Can new optical techniques for in vivo imaging and flow cytometry of the microcirculation benefit sickle cell disease research?

Effects of haemoglobin levels on the sublingual microcirculation in pregnant women

Anemia in pregnant women is associated with increased maternal and perinatal mortality and represents an important economic burden in many developing countries. Our goal was to evaluate the impact of anemia on the capillary network during pregnancy. Therefore, we compared microcirculatory parameters of anemic pregnant study participants to that of non-anemic pregnant women employing sublingual microcirculation video imaging technology and novel automated video analysis software.Non-anemic (n = 7) and anemic (n = 44) pregnant women were enrolled in the study at second and third trimesters. Video imaging was applied to the sublingual mucosal surface in five visual fields. The resultant videos were analyzed automatically, avoiding observer bias. Total vessel density (TVD), perfused vessel density (PVD) and proportion of perfused vessels (PPV) were calculated by the software. Both, mean TVD and PVD were significantly increased in the anemic pregnant group, while the PPV was not significantly different. Significant negative correlations were observed between haemoglobin (Hb) levels and both, TVD and PVD. Haemoglobin level seems to play an important determinant role in restructuring the capillary network. An effect that could compensate the impaired tissue oxygen delivery associated with anemia during pregnancy.

Emerging point-of-care technologies for sickle cell disease screening and monitoring

INTRODUCTION

Sickle Cell Disease (SCD) affects 100,000 Americans and more than 14 million people globally, mostly in economically disadvantaged populations, and requires early diagnosis after birth and constant monitoring throughout the life-span of the patient. Areas covered: Early diagnosis of SCD still remains a challenge in preventing childhood mortality in the developing world due to requirements of skilled personnel and high-cost of currently available modalities. On the other hand, SCD monitoring presents insurmountable challenges due to heterogeneities among patient populations, as well as in the same individual longitudinally. Here, we describe emerging point-of-care micro/nano platform technologies for SCD screening and monitoring, and critically discuss current state of the art, potential challenges associated with these technologies, and future directions. Expert commentary: Recently developed microtechnologies offer simple, rapid, and affordable screening of SCD and have the potential to facilitate universal screening in resource-limited settings and developing countries. On the other hand, monitoring of SCD is more complicated compared to diagnosis and requires comprehensive validation of efficacy. Early use of novel microdevices for patient monitoring might come in especially handy in new clinical trial designs of emerging therapies.

Multicolor multiphoton in vivo imaging flow cytometry

In vivo flow cytometry provides a non-invasive way of probing the biology of circulating cells during disease progression and studying cellular response to therapy. However, current methods provide little morphological information which potentially could be new biological marker for early disease diagnosis, and fail to reveal intercellular interactions. Here we report a multi-color, multiphoton in vivo imaging flow cytometry, to image circulating cells within the vasculature of scattering tissues at high spatiotemporal resolution. We apply it in imaging of cellular dynamics in bone marrow through the intact mouse skull, in situ deformability cytometry, distinguishing cellular clusters, and simultaneously monitoring multiple types of trafficking cells based on their morphologies and fluorescence emission colors.

In vivo flow cytometry: a horizon of opportunities

Flow cytometry (FCM) has been a fundamental tool of biological discovery for many years. Invasive extraction of cells from a living organism, however, may lead to changes in cell properties and prevents studying cells in their native environment. These problems can be overcome by use of in vivo FCM, which provides detection and imaging of circulating normal and abnormal cells directly in blood or lymph flow. The goal of this review is to provide a brief history, features, and challenges of this new generation of FCM methods and instruments. Spectrum of possibilities of in vivo FCM in biological science (e.g., cell metabolism, immune function, or apoptosis) and medical fields (e.g., cancer, infection, and cardiovascular disorder) including integrated photoacoustic-photothermal theranostics of circulating abnormal cells are discussed with focus on recent advances of this new platform.