Biology subjects

Balu, M.

Publications and source records attributed to Balu, M..

5 recordsLinked to original sources

bioRxiv2025

GSLab: Open-Source Platform for Advanced Phasor Analysis in Fluorescence Microscopy

GSLab addresses the need for effective image analysis tools in fluorescence microscopy by providing an open-source platform that enhances traditional phasor analysis with advanced features. Key capabilities include machine learning-based clustering, real-time monitoring, and quantitative unmixing of fluorescent species. Designed for both commercial and custom systems, GSLab provides researchers with comprehensive lifetime and spectral phasor image analysis tools to tackle complex biological problems.

bioinformatics↗

bioRxiv2023

Non-invasive Imaging Techniques for Monitoring Cellular Response to Treatment in Stable Vitiligo

Punch grafting procedures, where small pieces of normal skin are transplanted into stable vitiligo patches, results in repigmentation in only half of patients treated, yet the factors that determine whether a patient responds to treatment or not are still unknown. Reflectance confocal microscopy (RCM) is adept at visualizing melanocyte migration and epidermal changes over large areas while multiphoton microscopy (MPM) can capture metabolic changes in keratinocytes. With the overall goal of identifying optical biomarkers for early treatment response, we followed 12 vitiligo lesions undergoing punch grafting. Dendritic melanocytes adjacent to the graft site were observed before clinical evidence of repigmentation in treatment responsive patients but not in treatment non-responsive patients, suggesting that the early visualization of melanocytes is indicative of a therapeutic response. Keratinocyte metabolic changes in vitiligo skin adjacent to the graft site also correlated with treatment response, indicating that a keratinocyte microenvironment that more closely resembles normal skin is more hospitable for migrating melanocytes. Taken together, these studies suggest that successful melanocyte transplantation requires both the introduction of new melanocytes and modulation of the local tissue microenvironment.

bioengineering↗

bioRxiv2022

Multiscale mapping of in vivo 3D epidermal melanin distribution of human skin using a fast large-area multiphoton exoscope (FLAME)

Melanin plays a significant role in the regulation of epidermal homeostasis and photoprotection of human skin. The assessment of its epidermal distribution and overall content is of great interest due to its involvement in a wide range of physiological and pathological skin processes. Among several spectroscopic and optical imaging methods that have been reported for non-invasive quantification of melanin in human skin, the approach based on the detection of two-photon excited fluorescence lifetime distinguishes itself by enabling selective detection of melanin with sub-cellular resolution, thus facilitating its quantification while also resolving its depth-profile. A key limitation of prior studies on the melanin assessment based on this approach is their inability to account for the skin heterogeneity due to the reduced field of view of the images, which results in high dispersion of the measurement values. Pigmentation in both normal and pathological human skin is highly heterogeneous and its macroscopic quantification is critical for reliable measurements of the epidermal melanin distribution and for capturing melanin-related sensitive dynamic changes as a response to treatment. In this work, we employ a fast large-area multiphoton exoscope (FLAME), recently developed by our group for clinical skin imaging, that has the ability to evaluate the 3D distribution of epidermal melanin content in vivo macroscopically (millimeter scale) with microscopic resolution (sub-micron) and rapid acquisition rates (minutes). We demonstrate significant enhancement in the reliability of the melanin density and distribution measurements across Fitzpatrick skin types I to V by capturing the intra-subject pigmentation heterogeneity enabled by the large volumetric sampling. We also demonstrate the potential of this approach to provide consistent measurement results when imaging the same skin area at different times. These advances are critical for clinical and research applications related to monitoring pigment modulation as a response to therapies against pigmentary skin disorders, skin aging, as well as skin cancers.

bioengineering↗

bioRxiv2021

Multimodal Analyses of Stable Vitiligo Skin Identify Tissue Interactions That Control Disease Persistence

Vitiligo is an autoimmune skin disease that is characterized by the progressive destruction of melanocytes by autoreactive CD8+ T cells. Melanocyte destruction in active vitiligo is mediated by CD8+ T cells but why white patches in stable disease persist is poorly understood. The interaction between immune cells, melanocytes, and keratinocytes in situ in human skin has been difficult to study due to the lack of proper tools. Here, we combine non-invasive multiphoton microscopy (MPM) imaging and single-cell RNA sequencing (scRNA-seq) to identify distinct subpopulations of keratinocytes in lesional skin of stable vitiligo patients. We show that these keratinocytes are enriched in lesional vitiligo skin and differ in metabolism, an observation corroborated by both MPM and scRNA-seq. Systematic investigation of cell-cell communication show that CXCL is the prominent signaling change in this small population of keratinocytes, which secrete CXCL9 and CXCL10 to create local inflammatory cytokine loops with T cells to drive stable vitiligo persistence. Pseudotemporal dynamics analyses predict an alternative keratinocyte differentiation trajectory that generates this new population of keratinocytes in vitiligo skin. In summary, we couple advanced imaging with transcriptomics and bioinformatics to discover cellcell communication networks and keratinocyte cell states that perpetuate inflammation and prevent repigmentation. One Sentence SummaryCommunication between keratinocytes, immune cells, and melanocytes maintain depigmented patches in stable vitiligo.

molecular biology↗

bioRxiv2020

FLAME: Macroscopic imaging with microscopic resolution. Optical biopsy of human skin

We introduce a compact, fast large area multiphoton exoscope (FLAME) system with enhanced molecular contrast for macroscopic imaging of human skin with microscopic resolution. A versatile imaging platform with multiple modes of operation for comprehensive analysis of live or resected thick human skin tissue, it produces 3D images that encompass sub-mm2 to cm2 scale areas of tissue within minutes. The FLAME imaging platform, which expands on a design recently introduced by our group, features deep learning, additional scanning hardware elements and time-resolved single photon counting detection to uniquely allow fast discrimination and 3D virtual staining of melanin. We demonstrate its performance and utility by fast ex vivo and in vivo imaging of human skin. With the ability to provide rapid access to depth resolved images of skin over cm2 area and to generate 3D distribution maps of key sub-cellular skin components such as melanocytic dendrites and melanin, FLAME represents a promising imaging tool for enhancing diagnosis accuracy, guiding therapy and understanding skin biology.

bioengineering↗