Improved technique for manually constructing tissue microarrays for large-core arrays

Tissue microarrays were originally developed to enable alignment of multiple tissue cores in a single paraffin block and to enable high-throughput laboratory analysis. However, a major drawback is the loss of tissue cores during slide preparation, especially when sectioning the tissue block. Tissue cylinders directly aligned in the metal box without preheating tend to detach from the surrounding paraffin, which results in incomplete or folded tissue sections. The proposed solution is preheating all tissue cylinders on a hot plate to facilitate fusion between the paraffin within the core and the paraffin surrounding the core. In this study, 6 tissue microarray blocks were constructed from 528 tissue cores extracted from various formalin-fixed, paraffin-embedded human tissue samples. The tissue cores in the arrays revealed good homogenization with the surrounding paraffin wax, and the tissue sections were obtained intact. Both hematoxylin-eosin and immunohistochemical staining confirmed satisfactory results. This simple and economical method is easily performed in the laboratory without expensive instrumentation.