"From a medical standpoint," Nitkowski says, "[the treatments have] been a success. I'm healthy."
But the route he took to get to this point is, in many ways, misunderstood.
Nitkowski received treatment identical to the one that picked Bartolo Colon's ailing arm and career off the scrap heap and made him a prominent member of the Yankees rotation last season. It's a treatment that, in Colon's case, caused a bit of an uproar in the headlines last summer, as such labels as "disputed" and "controversial" were used to describe it.
In reality, though, the use of one's own stem cells to promote healing in an injured area is far from a new development. In fact, the microfracture procedure that is becoming more and more common in the treatment of knee injuries (it was performed on Victor Martinez last month) is, at its core, a stem-cell procedure. In microfracture, tiny holes are drilled in the bone to allow marrow to drip out and repair damaged tissue -- the mesenchymal stem cells inside the marrow provide the repairing power.
In the cases of Nitkowski and Colon, the mesenchymal stem cells were extracted from bone marrow and from body fat and then injected into a blood-poor area -- Nitkowski's left shoulder and Colon's right shoulder and elbow -- to promote healing.
Now, is this really a reliable way to treat an ailing athlete? That's a subject of scrutiny.
Embryonic stem cells are the cause of controversy all their own, given the ethical and political debates over their use and concern by some members of the medical community that they have the potential to become cancerous tumors.
With mesenchymal stem cells, on the other hand, the debate is not over morals or safety but, rather, efficacy.
"There's very little evidence that bone marrow stem cells taken from one site and injected into another will do anything," Theodore Friedmann, a geneticist at the University of California at San Diego who heads the World Anti-Doping Agency's (WADA) gene doping panel, told ESPN The Magazine recently. "The most likely outcome is that if you put stem cells in places that are unfamiliar to them, like a knee or shoulder, most of them will just die."
WADA initially banned all blood-spinning therapies before reversing its position in 2011 after studies failed to demonstrate that they enhance performance the way steroids do. So WADA currently has no position on the use of stem-cell treatments.
In the face of skepticism, you have the case of Colon, who in the spring of 2010 was unsigned, unable to get any of his old velocity on his fastball and seemingly at the end of a once-dazzling career. Dr. James Purita, founder of the Institute of Regenerative and Molecular Orthopedics in Boca Raton, Fla., traveled to the Dominican Republic to perform platelet-rich plasma (PRP) and stem-cell treatments to help repair ligament damage in Colon's elbow and aid a torn rotator cuff.
"There was a stigma that it was illegal, because we did it in the Dominican," Purita said. "But it was just because he lived there."
And there was another stigma. Because Colon not only returned to the Majors but thrived in the first half of the 2011 season, some wondered if the procedure could be labeled a performance-enhancer.
When Colon's story became public, Purita was questioned by Major League Baseball officials to ensure that he did not use human growth hormone in the procedure. Purita has admitted using HGH when treating non-athletes but said he knows better than to do so in these cases. MLB did a complete investigation, and no further action was taken.
"We're not reinventing the wheel here," Purita said. "We've done a number of these procedures on people from all the major sports, with the exception of hockey. We've done some of the top players. But we keep it very discreet."
The reason for the discretion, beyond the obvious HIPAA standards, is that some teams are leery of or reluctant to trust these stem-cell treatments. Purita said that he performed the procedure this winter on a Major League free agent who expressed an explicit desire that word not get out, because he didn't want it to affect his contract negotiations.
However, the case of Colon, who signed a one-year, $2 million contract with the A's this winter, makes one wonder if biologic stem cells could be the next medical revolution, following arthroscopy and the ulnar collateral ligament replacement known as Tommy John surgery.
Nitkowski, for one, hopes to find out.
A member of eight Major League teams over parts of 10 seasons from 1995-2005, the left-handed Nitkowski appeared in 336 games, mostly in a relief role. In 2006 he began a five-year stint pitching for various teams in Asia -- first in the Japanese Pacific League, then in the Korean Baseball Organization.
A year ago, hoping for another shot in the bigs, he began working on a sidearm delivery, only to injure his shoulder.
It was around that time that Nitkowski heard about Colon. Intrigued, he made a call to Purita's office, and, within weeks he was in Boca Raton to undergo the procedure himself.
Purita first drew fat from Nitkowski's waist, then drew bone marrow from the left side of Nitkowski's lower back. The liquids were spun in a centrifuge at 2,000 rotations per minute for about 15 minutes, isolating the platelets. They were then inserted into syringes and placed under an LED light for about 20 minutes -- a process that supposedly "kick starts" the cells inside. Once this process was complete, Purita injected the platelet-rich plasma and stem cells into Nitkowski's labrum and rotator cuff.
This is an important distinction. Under U.S. Food and Drug Administration guidelines, mesenchymal stem cells must be "minimally manipulated," meaning they can't be harvested in a lab for days or weeks or transported elsewhere.
"Everything," Purita said, "has to be used the same day, on the same patient, and everything has to be done at the point of care."
In Nitkowski's case, the whole process took about four hours. Much to his amazement, he had full range of motion within 24 hours.
"The rehab starts right away," he said. "You have to commit to it, like any injury. I never thought I had the mindset to do the tedious rehab work. But if you want it bad enough, you'll do it."
Nitkowski's stem-cell treatment was performed in July of last year. And per the usual protocol in Purita's treatment plan, Nitkowski had a second PRP treatment four weeks later. By November he was throwing off a mound, and he was pleased with how his arm felt and how his sidearm-delivered stuff worked in the Dominican Republic last month.
"I was sitting at 86, 87 [mph] and hitting 88-89," he said. "That's more than enough [velocity] from that arm angle."
Though he hasn't pitched in the bigs in seven years, Nitkowski believes he could help a team, and he's hoping someone will give him a tryout in Spring Training.
"I at least want to get in front of people and be told no," he said. "I can live with that. I would love the opportunity. This is either going to happen fast, or it's not going to happen at all."
Nitkowski's about to turn 39. But he's left-handed, and he's healthy. And he firmly believes the latter would not have been possible without the treatment he received.
"My arm feels really good," he said. "Every pitcher has little tears. It just comes with the territory. But this seems like it could be a good maintenance plan."
There are skeptics, and there are critics. Nitkowski knows how some people feel when they hear about stem-cell treatments or about Alex Rodriguez flying to Germany for blood-spinning therapy to address his chronic knee and shoulder problems. They wonder if that precious line between therapy and enhancement is being straddled too closely.
Having experienced it for himself, Nitkowski is a believer in the safety, the purity and the benefits of the treatment he had performed on his arm.
And he thinks many other athletes will follow.
"This," he said, "is going to be mainstream sooner rather than later."