Most regenerative medicine clinic owners think “361” means they are in the clear. It does not. Section 361 is a narrow exemption, not a free pass. And your own marketing copy can strip it away. The FDA does not just regulate what products you use. It reads what you say about them. One marketing claim in the wrong direction can reclassify your service as an unapproved drug under federal law. This guide explains the 361 vs. 351 distinction in plain English and shows you exactly how your website, social media, and ads interact with it.
TLDR: The FDA classifies most regenerative medicine products under one of two pathways: Section 361 (lightly regulated, no premarket approval required if four criteria are met) or Section 351 (full biologic/drug regulation requiring FDA approval). The critical insight most clinic owners miss is that marketing language directly affects this classification. If your copy implies a product treats, cures, or prevents a disease, you have potentially reclassified a 361 product as a 351 biologic, which is an unapproved drug. This guide covers the four criteria, the product-by-product breakdown, and how to audit your marketing before the FDA does it for you.
Important Note
This article is for educational purposes only and does not constitute legal, medical, or regulatory advice. Marketing strategies discussed should be reviewed by qualified legal counsel before implementation, particularly regarding FDA, FTC, and state-specific advertising regulations. Regen Portal is a marketing company, not a law firm or compliance consultancy.
If you work in regenerative medicine, you have probably heard the numbers 361 and 351 thrown around in conversations with distributors, manufacturers, or compliance consultants. Maybe someone told you your product is “361 compliant” and you felt reassured. Maybe you have no idea what these numbers mean but you know they are important.
Here is what I can tell you after 15 years in this industry, working with over 200 doctors and dozens of manufacturers and distributors: most clinic owners do not fully understand this framework. And the ones who get it wrong, often because of what their marketing says rather than what they actually do clinically, are the ones who end up in enforcement trouble.
We covered what happens when clinics get FDA warning letters and the traffic light framework for compliant marketing language. This article is the regulatory foundation underneath both of those. If you understand 361 vs. 351, everything else about compliant marketing makes more sense.
What Is an HCT/P and Why Should Marketers Care?
HCT/P stands for Human Cells, Tissues, and Cellular and Tissue-Based Products. Under 21 CFR Part 1271, this is the regulatory framework that governs most of the products at the center of regenerative medicine practices.
If your clinic works with PRP, amniotic tissue, cord blood products, umbilical cord tissue, placental tissue, adipose-derived cells, or exosomes, you are operating within this framework. These are all HCT/Ps. The rules in Part 1271 determine how these products can be manufactured, distributed, and, critically for this article, marketed.
Most marketers outside the regenerative medicine industry have never heard of HCT/Ps. That is why generic marketing agencies get regen clinics into trouble. They write copy the same way they would for a dental practice or a med spa, without understanding that the words they choose carry specific regulatory consequences in the HCT/P world.
What this means for your practice: If you are using any of the products listed above, Part 1271 applies to you. And the marketing rules that flow from it are not optional. They are federal law.
361 vs. 351: The Plain-English Breakdown
There are two regulatory pathways for HCT/Ps. The difference between them determines everything about what you can legally say in your marketing.
Section 361 products are lightly regulated. They do not require premarket approval from the FDA. They do not need an Investigational New Drug (IND) application or a Biologics License Application (BLA). The FDA regulates them primarily to prevent the spread of communicable diseases. This is the pathway most clinic owners want their products to fall under because it means fewer regulatory hurdles.
But 361 status is not a label you choose. It is a status your product earns only if it meets all four criteria under 21 CFR 1271.10(a). Miss any one of the four, and the product falls into 351 territory.
Section 351 products are fully regulated as drugs or biologics. They require IND applications, clinical trials, and a BLA before they can be legally marketed as treatments. The approval process takes years and costs millions. Most regenerative medicine products marketed to consumers do not have this approval. If a product falls into the 351 category and does not have FDA approval, marketing it as a treatment is illegal.
