A novel fabrication method to create a thick collagen bundle composed of uniaxially aligned fibrils: An essential technology for the development of artificial tendon/ligament matrices

Abstract

In this study, we developed a fabrication method for thick collagen gel bundles comprising uniaxially aligned fibrils of sufficient size for filling defects in ligament tissues. The fabrication involved rotary shearing to dense collagen sols using a rheometer and then warming them from 23°C to 37°C to trigger gelation upon rotation. Gelation due to collagen fibril formation was accelerated by increased concentrations of neutral phosphate buffer, and fibril alignment occurred within 20 s during the early stage of rapid gelation. Fabrication of gels was completed with slippage between gels and the movable upper plate, and well-aligned fibrils along the rotation direction were observed in the marginal regions of disc-shaped gels. Gel thickness could be increased from 1 to 3 mm with homogeneous alignment of fibrils in the entire sample. The alignment of fibrils improved mechanical properties against tensile loads that were placed parallel to the alignment axis. Elongation of cultured fibroblast along the alignment was observed on the gels. The present method will enable the bottom-up fabrication of an artificial tendon for ligament reconstruction and repair.

In situ gelation properties of a collagen–genipin sol with a potential for the treatment of gastrointestinal ulcers

“…Temperature-responsive gelation of collagen sols was evaluated using dynamic viscoelastic tests in the oscillation mode under controlled deformation (frequency, 1 Hz; shear deformation, 0.005) with a double-cone sensor, according to previously described methods15 with minor modifications. Briefly, temperature was maintained at 23°C for 5 min, was increased from 23°C to 37°C over 30 s to trigger gelation, and was then maintained at 37°C to promote gelation.…”

“…Retention of fluidity of collagen sols at constant temperatures (23°C or 30°C) was evaluated using dynamic viscoelastic tests in the oscillation mode under controlled stress (frequency, 1 Hz; shear stress, 0.01–1 Pa) according to a previously described method15 with minor modifications. Briefly, shear stresses were determined in advance using stress sweep tests to provide a linear viscoelastic regimen, and retention of fluidity of collagen sols was determined according to gelation times ( tg 23 or tg 30 ), which were defined as the time to reach the gel point at a constant temperature of 23°C or 30°C.…”

“…Mechanical properties of collagen gels were evaluated using penetration tests with a mechanical tester (TA.XT plus; Stable Micro Systems, Godalming, UK) according to previously described methods15 with slight modifications. Briefly, aliquots (3 g/well) of collagen sols were poured into six-well biological plates (well diameter, 35 mm) and were placed on the surface of a water bath at 37°C.…”

A novel method for continuous formation of cord‐like collagen gels to fabricate durable fibers in which collagen fibrils are longitudinally aligned

“…The gelation of the neutral collagen sols was measured by rotational tests using a parallel‐plate rheometer equipped with a Peltier temperature controller (HAAKE MARS III; Thermo Fisher Scientific, Waltham, MA), by a slightly modified version of a method described in our previous article . The gelation occurs as a function of collagen fibril formation; therefore, the gelation reflects collagen fibril formation when the collagen concentration is constant.…”

“…Recently, we conducted a series of studies to develop cord‐like collagen gels comprised of collagen fibrils preferentially aligned along the geometrical axes (such a collagen gel was designated “CCG”). In our previous study, we found that a millimeter‐sized disc‐shaped collagen sheet, in which collagen fibrils are concentrically aligned, can be fabricated from neutral collagen sols by applying shear deformation (shear rate 2–10 s −1 ) to the sol using a parallel‐plate rheometer with a gap of 1 mm at 37°C. This finding suggested that collagen fibril alignment and gelation of neutral collagen sol can be completed in a cylinder by applying adequate shear deformation to the collagen sol, allowing for continuous ejection of CCG from the cylinder.…”