Redskins tight end Chris Cooley, center, is shown stretching during training camp. Of platelet-rich plasma (PRP) therapy, he says: “It’s a neat treatment. I can’t tell you the ultimate benefits to it. No one can. It’s still new. But I did feel better.” (Ricky Carioti/WASHINGTON POST)

When his trainer advised him to try a popular but unproven healing therapy for his injured Achilles’ tendon last year, Washington Redskins safety LaRon Landry did not hesitate. He wanted to get back to work.

It did not concern him that the recommended treatment, platelet-rich plasma (PRP) therapy, lacks scientific validation, has shown mixed results in a limited number of studies and involves drawing a dose of one’s own blood and reinjecting it.

Landry now evangelizes like a PRP prophet. Since using the treatment for three different injuries, he’s been spreading the word to teammates.

“I’m happy I went with it,” Landry said. “A lot of guys ask me about it, and when guys get hurt, I try to put them onto the PRP because I think it’s something they should be knowledgeable of if they’re trying to recover.”

Landry’s attitude is shared by increasing numbers of injured athletes in locker rooms and clubhouses nationwide, who are grasping at non-surgical options for fast healing. For men whose livelihoods depend on staying healthy, the occasional, and widely publicized, PRP success stories have caused the popularity of the procedure to far outpace the research behind it, experts say.

Published studies on the procedure are limited. One of the earliest, co-authored by Allan K. Mishra, a Menlo Park, Calif., orthopedist, suggests that PRP is effective at treating tennis elbow, but a later one concluded that it did not markedly help rotator cuff injuries.

The available research does not provide complete clarity, according to doctors, because no two PRP procedures are exactly the same. Doctors say they are not only uncertain about when to administer it, but precisely how to do it for optimal effect.

“There’s tremendous variation among different types of PRP,” said Scott Rodeo, who participated in the rotator cuff study and will be the team physician for the U.S. swimming Olympic team at the 2012 Summer Games in London. “My PRP is different than your PRP, because my blood is different than yours. All of those things add up to such variability it’s hard to analyze the data to get a handle on it.”

‘The pioneering beginning’

Athletes, however, seem to care little about such details. In the last few months alone, a host of players have tried PRP, including major league pitchers Jose Contreras of the Philadelphia Phillies, Daisuke Matsuzaka and Bobby Jenks of the Boston Red Sox, Brett Anderson of the Oakland Athletics and Jesse Carlson of the Toronto Blue Jays, as well as Wesley Matthews of the NBA’s Portland Trail Blazers.

“The athletes are the ones at the pioneering beginning, trying new things to accelerate healing,” Mishra said. “Athletes are dissatisfied with other options presented to them.”

Landry believed PRP therapy helped his Achilles’ tendon so much he also used it when he injured his shoulder and hamstring. Teammates Chris Cooley and Brandon Banks recently sought out PRP injections for their injured knees.

Some athletes are turning to even more unproven and newfangled therapies involving the use of adult stem cells; Indianapolis Colts quarterback Peyton Manning reportedly traveled to Europe for treatment on his neck that was not approved in the United States.

New York Yankees pitcher Bartolo Colon received stem-cell therapy in the Dominican Republic in 2010 that appeared to yield huge dividends but also sparked a Major League Baseball investigation.

Unlike stem-cell treatment and other methods that remain on the fringe in pro sports, PRP has become nearly as available as cortisone shots. Developed well over a decade ago, the treatment first garnered mainstream attention when Pittsburgh Steelers wide receiver Hines Ward used it to help him play in the Super Bowl in 2009. Its use spread quickly after that.

Landry traveled to Arizona for his PRP, but some teams now offer the procedure in-house. Even noted sports surgeon James Andrews — Banks’s physician — acknowledged that his Birmingham, Ala., clinic has in the last year begun offering PRP, though only in certain cases. Andrews does not personally perform the therapy.

“It definitely has a future in trying to get certain injuries to heal, and to heal with a better response,” Andrews said. “The problem is we don’t know quite when to use it, and don’t know the different injuries that will respond best to it. All of it is pretty much anecdotal.”

Virtually no risk factors

Doctors and athletes say they are attracted to PRP because of its apparent safety, simplicity and lack of side effects. Blood is removed from the injured region and spun in a centrifuge to concentrate the platelets. When reinjected into the body, the concentrated platelets release growth factors that theoretically should promote faster healing. Because patients are receiving their own blood, risk factors are virtually eliminated.

Landry said his Arizona-based trainer persuaded him to use PRP therapy last year. He actually ignored the advice at first, trying to play through the pain. That decision, he said, made the injury worse. After he was placed on injured reserve, he eventually traveled to Arizona for the PRP treatment — and immediately became a believer. This summer, when he aggravated his right hamstring, he didn’t waste any time.

“The PRP doesn’t work for everybody; it’s more so trial and error,” he said. But “I loved it. . . . [It] really healed my Achilles. And my hamstring.”

Atlanta Braves left-handed reliever George Sherrill grew frustrated with nagging elbow pain that left him unable to lob a baseball from the pitcher’s mound to the catcher a day after facing any hitters in games. But unlike Landry, he did not have to seek out the treatment. He received the PRP therapy from one of Atlanta’s team physicians. Earlier in the season, teammate Kris Medlen also received a PRP injection.

“The [team] doctors brought it to me,” Sherrill said before a game against the Florida Marlins in Miami last month. “They said it was an avenue to take. I said, ‘If it will mean me throwing again this year, getting into the playoffs and, on a personal side, showing people I would be healthy next year, I’ll give it a whirl.’”

Sherrill isn’t sure the therapy made any difference at all; he speculated the rest he got before and after the procedure might have been responsible for the small benefit he noticed. Cooley, however, said each time he received it he felt 50 percent better.

Sherrill noted there also was an important side effect in his case.

“It was like this, after,” Sherrill said, holding up his left arm and shaking it violently. “I had cortisone shots before, and this was 50 times worse than that. [A cortisone shot] feels like you stuck your arm over a stove. This felt like a truck ran over my elbow.”

Negative press

Another downside is the negative publicity PRP has attracted when it has been abused. Canadian doctor Anthony Galea, who in July pleaded guilty to bringing misbranded drugs across the U.S. border, was accused by his personal assistant of mixing human growth hormone (HGH), a drug banned by nearly every sports league in the world, with the blood of some of his athlete patients before reinjecting it as part of the PRP therapy. Galea treated a host of prominent athletes, including golfer Tiger Woods, the Yankees’ Alex Rodriguez and Redskins wide receiver Santana Moss.

Major League Baseball investigated Colon’s treatment for a similar reason: The doctor who administered it had been known for using HGH as part of healing treatments.

PRP therapy has flummoxed the World Anti-Doping Agency, which originally banned it for intra-muscular use but lifted the ban this year — saying it did not have enough evidence to conclude that PRP aided performance in any way.

The key for players, of course, is whether it helps them heal.

“It’s a neat treatment,” Cooley said. “I can’t tell you the ultimate benefits to it. No one can. It’s still new. But I did feel better. . . . I’ve now had two or three guys around the league call me for advice on PRP and the effects of it.”

Staff writer Rick Maese contributed to this report.