The FDA’s framework for regulation of regenerative medicine products outlines this distinction in detail. But here is what matters for marketers: the classification is not just about the product itself. It is about how you describe the product’s use.
| Factor | Section 361 | Section 351 |
|---|---|---|
| Premarket approval required | No | Yes (IND, BLA) |
| Primary regulation focus | Communicable disease prevention | Full drug/biologic safety and efficacy |
| Can be marketed as a treatment | No (unless approved for specific use) | Only if FDA-approved |
| Marketing language allowed | Education, process, consultation CTAs | Only approved indications |
| Enforcement risk from marketing | High if claims imply treatment | High if unapproved |
What this means for your practice: 361 status does not mean you can market freely. It means you can operate with less regulatory burden if, and only if, you meet all four criteria and your marketing does not imply uses that push you into 351 territory.
The Four Criteria That Determine 361 Status
Under 21 CFR 1271.10(a), an HCT/P qualifies for Section 361 regulation only if it meets all four of these criteria simultaneously.
Criterion 1: Minimally manipulated. The product must not be processed in a way that alters its original relevant characteristics. For structural tissues (bone, skin, tendons), this means processing must not change the physical structure. For cells and nonstructural tissues, this means processing must not alter the biological characteristics. Centrifuging blood to create PRP generally qualifies as minimal manipulation. Expanding cells in a lab does not.
Criterion 2: Intended solely for homologous use. This is where marketing language becomes critical. Homologous use means the HCT/P performs the same basic function in the recipient as it performed in the donor. Skin used as a wound covering is homologous. Amniotic tissue used as a joint injection “to regenerate cartilage” is not. The moment your marketing describes a product performing a function it does not naturally perform, you have implied non-homologous use.
Criterion 3: Not combined with another article. The HCT/P must not be combined with another substance, except for water, crystalloids, or a sterilizing, preserving, or storage agent. If the product is mixed with a drug or another biologic, it loses 361 eligibility.
Criterion 4: No systemic effect and not dependent on metabolic activity of living cells. The HCT/P must act locally and must not depend on living cells doing metabolic work to achieve its effect. If the product is described as having body-wide effects or relying on living cell activity, it moves toward 351.
The critical insight for marketers is Criterion 2. Your website copy directly affects whether the FDA considers a product to be used homologously. If your homepage says your amniotic tissue product “regenerates damaged nerves” or “restores joint cartilage,” you have described a non-homologous function. The product is no longer performing what it naturally does in the body. You have just implied a 351 use, which makes your marketing evidence of an unapproved drug claim.
What this means for your practice: The four criteria are not just manufacturing rules. They are marketing rules. Criterion 2 in particular means that your own words on your own website can change your product’s regulatory classification. This is the single most important concept in this article.
How Your Website Copy Can Change Your FDA Classification
This is the core insight that separates this guide from everything else written about 361 vs. 351.
Consider a clinic that uses amniotic tissue products. Under proper conditions, these products can qualify as 361 HCT/Ps. The clinic’s supplier provides them under 361 registration. Clinically, the physician uses them within appropriate parameters. Everything is fine, until the marketing team writes a homepage headline that says: “Our amniotic tissue therapy regenerates damaged tissue and restores joint function.”
That headline just implied non-homologous, systemic therapeutic use. The product is no longer being described as performing its natural function. It is now being marketed as a treatment that changes how the body works. In the FDA’s eyes, this marketing language has reclassified the product from a 361 HCT/P into a 351 biologic. And since it does not have BLA approval, the clinic is now marketing an unapproved drug.
This is not theoretical. In 2021, the 11th Circuit Court of Appeals upheld the FDA’s authority to regulate the US Stem Cell Clinic specifically because the clinic’s own marketed use of stem cells implied non-homologous application. According to a Hogan Lovells analysis of the ruling, the court agreed that the way the clinic described its treatments to patients constituted evidence that the products were being used outside their natural function.
The 2025 and 2026 enforcement trend has intensified this. The FDA is now actively scrutinizing clinic websites as primary evidence of intent. We covered this in detail in our guide on FDA warning letters for regenerative medicine clinics.
