Product Contamination and Route-Specific Risks

Urgent first

If you or someone you know has fever, chills, severe pain, spreading redness, a sudden change in vision, new weakness or numbness, or a severe headache after any injection or infusion of cells, exosomes or similar products, get medical care right away. In the United States, call 911 for an emergency. Bring the product name and clinic details, and report the problem to the FDA's MedWatch program. [1]

This page is information only. It describes what regulators and published reports found. It gives no instructions for making, processing, giving or testing any product.

Why contamination matters for cell-based products

Cell products are made from human cells or tissue, and handling steps can introduce germs. The FDA lists "cross-contamination with bacteria, viruses or mold related to processing" and products "not tested for infectious diseases such as hepatitis and HIV" among the safety concerns with illegally marketed regenerative products. [2] The ISSCR also notes that any time cells are removed from the body they may be contaminated with viruses, bacteria or other pathogens. [3]

What FDA inspections and letters have described

These are FDA statements at the time of each letter, not court findings. They show the kinds of failures regulators look for.

• Stemell (2019): the FDA said an inspection found deficient donor eligibility practices, unvalidated manufacturing processes, deficient environmental monitoring and inadequate aseptic (germ-free) processes in making umbilical cord blood and cord products. It said these deviations pose a risk that products may be contaminated with viruses or microorganisms. [4]
• R3 Medical Companies / Bello Bio and Regen Suppliers (August 14, 2026): the FDA cited a failure to follow written procedures to prevent microbiological contamination of umbilical cord derived products meant to be sterile, including aseptic processes that had not been validated. [5] It also described sterility test samples that were frozen and thawed before testing, which it said could hide contamination. [5]
• Exosome products in Nebraska (2019): the FDA reported serious adverse events in patients treated with unapproved products marketed as containing exosomes, brought to its attention by the CDC and others. [6] The notification does not describe the cause in detail, so no cause is stated here.

Route-specific risks: where a product is placed matters

The same product can carry different risks depending on the body site. The reports below are case-level evidence of harm, not rates.

For joints, skin, fat and other sites, Proper evidence not found in the sources read this session for route-specific complication rates. We checked FDA pages, ISSCR patient pages and PubMed case literature. The FDA does say reactions can occur at the site of collection and the site of administration. [2]

Same cell type, different risk

Moving cells to a different location than where they normally live is a concern the ISSCR names directly: some clinics place cells in parts of the body where they are not normally present. [3] The FDA similarly lists cells moving to another part of the body and forming unintended tissue. [2] Pluripotent stem cells (embryonic or induced) can overgrow and form tumors if not properly directed, according to the ISSCR, which is why they are not used directly as treatments. [3]

What labels and claims do not tell you

• A sterility statement on a website is not an inspection result. The 2026 letter above described a firm that sold products purporting to be sterile without validated aseptic processing. [5]
• A registration with the FDA or a listing on clinicaltrials.gov does not mean a product is legally marketed. [2]
• Products that the FDA has approved are listed on its approved-products page; for that list, see regulatory status.

Related guides

General harm types are in cell-therapy safety. Exosome laboratory science is in extracellular vesicles and exosomes, and marketed products are compared with lab findings in laboratory findings vs marketed exosome products. Platelet-rich plasma, which is made from a person's blood, is covered in platelet-rich plasma.