Assessment of collagen lattice thickness by B-scan echography

Collagen lattices are an in vitro dermal equivalent that has led to the development of an original model of dermal tissue. Fibroblasts cultured in three-dimensions in a collagen matrix differentiate similarly to in vivo. New technological performances in ultrasonic imaging can now provide precise measurements of tissue thickness with good resolution. The aim of this study was to assess, by B-scan echography, the correlation between collagen lattice thickness and various collagen and cell concentrations.

Three concentrations of human dermal fibroblasts (F1 = 8.10(5)C/mL, F2 = 16.10(5)C/mL, F3 = 32.10(5)C/mL) and three concentrations of rat tail collagen (C1 = 2 mg mL(-1), C2 = 3 mg mL(-1), C3 = 4 mg mL(-1)) were prepared for five different kinds of collagen lattices: F(2)C(1), F(2)C(2), F(2)C(3), F(1)C(1) and F(3)C(1) (n = 5 per case). Ultrasonic imaging was performed on day 0, 4, 6, 10, 12 and 14 using a Dermcup 2020 scanner. The scans measured thickness in the centre and periphery of the lattice.

The collagen lattice echogenicity was similar to a dermis in vivo. For each assessment, the collagen lattice thickness increased until day 12 and then stabilized. The lattice was thicker when the cellular concentration was higher, (at day 14: F(1C1) = 0.66 mm, F(2C1) = 0.86 mm, F(3C1) = 1.21 mm). The collagen concentration did not significantly influence lattice thickness.

Collagen lattice thickness increased with retraction time and cellular concentration.