A California stem cell company on Friday announced the immediate suspension of sales of umbilical cord blood-derived products, a week after federal regulators said the treatments were unapproved drugs and posed safety risks.

In a letter to clients, Liveyon LLC Chief Executive Officer John Kosolcharoen said the company has halted distribution of its products, Pure and Pure Pro, to “focus its efforts” on getting the nod from the Food and Drug Administration to conduct a clinical trial and eventually apply for approval of the products.

The FDA said in its recent warning letter that a May inspection showed the products are unapproved drugs that required advance agency approval. The agency also warned the company for “significant deviations” from good manufacturing processes. It said Liveyon failed to screen donors adequately for communicable diseases, and didn’t follow procedures to prevent microbiological contamination or establish a system for cleaning and disinfecting the processing room and equipment.

The FDA action against Liveyon is part of an effort to clamp down on stem-cell products that are not approved by federal regulators or supported by clinical research, and may endanger consumers. A year ago, Liveyon, based in Yorba Linda, was linked to distribution of another manufacturer’s contaminated umbilical cord blood products that sickened 12 people in three states. That product was recalled.

Pure and Pure Pro are marketed mainly as treatments for patients with back, knee and other joint problems.

The Liveyon client letter said the company is preparing a “detailed response” to the FDA that will be submitted by Dec. 27. It argued the FDA’s assertion that the umbilical cord blood-derived products required agency approval was based on a “narrow interpretation” of federal rules on stem cells.

Liveyon added that while the company contends “its products have been appropriately marketed, we believe proving the efficacy of the product through FDA clinical trials, is in the company’s best interest for the future.”

Kosolcharoen, in an email, said that the company will meet with the FDA in January about starting a clinical trial.

“I’m going to prove the efficacy of this product and raise the standard for regenerative medicine through the FDA’s pathway of clinical trials,” he said.

The FDA declined to comment on the Liveyon letter, noting, “This is an ongoing compliance matter."

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