New JetChris Johnson had stem cells from his bone marrow reinjected into his knee to augment Januarysurgery for a torn meniscus. The hope is that it wouldboost healingand perhaps rebuild cartilage. (AP)

Hes 28. He has five 1,000-yard NFL rushing seasons to his name, one 2,000-yarder and a burning desire to prove hes the same speedster hes always been. So when Chris Johnson visited orthopedic surgeon James Andrews in January to fix his ailing left knee, he liked the sound of two intriguing words: Stem cells.

The veteran running back tore the meniscus in that knee in Week 3 of the 2013 seasonhis last with the Titans before being cutbut never missed a game. The injury to the knees natural shock absorber also caused other damage in the joint, and Andrews presented an option that might augment what surgery alone could do. The plan: Take stem cells, the bodys universal building blocks, and deliver them directly to the construction site.

When I tore my meniscus and played the season out, through the wear and tear, I lost a lot of cartilage, says Johnson, who was signed by the Jets to bring explosiveness to their offense. When you put the stem cells in, it might be able to help rebuild that cartilage in your knee. Hopefully, it makes your knee better for even more years.

On the day of his surgery at the Andrews Institute in Gulf Breeze, Fla., Johnson had a small amount of his bone marrow60 milliliters, or the volume of a shot glasssiphoned out of the iliac crest of his pelvis with a long needle pushed through a tiny incision in his skin. Less than an hour later, at the end of the arthroscopic procedure to repair his meniscus, a concentrate of thousands of stem cells from the bone marrow was injected directly into Johnsons knee joint.

Instead of the usual four-to-six-week recovery time from the scope, Johnson stayed off the practice field for the rest of the offseason, giving the stem-cell treatment maximum time to work. At the least, stem cells are a powerful anti-inflammatory. But the hope is they may also play a role in boosting the healing of injured tissues, including stubborn ones like the meniscus, which lacks a robust blood supply, or cartilage, which has long been irreplaceable.

Stem cells are far from mainstreamNFL teams will often not pick up the bill, and the overseas market for treatments not approved in the U.S. makes the whole field seem somewhat taboo.

Johnson is one of hundredsyes, hundredsof NFL players who have invested in the promise of stem cells in the past few years. Peyton Manning reportedly tried a stem-cell treatment in Europe in 2011, his final year with the Colts, to fast-track his recovery from neck surgery. Giants cornerback Prince Amukamara had a slow-healing broken metatarsal treated with stem cells by a foot specialist in North Carolina after his teams Super Bowl XLVI run. One NFL linebacker paid $6,000 a pop for a 1-milliliter vial of donated placenta tissue containing stem cells to be injected into each of his beat-up knees this offseasonbut asked for his name not to be used in this story because he didnt tell his teams medical staff.

Such treatment is more common than you might realize among NFL players (hundreds of players across 32 teams averages to at least six players per team), but its also far from mainstream. Stem cells are still somewhat in the shadowsevidence of their usefulness in treating athletes injuries is so far largely anecdotal, NFL teams often will not pick up the bill for players, and the overseas market for treatments not approved in the U.S. makes the whole field seem somewhat taboo.

Theres a push to change that, though, and Andrews is an important figure at the forefront. His group is currently building a laboratory at its Florida facility specifically dedicated to biologicsthe term refers to substances that are produced in living systems such as humans, animals and microorganisms, rather than manufactured like drugsto be able to offer their star-studded clientele more of these treatments more effectively in the U.S. The agenda includes a research study with retired NFL players on how well stem cells work in treating arthritis of the knee; a trial of a Malaysian technique for regenerating cartilage by using stem cells from the blood after microfracture surgery; and exploring whether torn ACL tissue can be repurposed to help the new ligament graft heal more quickly.

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Stem cell treatment used by Chris Johnson, hundreds of NFL ...