Laser speckle imaging of flowing blood: A numerical study

Exploration of Chick Embryo and Chorioallantoic Membrane on Imaging Navigated Platforms for Anticancer Pharmaceutical Evaluations

Conforming to the current replace-reduce-refine 3Rs' guidelines in animal experiments, a series of explorative efforts have been made to set up operable biomedical imaging-guided platforms for qualitative and quantitative evaluations on pharmacological effects of tumor vascular-disrupting agents (VDAs), based on the chick embryos (CEs) with its chorioallantoic membrane (CAM), in this overview. The techniques and platforms have been hierarchically elaborated, from macroscopic to microscopic and from overall to specific aspects. A protocol of LED lamplight associated with a new deep-learning algorithm was consolidated to screen out weak CEs by using the CAM vasculature imaging. 3D magnetic resonance imaging (MRI) and laser speckle contrast imaging (LSCI) to monitor the evolution of CE and vascular changes in CAM are introduced. A LSCI-CAM platform for studying the effects of VDAs on normal and cancerous vasculature of CAM and possible molecular mechanisms has been demonstrated. Finally, practical challenges and future perspectives are highlighted. The aim of this article is to help peers in biomedical research to familiarize with the CAM platform and to optimize imaging protocols for the evaluation of vasoactive pharmaceuticals, especially anticancer vascular targeted therapy.

Development and characterization of a chick embryo chorioallantoic membrane (CAM) based platform for evaluation of vasoactive medications

Among various anti-cancer therapies, tumor vascular disrupting agents (VDAs) play a crucial role, for which their off-targeting effects on normal vessels need also to be investigated. The purpose of this study was to set up an in-ovo platform that combines a laser speckle contrast imaging (LSCI) modality with chick embryo chorioallantoic membrane (CAM) to real-time monitor vascular diameters and perfusion without and with intravascular injection. Two eggshell windows for both observation or measurement and injection were opened. Dynamic blood perfusion images and corresponding statistic graphs were acquired by using a LSCI unit on CAMs from embryo date (ED) 9 to ED15. A dedicated fine needle catheter was made for slow intravascular administration over 30 min with simultaneous LSCI acquisition. To verify the connectivity between CAM vessels and the embryonic circulations in the egg, contrast-enhanced 3D micro computed tomography (μCT), 2D angiography and histology were executed. This platform was successfully established to acquire, quantify and demonstrate vascular and hemodynamic information from the CAM. Chick embryos even with air cell opened remained alive from ED9 to ED15. Through collecting LSCI derived CAM vascular diameter and perfusion parameters, ED12 was determined as the best time window for vasoactive drug studies. A reverse correlation between CAM vessel diameter and blood perfusion rate was found (p < 0.002). Intravascular infusion and simultaneous LSCI acquisition for 30 min in ovo proved feasible. Contrast-enhanced angiography and histomorphology could characterize the connectivity between CAM vasculature and embryonic circulation. This LSCI-CAM platform was proved effective for investigating the in-ovo hemodynamics, which paves the road for further preclinical research on vasoactive medications including VDAs.

Utilisation of Chick Embryo Chorioallantoic Membrane as a Model Platform for Imaging-Navigated Biomedical Research

The fertilised chick egg and particularly its chorioallantoic membrane (CAM) have drawn continuing interest in biomedicine and bioengineering fields, especially for research on vascular study, cancer, drug screening and development, cell factors, stem cells, etc. This literature review systemically introduces the CAM's structural evolution, functions, vascular features and the circulation system, and cell regulatory factors. It also presents the major and updated applications of the CAM in assays for pharmacokinetics and biodistribution, drug efficacy and toxicology testing/screening in preclinical pharmacological research. The time course of CAM applications for different assays and their advantages and limitations are summarised. Among these applications, two aspects are emphasised: (1) potential utility of the CAM for preclinical studies on vascular-disrupting agents (VDAs), promising for anti-cancer vascular-targeted therapy, and (2) modern imaging technologies, including modalities and their applications for real-time visualisation, monitoring and evaluation of the changes in CAM vasculature as well as the interactions occurring after introducing the tested medical, pharmaceutical and biological agents into the system. The aim of this article is to help those working in the biomedical field to familiarise themselves with the chick embryo CAM as an alternative platform and to utilise it to design and optimise experimental settings for their specific research topics.

Experimental study of speckle patterns generated by low-coherence semiconductor laser light

Speckle is a wave interference phenomenon that has been studied in various fields, including optics, hydrodynamics, and acoustics. Speckle patterns contain spectral information of the interfering waves and of the scattering medium that generates the pattern. Here, we study experimentally the speckle patterns generated by the light emitted by two types of semiconductor lasers: conventional laser diodes, where we induce low-coherence emission by optical feedback or by pump current modulation, and coupled nanolasers. In both cases, we analyze the intensity statistics of the respective speckle patterns to inspect the degree of coherence of the light. We show that the speckle analysis provides a non-spectral way to assess the coherence of semiconductor laser light.