[Experimental study on human collagen and autologous fat injected into canine vocal cords]

To explore the histological fate of human collagen and autologous fat injected into vocal cords in treating glottic insufficiency.

Human collagen and autologous fat were injected respectively into two dogs(group A) to correct glottic incompetence caused by left vocal cord paralysis. Autologous fat and human collagen 0.3 ml were injected respectively into left and right vocal cords of 9 dogs (B, C, D groups, 3 dogs in each group). These animals were killed after 1, 3 and 5 months. The histology, volume and curative effect of both substances were evaluated.

Autologous fat grafts survived in the canine vocal cords after 5 months but the absorption was rapid. The average speed of reduction in volume was 38.51% from 1 to 5 months and the effect of treatment couldn't last long. Human collagen was easily injected and well-tolerated. The injected collagen was colonized by host fibroblasts and capillaries. At the same time, new host collagen deposited. There was a trend to allow the eventual replacement of the implant by new host tissue. The average speed of reduction in volume was 0.65% and the curative effect was constantly stable from 1 to 5 months.

The results suggested that autologous fat has only a potential use for short-term(< 5 months) augmentation of vocal cord. Human collagen can be used as long-term augmentative material to manage glottic insufficiency caused by various etiologies.