EDITORIAL   

Panminerva Medica 2004 March;46(1):1-11

Copyright © 2009 EDIZIONI MINERVA MEDICA

lingua: Inglese

Circulating stem cells and tissue repair

Hennessy B., Körbling M., Estrov Z.

Department of Bioimmunotherapy and Blood and Marrow Transplantation The University of Texas MD Anderson Cancer Center Houston, Texas, USA

Stem ­cells are ­defined as ­cells ­that ­have clon­o­gen­ic, ­self-renew­ing capac­ities and the capa­bil­ity to dif­fer­en­tiate ­into mul­ti­ple ­cell lin­e­ag­es. Whereas embryon­ic ­stem ­cells are ­derived ­from mam­mal­ian ­embryos in the blas­to­cyst ­stage and can gen­er­ate ter­mi­nal­ly dif­fer­en­tiat­ed ­cells of all 3 embryon­ic ­germ ­layers, ­adult ­human ­stem ­cells are ­capable of main­tain­ing, gen­er­at­ing, and replac­ing ter­mi­nal­ly dif­fer­en­tiat­ed ­cells with­in ­their own spe­cif­ic tis­sue as a con­se­quence of phys­io­log­ic ­cell turn­over or tis­sue inju­ry. The tra­di­tion­al ­idea of ­organ-restrict­ed ­stem-­cell dif­fe­ren­ti­a­tion is now ­being chal­lenged by the sug­ges­tion ­that ­adult ­stem ­cells ­retain devel­op­men­tal plas­tic­ity. Preclinical and clin­i­cal stud­ies ­described in ­this ­review pro­vide evi­dence ­that with­in the ­blood cir­cu­late not ­only pro­gen­i­tor ­cells ­that dif­fer­en­tiate ­into hemat­o­poiet­ic ­cells, but ­also ­stem/pro­gen­i­tor ­cells ­which can par­tic­i­pate in the homeo­sta­sis, ­repair and replace­ment of sol­id ­organ tis­sues. In addi­tion to the occur­rence of ­cell ­fusion, ­there are 4 sug­gest­ed mech­a­nisms of ­adult ­stem ­cell dif­fe­ren­ti­a­tion ­into sol­id ­organ ­cells. Preclinical ­data sup­port ­these mod­els par­tic­u­lar­ly ­that of trans­dif­fe­ren­ti­a­tion as the ­most like­ly mod­el, allow­ing ­stem/pro­gen­i­tor ­cells to dif­fer­en­tiate ­across lin­e­age, tis­sue, and ­germ ­layer boun­dar­ies. There is increas­ing evi­dence ­that we can manip­u­late in ­vivo cir­cu­lat­ing ­adult ­stem ­cells to ­repair or regen­er­ate sol­id ­organ tis­sue, ­which ­offers poten­tial clin­i­cal ben­e­fit in the treat­ment of ­many hered­i­tary and ­acquired dis­eas­es.