Effect of media mixing on ECM assembly and mechanical properties of anatomically-shaped tissue engineered meniscus

Abstract

This study investigated the hypothesis that controlled media mixing will enhance tissue formation and increase mechanical properties of anatomically-shaped tissue engineered menisci. Bovine meniscal fibrochondrocytes were seeded in 2% w/v alginate, cross-linked with 0.02 g/mL CaSO4, and injected into molds of menisci. Engineered menisci were incubated for up to 6 weeks. A mixing media bioreactor was designed to ensure proper mixing of culture medium while protecting constructs from the spinning impeller. Impeller speeds were calibrated to produce Reynolds number (Re) of 0.5, 2.9, 5.8, 10.2, and 21.8. Constructs were divided an tested in confined compression and in tension to determine the equilibrium and tensile moduli, respectively. Media stimulation resulted in a 2 to 5 fold increase in mechanical properties and a 2 to 3 fold increase in matrix accumulation in constructs over 6 weeks in culture. Benefits from mixing stimulation for collagen accumulation and compressive modulus appeared to peak near Re 2.9, and decreased with increased mixing intensity. This study suggests that fluid mixing can be optimized to enhance mechanical properties of anatomically-shaped engineered constructs.

Induction of fiber alignment and mechanical anisotropy in tissue engineered menisci with mechanical anchoring

“…The equilibrium and tensile moduli were determined as previously described (Ballyns et al, 2010;Gleghorn et al, 2007;Puetzer and Bonassar, 2013). Briefly, 2-4 4 Â 1 mm 2 plugs from each construct were obtained for compression testing, while radial and circumferential dogbone punches were taken to determine directional tensile properties.…”

Biological Augmentation and Tissue Engineering Approaches in Meniscus Surgery

“…54 There are growing data to show that the use of dynamic culture or fluid mixing can be optimized to modulate the spatial heterogeneity of engineered menisci as well as the correlated mechanical properties. [55][56][57] Compressive deformation or hydrostatic pressure has been shown to enhance the structure and function of engineered meniscus tissues. [58][59][60] Dynamic compression of constructs based on microchanneled scaffolds resulted in aligned cell layers and collagen fibers, 58 whereas hydrostatic pressure combined with TGF-b1 increased collagen and glycosaminoglycan deposition by meniscus cells, ultimately leading to enhanced compressive properties.…”

Meniscus repair and regeneration: review on current methods and research potential

“…Their semi-liquid nature allows engineering anatomic geometries derived from medical imaging techniques, such as computed tomography or magnetic resonance, by the use of custom-printed moulds (Ballyns et al, 2008). Promising results were reported with alginate (Ballyns et al, 2010;Ballyns et al, 2008) and polyvinyl alcohol (PVA) (Kobayashi et al, 2003;Kobayashi et al, 2005). However, despite their wide implementation in cartilage tissue engineering they have been hardly utilised for meniscus engineering.…”

“…This resulted in the formation of circumferential collagen fibres in the peripheral region, associated with higher stiffness in tension, and in increased amounts of GAGs in the central region, associated with higher stiffness in compression. The range of effective mixing intensities, generated by different impeller speeds and quantified by the corresponding Reynolds numbers, was further investigated using anatomically shaped engineered constructs (Ballyns et al, 2010). The findings indicated that fluid mixing can be optimised to modulate the spatial heterogeneity of engineered menisci, as well as the correlated mechanical properties.…”

“…Due in large part to the limited vascularity of the meniscus, which is restricted to the external third, this tissue has a poor healing potential (Arnoczky and Warren, 1982;Arnoczky and Warren, 1983). Although common in the past, total meniscectomy has been largely abandoned, for the direct relationship between meniscectomy and development of early osteoarthritis (Allen et al, 1984;Appel, 1970;Berjon et al, 1991;Ghosh et al, 1990;Hoch et al, 1983;Huckell, 1965;Jackson, 1968;Lufti, 1975;Northmore-Ball and Dandy, 1982;Voloshin and Wosk, 1983). Partial meniscectomy is still indicated if the lesion cannot be satisfactorily sutured (Sommerlath, 1991;Shelbourne and Carr, 2003).…”