The organ transplant recipient, a chimera subject, who develops a neoplastic lesion may be the suitable model to reconstruct the hierarchical organization of tumors

Tumors are collections of cells that grow out of control and invade tissue. These cells originate from a single mutated one whose lineage continuously accrues somatic aberrations resulting in a heterogeneous population where a hierarchical organisation seems possible. The recognition of first cells, faintly changed compared to the normal ones, is extremely difficult: the differences are nearly undetectable, but of critical importance for understanding the earliest events in tumorigenesis and may pave the way for earlier detection and prevention, since early stages in cancer development might be present years before cancer becomes clinically apparent. To discriminate these cells, which are at the apex of the hierarchy, we hypothesize that the transplanted patient who develops a donor-derived tumor might be a useful model. In fact, as a chimera subject, he might allow the identification and detection of the tumor-initiating cells taking advantage of signature consisting in the genomic mismatch.