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First baby born from eggs matured in lab, frozen

Related research could lead to preserving reproductive abilities in childhood cancer survivors 

July 2, 2007
Special to World Science  

The first ba­by to be cre­at­ed from an egg that was ma­tured in the lab­o­r­a­to­ry, fro­zen, thawed and then fer­ti­lised has been born in Can­a­da, sci­en­tists re­port.

An ova­ry con­tains many fol­li­cles, egg-con­taining struc­tures that grow and de­vel­op be­tween pu­ber­ty, mat­u­ra­tion, and men­o­pause. When a wom­an is fer­tile, each month a fol­li­cle trav­els to the sur­face of the ova­ry, bursts, and re­leases an egg in prep­a­ra­tion for fer­ti­li­za­tion. The im­age above shows fol­li­cles which along with their eggs are in var­i­ous stages of de­vel­opment. Pri­mor­di­al fol­li­cles are the form that is pre­s­ent at birth and through­out child­hood. The ovaries al­so con­tain small num­bers of cor­pus lutea, or burst fol­li­cles, which pro­duce the preg­nan­cy hor­mone pro­ges­ter­one. (Im­age cour­tesy US Nat'l In­s­ti­tutes of Health)


The ex­peri­ment­al fer­ti­lity treat­ment also re­sult­ed in three other preg­nan­cies, they add­ed. The re­search was pre­sented at the an­nu­al meet­ing of the Eu­ro­pe­an So­ci­e­ty of Hu­man Re­pro­duc­tion and Em­bry­ol­o­gy in Ly­on, France on Ju­ly 2.

The healthy ba­by girl was born to a pa­tient with poly­cys­tic ovar­i­an syn­d
­rome, a con­di­tion that can dis­rupt a wom­an’s men­s­tru­al cy­cle, abi­l­ity to have chil­dren, hor­mones and cir­cula­t­ion, the re­search­ers said. 

Twen­ty pa­tients di­ag­nosed with the syn­drome or re­lat­ed con­di­tions took part in a tri­al at Mc
­Gill Re­pro­duc­tive Cen­ter in Mont­real.

Freez­ing a wom­an’s eggs, or oo
­cytes, has be­come an “in­te­gral part of fer­til­ity treat­ment,” said the cen­ter’s Ha­n­a­nel Hol­zer, who led the team. New freez­ing tech­niques have boosted egg sur­viv­al and preg­nan­cy rates, he added. 

But preg­nan­cies re­ported to date have re­sulted from fer­tilisa­t­ion of fro­zen, then thawed eggs col­lect­ed af­ter wom­en’s ovaries had been stim­u­lat­ed to pro­duce eggs. And this can’t be done in some pa­tients.

In these cases, sci­en­tists can col­lect im­ma­ture eggs and ma­ture them in the lab­o­r­a­to­ry be­fore freez­ing them, Holzer said. But be­fore now it was­n’t known wheth­er such eggs could sur­vive thaw­ing and lead to suc­cess­ful preg­nan­cies.

“We have dem­on­strat­ed for the first time that it is pos­si­ble to do this and, so far, we have achieved four suc­cess­ful preg­nan­cies, one of which has re­sulted in a live birth,” he said. The re­sults are pre­lim­i­nary, he added, “and the preg­nan­cy rate is probably as­so­ci­at­ed with a learn­ing curve—three of the preg­nan­cies were achieved in the last five pa­tients.”

The team se­lected pa­tients with an av­er­age age of 30, and who were al­so infer­tile. The meth­od still is­n’t shown to work in can­cer pa­tients, Holzer added.

But in a re­lat­ed stu­dy, to be an­nounced at the same con­fer­ence on July 3, anoth­er team of sci­en­tists say they’ve made prog­ress to­ward pre­serv­ing fer­til­ity in child­hood can­cer sur­vivors—ob­tain­ing and freez­ing eggs from girls as young as five years.

