Development of an ultrasound-emitting device for performing rapid immunostaining procedures

Rapid multiplex immunohistochemistry for characterizing tumor-immune microenvironment

Intratumoral immune profiles are related to prognosis and therapeutic efficacy, and could result in personalized treatments based on biomarkers. To develop a multiplex, quantitative, and rapid tissue evaluation method based on the clinically established standard immunohistochemistry (IHC), a 6-marker rapid multiplex IHC was developed based on our previously reported 14-marker multiplex IHC by reducing the number of labels and accelerating the staining procedure. First, fewer labels were required to identify the same immunological features linked to prognosis in 14-marker multiplex IHC analyses. The six selected markers showed a significant correlation with the 14 markers in the immune classification. Next, a rapid staining protocol was developed by optimizing the reaction temperature, chromogen, and washing time, allowing the completion of 6-marker analysis in 5 h and 49 min, as opposed to the several days required for conventional multiplex IHC. Validation of benign tonsil and head and neck cancer tissues revealed a significant correlation between rapid and conventional 6-makrer multiplex IHC in terms of staining intensities, densities of T cells, macrophages, lymphoid/myeloid immune cell ratios, and spatial profiles of intratumoral immune infiltrates. This method may enable quantitative assessment of the tumor-immune microenvironment on a clinically feasible time scale, which promotes the development of tissue biomarker-guided therapeutic strategies.

Novel rapid immunohistochemistry using an alternating current electric field identifies Rac and Cdc42 activation in human colon cancer FFPE tissues

It is important to determine the activation status of Rac and Cdc42 in cancer tissues for the prediction of metastasis and patient prognosis. However, it has been impossible to detect their spatial activation on formalin-fixed paraffin embedded (FFPE) surgical specimens thus far. Here, we established a novel detection technique for activated Rac/Cdc42 in human colon cancer FFPE tissues by using a p21-activated kinase (PAK)-Rac binding domain (RBD) detection probe fused with glutathione S-transferase (GST), designated GST-PAK-RBD, and novel rapid-immunohistochemistry (R-IHC) systems using noncontact alterating-current electric field mixing, although there is a technical limitation in that it may not distinguish between Rac members and Cdc42. In 50 cases of colon cancer, various activation patterns of Rac/Cdc42 were observed, which were designated plasma membrane, cytoplasm, mixed pattern, and polarized distribution. The activity was striking in the invasive fronts of tumors and significantly correlated with tumor invasion properties evaluated by TNM classification. Of note, in tissue microarray (TMA) samples, 29 of 33 cases demonstrated higher Rac1/Cdc42 activity in the tumor area than the corresponding normal mucosa. In addition, positive correlations were detected between Rac/Cdc42 activity and clinicopathological factors such as venous and lymphatic vessel invasion. These results suggest that understanding Rac and Cdc42 activations in cancer tissues would be valuable as an option for molecular therapy as personalized medicine.

Application of Magnetic Nanoparticles for Rapid Detection and In Situ Diagnosis in Clinical Oncology

Screening, monitoring, and diagnosis are critical in oncology treatment. However, there are limitations with the current clinical methods, notably the time, cost, and special facilities required for radioisotope-based methods. An alternative approach, which uses magnetic beads, offers faster analyses with safer materials over a wide range of oncological applications. Magnetic beads have been used to detect extracellular vesicles (EVs) in the serum of pancreatic cancer patients with statistically different EV levels in preoperative, postoperative, and negative control samples. By incorporating fluorescence, magnetic beads have been used to quantitatively measure prostate-specific antigen (PSA), a prostate cancer biomarker, which is sensitive enough even at levels found in healthy patients. Immunostaining has also been incorporated with magnetic beads and compared with conventional immunohistochemical methods to detect lesions; the results suggest that immunostained magnetic beads could be used for pathological diagnosis during surgery. Furthermore, magnetic nanoparticles, such as superparamagnetic iron oxide nanoparticles (SPIONs), can detect sentinel lymph nodes in breast cancer in a clinical setting, as well as those in gallbladder cancer in animal models, in a surgery-applicable timeframe. Ultimately, recent research into the applications of magnetic beads in oncology suggests that the screening, monitoring, and diagnosis of cancers could be improved and made more accessible through the adoption of this technology.

Utility of Ethylene-Diamine-Tetraacetic Acid Buffer Solution With Boric Acid for Immunostaining of Specimens Stored for an Extended Period

Antigen modification and denaturation are recognized causes of false negatives in immunostaining. Specimens that have been stored for an extended period at room temperature show decreased immunoreactivity and may mislead the diagnosis. Studies of the molecular targeting of drugs often involve immunostaining of previous samples and, in some situations, only unstained specimens can be used. The present study aimed to develop an effective staining method to recover antigen activation in unstained specimens stored for an extended period by using ethylene-diamine-tetraacetic acid (EDTA) buffer solution with boric acid. We compared several commonly used antigen retrieval solutions and found that Tris-borate-EDTA (TBE) buffer solution with a pH ≥8.3 provided sufficient antigen retrieval. However, pH values higher than 8.3 (9.0, 10.0, and 11.0) frequently caused severe tissue damage. Thus, TBE with pH 8.3 was the most suitable antigen retrieval solution for recovering the antigenicity of specimens stored for an extended period. This procedure may allow useful immunohistochemical information, even from sections that have been stored for an extended period.

