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  1. Development & Approval Process

Veterinary Regenerative Medicine & Cell and Tissue Therapies for Animals

In the fast-growing field of veterinary regenerative medicine, material from cells and tissues — such as living cells, serum, or bone — is used in animals with the hope of repairing diseased or damaged tissues or organs. For example, in a horse with tendonitis, the damaged tendon may heal with scar tissue that isn’t as strong or elastic as the original tendon before it was damaged. The goal is to transplant living cells or other tissues into the injured tendon, hopefully stimulating it to regenerate and heal.

Veterinary regenerative medicine is an active area of research for developing new cell and tissue therapies for animals. Such therapies are called animal cells, tissues, and cell- and tissue-based products, or ACTPs for short. This term refers to products for use in animals that contain, consist of, or are derived from cells or tissues. Examples include animal stem cells, differentiated cells, and tissues such as blood, platelet-rich plasma, and amnion. 

ACTPs are intended to be implanted, transplanted, infused, or transferred from a donor into an animal recipient. Sometimes the donor and recipient are the same animal. Sometimes the donor and recipient are different animals of the same species. And other times, the donor and recipient are separate species.

Most ACTPs are Animal Drugs

Most ACTPs meet the legal definition of “drug” because they are intended to treat, control, or prevent a disease or other condition — such as osteoarthritis — or to affect the structure or function of the body — such as improving fertility. Therefore, FDA regulates these products as animal drugs. The same laws and regulations that apply to other animal drugs also apply to ACTPs. FDA must review and approve these products before companies can legally market them.

The pre-market review is integral to FDA’s ability to protect animal and public health. During the review, the agency evaluates information submitted by the sponsor to make sure the animal drug is safe and effective for its intended use and that the drug is properly manufactured and adequately labeled and packaged. (A sponsor is the individual, company, university, or other entity working to get a drug approved.) If FDA determines that the data show the animal drug is safe, effective, and high-quality, the agency approves the drug for the uses listed on the label.

Unapproved Animal Drugs

An ACTP that meets the legal definition of a drug but is marketed without FDA approval is an unapproved animal drug. It is illegal to market an unapproved ACTP because it hasn’t gone through the required FDA pre-market review and approval process. Unapproved ACTPs may not be safe, effective, properly manufactured, or adequately labeled or packaged. Currently, no ACTPs are FDA-approved.

FDA recognizes that certain ACTPs, while unapproved, pose a lower risk to human and animal safety than other categories of ACTPs. The agency intends to prioritize use of its resources for certain ACTPs in a manner that is protective of human and animal health, based on risk, and informed by available science and data. FDA provides a publicly-available list of those ACTPs that the agency has determined are lower risk following a review of product-specific information.

Navigating the Approval Process

FDA is committed to helping those involved in the manufacturing of ACTPs navigate the approval process. FDA understands the need to have safe and effective ACTPs approved and available for use in animals and has taken several actions to encourage the development of these products:

  • In June 2015, FDA issued a final guidance for industry (GFI #218), which discusses the approval requirements for ACTPs that meet the legal definition of a “drug” and how the agency intends to regulate them. FDA also sent a letter to all U.S. veterinary schools informing them of the June 2015 guidance. As FDA stated in the letter, veterinary schools that manufacture, market, or investigate ACTPs should be aware of the regulatory requirements and their responsibilities regarding these products.
  • In 2018, FDA started the Veterinary Innovation Program, or VIP. VIP is open to sponsors of innovative animal drugs, including certain ACTPs. The program’s goals are to encourage sponsors to research and develop innovative animal products and to help them address the challenges of moving such products through the approval process.  
  • In September 2021, FDA issued two draft guidance documents that, if finalized, will help sponsors and manufacturers of ACTPs understand current good manufacturing practices (CGMPs). These practices help prevent the contamination of new animal drugs and ensure the drugs’ quality. 

    The first draft guidance for industry (GFI #253) provides manufacturers of ACTPs with recommendations on aspects of manufacturing that are unique to ACTPs and on how to meet CGMPs. 

    The second draft guidance for industry (GFI #254) is intended to help sponsors, veterinarians, and others who determine donor eligibility for ACTPs. Selecting an appropriate donor is critical to ensuring the quality of an ACTP and to preventing the spread of diseases from donor to animal recipient. 

    FDA also issued letters to veterinarians and universities informing them of the two draft guidance documents. Some veterinarians participate in the manufacturing of ACTPs, and many universities conduct research on these products. Therefore, both groups should be aware of the information covered in the two documents.  

    The concepts and principles for ACTPs outlined in the two draft guidance documents are consistent with FDA’s regulations and guidance documents for similar products for people. 

Clinical Field Studies

FDA keeps a list of current clinical field studies that are investigating the use of ACTPs. (A clinical field study is a type of research study that tests how well a new medical product works in animals.) FDA’s list is publicly available and includes information about the condition being studied and in which species. Depending on the study, enrolled animals may be pets, such as dogs and cats, or food-producing animals, such as cattle and pigs. There is also contact information for each study, so the public can find out further information.

Great Promise but Proof Needed

In recent years, the scientific community has made significant advances in developing ACTPs, and scientists continue to research these innovative therapies. Veterinary regenerative medicine holds great promise for future safe and effective treatments for many animal diseases and other conditions. However, the ultimate proof rests in obtaining high quality data from well-conducted, well-controlled, and well-designed scientific studies. The results of these studies will help FDA, sponsors, veterinarians, and others better understand the potential benefits and risks of ACTPs. 

Because of the novelty and complexity of ACTPs, FDA encourages individuals, universities, and companies interested in developing these products to contact the agency at 240-402-7002 or [email protected].

Additional Information

Regulatory Actions

FDA issued the following Warning Letters to companies that were illegally marketing ACTPs without FDA approval: 


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