Histochemical quantification of collagen content in articular cartilage

Abstract Background: Articular cartilage (AC) is mainly composed of water, type II collagen, proteoglycans (PGs) and chondrocytes. The amount of PGs in AC is routinely quantified with digital densitometry (DD) from Safranin O-stained sections, but it is unclear whether similar method could be used for collagens. Objective: The aim of this study was to clarify whether collagens can be quantified from histological AC sections using DD. Material and methods: Sixteen human AC samples were stained with Masson’s trichrome or Picrosirius red. Optical densities of histological stains were compared to two commonly used collagen parameters (amide I and collagen CH2 side chain peak at 1338cm-1) measured using Fourier Transform Infrared (FTIR) spectroscopic imaging. Results: Optical density of Modified Masson’s trichrome staining, which included enzymatic removal of PGs before staining, correlated significantly with FTIR-derived collagen parameters at almost all depths of cartilage. The other studied staining protocols displayed significant correlations with the reference parameters at only few depth layers. Conclusions: Based on our findings, modified Masson’s trichrome staining protocol is suitable for quantification of AC collagen content. Enzymatic removal of PGs prior to staining is critical as us allows better staining of the collagen. Further optimization of staining protocols may improve the results in the future studies

Vertically aligned carbon nanotube micropillars induce unidirectional chondrocyte orientation

Abstract Articular cartilage is a highly organized tissue with very limited regenerative capacities. One limitation to mimic cartilage structure in tissue engineering is due to specific orientation of chondrocytes. Here, we use vertically aligned multi-wall carbon nanotubes (VA-MWCNT) micropillars to achieve unidirectional orientation of chondrocytes. We demonstrate that the attachment, proliferation and extracellular matrix (ECM) production by the chondrocytes is enhanced on VA-MWCNT micropillars compared to controls. The nanostructures offered by the VA-MWCNT allow the chondrocytes to anchor at cellular structure level, while mechanical flexibility of the VA-MWCNT micropillars mimics the cartilage’s natural ECM Young’s modulus. We exploit these features to extrapolate the contractile forces exerted by the chondrocytes on the micropillars. Our findings will guide the design of VA-MWCNT templates to model cell’s contractile forces. Furthermore, the capability of VA-MWCNTs to induce unidirectional chondrocytes orientation open new perspectives in cartilage tissue engineering

Nanotechnological strategies for osteoarthritis diagnosis, monitoring, clinical management, and regenerative medicine:recent advances and future opportunities

Abstract Purpose of Review: In this review article, we discuss the potential for employing nanotechnological strategies for the diagnosis, monitoring, and clinical management of osteoarthritis (OA) and explore how nanotechnology is being integrated rapidly into regenerative medicine for OA and related osteoarticular disorders. Recent Findings: We review recent advances in this rapidly emerging field and discuss future opportunities for innovations in enhanced diagnosis, prognosis, and treatment of OA and other osteoarticular disorders, the smart delivery of drugs and biological agents, and the development of biomimetic regenerative platforms to support cell and gene therapies for arresting OA and promoting cartilage and bone repair. Summary: Nanotubes, magnetic nanoparticles, and other nanotechnology-based drug and gene delivery systems may be used for targeting molecular pathways and pathogenic mechanisms involved in OA development. Nanocomposites are also being explored as potential tools for promoting cartilage repair. Nanotechnology platforms may be combined with cell, gene, and biological therapies for the development of a new generation of future OA therapeutics

Carbon nanotube micropillars trigger guided growth of complex human neural stem cells networks

Abstract New strategies for spatially controlled growth of human neurons may provide viable solutions to treat and recover peripheral or spinal cord injuries. While topography cues are known to promote attachment and direct proliferation of many cell types, guided outgrowth of human neurites has been found difficult to achieve so far. Here, three-dimensional (3D) micropatterned carbon nanotube (CNT) templates are used to effectively direct human neurite stem cell growth. By exploiting the mechanical flexibility, electrically conductivity and texture of the 3D CNT micropillars, a perfect environment is created to achieve specific guidance of human neurites, which may lead to enhanced therapeutic effects within the injured spinal cord or peripheral nerves. It is found that the 3D CNT micropillars grant excellent anchoring for adjacent neurites to form seamless neuronal networks that can be grown to any arbitrary shape and size. Apart from clear practical relevance in regenerative medicine, these results using the CNT based templates on Si chips also can pave the road for new types of microelectrode arrays to study cell network electrophysiology

Aligned multi-walled carbon nanotube-embodied hydrogel via low magnetic field:a strategy for engineering aligned injectable scaffolds

Abstract Injectable scaffolds are a promising strategy to restore and regenerate damaged and diseased tissues. They require minimally invasive procedure and allow the formation of an in-situ structure of any shape. However, the formation of 3D in-situ structure with aligned morphologies using a method which could be easily transferred to clinical settings remains a challenge. Herein, the rational design of an aligned injectable hydrogel-based scaffold via remote-induced alignment is reported. Carboxylated multi-walled carbon nanotubes (cMWCNT) are aligned into hydrogel via low magnetic field. The uniform dispersion and alignment of cMWCNT into the hydrogel are clearly demonstrated by small angle neutron scattering. The obtained aligned cMWCNT-embodied hydrogel is stable over 7 days at room temperature and as well at body temperature (i.e. 37 °C). As unique approach, the formation of MWCNT-hydrogel composite is investigated combining rheology with molecular dynamic and quantum mechanical calculations. The increase of MWCNT concentration into the hydrogel decreases the total energy promoting structural stabilization and increase of stiffness. The remote aligning of injectable hydrogel-based scaffold opens up horizons in the engineering of functional tissues which requires specific cell orientation