Immunohistochemical characterization and functional identification of mammary gland telocytes in the self‐assembly of reconstituted breast cancer tissue in vitro

Abstract

Telocyte (TC) as a special stromal cell exists in mammary gland and might play an important role in the balance of epithelium-stroma of mammary gland. Considering that different types of breast interstitial cells influence the development and progression of breast cancer, TCs may have its distinct role in this process. We here studied the roles of TCs in the self-assembly of reconstituted breast cancer tissue. We co-cultured primary isolated TCs and other breast stromal cells with breast cancer EMT-6 cells in collagen/Matrigel scaffolds to reconstitute breast cancer tissue in vitro. Using histology methods, we investigated the immunohistochemical characteristics and potential functions of TCs in reconstituted breast cancer tissue. TCs in primary mammary gland stromal cells with long and thin overlapping cytoplasmic processes, expressed c-kit/CD117, CD34 and vimentin in reconstitute breast cancer tissue. The transmission electron microscopy showed that the telocyte-like cells closely communicated with breast cancer cells as well as other stromal cells, and might serve as a bridge that directly linked the adjacent cells through membrane-to-membrane contact. Compared with cancer tissue sheets of EMT-6 alone, PCNA proliferation index analysis and TUNEL assay showed that TCs and other breast stromal cells facilitated the formation of typical nest structure, promoted the proliferation of breast cancer cells, and inhibited their apoptosis. In conclusion, we successfully reconstituted breast cancer tissue in vitro, and it seems to be attractive that TCs had potential functions in self-assembly of EMT-6/stromal cells reconstituted breast cancer tissue.

Telocytes in liver: electron microscopic and immunofluorescent evidence

“…Immunofluorescence is also of importance to determine the phenotype of TCs . Four different double labelling immunofluorescence methods were used to provide evidence for the existence of TCs in mice liver.…”

“…Telopodes present dilatations called podoms and thin segments (below the resolving power of light microscopy, named podomeres) [2][3][4][5][6][7][8]. Telocytes are connected by Tps and consequently form a network [24,27]. The microRNA signatures [28] of TCs as well as the gene profiles [29] were established.…”

Telocytes in human heart valves

“…Telocytes (TCs), a special type of interstitial cells, have been identified by Popescu's group and the concept of TCs has been adopted by many laboratories worldwide (for details visit http://www.telocytes.com). Telocytes are described as interstitial cells with extremely long and thin prolongations, called telopodes (Tps) .…”

Telocytes of the mammary gland stroma

“…However, CD34, as well as CD117/c-kit, are well known markers of cells with different levels of stemness [44]. Although CD34 was used for the in vitro study of MG TCs [25], that antibody was not applied for the in situ evidence of MG ICLCs [30], further renamed to TCs. Therefore, we aimed at studying by immunohistochemistry the in situ CD34 phenotype of the MG spindle-shaped stromal cells in normal human tissue.…”

“…In these regards, the initial identification of MG ICLCs in light microscopy [30], which keeps as the only in situ evidence of MG TCs in human tissue, could raise doubts. The only proofs of mammary telocyte-like cells resulted after an in vitro experiment of breast cancer reconstitution performed recently, in which TCs were identified in primary culture cells by phase contrast microscope [25], no specific marker being used then. Indeed, at this time a specific immune phenotype of TCs was not clearly established [34]; although the most used markers which point to TCs, but not exclusively, are CD34 and c-kit [15].…”