The effect of collagen ageing on its structure and cellular behaviour

Collagen is the most important component in extracellular matrix (ECM) and plays a pivotal role in individual tissue function in mammals. During ageing, collagen structure changes, which can detrimentally affect its biophysical and biomechanical properties due to an accumulation of advanced glycation end-products (AGEs). AGEs have been linked to non-enzymatic cross-linking of proteins resulting in the alteration of mechanical properties of the tissue. In this study we investigate the influence of different aged collagens on the mechanical and contractile properties of reconstituted hydrogel constructs seeded with corneal stromal fibroblasts. A non-destructive indentation technique and optical coherence tomography (OCT) are used to determine the elastic modulus and dimensional changes respectively. It is revealed that the youngest collagen constructs have a higher elastic modulus and increased contraction compared to the older collagen. These results provide new insights into the relationship between collagen molecular structures and their biomechanical properties

A microscopic and macroscopic study of aging collagen on its molecular structure, mechanical properties, and cellular response

During aging, collagen structure changes, detrimentally affecting tissues' biophysical and biomechanical properties due to an accumulation of advanced glycation end-products (AGEs). In this investigation, we conducted a parallel study of microscopic and macroscopic properties of different-aged collagens from newborn to 2-yr-old rats, to examine the effect of aging on fibrillogenesis, mechanical and contractile properties of reconstituted hydrogels from these collagens seeded with or without fibroblasts. In addition to fibrillogenesis of collagen under the conventional conditions, some fibrillogenesis was conducted alongside a 12-T magnetic field, and gelation rate and AGE content were measured. A nondestructive indentation technique and optical coherence tomography were used to determine the elastic modulus and dimensional changes, respectively. It was revealed that in comparison to younger specimens, older collagens exhibited higher viscosity, faster gelation rates, and a higher AGE-specific fluorescence. Exceptionally, only young collagens formed highly aligned fibrils under magnetic fields. The youngest collagen demonstrated a higher elastic modulus and contraction in comparison to the older collagen. We conclude that aging changes collagen monomer structure, which considerably affects the fibrillogenesis process, the architecture of the resulting collagen fibers and the global network, and the macroscopic properties of the formed constructs

Mapping and optical image of a birefringent structure.

<p>The poorly soluble foscarnet can be detected and quantified after a mapping of the biopsy thanks to the characteristic peak at 936 cm^-1.</p

Optical image and mapping of BR165 biopsy (scale from blue to red with increasing concentration), and FT-IR spectra of crystals.

<p>a) Optical image of BR165, b) carbapatite map (done at 1030 cm^-1), c) sodium hydrogen urate monohydrate map (done at 3600 cm^-1), d) FT-IR spectra of those compounds.</p

Selected examples of infrared spectra from biopsies.

<p>a) Amorphous silica identified by a band at 1102 cm⁻¹, b) sodium hydrogen urate monohydrate identified by specific bands at 3600 and 1004 cm⁻¹, c) several calcium phosphates including whitlockite (peaks at 1080, 1025 cm⁻¹ and associated shoulders, d) octacalcium phosphate and carbapatite, identified by a shoulder at 1119 cm⁻¹, e) normal tissue, with signal of water (3300 cm⁻¹ and peaks around 1600 cm⁻¹) and proteins (peaks at 2900 cm⁻¹).</p