SignificanceBrief disruptions in capillary flow, commonly referred to as capillary “stalling,” have gained interest recently for their potential role in disrupting cerebral blood flow and oxygen delivery. Approaches to studying this phenomenon have been hindered by limited volumetric imaging rates and cumbersome manual analysis. The ability to precisely and efficiently quantify the dynamics of these events will be key in understanding their potential role in stroke and neurodegenerative diseases, such as Alzheimer’s disease.AimOur study aimed to demonstrate that the fast volumetric imaging rates offered by Bessel beam two-photon microscopy combined with improved data analysis throughput allows for faster and more precise measurement of capillary stall dynamics.ResultsWe found that while our analysis approach was unable to achieve full automation, we were able to cut analysis time in half while also finding stalling events that were missed in traditional blind manual analysis. The resulting data showed that our Bessel beam system was captured more stalling events compared to optical coherence tomography, particularly shorter stalling events. We then compare differences in stall dynamics between a young and old group of mice as well as a demonstrate changes in stalling before and after photothrombotic model of stroke. Finally, we also demonstrate the ability to monitor arteriole dynamics alongside stall dynamics.ConclusionsBessel beam two-photon microscopy combined with high throughput analysis is a powerful tool for studying capillary stalling due to its ability to monitor hundreds of capillaries simultaneously at high frame rates.
KEYWORDS: Cartilage, Raman spectroscopy, In vivo imaging, Tissues, Tissue engineering, Systems modeling, Non-invasive medical diagnostics, Magnetic resonance imaging, Collagen
Cartilage tissue engineering (TE) is a promising osteoarthritis treatment strategy, whereby cellularized tissue constructs are implanted in cartilage defect sites to promote tissue repair. A significant impediment to developing effective TE strategies is a lack of in vivo diagnostic platforms to monitor engineered cartilage growth. Here, we utilize an ex vivo model system of chondrocyte-seeded tissue constructs, demonstrating the capability of a novel Raman arthroscopic-configured needle probe to monitor the composition and material properties of developing TE cartilage over time. This work supports Raman arthroscopy as a clinical tool for monitoring TE cartilage, providing objective assessments of TE platform efficacies.
This work investigates the capability of a novel Raman arthroscopic needle probe to assess cartilage-tissue-specific biomarkers that are predictive of articular cartilage health during the progression of osteoarthritis. Using ex vivo models of cartilage over a range of degenerative states, we demonstrate that Raman probe-derived biomarkers can predict the composition and material properties of cartilage tissue specimens. This work supports the future use of Raman arthroscopy as an intraarticular clinical platform for ‘molecular assessment’ cartilage to achieve diagnostics of osteoarthritis early in the disease process and assess the efficacy of emerging clinical therapies in restoring cartilage health.
Osteoarthritis (OA) is a painful, debilitating disease characterized by the degeneration of articular cartilage. We have developed a novel multiplexed polarized, hypodermic-needle-compatible Raman arthroscope probe that can achieve intra-articular assessments of the compositional and structural changes to cartilage associated with early-stage OA, including depletion of glycosaminoglycans from the cartilage superficial regions and changes to superficial zone collagen alignment. Through ex vivo models on human and bovine cartilage, we demonstrate that using multivariate linear regression, this platform can accurately measure superficial zone cartilage GAG depletion. This work shows that Raman needle arthroscopy can provide a practical, minimally invasive, point-of-care clinical tool capable of diagnosing OA before irreparable cartilage degeneration is radiographically evident.
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