Ze­brafish of­fers hope for spinal cord re­pair

Kuwait Times - - HEALTH -

WASHINGTON:

The Ze­brafish, which can com­pletely re­gen­er­ate its sev­ered spinal cord, might hold prom­ise for re­search into tis­sue re­pair in hu­mans, re­searchers said Thurs­day. Sci­en­tists are look­ing at one pro­tein in par­tic­u­lar that is key to this ac­com­plish­ment in the fish, the re­searchers said. “This is one of na­ture’s most re­mark­able feats of re­gen­er­a­tion,” said the study’s se­nior in­ves­ti­ga­tor Ken­neth Poss, a pro­fes­sor of cell bi­ol­ogy at Duke Univer­sity.

“Given the lim­ited num­ber of suc­cess­ful ther­a­pies avail­able to­day for re­pair­ing lost tis­sues, we need to look to an­i­mals like ze­brafish for new clues about how to stim­u­late re­gen­er­a­tion,” said Poss, whose study was pub­lished in the jour­nal Science.

When the sev­ered spinal cord of the ze­brafish un­der­goes re­gen­er­a­tion, a bridge forms. Nerve cells fol­low and within eight weeks new nerve tis­sue has plugged the gap, al­low­ing the fish to re­verse their paral­y­sis com­pletely, the Poss team re­ported.

To fig­ure out what is go­ing on, sci­en­tists searched for all of the genes whose ac­tiv­ity abruptly changed af­ter spinal cord in­jury. Seven of these were found to code for pro­teins se­creted from cells. One of these pro­teins, called CTGF-con­nec­tive tis­sue growth fac­tor-was in­trigu­ing be­cause its lev­els rose in sup­port­ing cells that formed the bridge in the first two weeks fol­low­ing in­jury.

When the pro­tein was deleted ge­net­i­cally, those fish failed to re­gen­er­ate. Peo­ple and ze­brafish share many genes, and hu­man CTGF pro­tein is nearly 90 per­cent sim­i­lar in its amino acid com­po­nents to that of ze­bra fish.

In­sert­ing hu­man CTGF into the in­jury site in fish helped the re­gen­er­a­tion process. “The fish go from par­a­lyzed to swim­ming in the tank. The ef­fect of the pro­tein is strik­ing,” said Mayssa Mokalled, a post­doc­toral fel­low in Poss’s group.

But CTGF alone is prob­a­bly not enough for peo­ple to re­gen­er­ate their spinal cords, the team said. The process is more com­plex in mam­mals, in part be­cause scar tis­sue forms around an in­jury. Fu­ture stud­ies will look at mice to de­ter­mine which of their cells ex­press CTGF, the team said. Re­searchers also plan to look at other pro­teins in­volved in the re­gen­er­a­tion process in ze­brafish.—AFP

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