on investigating the spatiotemporal accumulation of different sized NPs after TBI. Specifically, animal cohorts sustaining a controlled cortical impact injury received an intravenous injection of PEGylated NP cocktail (20, 40, 100, and 500 nm, each with a unique fluorophore) immediately (0 h), 2 h, 5 h, 12 h, or 23 h after injury. NPs were allowed to circulate for 1 h before perfusion and brain harvest. Confocal microscopy demonstrated peak NP accumulation within the injury penumbra 1 h post-injury. An inverse relationship was found between NP size and their continued accumulation within the penumbra. NP accumulation preferentially occurred in the primary motor and somatosensory areas of the injury penumbra as compared to the parietal association and visual area. Thus, we characterized the accumulation of particles up to 500 nm at different times acutely after injury, indicating the potential of NP-based TBI theranostics in the acute period after injury.
Background: Tumor Necrosis Factor-α Related Apoptosis Inducing Ligand (TRAIL) and agonistic antibodies to death receptor 4 and 5 are promising candidates for cancer therapy due to their ability to induce apoptosis selectively in a variety of human cancer cells, while demonstrating little cytotoxicity in normal cells. Although TRAIL and agonistic antibodies to DR4 and DR5 are considered safe and promising candidates in cancer therapy, many malignant cells are resistant to DR-mediated, TRAIL-induced apoptosis. In the current work, we screened a small library of fifty-five FDA and foreign-approved anti-neoplastic drugs in order to identify candidates that sensitized resistant prostate and pancreatic cancer cells to TRAIL-induced apoptosis.
Methods: FDA-approved drugs were screened for their ability to sensitize TRAIL resistant prostate cancer cells to TRAIL using an MTT assay for cell viability. Analysis of variance was used to identify drugs that exhibited synergy with TRAIL. Drugs demonstrating the highest synergy were selected as leads and tested in different prostate and pancreatic cancer cell lines, and one immortalized human pancreatic epithelial cell line. Sequential and simultaneous dosing modalities were investigated and the annexin V/propidium iodide assay, in concert with fluorescence microscopy, was employed to visualize cells undergoing apoptosis.
Results: Fourteen drugs were identified as having synergy with TRAIL, including those whose TRAIL sensitization activities were previously unknown in either prostate or pancreatic cancer cells or both. Five leads were tested in additional cancer cell lines of which, doxorubicin, mitoxantrone, and mithramycin demonstrated synergy in all lines. In particular, mitoxantrone and mithramycin demonstrated significant synergy with TRAIL and led to reduction of cancer cell viability at concentrations lower than 1 μM. At these low concentrations, mitoxantrone demonstrated selectivity toward malignant cells over normal pancreatic epithelial cells.
Conclusions: The identification of a number of FDA-approved drugs as TRAIL sensitizers can expand chemotherapeutic options for combination treatments in prostate and pancreatic cancer diseases.
Background: Magnetic Resonance Spectroscopic Imaging (MRSI) has wide applicability for non-invasive biochemical assessment in clinical and pre-clinical applications but suffers from long scan times. Compressed sensing (CS) has been successfully applied to clinical H-1 MRSI, however a detailed evaluation of CS for conventional chemical shift imaging is lacking. Here we evaluate the performance of CS accelerated MRSI, and specifically apply it to accelerate Na-23-MRSI on mouse hearts in vivo at 9.4 T.
Methods: Synthetic phantom data representing a simplified section across a mouse thorax were used to evaluate the fidelity of the CS reconstruction for varying levels of under-sampling, resolution and signal-to-noise ratios (SNR). The amplitude of signals arising from within a compartment, and signal contamination arising from outside the compartment relative to noise-free Fourier-transformed (FT) data were determined. Simulation results were subsequently verified experimentally in phantoms and in three mouse hearts in vivo.
Results: CS reconstructed MRSI data are scaled linearly relative to absolute signal intensities from the fully-sampled FT reconstructed case (R-2 > 0.8, p-value < 0.001). Higher acceleration factors resulted in a denoising of the reconstructed spectra, but also in an increased blurring of compartment boundaries, particularly at lower spatial resolutions. Increasing resolution and SNR decreased cross-compartment contamination and yielded signal amplitudes closer to the FT data. Proof-of-concept high-resolution, 3-fold accelerated Na-23-amplitude maps of murine myocardium could be obtained within similar to 23 mins.
Conclusions: Relative signal amplitudes (i.e. metabolite ratios) and absolute quantification of metabolite concentrations can be accurately determined with up to 5-fold under-sampled, CS-reconstructed MRSI. Although this work focused on murine cardiac Na-23-MRSI, the results are equally applicable to other nuclei and tissues (e.g. H-1 MRSI in brain). Significant reduction in MRSI scan time will reduce the burden on the subject, increase scanner throughput, and may open new avenues for (pre-) clinical metabolic studies.
Exosomes are nanoscale extracellular vesicles that are shed from different cells in the body. Exosomes encapsulate several biomolecules including lipids, proteins, and nucleic acids, and can therefore play a key role in cellular communication. These vesicles can be isolated from different body fluids and their small sizes make them attractive in various biomedical applications. Here, we review state-of-the art approaches in exosome isolation and purification, and describe their potential use in cancer vaccines, drug delivery, and diagnostics.