What this means for your practice: Your website is not just a marketing tool. It is a regulatory document. The FDA reads it. Courts reference it. Your marketing language is evidence of how you intend your products to be used. If that language implies non-homologous, therapeutic use, you have created an enforcement problem regardless of how the product is actually used clinically.
Product-by-Product: Where PRP, Exosomes, and Stem Cells Stand
Here is a quick reference for the most common modalities in regenerative medicine.
PRP and PRF. Generally 361-eligible when prepared from the patient’s own blood through minimal manipulation (centrifugation). PRP devices are 510(k) cleared specifically for bone graft handling. Every other use (joints, hair, aesthetics, sports injuries) is off-label. Marketing must not imply systemic or non-homologous effects. “PRP concentrates platelets from your own blood” is compliant. “PRP regenerates your knee cartilage” is not.
Exosomes. No FDA-approved exosome products exist for any human therapeutic use. Any marketing that positions exosomes as a treatment automatically creates a 351 problem. Education-only content is the only compliant approach. You can describe what exosomes are biologically. You cannot market them as therapy.
Allogeneic stem cells and cord-derived products. Almost always fall into 351 territory unless they meet all four criteria under 1271.10(a) and are used homologously. Most commercial stem cell products marketed to consumers do not have BLA approval. Marketing must clearly reflect the unapproved status.
SVF (adipose-derived stromal vascular fraction). The US Stem Cell Clinic ruling established that SVF is a 351 product. It does not qualify for the same-surgical-procedure exemption. Marketing SVF as a treatment carries the same enforcement risk as any other unapproved biologic.
Amniotic and placental tissue. Can qualify as 361 when used homologously (as a wound covering or protective barrier). Marketing these products as “regenerating tissue” or “healing joints” implies non-homologous use and pushes them into 351 territory.
| Product | Typical Classification | Marketing Guardrail |
|---|---|---|
| PRP/PRF | 361 (autologous, minimal manipulation) | No disease treatment claims; off-label disclosure for non-bone-graft uses |
| Exosomes | No approval exists | Education only; no treatment marketing |
| Allogeneic stem cells | 351 (unless specific approval) | Must reflect unapproved status |
| SVF | 351 (per US Stem Cell ruling) | No treatment marketing |
| Amniotic/placental tissue | 361 if homologous use | No “regenerates” or “heals” language |
What This Means for Your Day-to-Day Marketing
Before publishing any piece of content (web page, blog post, social media caption, email, or ad), run it through two questions.
Does this language imply that a product treats, prevents, cures, or mitigates a disease or condition? If yes, rewrite it. Use education framing, process descriptions, or consultation CTAs instead.
Does this language imply that a product is being used in a way that goes beyond its natural, homologous function? If yes, rewrite it. Describe the process, not the therapeutic outcome.
Here are four common problem phrases and their compliant rewrites.
“Our amniotic tissue therapy regenerates damaged joints.” Compliant rewrite: “Our practice offers consultations for patients interested in learning about amniotic tissue applications. Schedule a consultation to discuss your options.”
“Exosomes heal your body at the cellular level.” Compliant rewrite: “Exosomes are small vesicles involved in cell-to-cell communication. There are no FDA-approved exosome products for human therapeutic use.”
“Stem cell injections restore your cartilage.” Compliant rewrite: “Our practice provides education about regenerative medicine approaches. Only cord-blood hematopoietic progenitor cells are FDA-approved, and only for specific blood disorders.”
“PRP treatment cures chronic knee pain.” Compliant rewrite: “PRP is prepared by concentrating platelets from your own blood. PRP devices are cleared for bone graft handling; other uses are considered off-label. Individual results vary.”
Your content creation and SEO strategy should build on this foundation. Every piece of content should pass both questions before it goes live. Always consult qualified legal counsel for product-specific compliance questions relevant to your practice.
Frequently Asked Questions
What Does 361 vs. 351 Actually Mean in Plain English?
