Simultaneous phenotyping and genotyping (FICTION-methodology) on paraffin sections and cytologic specimens: a comparison of 2 different protocols

Chromosomal defects in multiple myeloma

Multiple myeloma is a plasma cell neoplasm driven by primary (e.g. hyperdiploidy; IGH translocations) and secondary (e.g. 1q21 gains/amplifications; del(17p); MYC translocations) chromosomal events. These are important to detect as they influence prognosis, therapeutic response and disease survival. Currently, cytogenetic testing is most commonly performed by interphase fluorescence in situ hybridisation (FISH) on aspirated bone marrow samples. A number of variations to FISH methodology are available, including prior plasma cell enrichment and incorporation of immunophenotypic plasma cell identification. Other molecular methods are increasingly being utilised to provide a genome-wide view at high resolution (e.g. single nucleotide polymorphism (SNP) microarray analysis) and these can detect abnormalities in most cases. Despite their wide application at diagnostic assessment, both FISH and SNP-array have relatively low sensitivity, limiting their use for identification of prognostically significant low-level sub-clones or for disease monitoring. Next-generation sequencing is increasingly being used to detect mutations and new FISH techniques such as by flow cytometry are in development and may address some of the current test limitations. Here we review the primary and secondary cytogenetic aberrations in myeloma and discuss the range of techniques available for their assessment.

Origin of cancer-associated fibroblasts and tumor-associated macrophages in humans after sex-mismatched bone marrow transplantation

Cancer-associated fibroblasts (CAFs) and tumor-associated macrophages (TAMs) in tumor stroma play a key role in disease progression. Recent studies using mice models suggest that CAFs are partly derived from bone marrow and TAMs primarily originate from bone marrow-derived inflammatory monocytes. However, the origin of these cells in humans remains unclear. Hence, we investigated their human origin, using specimens from human secondary tumors that developed after sex-mismatched bone marrow transplantation, by modified immunofluorescent in situ hybridization analysis and triple immunostaining. We observed that most of the α-smooth muscle actin (αSMA)-positive CAFs in the mammary gland, liver, and oral mucosa specimens obtained 3-19 years after bone marrow transplantation are recipient-derived cells. In contrast, the majority of the peritumoral αSMA-negative fibroblast-like cells are actually bone marrow-derived HLA-DR-positive myeloid cells, such as macrophages and dendritic cells. Furthermore, almost all CD163-positive TAMs and macrophages present in the non-tumor areas are derived from bone marrow.

Recurrence of posterior polymorphous corneal dystrophy is caused by the overgrowth of the original diseased host endothelium

Posterior polymorphous corneal dystrophy (PPCD) is a rare, bilateral autosomal dominant disorder affecting primarily the corneal endothelium and descemet membrane (DM). The aim of this study was to establish the origin of abnormal endothelium in a patient with PPCD exhibiting cornea graft failure after keratoplasty surgery. A sex-mismatched graft obtained from a patient with PPCD who underwent repeat penetrating keratoplasty and the patient's original cornea were investigated. Combined fluorescent immunohistochemistry for cytokeratin (CK) 19 (a marker of aberrant PPCD endothelium) with fluorescence in situ hybridization (FISH) of the sex chromosomes were used in order to characterize the cells on the posterior graft surface. The pathological endothelium of the failed PPCD cornea revealed strong positivity for CK19 using fluorescent immunohistochemistry. In all the CK19-positive cells, both X and Y chromosomes were simultaneously detected using FISH. The results clearly showed the original cells of the patient (XY), within 3.5 years, almost totally overgrown the posterior corneal surface of the graft (XX). Moreover, an abnormal posterior collagenous layer populated by fibroblast-like cells was observed between DM and the endothelium in the failed graft, but its exact origin could not be established due to the low number of cells. Simultaneous detection of CK19 using fluorescent immunohistochemistry together with the detection of gonosomes using FISH was performed for the first time in the cornea and allowed us to prove that the recurrence of PPCD was caused by pathological abnormal proliferation and migration of recipient cells into donor graft.