Biology subjects

Albro, M. B.

Publications and source records attributed to Albro, M. B..

6 recordsLinked to original sources

bioRxiv2026

Raman-probe-derived biomarkers account for cartilage composition, structure, and viscoelastic properties

Raman spectroscopy is an inelastic light scattering technique that reflects the vibrational modes of the biochemical building blocks of the major constituents that comprise the cartilage extracellular matrix (ECM): glycosaminoglycans (GAG), type-II collagen (COL), and water. We investigated whether ECM-specific biomarkers measured with our recently developed arthroscopy-compatible Raman needle probe characterize the functional viscoelastic properties of articular cartilage explants. Equine osteochondral explants were harvested from high-load (femoral condyle) and low-load (intertrochlear groove) sites to evaluate Raman-derived biomarkers of cartilage structure and function. Viscoelastic material properties (equilibrium/dynamic modulus, phase shift) were determined by mechanical indentation. A computational fibril-reinforced biphasic material model was used to estimate the glycosaminoglycan-associated non-fibrillar-matrix modulus, the collagen-associated fibril-network modulus, and hydraulic permeability. Raman-derived biomarkers enabled evaluation of cartilage tissue composition and structure, accounting for 81% of the variation in GAG content, 53% of the variation in COL content, and 58% of the variation in COL anisotropy. Biomarkers also accounted for 81% of the variation in equilibrium modulus, 58% in dynamic modulus, and 51% in phase shift. For poroelastic properties, biomarkers accounted for 83% of the variation in non-fibrillar-matrix modulus, 25% of the variation in fibril-network modulus, and 34% of the variation in hydraulic permeability. Clinical Significance: Raman spectroscopy provides objective compositional biomarkers that account for viscoelastic material properties underlying articular cartilage function. These findings support its future use as an arthroscopic platform for objective assessment of cartilage injury, monitoring of disease progression, and evaluation of therapeutic interventions.

bioengineering↗

bioRxiv2026

Arthroscopic Raman Probe Provides Biomarkers of TMJ Tissue Composition that Account for Tissue Function

Background: Temporomandibular joint (TMJ) disorders affect up to 25% of the population and may require diverse surgical interventions. However, intraoperative decision-making relies largely on visual assessment, which does not quantitatively characterize tissue composition or mechanical function. Raman spectroscopy offers a nondestructive approach to molecular-level tissue characterization, but its application to TMJ tissues remains unvalidated. Methods: An arthroscopy-compatible Raman probe was used to characterize mandibular condyles (n=15 porcine, n=11 human) and human articular discs (n=7). Raman-derived biomarkers associated with glycosaminoglycans (GAG), collagen (COL), water (H2O), and hydroxyapatite (HA) were evaluated against condylar indentation modulus and disc tensile modulus. Arthroscopic measurements in cadaveric TMJs assessed technical feasibility, while hyperspectral Raman imaging characterized spatial compositional distributions. Results: For condylar cartilage, combined GAG and H2O biomarkers accounted for 86% of the variation in indentation modulus (R2=0.86), compared with 4% for Outerbridge grading (R2=0.04). For articular discs, combined proline and water-associated biomarkers accounted for 88% of the variation in tensile modulus (R2=0.88). Raman spectra acquired in situ under simulated arthroscopic conditions were comparable in quality to ex vivo measurements. Raman imaging revealed distinct compositional patterns in healthy and degenerated tissues, including GAG depletion and cartilage thinning in degenerated condylar cartilage. Conclusions: Raman-derived biomarkers are strongly associated with TMJ cartilage and disc mechanical properties and outperform Outerbridge grading in explaining variation in condylar indentation modulus. Arthroscopic Raman spectroscopy is technically feasible and may complement visual assessment by providing objective compositional information to support future development of tissue-informed surgical decision-making.

pathology↗

bioRxiv2025

A Bio-inspired Latent TGF-β Conjugated Scaffold Improves Neocartilage Development

In cartilage tissue engineering, active TGF-{beta} is conventionally supplemented in culture medium at highly supraphysiologic doses to accelerate neocartilage development. While this approach enhances cartilage extracellular matrix (ECM) biosynthesis, it further promotes tissue features detrimental to hyaline cartilage function, including the induction of tissue swelling, hyperplasia, hypertrophy, and ECM heterogeneities. In contrast, during native cartilage development, chondrocytes are surrounded by TGF-{beta} configured in a latent complex (LTGF-{beta}), which undergoes cell-mediated activation, giving rise to moderated, physiologic dosing regimens that enhance ECM biosynthesis while avoiding detrimental features associated with TGF-{beta} excesses. Here, we explore a bio-inspired strategy, consisting of LTGF-{beta}-conjugated scaffolds, providing TGF-{beta} exposure regimens that are moderated and uniformly administered throughout the construct. Specifically, we evaluate the performance of LTGF-{beta} scaffolds to improve neocartilage development with bovine chondrocyte-seeded agarose constructs compared to outcomes from active TGF-{beta} media supplementation (MS) at a physiologic 0.3 ng/mL dose (MS-0.3), supraphysiologic 10 ng/mL dose (MS-10), or TGF-{beta} free. For small-size constructs ({emptyset}3x2 mm), LTGF-{beta} scaffolds yield neocartilage that achieves native-matched mechanical properties (800-925 kPa) and sGAG content (6.6%-7.1%), while providing a cell morphology and collagen distribution more reminiscent of hyaline cartilage. LTGF-{beta} scaffolds further afford an optimal chondrogenic phenotype, marked by a 12-to 28-fold reduction of COL-I expression relative to TGF-{beta}-free and a 7-to 17-fold reduction of COL-X expression relative to MS-10. Further, for large-size constructs, which approach the dimensions needed for clinical cartilage repair, LTGF-{beta} scaffolds significantly reduce mechanical and biochemical heterogeneities relative to MS-0.3 and MS-10. Overall, the use of LTGF-{beta} scaffolds improves the composition, structure, material properties, and cell phenotype of neocartilage.