Section 361 is a lighter regulatory pathway for human tissue products that meet four specific criteria. These products do not need FDA premarket approval. Section 351 is the full drug/biologic pathway requiring FDA approval through clinical trials and a Biologics License Application. Most regenerative medicine products marketed to consumers as treatments do not have 351 approval.
Can My Marketing Language Actually Change My FDA Product Classification?
Yes. The FDA determines a product’s intended use partly by how it is marketed. If your website describes a 361 product performing a non-homologous function (like “regenerating cartilage” or “healing nerves”), you have implied a use that moves the product into 351 territory. Your marketing language is evidence of intent.
What Are the Four Criteria for 361 Status?
The product must be minimally manipulated, intended solely for homologous use, not combined with another article (with limited exceptions), and must not have a systemic effect or depend on living cell metabolic activity. All four criteria must be met simultaneously.
Which Products in My Clinic Are Most Likely to Be 361 vs. 351?
PRP (autologous, minimal manipulation) is generally 361-eligible. Amniotic and placental tissue can qualify if used homologously. Exosomes have no FDA approval at all. Allogeneic stem cells are almost always 351. SVF is 351 per the US Stem Cell Clinic ruling.
What Happened to Clinics That Marketed 361 Products as Treatments?
The US Stem Cell Clinic received a permanent injunction after the 11th Circuit upheld FDA authority in 2021. The court cited the clinic’s own marketing as evidence of non-homologous use. Multiple clinics received warning letters in 2025 for website and social media content that made treatment claims for unapproved products.
Does This Apply to PRP Since It Comes From the Patient’s Own Blood?
PRP is generally 361-eligible because it is autologous and minimally manipulated. But PRP devices are only cleared for bone graft handling. All other uses are off-label. Your marketing must include off-label disclosure and must not claim PRP treats, cures, or heals any disease or condition.
How Do I Make Sure My Marketing Does Not Cross the Line?
Run every piece of content through two questions: Does it imply a product treats, prevents, or cures a disease? Does it imply non-homologous use? If yes to either, rewrite using education framing, process descriptions, or consultation CTAs. Consult qualified legal counsel for product-specific questions.
For more on the regulatory landscape affecting regenerative medicine marketing, subscribe to Oscar’s YouTube channel for weekly insights from industry leaders: https://www.youtube.com/@oatellez
Key Takeaways
- 361 is a narrow exemption, not a free pass. It only applies when all four criteria under 21 CFR 1271.10(a) are met simultaneously.
- Your marketing language can change your product’s classification. The FDA determines intended use partly by how you describe a product. Non-homologous marketing claims can reclassify a 361 product as a 351 biologic.
- Courts have upheld this principle. The 11th Circuit ruled against US Stem Cell Clinic in part because their marketing implied non-homologous use.
- Exosomes have no FDA approval at all. Marketing them as therapy is a violation regardless of the 361/351 distinction.
- PRP is 361-eligible but off-label for most clinical uses. Marketing must reflect the off-label status and avoid treatment claims.
- Two questions filter everything. Does the language imply disease treatment? Does it imply non-homologous use? If yes to either, rewrite before publishing.
Ready to Get Your Marketing Right?
The 361 vs. 351 framework is the regulatory foundation of all compliant regenerative medicine marketing. If you are not sure whether your current website reflects this correctly, that is a conversation worth having. Regen Portal’s full services are built to help regenerative medicine clinics market within the rules.
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About Regen Portal
Regen Portal is a marketing company serving the regenerative medicine industry. We provide SEO, content creation, social media management, paid advertising, website development, and branding services for clinics, manufacturers, distributors, and independent providers. Some strategies discussed in our educational content align with services we offer. For more information, contact us.
Oscar Tellez is the founder of Regen Portal, a marketing company built for the regenerative medicine industry. With over 15 years of experience spanning clinical operations, product distribution, and digital marketing, Oscar has helped hundreds of practices, manufacturers, and distributors grow through compliant, high-performance marketing strategies. He holds a B.S. in Exercise Physiology and Health Promotion from Florida Atlantic University.
