Services
The UCLA Tissue Array Core Facility provides a number of tissue array platform services including:
- Tissue array project consultation
- Tissue array construction
- Collection and databasing of supporting pathology, clinical and marker expression data sets
- Biostatistical analysis or study data
- Preparation of figures and text for manuscripts and grants
- Educational and training sessions in tissue array and analysis techniques
Background
The purpose of the tissue microarray (TMA) is to represent, with small samplings of tissue, the histomorphological spectrum of the original surgical specimen. Therefore, construction of a TMA that will provide this appropriate representation necessitates careful case choice, case review, array design, technical skill at construction, and quality control. The strength of this resource is best exemplified by the combined power of well-crafted tissue array linked to a clinicopathological database encompassing the arrayed patients, together forming a powerful research tool.
Process
After collection of surgical pathology case material and reports, H&E sections are examined histomorphologically to determine where to biopsy the donor tissue materials to best represent the histologies desired for the tissue array block.
Once the desired regions are marked on these H&E sections the areas are matched to the donor blocks and the tissue is extracted from them and placed into a growing tissue array block utilizing a tissue array instrument.
The process is repeated from numerous donor blocks until the new tissue array block is fully constructed. With this technique, as many as 700 cylindrical 0.6 mm diameter formalin-fixed and paraffin-embedded tissue cores are densely and precisely arrayed into a single typical paraffin block. On very large tissue arrays multiple array blocks will be produced to create one tissue array “set”.
From each array block, up to 300 serial 4-8um thick sections can be produced and placed on individual glass microscopic slides. An adhesive-coated tape system is useful in maintaining array formatting in the transfer of cut ribbons to the glass slides.
Assays performed with tissue arrays are the same as can be done with conventional whole tissue sections including morphologic brightfield examination (H&E), protein expression studies (immunohistochemistry), and DNA copy number analysis (fluorescence in situ hybridization FISH). Also, in situ PCR as well as a vast panel of traditional histologic special stains may be applied to tissue array slides.
The tissue arrays provide a lasting resource tool for future studies. The large number of available replicate slides allows consecutive analysis of numerous molecular markers, and therefore construction of rich databases for correlative analyses of protein expression, gene copy number, morphohistological phenotypes and clinical outcomes.
