3.4. Impact of the Finding
Researchers working with modern TMA technologies have a growing interest in the possible application of TMA instrumentation for purposes other than TMA block construction. Especially, a combined digital pathology/TMA approach is ideal for assessing issues of heterogeneity and allows very precisely annotated histological regions to be transferred either to TMAs or to tubes for storage and/or analysis of nucleic acids. With or without a digital pathology platform, neighboring punches side-by-side for TMA construction and simultaneous molecular analysis is clearly advantageous in the era of molecular pathology.
This study was motivated by the growing concerns over cross-contamination between samples and appears to be the first study to date to address this issue. Using two different PCR methods and alternating between positive/mutated and negative/wild-type samples, our findings underline no evidence of transfer of material from one tissue block to the next.
Figure 3  Electropherograms used to evaluate the presence of mycobacterium in donor blocks from a previously confirmed positive and negative tissue sample. (A) positive control and (B) negative control. Tissue samples were alternated in the tissue arrayer three times leading to the following results: (C,E,G) mycobacterium tuberculosis samples and (D,F,H) mycobacterium tuberculosis negative samples. No evidence for cross-contamination between samples.

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