Experimental application of xenogenous antlerogenic cells in replacement of auricular cartilage in rabbits

Regenerative medicine in the recent years aims at explaining involvement of stem cells in regenerative processes and applying this knowledge in fulfilling human needs to find new, more efficient therapeutic methods. Growing antlers constitute a model organ for examining regeneration processes of tissues because they are the only mammalian appendages capable of regeneration. The rate of growth of deer antlers makes them one of the quickest growing structures in mammals. The cells taking part in this process have a considerable proliferating potential. The aim of the study was to analyze the possibility of using xenogenous antlerogenic cells (AC) in regeneration of cartilaginous tissues in non-immunosuppressed animals.

We undertook to use a xenogenous implant consisting of cultured antlerogenic mesenchymal cells suspended in hemostatic sponge in the reconstruction of lesions of ear cartilage in nine rabbits. A surgical site was prepared half-way up the outer, dorsal part of the right ear. About 1 cm from the free edge of the ear, a centrally peduncled flap of skin and perichondrium was prepared, measuring 1.5 cm x 1.5 cm. The exposed cartilage was excised in an area of about 1 cm x 1 cm. In the operated rabbits, in the prepared perichondrial pocket, we placed a flake of Spongostan saturated with the suspension of AC. Xenogenous cell survival and regeneration abilities were determined by histologic, immunohistochemical, and electron microscopy analysis of the grafts.

In each case, healing occurred properly and neither local inflammation, necrosis nor implant rejection was observed. The hyaline cartilage lesion was replaced by new fibrous cartilage. This is similar to the histologic process occurring in growing deer antlers. The histologic, immunohistochemical, and electron microscopy analysis demonstrated the presence (and thus possible participation) of exogenous cells in the reconstructive process. At the same time, the immune response was very weak, which was confirmed by immunohistochemical reactions.

Implanted antlerogenic cells were not rejected and possibly took part in the reconstruction of missing sections of the scaffolding of the rabbits' ear cartilages (although the mechanism is yet unknown). Low immunogenicity of AC, simplicity, efficiency, and low costs of production of implant material are the benefits of this method. Further research should unequivocally answer the question whether the MIC-1 cells are or are not the long-sought-after ideal material for the reconstruction of cartilaginous tissue lesions in various species, including human.