Ar­i­el Rev­el of Ha­das­sah Un­ivers­ity Hos­pi­tal in Je­ru­sa­lem, a mem­ber of the team, said the grow­ing num­ber of sur­vivors of child­hood can­cers means such tech­niques would be­come in­creas­ingly im­por­tant. Child­hood can­cers tend to have rel­a­tively good cure rates, of 70 to 90 per­cent. But the ag­gres­sive chemoth­erapy usu­ally leads to steril­ity.

In adult wom­en, ovaries can be stim­u­lat­ed to pro­duce eggs that are re­moved, fer­ti­lised and fro­zen. In young girls this is­n’t pos­si­ble. Doc­tors in­stead typ­ic­ally freeze egg-producing tis­sue of the ovaries for trans­planta­t­ion at a lat­er date. But freez­ing of­ten dam­ag­es the tis­sue, called ovar­i­an cor­tex.

As an al­ter­na­tive, Rev­el and col­league col­lect­ed and froze in­di­vid­ual eggs from the tis­sue, which are more cold-resistant, they said. To their sur­prise, the team found eggs in girls be­tween five and 10 years old who had not reached pu­ber­ty, and were able to ex­tract these with a nee­dle. “No eggs have yet been thawed”, said Dr.Rev­el, “so we do not know wheth­er preg­nan­cies will re­sult. But we are en­cour­aged by our re­sults so far.”


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The first baby to be created from an egg that was matured in the laboratory, frozen, thawed and then fertilised has been born in Canada, scientists report. Three other women are pregnant by the same process, they added. The research was presented to the annual meeting of the European Society of Human Reproduction and Embryology in Lyon, France on July 2. The healthy baby girl was born to a patient with polycystic ovarian syndrome, a condition that can disrupt a woman’s menstrual cycle, ability to have children, hormones and circulation, the researchers said. Twenty patients diagnosed with the syndrome or a related condition took part in a trial at McGill Reproductive Center in Montreal. “Freezing a woman’s eggs, or oocytes, has become an important and integral part of fertility treatment,” said the center’s Hananel Holzer, who led the team. New freezing techniques have boosted egg survival and pregnancy rates, he added. But pregnancies reported to date have resulted from fertilisation of frozen, then thawed eggs collected after women’s ovaries had been stimulated to produce eggs. And this can’t be done in some patients. In these cases, scientists can collect immature eggs and mature them in the laboratory before freezing them, Holzer said. But before now it wasn’t known whether such eggs could survive thawing and lead to successful pregnancies. “We have demonstrated for the first time that it is possible to do this and, so far, we have achieved four successful pregnancies, one of which has resulted in a live birth,” he said. The results are preliminary, he added, “and the pregnancy rate is probably associated with a learning curve—three of the pregnancies were achieved in the last five patients.” The team selected patients with an average age of 30, and who were also infertile. The method still isn’t shown to work in cancer patients, Holzer added. But in a related study, to be announced at the same conference on July 3, another team of scientists say they’ve made progress toward preserving fertility in childhood cancer survivors—obtaining and freezing eggs from girls as young as five years. Ariel Revel of Hadassah University Hospital in Jerusalem, a member of the team, said the growing number of survivors of childhood cancers means such techniques would become increasingly important. Childhood cancers tend to have relatively good cure rates, of 70 to 90 percent. But the aggressive chemotherapy usually leads to sterility. In adult women, ovaries can be stimulated to produce eggs that are removed, fertilised and frozen. In young girls this isn’t possible. Doctors instead typically freeze egg-producing tissue of the ovaries for transplantation at a later date. But freezing often damages the tissue, called ovarian cortex. As an alternative, Revel and colleague collected and froze individual eggs from the tissue, which are more cold-resistant, they said. To their surprise, the team found eggs in girls between five and 10 years old who had not reached puberty, and were able to extract these with a needle. “No eggs have yet been thawed”, said Dr.Revel, “so we do not know whether pregnancies will result. But we are encouraged by our results so far.”