Characterisation of freeze-dried type II collagen and chondroitin sulfate scaffolds

Abstract

Collagen type-II is the dominant type of collagen in articular cartilage and chondroitin sulfate is one of the main components of cartilage extracellular matrix. Afibrillar and fibrillar type-II atelocollagen scaffolds with and without chondroitin sulfate were prepared using casting and freeze-drying methods. The scaffolds were characterised to highlight the effects of fibrillogenesis and chondroitin sulfate addition on viscosity, pore structure, porosity and mechanical properties. Microstructure analysis showed that fibrillogenesis increased the circularity of pores significantly in collagen-only scaffolds, whereas with it, no significant change was observed in chondroitin sulfate-containing scaffolds. Addition of chondroitin sulfate to afibrillar scaffolds increased the circularity of the pores and the proportion of pores between 50 and 300 μm suitable for chondrocytes growth. Fourier transform infrared spectroscopy explained the bonding between chondroitin sulfate and afibrillar collagen- confirmed with rheology results- which increased the compressive modulus 10-fold to 0.28 kPa. No bonding was observed in other scaffolds and consequently no significant changes in compressive modulus were detected.

Monomeric, porous type II collagen scaffolds promote chondrogenic differentiation of human bone marrow mesenchymal stem cells in vitro

“…Comparing characteristics of 1af scaffolds to those of our previously characterised type II scaffolds (Table 2-some data reproduced with permission for comparison17), many properties, including the compressive modulus of 1af scaffolds were comparable to that of 2af scaffolds. Scaffold stiffness may affect stem cell fate32 and porosity has been shown to regulate cellular behaviours42, including adhesion and ingrowth.…”

“…Chondroitin sulfate A (from bovine trachea) was purchased from Sigma-Aldrich (Poole, Dorset, UK). Type-I and II porous collagenous matrices were prepared as previously described17. Briefly, pure afibrillar collagen solutions (type I and II) were produced by adding lyophilised monomers to dilute acetic acid (pH 3.2) to achieve a 0.5% (w/v) solution.…”

“…We characterised 1af scaffolds according to our previously described methods17 for comparison to 2af, 2af-CS, 2rf and 2rf-CS conditions. Briefly, compression testing was performed on a Perkin Elmer Dynamic Mechanical Analyzer 7e at a strain rate of 3.5%/min to determine compressive modulus (n = 5).…”

“…Isolated collagen triple helices are “monomeric”, whereas extractions of collagen with a retained fibrillar structure are “polymeric”. Monomeric forms of collagen may be free of telopeptides (atelocollagen) or have the telopeptides intact (tropocollagen), whilst the polymeric form is insoluble and is composed of naturally cross-linked tropocollagen17. The majority of collagenous scaffolds181920 for TE are fabricated using polymeric collagen due to the ease and low cost of its extraction.…”

“…We have previously produced and characterised monomeric type II collagen–CS scaffolds17 and reported on their microstructure and mechanical properties. Here, we also produced atelocollagen afibrillar type I scaffolds and investigated the effect of collagen type and the incorporation of CS on cellular behaviour and their potential to direct stem cell differentiation in the absence of chemical induction or growth factors (Fig.…”