Stem cells from anyone?
Jun 08,2007 00:00 by Bend_Weekly_News_Sources
Or­di­nary cells of the body can be “re­pro­grammed” to be­come markedly si­m­i­lar to stem cells, the “mas­ter cells” that can grow in­to many dif­fer­ent or­gans and cure a range of dis­eases, sci­en­tists say.

The find­ings are stir­ring ex­cite­ment be­cause stem cells are nor­mally ob­tain­able only from em­bryos, a pro­cess that or­di­narily kills the em­bryos and is thus fraught with eth­i­cal con­tro­ver­sy.

Re­search­ers have be­gun fig­ur­ing out ways to create stem cells without kil­ling emb­ryos in the past few years. A new ap­proach reported this week both builds and im­proves on some of these strate­gies, and could al­so side­step con­cerns about tis­sue re­jec­tion that ac­com­pa­ny oth­er stem cell treat­ments, re­search­ers said. 

This is be­cause the new pro­ce­dure raises the pos­si­bil­ity of a pa­tient be­ing treated with stem cells from his or her own body, pro­vid­ing an ex­act ge­net­ic match.

Kon­rad Hochedlinger of the Mas­sa­chu­setts Gen­er­al Hos­pi­tal in Boston and col­leagues worked with a pre­vi­ously de­vel­oped tech­nique in which four genes were added to com­mon cells called fi­brob­lasts in mice. Fi­brob­lasts are plen­ti­ful in the skin. In pre­vi­ous stud­ies, the pro­ce­dure had re­sulted in “re-setting” the cells’ ge­net­ic struc­ture to make them si­m­i­lar to stem cells, but with some no­ta­ble dif­fer­ences. 

Hochedlinger’s team com­bined this ap­proach with a new pro­ce­dure that al­lowed them to choose only the gen­er­at­ed cells that met cer­tain ge­net­ic spe­cif­ica­t­ions. This led them to find cells that they called indis­tin­guish­able, based on sev­er­al tests, from em­bry­on­ic stem cells.

Ex­perts cau­tioned that it will still be a long time be­fore such tech­niques can be per­fected and used in hu­mans, but that the re­sults are prom­is­ing.

The re­search­ers went on to show that the newly gen­er­at­ed cells could dif­fer­entiate in­to a wide range of cell types, in­clud­ing blood cells and egg cells. Hochedlinger’s find­ings ap­pear in the in­au­gu­ral July is­sue of a new re­search jour­nal, Cell Stem Cell, an af­fil­i­ate pub­lica­t­ion of the jour­nal Cell.

Two re­lat­ed stud­ies ap­pear in the July 7 is­sue of the jour­nal Na­ture. One of these found that stem-like cells si­m­i­lar to those of Ho­ch­ed­lin­ger’s team could give rise to fer­ti­lized em­bryos, al­though these lat­er died. 

A sec­ond pa­per, by a team in­clud­ing Shinya Ya­manaka of Kyo­to Un­ivers­ity, Ja­pan—who pi­o­neered the tech­nique of us­ing the four genes to re­pro­gram cells—at­tempted to in­ject si­m­i­lar cells in­to early de­vel­op­ing mouse em­bryos. The mice reached adul­thood and the re­pro­grammed cells con­tri­but­ed to and func­tioned in var­i­ous or­gans, they found. A set­back was that 20 per­cent of these mice de­vel­oped can­cer, which was blamed on one of the four genes used in the re­pro­gramming pro­cess, called c-myc.

“There may be ways to over­come this prob­lem,” Ya­manaka and col­leagues wrote. The au­thors of the oth­er Na­ture pa­per, Ru­dolf Jae­nisch of the White­head In­sti­tute for Bi­o­med­i­cal Re­search in Cam­bridge, Mass. and col­leagues, wrote that the find­ings in­di­cate that or­di­nary cells po­ten­tially can be re­pro­grammed to be­come “sim­i­lar, if not iden­ti­cal” to em­bry­on­ic stem cells.

Courtesy World Science