NEW YORK (CBSNewYork) – A company using young people’s blood in hopes of reversing the aging process has stopped the practice after a warning from the FDA.

CBS2 first told you about the startup “Ambrosia Health” in October.

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The company was offering transfusions that people could buy for anywhere from $8,000 to $12,000.

Dr. Jesse Karmazin claims human subjects who’ve had it say they feel amazing and that he’s seen evidence of reversing the aging process in rats.

“They’re actually younger in sort of every way. Their brains are younger, their hearts, their hair – if it was gray it turns dark again,” the doctor told CBS2 last year.

There has also been encouraging Alzheimer’s research using young blood at Stanford as well.

Platelet rich plasma, or PRP treatments using a patient’s own blood have been in demand as trendy but controversial “vampire facials” to fight wrinkles. It’s also been used as a joint and tissue treatment to accelerate healing.

(Credit: CBS2)

On Tuesday, the FDA said it had significant public health concerns about the use of plasma from young donors as a means to halt normal aging or medical conditions.

The idea of infusing plasma into aging adults has gained steam, but further research using mice has reportedly yielded mixed results.