tissueonly

Tissueonly is a term used in biology and medicine to describe datasets, analyses, or experimental designs that include only tissue-derived material, excluding data from blood, urine, cell lines, cultured cells, or other non-tissue sources. The concept emphasizes tissue context, enabling examination of tissue-specific molecular profiles, histology, and pathology.

In genomics and transcriptomics, tissue-only approaches focus on gene expression, DNA methylation, or chromatin states within biopsy or surgically excised tissue, often employing microdissection to enrich for regions of interest. In proteomics and metabolomics, tissue-only studies profile proteins and metabolites within the tissue milieu.

Applications include cancer research, organ-specific biology, and biomarker discovery where tissue context matters. Methods commonly used include laser capture microdissection, processing of tissue sections (including FFPE samples), RNA sequencing on tissue extracts, and imaging-based assays such as immunohistochemistry. Imaging can be integrated with tissue-only analyses to map molecular signals to histological features.

Limitations include intrinsic tissue heterogeneity, sampling bias, ethical and logistical constraints in obtaining tissues, and potential degradation in stored samples. Because it excludes non-tissue sources, tissue-only analysis may miss systemic signals but gains specificity to the tissue of interest. The term is related to, but distinct from, tissue-centric analyses, tissue-specific datasets, and multi-omics strategies that integrate non-tissue sources.

See also histology, transcriptomics, proteomics, DNA methylation, laser capture microdissection.