Hyaluronate likely contributes to the immunesuppression of the regenerating tail blastema in lizards: Implications for organ regeneration in amniotes

Abstract
The regenerating tail blastema of lizards appears immunesuppressed, and the distribution of hyaluronate, a possible agent of immunesuppression, is evaluated. Transcriptome data show upregulation of genes stimulating hyaluronate production in the tail and limb blastemas. The distribution of hyaluronate in the tail and limb blastemas has been studied using alcian blue at pH 2.5 and 1.0 and by immunohistochemistry for hyaluronate receptors. Both tail and limb blastemas initially contain hyaluronate, but this glycosaminoglycan disappears in the scarring limb blastema at 25‐ to 30‐day postamputation after intense inflammation. The regenerating tail tip moves distally during regeneration but conserves hyaluronate that is replaced by sulphated glycosaminoglycans and glycoproteins in proximal regions of the regenerating tail. Hyaluronate receptors are diffuse among blastema cells and ependyma of the tail, intense in wound epidermis but low to absent in the scarring limb. The electron microscope shows that an amorphous extracellular matrix likely containing hyaluronate surrounds mesenchymal cells, ependyma and wound epidermis in the tail but is scarce to absent in the limb, whereas collagen fibrils prevail. Extracellular matrix containing hyaluronate may shield blastema cells from circulating immune cells preventing deleterious immune reactions in the tail but not in the limb, a process leading to scarring.

Source: Acta Zoologica - July 1, 2017 Category: Zoology Authors: Lorenzo Alibardi Tags: ORIGINAL ARTICLE Source Type: research