Functional label-free assessment of fibroblast differentiation in 3D collagen-I-matrices using particle image velocimetry

Synthetic color-and-depth encoded (sCade) illumination-based high-resolution light field particle imaging velocimetry

Light-field particle imaging velocimetry (LF-PIV) is widely used in large-scale flow field measurement scenarios due to its instant 3D imaging capability. However, conventional LF-PIV systems suffer low axial resolution and thereby have limited application in high-resolution and volumetric velocity measurements. Here, we report the use of synthetic color-and-depth-encoded (sCade) illumination to improve the axial resolution of LF-PIV. The sCade LF-PIV illuminated the imaging region with a color-and-depth encoded beam synthesized by structured beams of three lasers with distinct wavelengths and attained high-fidelity particle localization by decoding the color and depth information encoded in the acquired image. We systematically characterized the system performance by imaging particles and obtained 29 times improvement in axial resolution when compared to traditional LF-PIV. The high axial resolution of sCade LF-PIV allowed it to reconstruct vortices generated by square lid-driven cavity flow and a stirring disk with higher accuracy and smaller errors than the conventional method, highlighting the possibility and advantage of sCade LF-PIV for high-resolution and volumetric flow measurement applications. This approach can favorably advance the development of fluid measurement technology.

Fibrillar biopolymer-based scaffolds to study macrophage-fibroblast crosstalk in wound repair

Controlled wound healing requires a temporal and spatial coordination of cellular activities within the surrounding extracellular matrix (ECM). Disruption of cell-cell and cell-matrix communication results in defective repair, like chronic or fibrotic wounds. Activities of macrophages and fibroblasts crucially contribute to the fate of closing wounds. To investigate the influence of the ECM as an active part controlling cellular behavior, coculture models based on fibrillar 3D biopolymers such as collagen have already been successfully used. With well-defined biochemical and biophysical properties such 3D scaffolds enable in vitro studies on cellular processes including infiltration and differentiation in an in vivo like microenvironment. Further, paracrine and autocrine signaling as well as modulation of soluble mediator transport inside the ECM can be modeled using fibrillar 3D scaffolds. Herein, we review the usage of these scaffolds in in vitro coculture models allowing in-depth studies on the crosstalk between macrophages and fibroblasts during different stages of cutaneous wound healing. A more accurate mimicry of the various processes of cellular crosstalk at the different stages of wound healing will contribute to a better understanding of the impact of biochemical and biophysical environmental parameters and help to develop further strategies against diseases such as fibrosis.

Myofibroblasts: Function, Formation, and Scope of Molecular Therapies for Skin Fibrosis

Myofibroblasts are contractile, α-smooth muscle actin-positive cells with multiple roles in pathophysiological processes. Myofibroblasts mediate wound contractions, but their persistent presence in tissues is central to driving fibrosis, making them attractive cell targets for the development of therapeutic treatments. However, due to shared cellular markers with several other phenotypes, the specific targeting of myofibroblasts has long presented a scientific and clinical challenge. In recent years, myofibroblasts have drawn much attention among scientific research communities from multiple disciplines and specialisations. As further research uncovers the characterisations of myofibroblast formation, function, and regulation, the realisation of novel interventional routes for myofibroblasts within pathologies has emerged. The research community is approaching the means to finally target these cells, to prevent fibrosis, accelerate scarless wound healing, and attenuate associated disease-processes in clinical settings. This comprehensive review article describes the myofibroblast cell phenotype, their origins, and their diverse physiological and pathological functionality. Special attention has been given to mechanisms and molecular pathways governing myofibroblast differentiation, and updates in molecular interventions.