Biomedical Applications of Collagen

Extracellular matrix proteins (ECMs) provide structural support and dynamic signaling cues that regulate cell behavior and tissue morphogenesis [...

Fibril size-dependent control of polar ordering in type I collagen membranes

The most abundant protein in the human body, collagen, is widely used in tissue culture and engineering applications, spanning from substrate functionalization to fibrillar architectures and three-dimensional constructs. Collagen piezoelectricity provides an opportunity to exploit electromechanical coupling in these applications, wherein an applied mechanical stress generates charge, which might influence ion screening, protein absorption, and cell response. In type I collagen, the polarization direction follows the fibril orientation. Thus, control of fibril orientation and size in a collagen film or membrane may provide control of the polarization, enabling the creation of regions of uniform polarization direction. Here, aligned substrate-supported type I collagen membranes having fibril sizes from ∼100-500 nm are deposited using different osmotic concentrations (90, 190, and 290 mOsm/kg, from low to high ionic strength) to investigate the correlation between fibril size and piezoelectric properties. Lateral piezoresponse force microscopy is used to show that regions of uniform polarization orientation, as determined through 2D correlation analysis, decrease with increasing fibril size.European Commission Horizon 2020China Scholarship Counci

A Biomimetic High Throughput Model of Cancer Cell Spheroid Dissemination onto Aligned Fibrillar Collagen

Cell dissemination during tumor development is a characteristic of cancer metastasis. Dissemination from three-dimensional spheroid models on extracellular matrices designed to mimic tissue-specific physiological microenvironments may allow us to better elucidate the mechanism behind cancer metastasis and the response to therapeutic agents. The orientation of fibrillar collagen plays a key role in cellular processes and mediates metastasis through contact-guidance. Understanding how cells migrate on aligned collagen fibrils requires in vitro assays with reproducible and standardized orientation of collagen fibrils on the macro-to-nanoscale. Herein, we implement a spheroid-based migration assay, integrated with a fibrillar type I collagen matrix, in a manner compatible with high throughput image acquisition and quantitative analysis. The migration of highly proliferating U2OS osteosarcoma cell spheroids onto an aligned fibrillar type I collagen matrix were quantified. Cell dissemination from the spheroid was polarized with increased invasion in the direction of fibril alignment. The resulting area of cell dissemination had an aspect ratio of 1.2 ± 0.1 and an angle of maximum invasion distance of 5° ± 44° relative to the direction of collagen fibril alignment. The assay described here can be applied to a fully automated imaging and analysis pipeline for the assessment of tumor cell migration with high throughput screening.European Commission Horizon 2020Science Foundation IrelandMarie Skłodowska-CurieUCD School of Physics (SIRAT − Scholarship in Research and Teaching)Sustainable Energy Authority of Ireland (SEAI)In Press, Corrected Proof. To check details in 6 month

Bioengineering Cell Therapy for Treatment of Peripheral Artery Disease

Peripheral artery disease is an atherosclerotic disease associated with limb ischemia that necessitates limb amputation in severe cases. Cell therapies comprised of adult mononuclear or stromal cells have been clinically tested and show moderate benefits. Bioengineering strategies can be applied to modify cell behavior and function in a controllable fashion. Using mechanically tunable or spatially controllable biomaterials, we highlight examples in which biomaterials can increase the survival and function of the transplanted cells to improve their revascularization efficacy in preclinical models. Biomaterials can be used in conjunction with soluble factors or genetic approaches to further modulate the behavior of transplanted cells and the locally implanted tissue environment in vivo. We critically assess the advances in bioengineering strategies such as 3-dimensional bioprinting and immunomodulatory biomaterials that can be applied to the treatment of peripheral artery disease and then discuss the current challenges and future directions in the implementation of bioengineering strategies

Aligned-Braided Nanofibrillar Scaffold with Endothelial Cells Enhances Arteriogenesis

The objective of this study was to enhance the angiogenic capacity of endothelial cells (ECs) using nanoscale signaling cues from aligned nanofibrillar scaffolds in the setting of tissue ischemia. Thread-like nanofibrillar scaffolds with porous structure were fabricated from aligned-braided membranes generated under shear from liquid crystal collagen solution. Human ECs showed greater outgrowth from aligned scaffolds than from nonpatterned scaffolds. Integrin α1 was in part responsible for the enhanced cellular outgrowth on aligned nanofibrillar scaffolds, as the effect was abrogated by integrin α1 inhibition. To test the efficacy of EC-seeded aligned nanofibrillar scaffolds in improving neovascularization <i>in vivo</i>, the ischemic limbs of mice were treated with EC-seeded aligned nanofibrillar scaffold; EC-seeded nonpatterned scaffold; ECs in saline; aligned nanofibrillar scaffold alone; or no treatment. After 14 days, laser Doppler blood spectroscopy demonstrated significant improvement in blood perfusion recovery when treated with EC-seeded aligned nanofibrillar scaffolds, in comparison to ECs in saline or no treatment. In ischemic hindlimbs treated with scaffolds seeded with human ECs derived from induced pluripotent stem cells (iPSC-ECs), single-walled carbon nanotube (SWNT) fluorophores were systemically delivered to quantify microvascular density after 28 days. Near infrared-II (NIR-II, 1000–1700 nm) imaging of SWNT fluorophores demonstrated that iPSC-EC-seeded aligned scaffolds group showed significantly higher microvascular density than the saline or cells groups. These data suggest that treatment with EC-seeded aligned nanofibrillar scaffolds improved blood perfusion and arteriogenesis, when compared to treatment with cells alone or scaffold alone, and have important implications in the design of therapeutic cell delivery strategies