bioengineering↗

bioRxiv2023

Physiologic Doses of TGF-beta Improve the Composition of Engineered Articular Cartilage

For cartilage regeneration applications, transforming growth factor beta (TGF-{beta}) is conventionally administered at highly supraphysiologic doses (10-10,000 ng/mL) in an attempt to cue cells to fabricate neocartilage that matches the composition, structure, and functional properties of native hyaline cartilage. While supraphysiologic doses enhance ECM biosynthesis, they are also associated with inducing detrimental tissue features, such as fibrocartilage matrix deposition, pathologic-like chondrocyte clustering, and tissue swelling. Here we investigate the hypothesis that moderated TGF-{beta} doses (0.1-1 ng/mL), akin to those present during physiological cartilage development, can improve neocartilage composition. Variable doses of media-supplemented TGF-{beta} were administered to a model system of reduced-size cylindrical constructs (O2-O3 mm), which mitigate the TGF-{beta} spatial gradients observed in conventional-size constructs (O4-O6 mm), allowing for a novel assessment of the intrinsic effect of TGF-{beta} doses on macroscale neocartilage properties and composition. The administration of physiologic TGF-{beta} to reduced-size constructs yields neocartilage with native-matched sGAG content and mechanical properties while providing a more hyaline cartilage-like composition, marked by: 1) reduced fibrocartilage-associated type I collagen, 2) 77% reduction in the fraction of cells present in a clustered morphology, and 3) 45% reduction in the degree of tissue swelling. Physiologic TGF-{beta} appears to achieve an important balance of promoting requisite ECM biosynthesis, while mitigating hyaline cartilage compositional deficits. These results can guide the development of novel physiologic TGF-{beta}-delivering scaffolds to improve the regeneration clinical-sized neocartilage tissues.

bioengineering↗

bioRxiv2023

Label-free 3-D molecular imaging of living tissues using Raman Spectral Projection Tomography

The ability to image tissues in three-dimensions (3-D) with label-free molecular contrast at mesoscale would be a valuable capability in biology and biomedicine. Here, we introduce Raman spectral projection tomography (RSPT) for volumetric molecular imaging with sub-millimeter spatial resolution. We have developed a RSPT imaging instrument capable of providing 3-D molecular contrast in transparent and semi-transparent samples. A computational pipeline for multivariate reconstruction was established to extract label-free spatial molecular information from Raman projection data. We demonstrate imaging and visualization of phantoms of various complex shapes with label-free molecular contrast. Finally, we apply RSPT as a novel tool for imaging of molecular gradients and extracellular matrix heterogeneities in fixed and live tissue-engineered constructs and explanted native tissues. RSPT imaging opens new possibilities for label-free molecular monitoring of tissues.

bioengineering↗

bioRxiv2021

Raman Needle Arthroscopy for In Vivo Molecular Assessment of Cartilage

The development of treatments for osteoarthritis (OA) is burdened by the lack of standardized biomarkers of cartilage health that can be applied in clinical trials. We present a novel arthroscopic Raman probe that can "optically biopsy" cartilage and quantify key ECM biomarkers for determining cartilage composition, structure, and material properties in health and disease. Technological and analytical innovations to optimize Raman analysis include: 1) multivariate decomposition of cartilage Raman spectra into ECM-constituent-specific biomarkers (glycosaminoglycan [GAG], collagen [COL], water [H2O] scores), and 2) multiplexed polarized Raman spectroscopy to quantify superficial zone collagen anisotropy via a PLS-DA-derived Raman collagen alignment factor (RCAF). Raman measurements were performed on a series of ex vivo cartilage models: 1) chemically GAG-depleted bovine cartilage explants (n=40), 2) mechanically abraded bovine cartilage explants (n=30), 3) aging human cartilage explants (n=14), and 4) anatomical-site-varied ovine osteochondral explants (n=6). Derived Raman GAG score biomarkers predicted 95%, 66%, and 96% of the variation in GAG content of GAG-depleted bovine explants, human explants, and ovine explants, respectively (p<0.001). RCAF values were significantly different for explants with abrasion-induced superficial zone collagen loss (p<0.001). The multivariate linear regression of Raman-derived ECM biomarkers (GAG and H2O scores) predicted 94% of the variation in elastic modulus of ovine explants (p<0.001). Finally, we demonstrated the first in vivo Raman arthroscopy assessment of an ovine femoral condyle through intraarticular entry into the synovial capsule. This work advances Raman arthroscopy towards a transformative low cost, minimally invasive diagnostic platform for objective monitoring of treatment outcomes from emerging OA therapies.

bioengineering↗