Time-resolved video analysis and management system for monitoring cardiomyocyte differentiation processes and toxicology assays.

Cardiomyocytes (CM) derived from human embryonic stem cells (hESC) are used for cardio-toxicity evaluation and tested in many preclinical trials for their potential use in regenerative therapeutics. As more efficient CM differentiation protocols are developed, reliable automated platforms for characterization and detection are needed. An automated time-resolved video analysis and management system (TVAMS) has been developed for the evaluation of hESC differentiation to CM. The system was used for monitoring the kinetics of embryoid bodies (EB) generation (numbers and size) and differentiation into beating EBs (percentage beating area and beating EB count) in two differentiation protocols. We show that the percentage beating areas of EBs (from total area of the EBs) is a more sensitive and better predictor of CM differentiation efficiency than percentage of beating EBs (from total EBs) as the percentage beating areas of EBs correlates with cardiac troponin-T and myosin heavy chain expression levels. TVAMS can also be used to evaluate the effect of drugs and inhibitors (e.g. isoproterenol and ZD7288) on CM beating frequency. TVAMS can reliably replace the commonly practiced, time consuming, manual counting of total and beating EBs during CM differentiation. TVAMS is a high-throughput non-invasive video imaging platform that can be applied for the development of new CM differentiation protocols, as well as a tool to conduct CM toxicology assays.

Harnessing spectral property of dual wavelength white LED to improve vertical scanning interferometry.

Unlike a conventional white light source that emits a continuous and broad spectrum of light, the dual wavelength white light emitting diode (LED) generates white light by mixing blue and yellow lights, so there are two distinct peaks in its intensity spectrum. Prior works had shown that the spectral property of the dual wavelength white LED can affect the vertical scanning interferometry negatively if the spectral effects are not compensated. In this paper, we shall examine this issue by modeling the spectral property and variation of the dual wavelength white LED, followed by investigating its effects on the interference signal of vertical scanning interferometry. Instead of compensating the spectral effects of the dual wavelength white LED, we harness its spectral property to improve the performance of a phase-based height reconstruction algorithm in vertical scanning interferometry.

Effects of phosphor-based LEDs on vertical scanning interferometry.

High-power phosphor-based LEDs are replacing conventional white-light sources for vertical scanning interferometry, but the spectrum of the phosphor-based LED is different from that of the conventional light source. The phosphor-based LED has two peaks in its spectrum, while the conventional light source has only one peak in the Gaussian distribution. In this Letter, we investigate the effects of phosphor-based LEDs on vertical scanning interferometry. Our result shows that the use of a phosphor-based LED changes the fringe contrast function significantly, such that measurement repeatability decreases. We propose and demonstrate that a constraint on the input to the existing reconstruction algorithm improves the repeatability of the vertical scanning interferometer with a phosphor-based LED.

Computationally efficient signal modeling for vertical scanning interferometry.

This paper presents a computationally efficient model to simulate the interference signal of vertical scanning interferometry. Existing models are either oversimplified or computationally intensive. Our model incorporates the geometric and spectral effects on vertical scanning interferometry, but removes the computationally intensive numerical integration process by modeling the light spectrum as a sum of piecewise cosine functions. Compared to direct numerical integration of the generalized model, the computational time (for an interference signal) of the proposed model is 256,800 times faster. To verify the accuracy of the proposed model, we simulate the interference signal of a phosphor-based LED, and verify our result with experimental data and a computationally intensive counterpart. Other than reduced computational time, the elementary form of an interference signal derived in this paper will facilitate future work.