Test­ing stem cells in tini­est hearts to fight birth de­fect

Kuwait Times - - HEALTH & SCIENCE -

BAL­TI­MORE: The 4-month-old on the op­er­at­ing ta­ble has a shock­ing birth de­fect, nearly half his heart too small or even miss­ing. To save him, sur­geons will have to to­tally reroute how his blood flows, a dras­tic treat­ment that doesn’t al­ways work. So this time they are go­ing a step fur­ther. In a bold ex­per­i­ment, doc­tors in­jected do­nated stem cells di­rectly into the healthy side of Jo­sue Sali­nas Sal­gado’s lit­tle heart, aim­ing to boost its pump­ing power as it com­pen­sates for what’s miss­ing. It’s one of the first at­tempts in the US to test if stem cells that seem to help heart at­tack sur­vivors re­pair car­diac mus­cle might help these tini­est heart pa­tients, too.

“We think the young heart is able to be more re­spon­sive,” said Dr. Sun­jay Kaushal, chief of pe­di­atric car­diac surgery at the Univer­sity of Mary­land Med­i­cal Cen­ter, who is lead­ing the study in part­ner­ship with Univer­sity of Miami re­searchers. Kaushal bent over the baby’s right ven­tri­cle, the part of the heart that will take over for the ab­nor­mal left side. The sur­geon had re­paired as much as pos­si­ble for now. Next he mea­sured where to place eight shots of pre­cious stem cells. Then the bustling op­er­at­ing room went silent as Kaushal helped fel­low sur­geon Dr. Si M. Pham guide tiny nee­dles into the ven­tri­cle’s mus­cle.

“We’re not say­ing we’re go­ing to cure it,” Kaushal said of the birth de­fect, called hypo plas­tic left heart syn­drome. But, “my whole quest is to see if we can make these lit­tle kids do bet­ter.” Jo­sue’s par­ents knew there was no guar­an­tee the ex­per­i­men­tal in­jec­tions would make a dif­fer­ence. But their son had been hos­pi­tal­ized since birth and needed open-heart surgery any­way for a chance to go home. Teary-eyed, they clasped hands and prayed over Jo­sue’s crib mo­ments be­fore nurses wheeled him to the op­er­at­ing room. “We are march­ing ahead with God,” said Jo­sue’s fa­ther, Hidel­berto Sali­nas Ramos, speak­ing in Span­ish through a hospi­tal in­ter­preter. Nearly 1,000 ba­bies are born with hypo plas­tic left heart syn­drome in the US each year.

Un­der­ly­ing prob­lem

It’s the most com­plex car­diac birth de­fect. Jo­sue is miss­ing his left ven­tri­cle, the main pump­ing cham­ber that pushes oxy­gen-rich blood to the body. Other key struc­tures on his heart’s left side are too small or mal­formed to work. Al­ways lethal un­til a few decades ago, this de­fect now is treated with three open-heart surg­eries per­formed be­tween birth and age 3. Doc­tors route blood around the ab­nor­mal left heart and they con­vert the right ven­tri­cle which nor­mally would shut­tle oxy­gen-poor blood to the lungs - into the main pump­ing cham­ber. To­day, about 65 per­cent sur­vive at least five years, and many reach adult­hood, said Dr. Kristin Burns, a pe­di­atric car­di­ol­o­gist at the Na­tional In­sti­tutes of Health.

But too many chil­dren still die or re­quire a heart trans­plant be­cause the right ven­tri­cle wears out un­der its in­creased work­load. That’s why doc­tors are con­duct­ing this early-stage study of whether stems cells might help that ven­tri­cle work bet­ter. “This is very dif­fer­ent than a sur­gi­cal ap­proach or giv­ing a medicine just to treat the symp­toms. This is try­ing to treat the un­der­ly­ing prob­lem,” said Burns, of NIH’s Na­tional Heart, Lung and Blood In­sti­tute. “I know you’re re­ally ner­vous,” Kaushal told Jo­sue’s fa­ther, plac­ing a hand on his shoul­der. “Ev­ery­thing is go­ing to be fine.” Just 4 months old, Jo­sue was un­der­go­ing his sec­ond open­heart surgery.

The first op­er­a­tion, a day af­ter his birth, was a tem­po­rary fix to keep his heart pump­ing and cre­ate an aorta, the main artery lead­ing to the body, big enough for blood to flow. While he bab­bled hap­pily at his fam­ily and nurses, Jo­sue never got strong enough to be dis­charged to his Edgewater, Mary­land, home. This time, Kaushal would take pres­sure off Jo­sue’s right ven­tri­cle - and in­ject those stem cells. Even in adults, stem cell re­gen­er­a­tion is highly ex­per­i­men­tal. But small stud­ies in­volv­ing heart at­tack sur­vivors and older adults with heart fail­ure have found what Dr. De­nis Bux­ton, a stem cell spe­cial­ist at NIH’s heart in­sti­tute, calls a mod­est ben­e­fit in how well their hearts pump blood.

Long safety record

For test­ing in ba­bies, Kaushal turned to Dr. Joshua Hare at the Univer­sity of Miami’s In­ter­dis­ci­pli­nary Stem Cell In­sti­tute, who re­searches a spe­cific type of stem cell do­nated from the bone mar­row of healthy adults. Hare’s in­sti­tute freezes these so-called mes­enchy­mal stem cells, which have a long safety record in adult stud­ies, and is pro­vid­ing them free for the baby study. Ini­tially, Kaushal’s team tested piglets, whose hearts are sim­i­lar to hu­mans. When the right ven­tri­cle was dam­aged, they found stem cell in­jec­tions pre­served the piglets’ heart tis­sue. Ap­par­ently the cells spurred some of the heart’s ex­ist­ing re­pair mech­a­nisms.

Back in the Bal­ti­more op­er­at­ing room, Univer­sity of Miami re­searchers helped Kaushal’s nurses thaw the frozen stem cells and pre­pare in­jec­tions. A few feet away, Kaushal was mov­ing a large vein so it will drain de­oxy­genated blood from the top of Jo­sue’s body straight to his lungs with­out hav­ing to en­ter that over­worked right ven­tri­cle. (When he’s 3, Jo­sue will need a fi­nal op­er­a­tion to sim­i­larly reroute blood re­turn­ing from his lower body.) Then, just be­fore his chest was stitched back up, Jo­sue be­came the sec­ond baby with this de­fect to re­ceive the ex­per­i­men­tal bone mar­row stem cells. It’s an early-stage study that will com­pare 30 ba­bies, half given stem cells, to see if the strat­egy is safe and shows any dif­fer­ence over surgery alone. If so, it could open stem cell re­search for other pe­di­atric heart prob­lems. Other types of stem cells also are be­ing ex­plored for hypo plas­tic left heart syn­drome. Mayo Clinic re­searchers have tested stem cells taken from af­fected ba­bies’ um­bil­i­cal cord blood. Kaushal also plans to try stem cells from af­fected new­borns’ own heart tis­sue, some­thing re­searchers in Ja­pan are pur­su­ing. It will take sev­eral years to know if stem cell ex­per­i­ments work. But, like many ba­bies af­ter their sec­ond surgery for the heart de­fect, Jo­sue bounced back - and a week later, fi­nally got to go home.—AP

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