Bottom-up assembly of salivary gland microtissues for assessing myoepithelial cell function

Abstract

Myoepithelial cells are flat, stellate cells present in exocrine tissues including the salivary glands. While myoepithelial cells have been studied extensively in mammary and lacrimal gland tissues, less is known of the function of myoepithelial cells derived from human salivary glands. Several groups have isolated tumorigenic myoepithelial cells from cancer specimens, however, only one report has demonstrated isolation of normal human salivary myoepithelial cells needed for use in salivary gland tissue engineering applications. Establishing a functional organoid model consisting of myoepithelial and secretory acinar cells is therefore necessary for understanding the coordinated action of these two cell types in unidirectional fluid secretion. Here, we developed a bottom-up approach for generating salivary gland microtissues using primary human salivary myoepithelial cells (hSMECs) and stem/progenitor cells (hS/PCs) isolated from normal salivary gland tissues. Phenotypic characterization of isolated hSMECs confirmed that a myoepithelial cell phenotype consistent with that from other exocrine tissues was maintained over multiple passages of tissue culture. Additionally, hSMECs secreted basement membrane proteins, expressed adrenergic and cholinergic neurotransmitter receptors, and released intracellular calcium [Ca2+i] in response to parasympathetic agonists. In a collagen I contractility assay, activation of contractile machinery was observed in isolated hSMECs treated with parasympathetic agonists. Recombination of hSMECs with assembled hS/PC spheroids in a microwell system was used to create microtissues resembling secretory complexes of the salivary gland. We conclude that the engineered salivary gland microtissue complexes provide a physiologically relevant model for both mechanistic studies and as a building block for the successful engineering of the salivary gland for restoration of salivary function in patients suffering from hyposalivation.

Losartan and isoproterenol promote alterations in the local renin-angiotensin system of rat salivary glands

“…This association with other vasoactive systems was previously discussed, when captopril caused dipsogenic effects in rats when bradykinin was studied as a stimulator of thirst [17]. ACE was predominantly detected in salivary myoepithelial cells, similar to lacrimal glands [39] and other exocrine glands [53], contouring acinar and ductal epithelial cells in a stellate format (ACE, blue arrow detail in Figs 4–6). They have both epithelial and smooth muscle cell features.…”

“…Therefore, it is proposed that their contractions would induce the secretory function of these acini, as previously noticed in lacrimal glands [39]. Indeed, the characterization of myoepithelial cells presents novel perspectives on how salivary gland microtissues work, and therefore, proposes mechanisms for restoration of their function in hyposalivation [53].…”

Organotypic 3D Culture in Nanoscaffold Microwells Supports Salivary Gland Stem-Cell-Based Organization

“…16,24 Synthetic agarose gel–replicated organotypic scaffolds or natural ECM scaffolds were also introduced for assembly of salivary-gland microtissue. 25,26…”

Enabling in vivo Photocatalytic Activation of Rapid Bioorthogonal Chemistry by Repurposing Si-Rhodamine Fluorophores as Cytocompatible Far-Red Photocatalysts

“…For 3D encapsulation studies, LNCaP spheroids with an average diameter of 100 µm, prepared following our established procedure, 91 were suspended in the pre-hydrogel solution. Catalase, an enzyme extensively present in humans and all organisms exposed to oxygen, was added as a co-catalyst to disproportionate the hydrogen peroxide generated by the photoreaction.…”