Stretchable 3D cell laden hydrogel microarray platforms for combinatorial screening of cell mechanoresponses

Cells in vivo are constantly subjected to multiple microenvironmental mechanical stimuli that regulate cell function. Although two-dimensional (2D) cell responses to the mechanical stimulation have been established; these methods lack relevance as physiological cell microenvironments are in three-dimensions (3D). Moreover, the existing platforms developed for studying the cell responses to mechanical cues in 3D either offer low throughput, involve complex fabrication, or do not allow the combinatorial analysis of multiple cues. Considering this, a stretchable high-throughput (HT) 3D gelatin methacryloyl (GelMA) microarray platform is presented that can apply dynamic mechanical strain to cells encapsulated in arrayed 3D microgels. The platform uses bioprinting methods such as inkjet and stereolithography (SLA) techniques for printing cell-laden GelMA microgel array on an elastic composite substrate that is periodically stretched. The developed platform is highly biocompatible and transfers the applied strain from the stretched substrate to the cells. The HT analysis is conducted to analyze cell mechano-responses throughout the printed microgel array. Also, different GelMA microenvironmental stiffnesses is provided in addition to the dynamic stretch by inkjet bioprinting different GelMA hydrogel concentrations on the same substrate for the combinatorial analysis of distinct cell behaviors. The composite substrate of the developed platform is also improved to make its surface cell adhesive hence allowing the platform suitable for either 2D, 3D, 2D/3D co-culture cell stretching studies or stretchable microfluidics. The improved substrate is combined with the SLA bioprinting process to print cell-laden GelMA hydrogels with various shapes/geometries for the combinatorial screening of the cell mechanoresponses to both 3D geometry and dynamic stretch. Considering its throughput and flexibility, the developed platform can readily be scaled up to introduce a wide range of microenvironmental cues and to screen the cell responses in a HT way.Applied Science, Faculty ofEngineering, School of (Okanagan)Graduat

High-throughput three-dimensional cellular platforms for screening biophysical microenvironmental signals

Cells in vivo are subjected continuously to multiple biochemical and biophysical stimuli from their microenvironment that regulate cell fate and function. Although two-dimensional (2D) platforms to check cell responses to various microenvironmental factors have been established, these methods lack physiological relevance. Macroscale three-dimensional (3D) cell culture platforms were developed to provide physiologically relevant environments. However, most of these systems failed to analyze the effects of biophysical stimuli on high throughput. Screening microenvironmental factors is essential to mimic an in vitro model of physiological conditions. Multiple trial-and-error methods with a number of experimental conditions are required to analyze the appropriate microenvironmental factors, making the screening process complex, laborious, and expensive. High-throughput (HT) microscale cell culture platforms offer a cost-effective alternative to macroscale 3D cell cultures and allow efficient microenvironmental screening. This chapter introduces a variety of techniques to build microscale 3D cell culture platforms. The different HT and combinatorial platforms investigating the effects of various biophysical cues on cells are discussed in detail. Creating microscale tissue arrays on an HT platform is extremely useful for drug screening when recreating normal or diseased state tissues. These systems could also be extrapolated to incorporate combinations of multiple microenvironmental factors to analyze their synergistic effects on cell behaviors

Procedural and follow-up clinical outcomes after chronic total occlusion revascularization: Data from an Indian public hospital

Background: Chronic total occlusion (CTO) continues to be challenging lesion subset for percutaneous intervention. Last decade has seen tremendous increase in percutaneous coronary intervention (PCI) in this subset owing to improved understanding of the anatomy and enhanced skillset with availability of dedicated hardware. We sought to study the outcomes of CTO PCI in an Indian public hospital. Methods: This was a single-center non-randomized descriptive follow-up study on CTO PCI. The end-points were procedural success, immediate, and late adverse cardiovascular events [major adverse cardiac event (MACE)] and change in angina and left ventricular function at follow-up. Results: A total 389 CTO lesions were treated with a success rate of 87% (339/389). The mean Japanese chronic total occlusion (J-CTO) score was 1.78 ± 0.12 (mean ± standard deviation). Multivariate analysis of different angiographic components of J-CTO score identified tortuosity (p = 0.001), calcifications (p ≤ 0.001), and blunt stump (p = 0.007) as independent predictors of procedural failure. The periprocedural mortality was less than 1%, and the non-life threatening complications were about 4%. The MACE rate was significantly higher in the procedural failure group (60%) than in the procedural success group (5.3%, p < 0.001). An increase in left ventricular ejection fraction (LVEF) was noted following successful CTO PCI after complete revascularization. Conclusions: The success rates for CTO PCI in this registry were about 87%. Immediate and long-term clinical outcomes were better with lower MACE (5%) after a successful procedure. A key outcome variable included an increase in LVEF among patients after a successful CTO PCI. The overall periprocedural complications were about 5.5%, but majority were non-life threatening. Keywords: Total occlusion, Outcomes, Revascularization, Ejection fraction, Antegrade techniqu