Effects of the Human Amniotic Membrane on the Cartilage Graft: Prognosis and Absorption in White Rabbits

Abstract

Background: Cartilage grafts are generally accepted for the restoration and reconstruction of nasal contours. The main concern that plastic surgeons may need to address after surgery pertains to the resorption and disfigurement of the grafted cartilage, especially in allogenic and heterogenic grafts.

Methods: A total of 12 white rabbits were divided into three groups according to the types of graft including autograft, allograft, and heterograft. We used three shapes of grafts, including block, crushed, and diced cartilage in the upper, middle, and lower rows. However, in each rabbit, these grafts were divided into two columns of wrapped and unwrapped grafts, with human amniotic membrane (HAM) grafted on each side of the rabbit's back.

Results: In total, 60 specimens underwent histopathological examination. No inflammation was observed in about 50% of the block-shaped conchal cartilages with HAM, and in 50%, less than 25 inflammatory cells per unit were seen. The prognosis and absorption of autograft specimens in block-shaped cartilages with HAM were significantly better compared with other shapes of cartilages with HAM and without HAM. The proliferation rate of fibroblasts in autograft and allograft specimens was more than that in heterograft specimens with HAM.

Conclusion: Our findings have demonstrated the new role of HAM in clinical applications, indicating that HAM may be used as a low-cost, easily accessible alternative for wrapping in cartilage grafts instead of fascia or surgicel in early future. It is useful for improving the long-term outcomes and decreasing the resorption rate.

Keywords: Amniotic membrane; Cartilage; Graft; Rabbit.

Fig. 1

Illustrations of the methodology for preparation and placing of cartilages. Six subcutaneous pockets were created 3 cm from back midline and 5 cm from each other (A). Right column wrapped and left column is bare grafts. Upper row block grafts, middle row crushed grafts that made by hemostate and inferior row diced grafts (B)

Fig. 2

Histology of the different shapes of cartilages with different staining. Matrix demonstrates Safranin-O uptake by the matrix, which is an important evidence of viability of the diced fragments of HAM wrapped in autograft (Safranin-O, ×200) (A). Complete cartilage resorption and replacement by inflamed and neovascularized fibrous tissue in block and crushed heterograft (H&E, ×200, ×400) (B and C). Fibroblast prolifation in diced unwrapped allograft (Verhoeff–Van Gieson, ×200) (D). Positive immunoreactivity for Glial fibrillary acidic protein in crushed HAM Wrapped autogrft cartilage indicating a regeneration capacity (Verhoeff–Van Gieson, ×400) (E)