Magnetically Promoted Rapid Immunofluorescence Staining for Frozen Tissue Sections

Current immunohistochemistry methods for diagnosing abnormal cells, such as cancer cells, require multiple steps and can be relatively slow compared with intraoperative frozen hematoxylin and eosin staining, and are therefore rarely used for intraoperative examination. Thus, there is a need for novel rapid detection methods. We previously demonstrated that functionalized fluorescent ferrite beads (FF beads) magnetically promoted rapid immunoreactions. The aim of this study was to improve the magnetically promoted rapid immunoreaction method using antibody-coated FF beads and a magnet subjected to a magnetic field. Using frozen sections of xenograft samples of A431 human epidermoid cancer cells that express high levels of epidermal growth factor receptor (EGFR) and anti-EGFR antibody-coated FF beads, we reduced the magnetically promoted immunohistochemistry procedure to a 1-min reaction and 1-min wash. We also determined the optimum magnetic force for the antibody reaction (from 7.79 × 10^-15 N to 3.35 × 10^-15 N) and washing (4.78 × 10^-16 N), which are important steps in this technique. Furthermore, we stained paraffin-embedded tissue arrays and frozen sections of metastatic breast cancer lymph nodes with anti-pan-cytokeratin antibody-coated FF beads to validate the utility of this system in clinical specimens. Under optimal conditions, this ultra-rapid immunostaining method may provide an ancillary method for pathological diagnosis during surgery. (J Histochem Cytochem 58:XXX-XXX, 2010).

Eliminating Size-Associated Diffusion Constraints for Rapid On-Surface Bioassays with Nanoparticle Probes

Nanoparticle probes enable implementation of advanced on-surface assay formats, but impose often underappreciated size-associated constraints, in particular on assay kinetics and sensitivity. The present study highlights substantially slower diffusion-limited assay kinetics due to the rapid development of a nanoprobe depletion layer next to the surface, which static incubation and mixing of bulk solution employed in conventional assay setups often fail to disrupt. In contrast, cyclic solution draining and replenishing yields reaction-limited assay kinetics irrespective of the probe size. Using common surface bioassays, enzyme-linked immunosorbent assays and immunofluorescence, this study shows that this conceptually distinct approach effectively "erases" size-dependent diffusion constraints, providing a straightforward route to rapid on-surface bioassays employing bulky probes and procedures involving multiple labeling cycles, such as multicycle single-cell molecular profiling. For proof-of-concept, the study demonstrates that the assay time can be shortened from hours to minutes with the same probe concentration and, at a typical incubation time, comparable target labeling can be achieved with up to eight times lower nanoprobe concentration. The findings are expected to enable realization of novel assay formats and stimulate development of rapid on-surface bioassays with nanoparticle probes.

Novel method for immunofluorescence staining of mammalian eggs using non-contact alternating-current electric-field mixing of microdroplets

Recently, a new technique was developed for non-catalytically mixing microdroplets. In this method, an alternating-current (AC) electric field is used to promote the antigen–antibody reaction within the microdroplet. Previously, this technique has only been applied to histological examinations of flat structures, such as surgical specimens. In this study, we applied this technique for the first time to immunofluorescence staining of three-dimensional structures, specifically, mammalian eggs. We diluted an antibody against microtubules from 1:1,000 to 1:16,000, and compared the chromatic degree and extent of fading across dilutions. In addition, we varied the frequency of AC electric-field mixing from 5 Hz to 46 Hz and evaluated the effect on microtubule staining. Microtubules were more strongly stained after AC electric-field mixing for only 5 minutes, even when the concentration of primary antibody was 10 times lower than in conventional methods. AC electric-field mixing also alleviated microtubule fading. At all frequencies tested, AC electric-field mixing resulted in stronger microtubule staining than in controls. There was no clear difference in a microtubule staining between frequencies. These results suggest that the novel method could reduce antibody consumption and shorten immunofluorescence staining time.

A simple and rapid decalcification procedure of skeletal tissues for pathology using an ultrasonic cleaner with D-mannitol and formic acid

Decalcification procedures are required in order to prepare histopathological preparations of hard tissues such as bone and teeth. Decalcification is usually performed by immersing the hard tissue in different decalcification fluids with various properties. These decalcification fluids typically include inorganic and organic acids, a neutral fluid containing a chelating agent, or a mixture of solutions. Unfortunately, there is no universal decalcification fluid that satisfies all the requirements of pathologists such as rapid decalcification, easy handling, and minimal tissue damage. Techniques involving use of microwaves (MW) or ultrasonic apparatus (US) have been shown to be useful for shortening the time for decalcification procedures. In the present study, we investigated a unique decalcification procedure that uses a common commercial ultrasonic cleaner and a decalcification fluid (formic acid) containing a free-radical scavenger (D-mannitol). The time required to complete the procedure is approximately half of that required to complete a standard decalcification procedure. In addition, tissue morphology and antigenicity is fairly well preserved after decalcification. The procedure is quick, easy to perform, and achieves decalcification of hard tissue with minimal tissue damage.