Through vertex component analysis of hyperspectral imaging data in the visible spectral range, we differentiated erythematous and pigmented areas in patients with cutaneous chronic graft-versus-host disease. We explored the feasibility of hyperspectral imaging in combination with unsupervised learning algorithms to differentiate active disease from inactive post-inflammatory skin changes, a fundamental practice gap in caring for these patients. We compared erythema and pigment maps to the visual assessment by a dermatologist as the ground truth.
Through noninvasive monitoring of leukocyte motion in skin capillaries of patients after hematopoietic cell transplantation, we found increased leukocyte rolling and adhesion prior to clinical signs of disease. In this longitudinal pilot study, we explored the feasibility to detect changes in leukocyte-endothelial interactions that precede acute graft-versus-host disease in patients after hematopoietic cell transplantation. We present the pattern of change in leukocyte rolling and adhesion in three patients over the course of the first 100 days post-transplant. Our preliminary data show increased leukocyte-endothelial interactions prior to clinical signs of any organ acute graft-versus-host disease.
Inflammatory tissue response is one of the first and most common manifestations of acute graft-versus-host disease (aGVHD), a potentially deadly immune-mediated disease that occurs in 30-60% of patients after stem cell transplantation. A fundamental challenge in developing effective treatment strategies for aGVHD is the lack of tools to study disease biology in real-time in post-transplant patients. The inflammatory tissue response causes increased expression of specialized endothelial proteins on vessel walls making leukocytes to roll, adhere and eventually extravasate into the tissue at a higher rate than in normal conditions. Although the importance of leukocyte-endothelial interactions to detect and track inflammation has been well shown in murine models, there are no published clinical studies in humans. In this study, we explore the feasibility to detect presence of aGVHD in post-transplant patients through the imaging of in vivo leukocyte motion. We used a clinical confocal microscope (Vivascope 1500) to acquire videos of 5 aGVHD patients and 5 controls (no aGVHD) within 50±30 days post-transplant. The microscope is capable of real-time imaging of individual cells in the postcapillary vessels at 9 frames per second. Through video analysis, we extracted five quantitative parameters: number and velocity of rolling leukocytes, number of adherent leukocytes (stationary >30 s), blood flow velocity, and number of vessels. In a limited number of subjects, we show that parameters characteristic of the dynamic motion in skin capillaries can be observed noninvasively in post-transplant patients. Further studies are needed to test the diagnostic potential of these parameters.
Leukocyte-endothelial interactions have been well-characterized by intravital microscopy in mice. Quantitative parameters descriptive of these dynamic processes, e.g. the level of leukocyte rolling, adhesion and extravasation, can detect and track inflammation. Despite technology available to study individual cell motion noninvasively in human skin, we are not aware of any published exploratory or clinical studies. In this preliminary study, we explore the feasibility to extract parameters characteristic of individual cell motion in the postcapillary vessels of healthy human skin from videos taken by a noninvasive clinical confocal microscope (Vivascope 1500). The microscope is capable of real-time imaging of individual cells at 9 frames per second. We took videos of ten cutaneous vessels per each of two body sites (volar forearm and upper anterior chest) of ten healthy subjects. We then characterized the dynamic motion of cells via subsequent video analysis by extracting the following parameters: blood flow velocity, number of adherent leukocytes (stationary <30 s), and number and diameter of vessels. We observed variation in blood flow velocity within 1 minute in the same vessel, between vessels within an 8x8 mm field of view, and within two different body sites. Leukocyte adhesion, more commonly associated with inflammatory conditions, can also be observed in healthy skin. Further studies are needed to test the potential of this approach to detect inflammation.
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