融资意外地拯救了被遗弃的干细胞试验
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Funding ｗinｄfaｌｌ rｅscuｅｓ abandｏｎed ｓtem－ceｌl trial A ｌａndmark stem－ｃell ｔrｉal is sputtering back tｏ liｆe ｔwo－and-a-haｌf yeａｒｓ aｆtｅr?it was abａnｄoned ｂｙ tｈe Califｏrnia
company tｈaｔ starteｄ it. But it now fａceｓ a
ｆreｓｈ set of challenｇes, includｉng ａ field thaｔ is ｐaｃked ｗｉth cｏmpetitoｒs．?Ｔhe ｔrial aｉmｓ to tｅsｔ whether cellｓ
deｒived fｒoｍ humａn eｍbrｙonic ｓｔeｍ?cells can hｅlp nervｅs ｔo regrow iｎ cａseｓ
of spinａｌ-cｏrd ｉｎjury. It ｗａｓ ｓtopped
abrｕｐtly iｎ 20１１ bｙ Geｒon ofＮature 479, ４５9; ２0１１); ｔhｅfｉrｍ
ｓaid at the ｔime that it
wanted ｔo ｆocuｓ on sｅveral?pｒomisｉnｇ cancer tｒeａｔmｅｎts
ｉnsteaｄ. Nｏw, a neｗ compａｎy
— Ａｓtｅｒｉaｓ Ｂiothｅraｐｅｕtics， ａｌso oｆ Ｍenｌｏ Ｐaｒk — pｌans ｔo resuｒrｅct
the trｉaｌ with a US＄14.3－million?gｒant tｈat it rｅceiｖed oｎ 2９ Ｍay frｏm the
Ｃalifornｉa Insｔiｔute for Regｅneratiｖe Medicinｅ?(ＣIRM)， ｔhe ｓｔate’s stｅｍ-ｃｅll-funｄing agency. Bｕt tｈe ｆiｅld has moｖed ｏｎ sinｃe Ｇeron
treaｔｅｄ ｉｔｓ first pａtienｔ in ２010, aｎd the therapｙ?thａt Asterias inｈerited iｓ ｎo lｏnger thｅ ｏｎlｙ?pｏssibｉlity for spｉｎal-corｄ injｕry. StemCells, a biotechnｏlogｙ ｃoｍｐａny in Newarｋ, Caｌiｆｏrnia， has ｔrｅated 12 patients iｎ a safeｔy ｓtuｄy
oｆ a difｆerent tyｐe ｏf steｍ cｅll, anｄ it pｌaｎs ｔo?start ａ moｒｅ advaｎceｄ trｉal tｈｉs year to tｅst effectiveness. And anｏtｈｅr entraｎt ｔo ｔhe?field， Neｕｒaｌｓteｍ ｏf Gerｍaｎtown, Maryｌaｎｄ,
ｒeceｉveｄ regulａtory apｐroval iｎ January 201３
to beｇiｎ ｈuｍan ｔesｔs of its stｅm-cｅll ｐroduct.?Gｅron’s hｕmａn trial ｗas ｔhｅ ｆirｓt ａpproveｄ tｏ?usｅ ceｌｌs dｅrｉved from human embｒｙoｎic ｓｔeｍ?cｅlｌｓ. But reｇulatｏrs hａlted it twｉcｅ, once cｉｔ
ing?concerns about the ｐurity ａnｄ ｐredictａｂiｌitｙ ｏf the cｅllｓ ｂｅing iｍplantｅd, ａnd ａｇａｉn aｆteｒ the compaｎｙ ｒeｐorteｄ seeing microscopiｃ cｙsts in?the ｓｐｉnal ｃoｒｄs ｏｆ raｔｓ ｔhat ｈad been treaｔeｄ iｎ?ｐｒeclinｉｃal studｉｅｓ. Ｔhe worry was thａt ｔhｅ cysts couｌd ｂe terａtomas — uncｏnｔrolｌed grｏｗths
thａｔ can fｏrm fｒom ｅｍｂryｏｎic stem cells, a
feared side ｅffecｔ of treａtmｅnt． Geｒｏｎ lａter said?ｔhat the growtｈs werｅ noｔ teratｏ
mas, and the?US Food and Ｄｒug Admｉｎｉsｔration aｌlowｅｄ ｔｈe
triａl to proceed． But ａｆｔeｒ injeｃtiｎg the celｌｓ inｔo?fiｖe of the ｔeｎ inｔｅndeｄ pａtientｓ, the cｏｍｐany
sａiｄ ｔhat it hａｄ ruｎ ouｔ of moｎey for the triaｌ.?Geron ｆoｕndｅｒ Mｉchael West aｎd formｅｒ
ｃhｉef exeｃuｔｉve Ｔhomas Oｋａrma thｅｎ foｒmed?Aｓterias， whｉch boｕght Gｅronв??s ｓteｍ-cell?thｅrap
ｙ last year. The coｍｐany pｌaｎs ｆirsｔ ｔo?treat tｈree ｐatiｅnts ｗｉｔｈ spinal-cord ｄaｍａｇe?in ｔh
ｅ neck， using a ｌoｗ dose ｏf tｈe stem ｃｅｌls; it will theｎ ｔｒeａt difｆereｎt peｏple witｈ higheｒ?ｄoses ｔo sｅe ｉｆ tｈe tｈｅｒapy can ｒｅｓtｏre ａny sｅnsａtion?ｏｒ fuｎctｉoｎ iｎ thｅ trｕnｋ oｒ ｌimｂs.?Ｔｈe fivｅ patients ｐrevｉoｕslｙ treaｔed ｂy?Geron， whom Asterｉas coｎtinueｓ tｏ tｒaｃｋ, had
cord dａmage at cheｓt level. On 22 Ｍay, Asteriaｓ
reｐoｒｔed thaｔ noｎe oｆ thosｅ fｉve ｈad ｅxｐerｉenceｄ seｒiｏus side effectｓ from the tｒeatment or deｖeｌoｐｅd immunｅ ｒesponseｓ tｏ it.
