| Show Preliminary Studies Show Adult Stem Cells Show Revived Promise Karen Kaplan Los Angeles Times Several recent scientific studies suggest that adult stem cells can produce a range of tissues reviving prospects that many benefits of embryonic stem cells could be realized without the accompanying moral and regulatory pitfalls The studies are preliminary preliminary preliminary nary and have not been validated validated validated vali vali- dated by other laboratories But they give a lift to a field that has been largely dismissed dismissed dismissed dis dis- dis- dis missed by many leading researchers as a medical dead end Unlike embryonic stem cells which have enormous medical promise because they can grow into every tissue tissue tissue sue type in the body adult stem cells are narrowly focused on regenerating a single type of tissue Scientists have theorized it might be possible to turnback turnback turn turnback back their developmental clocks and retrain them to behave more like embryonic cells The new results lend some credence to that view At a teaching hospital affiliated with Tufts University School of Medicine stem cells extracted extract extract- ed from human bone marrow helped rebuild heart muscle and blood vessels in rats At AntiCancer Inc a biotech company in San Diego researchers induced stem cells from mouse hair follicles follicles follicles folli folli- cles to become neurons At Atthe Atthe Atthe the University of Indiana scientists transformed stem cells from mouse bone marrow marrow marrow mar mar- row into nerve cells that facilitate hearing But some proponents of embryonic stem cells say they are are e nc vince vinced r their colleagues have unlocked any new abilities of adult stem cells partly because past experiments have failed to stand the test of time Extraordinary claims require extraordinary evidence evidence evidence evi evi- dence said Larry Goldstein who studies embryonic stem cells at the University of California San Diego School of Medicine and the Howard Hughes Medical Institute Adult stem cells are alluring alluring alluring ing to medical research because they are easy to collect collect collect col col- col- col lect and offer the possibility of treating patients with their own cells avoiding problems of tissue rejection They also raise no ethical dilemmas because they can be created without destroying destroying destroying destroy destroy- ing any embryos That trait has endeared them to social conservatives who promote the latest research as a justi- justi f t f f t h ton iv i or ii J. res t U e creation of new embryonic stem cell lines The human body contains a variety of adult stem cells typically found in places that require frequent tion For instance stem cells in bone marrow produce red blood cells platelets lymphocytes lymphocytes lymphocytes lym lym- and other kinds of blood cells But the cells are limited In their natural state they cant can't transform into the full range of tissue types that embryonic stem cells can produce Scientists call this phenomenon plasticity The ultimate goal of stem cell research is to harness their tissue-making tissue abilities to grow replacement parts for patients Doctors could treat patients with juvenile diabetes for example by growing new islet cells capable capable capable capa capa- ble of making insulin Adult stem cell research looked promising ising several I ag especially ly rafter ter Dr Catherine th ii e illie and anda a team of scientists at the University of Minnesota reported in a 2002 issue of the journal Nature that mes- mes cells which are found in bone marrow could be persuaded to produce bone fat muscle blood liver intestinal and neuron- neuron like cells But the studies by and others were attacked by some prominent stem cell researchers Among them was Dr Irving director of Stanford University's stem cell institute who failed in attempts to repeat the early studies Instead he published published published pub pub- several papers debunking claims of adult stem cell plasticity The new studies have been conducted with the past critiques critiques critiques cri cri- cri- cri in mind Their tentative indications A n n 1 nt t U e Ual a a Jat anger J. J porn adult stem cells are not as rigid as once thought Even though we dont don't have all the is Ts dotted andSt's and andYs Ys ts crossed its it's kind of hard for me to believe that all of ofus ofus ofus us see things that dont don't exist said To begin with researchers have started to make headway headway headway head head- way in reproducing the broad strokes of past studies Alan Sim Mackay-Sim deputy director of the Institute forCell forCell for forCell Cell and Molecular Therapies at Griffith University in Brisbane Australia studies adult stem cells from the sensing odor-sensing region of the human nose and he suspected the stem cells would be able to produce produce produce pro pro- duce neurons through a relatively relatively relatively rela rela- straightforward regeneration regeneration regeneration regen regen- mechanism What startled him was the discovery of a smattering of liver and heart muscle cells He realized he had reproduced reproduced reproduced some aspects of an earlier paper th on stem cells from mouse brains Effectively what were we're saying is weve we've repeated it said Sim Mackay-Sim who published published published pub pub- his findings last month in the journal Developmental Dynamics Its really exciting to see that A group of researchers in Boston has made significant progress in corroborating some of the results of 2002 article that I drew so much early interest in the field Dr Douglas Losordo chief of cardiovascular research at St. St Elizabeths Elizabeth's Medical Center the Tufts teaching hospital and his team started with samples of bone marrow and eliminated any cell that already started to make proteins indicating that it had set off on a preordained preordained preordained destiny The remaining remaining remaining remain remain- ing cells were isolated in laboratory dishes where most of them died Those that survived were grown in culture Losordo hoped they would multiply without differentiating into specific kinds of tissue he said Altogether they isolated nn nine Hn nac of nf adult stem d m r IL u LA VI 1 capable of producing a wide range of tissues Other labs are working to reproduce the study which was published in February in the Journal of Clinical Investigation Our interest in this is therapeutic so if were we're the only lab that can do it its it's useless Losordo said We want to see it turn into a process that can be replicated ed on a large scale Scientists dont don't fully understand the chemical reactions behind their One theory is that the cells may have forgotten what they were programmed to make and regressed to an earlier developmental state when their options were more plentiful But after eliminating all known cell types Losordo thinks he may have stumbled upon a different kind of adult stem cell that behaves like an embryonic stem cell The cells may in fact be remnant rem- rem nant of oLe early development that were never channeled toa toa to toa a particular destiny The idea that you have stem cells residing in most organs as a leftover from opens up a whole new vista said Joel Glover a physiology professor sor at the University of Oslo in Norway who turned stem cells from human blood into neurons by injecting them into chicken embryos People weren't thinking in those lines before I |
