Influence of freezing rate on pore structure in freeze-dried collagen-GAG scaffolds

Addition of hyaluronic acid improves cellular infiltration and promotes early-stage chondrogenesis in a collagen-based scaffold for cartilage tissue engineering

“…CG scaffolds were fabricated using a freeze-drying method that has been previously described (O'Brien et al, 2004). CCS scaffolds were composed of collagen type I derived from bovine Achilles tendon (Collagen Matrix, USA) and CS derived from shark cartilage (Sigma-Aldrich, Arklow, Ireland).…”

Influence of flow rate and scaffold pore size on cell behavior during mechanical stimulation in a flow perfusion bioreactor

“…Scaffolds were fabricated in accordance with a previously developed protocol (O'Brien et al, 2004). Briefly, a CG suspension was created by blending micro-fibrillar bovine tendon collagen (Integra Life Sciences, Plainsboro, NJ) with chondroitin-6-sulphate sodium salt, respectively .…”

“…To date, the authors are unaware of any studies directed at evaluating the detachment of cells cultured on highly porous scaffolds in response to fluid-flow. Highly porous scaffolds contain exceedingly irregular geometries as a consequence of the freeze drying (Mandal and Kundu, 2008;O'Brien et al, 2004) or salt leaching (Kim et al, 2005) fabrication processes, resulting in non-uniform flow profiles that make shear stress characterisation very challenging. Furthermore, technical limitations in visualising cells internally within the construct, means correlating cell detachment to the magnitude of shear stress at the point of detachment is exceptionally difficult.…”

Influence of a novel calcium-phosphate coating on the mechanical properties of highly porous collagen scaffolds for bone repair

“…Collagen scaffolds were fabricated from a collagen suspension using a freeze drying method that has been previously described (O'Brien et al 2004, O'Brien et al 2005, Yannas et al 1989. The collagen suspension was produced from microfibrillar type I collagen, isolated from bovine tendon (Integra Life-Sciences, Plainsboro, NJ, USA) suspended in 0.05M acetic acid.…”

“…Natural collagen scaffolds coated with HA or CP have been investigated using a bi-phasic immersion process with promising results in terms of their biological performance (Du et al 2000, Yaylaoglu et al 1999. However, this study used commercially available collagen sheets with initial porosities of 50-60% which is very low compared to collagen sheets developed by O'Brien et al (2004) with a porosity of 99.5%. Such low porosities reduce cell migration into the scaffold and limit nutrient perfusion to, and diffusion of waste products from the cells reducing the potential of such materials for tissue engineering applications.…”