CLONAL CELL-CULTURES FROM ADULT SPINAL-CORD OF THE AMPHIBIAN URODELE PLEURODELES WALTL TO STUDY THE IDENTITY AND POTENTIALITIES OF CELLS DURING TAIL REGENERATION

The urodele amphibians are nearly the only adult vertebrates able to r egenerate their missing or amputated tail. The most striking feature o f this model lies in the ability of the spinal cord (SC) to differenti ate, within the regenerating tail, a new ependymal tube from which the SC and the peripheral nervous system originate. A fundamental questio n is whether, in response to tail excision, the ependymoglia of the ol d SC stump behaves as an embryonic neuroepithelium. To evaluate this p ossibility, cell lines from primary cell cultures of adult SC were est ablished for the first time in newts, and two cell clones, immunochemi cally characterized as ependymoglial cell populations, could be obtain ed. To analyze the potentialities of these clonal cells, after transpl antation in tail regenerates, cell-marking experiments, using either i n vitro transfection with lacZ gene or the lineage tracer lysinated rh odamine dextran (LRD), were performed. One to 2 weeks postimplantation , most of labeled derivatives were identified as melanocytes. Interest ingly, labeled cells were also seen integrated in the ependymoglia of the regenerating SC. Two to 6 weeks after implantation in young regene rates, we also observed LRD-labeled elongated cells close to nerves or myofibers which were unambiguously identified as Schwann cells by gal actocerebroside staining. Taken together, these findings showed that c lonal cells derived from adult newt SC cultures could largely find, in regenerate mesenchyme, suitable environmental conditions to different iate into melanocytes or Schwann cells. Because these two cell types a rise from neural crest cells during embryogenesis, this supports the i nteresting view that multipotent cells are still present in the SC of adult urodeles. (C) 1996 Wiley-Liss, Inc.