PreservCyt Is an Optimal Fixative that Permits Cytologic and Molecular Analyses of Vitreoretinal Lymphoma Biopsies

Long-Chain Fluorescent Probe for Straightforward and Nondestructive Staining Mitochondria in Fixed Cells and Tissues

Normally, small-molecule fluorescent probes dependent on the mitochondrial membrane potential (MMP) are invalid for fixed cells and tissues, which limits their clinical applications when the fixation of pathological specimens is imperative. Given that mitochondrial morphology is closely associated with disease, we developed a long-chain mitochondrial probe for fixed cells and tissues, DMPQ-12, by installing a C12-alkyl chain into the quinoline moiety. In fixed cells stained with DMPQ-12, filament mitochondria and folded cristae were observed with confocal and structural illumination microscopy, respectively. In titration test with three major phospholipids, DMPQ-12 exhibited a stronger binding force to mitochondria-exclusive cardiolipin, revealing its targeting mechanism. Moreover, mitochondrial morphological changes in the three lesion models were clearly visualized in fixed cells. Finally, by DMPQ-12, three kinds of mitochondria with different morphologies were observed in situ in fixed muscle tissues. This work breaks the conventional concept that organic fluorescent probes only stain mitochondria with normal membrane potentials and opens new avenues for comprehensive mitochondrial investigations in research and clinical settings.

Cytologic and Molecular Diagnostics for Vitreoretinal Lymphoma: Current Approaches and Emerging Single-Cell Analyses

Vitreoretinal lymphoma (VRL) is a rare ocular malignancy that manifests as diffuse large B-cell lymphoma. Early and accurate diagnosis is essential to prevent mistreatment and to reduce the high morbidity and mortality associated with VRL. The disease can be diagnosed using various methods, including cytology, immunohistochemistry, cytokine analysis, flow cytometry, and molecular analysis of bulk vitreous aspirates. Despite these options, VRL diagnosis remains challenging, as samples are often confounded by low cellularity, the presence of debris and non-target immunoreactive cells, and poor cytological preservation. As such, VRL diagnostic accuracy is limited by both false-positive and false-negative outcomes. Missed or inappropriate diagnosis may cause delays in treatment, which can have life-threatening consequences for patients with VRL. In this review, we summarize current knowledge and the diagnostic modalities used for VRL diagnosis. We also highlight several emerging molecular techniques, including high-resolution single cell-based analyses, which may enable more comprehensive and precise VRL diagnoses.

Analysis of Vitreous Samples by the Cellient® Automated Cell Block System: A Six-year Review of Specimens in a Uveitis Population

Purpose: To further evaluate the value of a standardized method to analyze vitreous samples using the Cellient® automated cell block system in the diagnosis of unsolved uveitis.Methods: Six hundred sixty-four pure vitreous samples obtained from patients with unsolved uveitis between March 2012 and May 2018 at University Hospitals Leuven, fixed in PreservCyt® and processed by the Cellient tissue processor, were included in the study.Results: In 86.3% of the cases, sufficient material was found for diagnosis. A diagnosis of acute inflammation was made in 20.2% of the cases. In 34.0% of the cases, the diagnosis was chronic active inflammation; in 26.5%, low-grade inflammation; and in 5.6%, a malignant process.Conclusion: Our standardized protocol can be used to diagnose endophthalmitis, lymphoma, granulomatous disease, inactive and storage disease, and metastatic infiltration. Cellient analysis of vitreous specimens had a diagnostic yield of 86.3% in unsolved uveitis cases.

Single B-Cell Genomic Analyses Differentiate Vitreoretinal Lymphoma from Chronic Inflammation

PURPOSE

To test whether analyzing DEPArray (Menarini Silicon Biosystems) isolated single B cells from the vitreous fluid can reveal crucial genomic and clinicopathological features to distinguish patients with vitreoretinal lymphoma (VRL) from those with chronic inflammation using immunoglobulin heavy chain (IGH), disease biomarker myeloid differentiation primary response 88 (MYD88)^L265P mutation, and copy number profiling.

DESIGN

A single-center, retrospective study.

PARTICIPANTS

Remnant vitreous biopsies from 7 patients with VRL and 4 patients with chronic inflammation were acquired for molecular analysis.

METHODS

Vitreous fluid samples were prefixed in PreservCyt (Hologic) and underwent cytologic analysis and immunohistochemistry examination. Single cells were isolated using the DEPArray NxT system, followed by downstream genomic analysis.

MAIN OUTCOME MEASURES

The frequencies of the dominant IGH and MYD88^L265P mutation and the genome-wide copy number aberration (CNA) profiles of individual vitreous-isolated B cells were characterized.

RESULTS

An average of 10 to 13 vitreous B cells were used in the single-cell IGH and MYD88 analyses. Higher frequencies of dominant IGH (88.8% ± 13.2%) and MYD88^L265P mutations (35.0% ± 31.3%) were detected in patients with VRL than in patients with chronic inflammation (65.9% ± 13.4% and 1.5% ± 2.6% for IGH and MYD88^L265P, respectively). In a cytology-proven VRL case, all 15 vitreous isolated B cells were derived from the same clone with 100% paired IGH: immunoglobulin light chain (IGK) sequences. Genome-wide copy number profiling revealed a high degree of similarity between B cells from the same patient with VRL, with extensive gains and losses at the same areas across the whole genome. In addition, 14 of 15 B cells showed a BCL2/JH t(14;18) translocation, confirming cellular malignancy with a clonal origin. Clustering analysis of the copy number profiles revealed that malignant B cells derived from different patients with VRL had no common genome-wide signatures.

CONCLUSIONS

Single B-cell genomic characterization of the IGH, MYD88^L265P mutation, and copy number profile enables VRL diagnosis. Because our study involved only a small cohort, these meaningful proof-of-concept data now warrant further investigation in a larger patient cohort.