Scarring of the vocal fold lamina propria can lead to debilitating voice disorders that can significantly impair quality of life. The reduced pliability of the scar tissue-which diminishes proper vocal fold vibratory efficiency-results in part from abnormal extracellular matrix (ECM) deposition by vocal fold fibroblasts (VFF) that have taken on a fibrotic phenotype. To address this issue, bioactive materials containing cytokines and/or growth factors may provide a platform to transition fibrotic VFF within the scarred tissue toward an anti-fibrotic phenotype, thereby improving the quality of ECM within the scar tissue. However, for such an approach to be most effective, the acute host response resulting from biomaterial insertion/injection likely also needs to be considered. The goal of the present work was to evaluate the anti-fibrotic and anti-inflammatory capacity of an injectable hydrogel containing tethered basic fibroblast growth factor (bFGF) in the dual context of scar and biomaterial-induced acute inflammation. An in vitro co-culture system was utilized containing both activated, fibrotic VFF and activated, pro-inflammatory macrophages (MΦ) within a 3D poly(ethylene glycol) diacrylate (PEGDA) hydrogel containing tethered bFGF. Following 72 h of culture, alterations in VFF and macrophage phenotype were evaluated relative to mono-culture and co-culture controls. In our co-culture system, bFGF reduced the production of fibrotic markers collagen type I, α smooth muscle actin, and biglycan by activated VFF and promoted wound-healing/anti-inflammatory marker expression in activated MΦ. Cumulatively, these data indicate that bFGF-containing hydrogels warrant further investigation for the treatment of vocal fold lamina propria scar. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1258-1267, 2018.

Scarring of the vocal fold lamina propria (LP) can cause considerable voice disorders due to reduced pliability in scar tissue, attributed in part to abnormal extracellular matrix (ECM) deposition produced by the fibrotic vocal fold fibroblast (fVFF). Cytokines with anti-fibrotic potential have been investigated to limit abnormal LP ECM, but are limited by the need for repeat injections. Moreover, the potentially significant role played by activated macrophages (AMOs) is usually not considered even though the interaction between AMO and fibrotic fibroblasts is known to regulate scar formation across different tissues. AMO are also regulated by cytokines that are used for LP scar removal, but little is known about AMO behaviors in response to these cytokines within the context of LP scar. In the present study, we evaluated anti-fibrotic effects of hepatocyte growth factor (HGF), interleukin-10 (IL-10) and interleukin-6 (IL-6) in a 3D, in vitro fVFF-AMO co-culture system using poly(ethylene glycol) diacrylate (PEGDA) hydrogels. Data from all cytokines was synthesized into a heat-map that enabled assessment of specific associations between AMO and fVFF phenotypes. Cumulatively, our results indicated that both HGF and IL-10 are potentially anti-fibrotic (reduction in fibrotic markers and enhancement in normal, anti-fibrotic VFF markers), while IL-6 displays more complex, marker specific effects. Possible associations between AMO and fVFF phenotypes were found and may highlight a potential desirable macrophage phenotype. These data support the therapeutic potential of HGF and IL-10 for LP scar treatment, and shed light on future strategies aimed at targeting specific AMO phenotypes. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res B Part B: Appl Biomater, 2018.

Stromal collagen surrounding a solid tumor tends to present as dense, thick bundles. The collagen bundles are remodeled during tumor progression: first tangential to the tumor boundary (indicating growth) and later perpendicular to the tumor boundary (indicating likely metastasis). Current reconstituted-collagen in vitro tumor models are unable to recapitulate the in vivo structural features of collagen bundling and alignment. Here, we present a rapid yet simple procedure to fabricate collagen bundles with an average thickness of 9 µm, compared to the reticular dense collagen nanofiber (~900 nm-diameter, on average) prepared using common protocols. The versatility of the collagen bundles was demonstrated with their incorporation into two in vitro models where the thickness and alignment of the collagen bundles resembled the various in vivo arrangements. First, collagen bundles aligned by a microfluidic device elicited cancer cell contact guidance and enhanced their directional migration. Second, the presence of the collagen bundles in a bio-inert agarose hydrogel was shown to provide a highway for cancer cell invasion. The unique structural features of the collagen bundles advance the physiological relevance of in vitro collagen-based tumor models for accurately capturing cancer cell-stroma interactions.

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Tumor emboli—aggregates of tumor cells within vessels—pose a clinical challenge as they are associated with increased metastasis and tumor recurrence. When growing within a vessel, tumor emboli are subject to a unique mechanical constraint provided by the tubular geometry of the vessel. Current models of tumor emboli use unconstrained multicellular tumor spheroids, which neglect this mechanical interplay. Here, we modeled a lymphatic vessel as a 200 μm-diameter channel in either a stiff or soft, bioinert agarose matrix to create a vessel-like constraint model (VLCM), and we modeled colon or breast cancer tumor emboli with aggregates of HCT116 or SUM149PT cells, respectively. The stiff matrix VLCM constrained the tumor emboli to the cylindrical channel, which led to continuous growth of the emboli, in contrast to the growth rate reduction that unconstrained spheroids exhibit. Emboli morphology in the soft matrix VLCM, however, was dependent on the magnitude of mechanical mismatch between the matrix and the cell aggregates. In general, when the elastic modulus of the matrix of the VLCM was greater than the emboli (EVLCM/Eemb > 1), the emboli were constrained to grow within the channel, and when the elastic modulus of the matrix was less than the emboli (0 < EVLCM/Eemb < 1), the emboli bulged into the matrix. Due to a large difference in myosin II expression between the cell lines, we hypothesized that tumor cell aggregate stiffness is an indicator of cellular force-generating capability. Inhibitors of myosin-related force generation decreased the elastic modulus and/or increased the stress relaxation of the tumor cell aggregates, effectively increasing the mechanical mismatch. The increased mechanical mismatch after drug treatment was correlated with increased confinement of tumor emboli growth along the channel, which may translate to increased tumor burden due to the increased tumor volume within the diffusion distance of nutrients and oxygen.