Researcｈerｓ ｓaｙ ｔｈat ｔｈe contｉnuａtion oｆ ｔhｅ
foｒｍｅr Geｒoｎ triａl is iｍportant becａuse it uses?a tｙpｅ of ｃell diffeｒent from thｅ fetｕｓ-derｉved?ｏnｅs used ｂy ＳteｍCellｓ and Neurａlsteｍ. Geron?sｕｒ
gically impｌanted embrｙoｎｉc sｔeｍ ceｌls thaｔ?ｈad ｂeeｎ ｃoａｘed ｉｎ vitｒo ｔｏ grow inｔｏ imｍature
myeｌinａted gｌial ｃｅlls, wｈich inｓuｌatｅ neｒve?fibrｅs when maturｅ. The ｏther cｏmpanies aｒe?using partiａlｌy diffｅrentiatｅd cells ｄerived from
ｆetal brａｉｎ ｔｉssuｅ, ｗhich might produce ｓuｂstａnｃes that pｒotｅｃt survivinｇ ｔissue anｄ make?new ｃonｎecｔions in tｈｅ neural cirｃuitry.?в??Itв??s ｖery goｏｄ for the fiｅld, becausｅ wｅ now
ｈave ｍultiｐｌe celｌ lｉnes ｂｅing testｅd in very simiｌａr?ｐoｐulatioｎｓ ｏf patｉｅnts, ａnｄ ｔｈis ｗiｌl hｅlp us
defｉne what is ｎeeded to mａkｅ ｔｈis appｒoacｈ?work,в?? sａys Maｒｔin Marsaｌａ, a neuｒoscｉeｎｔiｓt
ｔhe Universｉty of Caｌｉfｏｒnｉａ, San Ｄiego,
whose work hａs ｓhown ｔhat Nｅuralｓｔｅm’s cells
ｃａｎ dｅvelop iｎto workiｎg neurons and resｔoｒe?movｅment to rats ｗith ｃord iｎｊｕries iｎ the necｋ.?Sｔiｌl， ｓome in the ｆｉelｄ questiｏｎ whethｅr?sｔem cells ａｒe a ｇｏod cａｎｄidａte for treａｔiｎｇ?paｒalysis. Spinal traumａ ｃan destroy ａ rａnｇｅ
oｆ cells; iｔ caｎ ｂe ｄiffiｃuｌｔ tｏ acｃｅｓｓ ｔhe ｉnjurｙ?ｓiｔｅ; anｄ damage can be verｙ ｓｅvere． Trｅatiｎg paralyｓis “ｍay be askinｇ ａ lot moｒe oｆ
tｈe ｃｅlls ｔｈaｎ they are capabｌｅ of biｏｌogicaｌly”， sａyｓ Roｂeｒt Laｎｚa, cｈief scientｉfic?offｉcer ａt Ａdvanｃed Cｅll Technolｏgy iｎ Maｒlｂorough,?Maｓsａchusetts, ｗｈich ｉs now ｔｅsting?eｍbryo-ｄerived stem cｅlls in tw
ｏ eye diseases.?Lanza ｓayｓ that his company oｐted noｔ tｏ?buy Geｒon’ｓ stem-cｅll theｒａpｙ iｎ part beｃausｅ?the treａtmenｔ did nｏt seem ｅｆfｅｃｔiｖe enｏｕｇh
ｉn anｉmal moｄelｓ. Sｏme ｏf the scienｔists wｈｏ?reｖｉｅwed Asteｒiａs’s gｒant pｒoposal to the?CＩＲＭ also exｐｒeｓsed ｃonｃern ａbｏut the treatmｅｎt’s?effeｃtivｅneｓs ｉｎ aｎiｍalｓ． “It woulｄ ｂe
faｎtａstic if [the celｌｓ] wｏｒk, but I ｔｈｉｎｋ iｔ wouｌd
aｌso bｅ ｗise ｎot to ｓet exｐectations too high,” ｓays Lanｚａ.?Maｒsalａ cｏunters thaｔ the ceｌls dｏ noｔ haｖe
to heal the ｓｐｉnal cｏｒｄ cｏmpｌeｔｅly to ｉmｐrove pｅoｐle’s lives. He nｏtｅs thaｔ simpｌy replacing injurｅd ｏr dead cｅlｌｓ wiｔh ｈealthｙ oneｓ migｈ
t?prevent thｅ damaｇe froｍ ｓpreaｄing. StｅmCellｓ?has reｐorteｄ ｔhat ｆour people in its stｕdiｅs havｅ?recｏverｅd some sensatiｏｎ; ｔwo ｐrevｉoｕsly hａｄ
no ｆeｅliｎg in tｈeiｒ ｌoweｒ ｌimｂs and another two?hａｄ some but were able to ｆeeｌ mｏrｅ after tｈｅ?ceｌｌ tranｓplant. Marsala ｓeｅs thｉｓ ａs a ｓｉgn tｈat ｔhｅ ｔhｅrapy ｉｓ ｗorkiｎg. “Nobody is ｃlaiｍing
tｈａt ｙｏu are going ｔo seｅ coｍplｅｔｅ rｅcoｖery iｎ?ｔhese ｐatｉｅnｔｓ,” he says．?Chriｓｔophｅr Scotｔ, an ethｉciｓt at Sｔanford?Unｉvｅｒsiｔｙ in Califｏｒnia, sａｙ
融资意外地拯救了被遗弃的干细胞试验
