Fibroblasts and Mesenchymal Stromal/Stem Cells Are Phenotypically Indistinguishable.

BACKGROUND/AIMS: Human mesenchymal stromal/stem cells (MSCs), derived from many different tissues, are characterized by a fibroblast-like morphology, the expression of certain cell surface markers and their ability to differentiate into adipocytes, chondrocytes and osteoblasts. A number of studies have shown that MSCs share many characteristics with fibroblasts; however, there is no well-defined set of phenotypic characteristics that could distinguish between these 2 types of cells. METHODS: We used 4 well-established human fibroblast strains from 3 different tissue sources and several human MSC strains from 2 different tissue sources to compare the phenotypic and immunological characteristics of these cells. RESULTS: Fibroblast strains had a similar morphology to MSCs, expressed the same cell surface markers as MSCs and could also differentiate into adipocytes, chondrocytes and osteoblasts. Also, similar to MSCs, these fibroblasts were capable of suppressing T cell proliferation and modulating the immunophenotype of macrophages. We also show that MSCs deposit extracellular matrices of collagen type I and fibronectin, and express FSP1 in patterns similar to fibroblasts. CONCLUSIONS: Based on currently accepted definitions for cultured human MSCs and fibroblasts, we could not find any immunophenotypic property that could make a characteristic distinction between MSCs and fibroblasts.

Differentiating arytenoid dislocation and recurrent laryngeal nerve paralysis by arytenoid movement in laryngoscopic video.

OBJECTIVE: To present a new method of quantifying arytenoid movement during inspiration and determine if it can be used to distinguish arytenoid dislocation from vocal fold paralysis. STUDY DESIGN: Case series with chart review. SETTING: Retrospective study conducted in a university laboratory based on university hospital data. SUBJECTS AND METHODS: Endoscopic videos from 8 patients with dislocation and 5 patients with vocal fold paralysis diagnosed by electromyography were included. Vector analysis measured cuneiform movement, an indirect measurement of arytenoid movement, during 1 inspiration. Measurements normalized and not normalized to vocal fold length were evaluated. Interrater reliability (2 raters) and intrarater reliability (1 rater performing the analysis twice) were evaluated using intraclass correlation coefficient (ICC) analysis. Raters were blinded to subject group during analysis. RESULTS: Pixel-valued cuneiform movement was 81.16 ± 25.62 for dislocation and 30.22 ± 23.60 for paralysis (P = .019). Unitless cuneiform movement was 0.58 ± 0.17 for dislocation and 0.24 ± 0.18 for paralysis (P = .030). Interrater ICC was 0.942 for pixel-valued measurements and 0.962 for unitless measurements. Intrarater ICC was 0.909 for pixel-valued measurements and 0.881 for unitless measurements. CONCLUSIONS: Both pixel-valued and unitless measures of arytenoid movement were significantly greater in arytenoid dislocation than vocal fold paralysis. Pixel-valued measurements were included to demonstrate the ability to make quantitative comparisons across subjects without precise knowledge of camera precision, provided position is approximately stable, as each measurement is inherently normalized by vocal tract length. Future studies will apply this new method of evaluating vocal fold immobility disorders on a larger scale and incorporate a more diverse group of etiologies.

Nonlinear source-filter coupling due to the addition of a simplified vocal tract model for excised larynx experiments.

OBJECTIVES: Traditional excised larynx dissection and setup calls for the removal of all supraglottal structures, eliminating any source-filter interactions that measurably affect the acoustic properties of phonation. We introduce a simplified vocal tract model that can be used in the excised larynx experiments and tested the nonlinear source-filter interactions that are present with the addition of highly coupled, supraglottal structures. METHODS: Aerodynamic and acoustic data were measured at phonation threshold pressure (PTP) and +25% PTP in 10 excised canine larynges using a modified dissection technique. PTP and phonation threshold flow (PTF) were defined as the pressure and flow at the phonation onset; phonation threshold power (PTW) is the product of these values. Data were recorded for four experimental conditions: PTP without vocal tract; +25% PTP without vocal tract; PTP with vocal tract; and +25% PTP with vocal tract. Differences in PTP, PTF, and PTW were evaluated. For trials conducted at +25% PTP, differences in airflow were evaluated. RESULTS: PTP (P = 0.009) and PTW (P = 0.002) were significantly reduced with the addition of the novel vocal tract. A reduction in PTF was also present with the vocal tract (P = 0.021), but airflow was not significantly reduced in +25% PTP trials (P = 0.196). CONCLUSION: The proposed vocal tract can be used with complete larynges when conducting excised larynx experiments. The effects of nonlinear source-filter interaction were observed during trials with the vocal tract, as evidenced by changes in threshold aerodynamic parameters.