SANTIAGO, Dominican Republic (CBS) — Stem cells are being credited for the improvements that former White Sox pitcher Bartolo Colón has seen to his shoulder and elbow issues.

Colón signed a minor-league deal with the New York Yankees earlier this year. The Dominican newspaper Diario Libre reported that last year, he received a transplant of stem cells to repair the damaged tissues in his right shoulder, followed by a “booster shot” six weeks later.

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The procedure involved taking 60 cc of blood from one of Colón’s veins, then processing it into 6 cc of platelet-rich plasma that was injected into Colón’s elbow, Diario Libre reported. Neither procedure took more than 40 minutes, the newspaper reported.

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“Since last October, there has not been a leaguer where he has not pitched effectively,” the publication said.

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Colón played for the White Sox during the 2003 and 2009 seasons, and won accolades for shutting out the Minnesota Twins 8-0 early in the 2009 season. But after an injury, he had to leave in the middle of the season, and he couldn’t pitch at all in 2010.