Hours after the Food and Drug Administration issued a forceful warning Tuesday about transfusions of young donor plasma, Ambrosia, a startup that has touted such treatments as anti-aging therapy, announced it had “ceased patient treatments.”

The FDA’s statement, which cautioned that young plasma transfusions have “no proven clinical benefits” for certain conditions as advertised and are “potentially harmful,” did not name any specific companies. But Ambrosia’s decision to halt treatments was made in compliance with the FDA announcement, according to the company’s website. Ambrosia’s CEO and founder, Jesse Karmazin, did not immediately respond to a request for comment.

Until Tuesday evening, Ambrosia advertised providing young blood therapy ― transfusions of blood plasma taken from young donors and injected into older patients ― in five U.S. cities, charging $8,000 for a single liter of plasma or $12,000 for two liters. In the media, Karmazin painted the treatments as anti-aging miracle remedies that could help with any number of ailments, including Alzheimer’s disease and greying hair.

The FDA’s statement strongly discouraged people from pursuing young plasma therapy outside of clinical trials conducted under “appropriate institutional review board and regulatory oversight.”

“Simply put, we’re concerned that some patients are being preyed upon by unscrupulous actors touting treatments of plasma from young donors as cures and remedies,” FDA Commissioner Scott Gottlieb said in the statement. Peter Marks, director of the agency’s Center for Biologics Evaluation and Research, joined him in issuing the warning.

The FDA’s announcement, and Ambrosia’s apparent indefinite hiatus, come less than two months after a HuffPost investigation into the startup.

Blood Boy

Karmazin, a Stanford University Medical School graduate, founded Ambrosia in 2016, the same year he signed a voluntary agreement with Massachusetts officials in which he promised to immediately stop practicing medicine in the state. Inspired by mice studies, he contracted physicians to carry out a study in which participants paid to receive young plasma transfusions. He saw no need to go through the FDA’s drug approval process for that study.

He declared the study a success — and regularly boasted to the media about the findings — but never released the results while promising they were coming soon.

There were other issues Karmazin wouldn’t talk about: He refused to say, for example, where exactly he got his blood plasma. Many blood banks HuffPost contacted raised questions and ethical concerns about supplying for Karmazin’s purposes. At least some of the plasma for Ambrosia’s study came from a South Texas blood bank that stopped selling young plasma after HuffPost reached out.

Karmazin also declined to put reporters in touch with a single study participant. The only patient who spoke publicly about Ambrosia’s transfusions — treatments he hoped would help him live healthier as he aged — died at 65 after going into cardiac arrest, HuffPost found. Karmazin told HuffPost there were no deaths during or after the study related to the treatment.