Abstract
Simple SummaryHuman breast tissue extracellular matrix (ECM) is a microenvironment essential for the survival and biological activities of mammary epithelial cells. The ECM structural features of human breast tissues remain poorly defined. In this study, we identified the structural and mechanical properties of human normal breast and invasive ductal carcinoma tissue ECM using histological methods and atomic force microscopy. Additionally, a protein hydrogel was generated using human breast tissue ECM and defined for its microstructural features using immunofluorescence imaging and machine learning. Furthermore, we examined the three-dimensional growth of normal mammary epithelial cells or breast cancer cells cultured on the ECM protein hydrogel, where the cells exhibited biological phenotypes like those seen in native breast tissues. Our data provide novel insights into cancer cell biology, tissue microenvironment mimicry and engineering, and native tissue ECM-based biomedical and pharmaceutical applications.Tissue extracellular matrix (ECM) is a structurally and compositionally unique microenvironment within which native cells can perform their natural biological activities. Cells grown on artificial substrata differ biologically and phenotypically from those grown within their native tissue microenvironment. Studies examining human tissue ECM structures and the biology of human tissue cells in their corresponding tissue ECM are lacking. Such investigations will improve our understanding about human pathophysiological conditions for better clinical care. We report here human normal breast tissue and invasive ductal carcinoma tissue ECM structural features. For the first time, a hydrogel was successfully fabricated using whole protein extracts of human normal breast ECM. Using immunofluorescence staining of type I collagen (Col I) and machine learning of its fibrous patterns in the polymerized human breast ECM hydrogel, we have defined the microstructural characteristics of the hydrogel and compared the microstructures with those of other native ECM hydrogels. Importantly, the ECM hydrogel supported 3D growth and cell-ECM interaction of both normal and cancerous mammary epithelial cells. This work represents further advancement toward full reconstitution of the human breast tissue microenvironment, an accomplishment that will accelerate the use of human pathophysiological tissue-derived matrices for individualized biomedical research and therapeutic development.
Highlights
The breast tissues of women dynamically change their morphologies, cellular activities, and expression of biomolecules during puberty, throughout the menstrual cycle, and perinatal period [1]
The normal and lesion specimens were divided into portions for planned experiments: formalin fixation and paraffin embedding for histological staining; optimal cutting temperature (OCT) compound fixation and cross sectioning for stiffness measurement with atomic force microscopy (AFM); extracellular matrix (ECM) extraction and hydrogel generation
To better understand the destructive features of breast cancer tissues, we carried out hematoxylin and eosin (H&E) as well as type I collagen (Col I) immunofluorescence (IF) staining on the cross sections of invasive ductal carcinoma (IDC) tissue, normal breast
Summary
The breast tissues of women dynamically change their morphologies, cellular activities, and expression of biomolecules during puberty, throughout the menstrual cycle, and perinatal period [1]. These physical and biochemical changes do not adversely alter the basic functions and structures of the tissues [2], but are disrupted in the setting of malignancy, which results in upregulated cancer and stromal cell activities, such as transcription, translation, uncontrolled proliferation, activation of tissue resident cells, de-differentiation, altered metabolism, secretion or degradation of biomolecules, and infiltration of immune cells into the stroma with resultant destruction of the breast tissue ECM architecture [3,4,5]. The distinction between ECM structures in human breast cancer tissues from those of normal breast tissues is poorly defined. It follows that the biological phenotypes of human breast cancer cells grown in a bioengineered native human breast tissue ECM microenvironment are heretofore undefined. The goal of this study was to define the ECM microstructural features of normal human breast and invasive breast cancer tissues and examine the biological phenotypes of normal and cancerous mammary epithelial cells grown in primary human breast tissue ECM microenvironment
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