Duan Bin, Yin Ziying, Hockaday Kang Laura, Magin Richard L, Butcher Jonathan T
Department of Biomedical Engineering, Cornell University, Ithaca, NY, USA.
Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, USA.
Acta Biomater. 2016 May;36:42-54. doi: 10.1016/j.actbio.2016.03.007. Epub 2016 Mar 3.
Calcific aortic valve disease (CAVD) progression is a highly dynamic process whereby normally fibroblastic valve interstitial cells (VIC) undergo osteogenic differentiation, maladaptive extracellular matrix (ECM) composition, structural remodeling, and tissue matrix stiffening. However, how VIC with different phenotypes dynamically affect matrix properties and how the altered matrix further affects VIC phenotypes in response to physiological and pathological conditions have not yet been determined. In this study, we develop 3D hydrogels with tunable matrix stiffness to investigate the dynamic interplay between VIC phenotypes and matrix biomechanics. We find that VIC populated within hydrogels with valve leaflet like stiffness differentiate towards myofibroblasts in osteogenic media, but surprisingly undergo osteogenic differentiation when cultured within lower initial stiffness hydrogels. VIC differentiation progressively stiffens the hydrogel microenvironment, which further upregulates both early and late osteogenic markers. These findings identify a dynamic positive feedback loop that governs acceleration of VIC calcification. Temporal stiffening of pathologically lower stiffness matrix back to normal level, or blocking the mechanosensitive RhoA/ROCK signaling pathway, delays the osteogenic differentiation process. Therefore, direct ECM biomechanical modulation can affect VIC phenotypes towards and against osteogenic differentiation in 3D culture. These findings highlight the importance of the homeostatic maintenance of matrix stiffness to restrict pathological VIC differentiation.
We implement 3D hydrogels with tunable matrix stiffness to investigate the dynamic interaction between valve interstitial cells (VIC, major cell population in heart valve) and matrix biomechanics. This work focuses on how human VIC responses to changing 3D culture environments. Our findings identify a dynamic positive feedback loop that governs acceleration of VIC calcification, which is the hallmark of calcific aortic valve disease. Temporal stiffening of pathologically lower stiffness matrix back to normal level, or blocking the mechanosensitive signaling pathway, delays VIC osteogenic differentiation. Our findings provide an improved understanding of VIC-matrix interactions to aid in interpretation of VIC calcification studies in vitro and suggest that ECM disruption resulting in local tissue stiffness decreases may promote calcific aortic valve disease.
钙化性主动脉瓣疾病（CAVD）进展是一个高度动态的过程，在此过程中，正常情况下呈成纤维细胞样的瓣膜间质细胞（VIC）会经历成骨分化、适应性不良的细胞外基质（ECM）组成、结构重塑以及组织基质硬化。然而，不同表型的VIC如何动态影响基质特性，以及改变后的基质如何在生理和病理条件下进一步影响VIC表型，目前尚未确定。在本研究中，我们开发了具有可调基质硬度的3D水凝胶，以研究VIC表型与基质生物力学之间的动态相互作用。我们发现，接种在具有瓣膜小叶样硬度水凝胶中的VIC在成骨培养基中向肌成纤维细胞分化，但令人惊讶的是，当在初始硬度较低的水凝胶中培养时，它们会经历成骨分化。VIC分化会逐渐使水凝胶微环境变硬，这进一步上调早期和晚期成骨标记物。这些发现确定了一个控制VIC钙化加速的动态正反馈回路。将病理状态下较低硬度的基质暂时变硬至正常水平，或阻断机械敏感的RhoA/ROCK信号通路，会延迟成骨分化过程。因此，直接的ECM生物力学调节可在3D培养中影响VIC表型向成骨分化或抑制成骨分化。这些发现突出了维持基质硬度稳态以限制病理性VIC分化的重要性。
我们采用具有可调基质硬度的3D水凝胶来研究瓣膜间质细胞（VIC，心脏瓣膜中的主要细胞群体）与基质生物力学之间的动态相互作用。这项工作重点关注人类VIC对不断变化的3D培养环境的反应。我们的发现确定了一个控制VIC钙化加速的动态正反馈回路，而钙化是钙化性主动脉瓣疾病的标志。将病理状态下较低硬度的基质暂时变硬至正常水平，或阻断机械敏感信号通路，会延迟VIC成骨分化。我们的发现有助于更好地理解VIC与基质的相互作用，以辅助解释体外VIC钙化研究，并表明导致局部组织硬度降低的ECM破坏可能会促进钙化性主动脉瓣疾病。
