Structural Tissue vs Cellular Tissue Under 21 CFR Part 1271

Classification of Human Cells, Tissues, and Cellular and Tissue-Based Products (HCT/Ps) as structural tissue or cellular/nonstructural tissue is a key step within the regulatory framework defined under 21 CFR Part 1271.

This classification directly determines how minimal manipulation is evaluated under 21 CFR 1271.3(f).

It is applied together with additional criteria including minimal manipulation, homologous use, combination status, and systemic effect considerations.

For a complete overview of regulatory criteria and how they interrelate, see the Regulatory Resource Library.

Structural Tissue

• Provides covering or barrier function
• Offers cushioning or support
• Maintains physical structure

Evaluation focuses on whether processing alters the tissue’s original structural characteristics.

Cells and Nonstructural Tissue

• Biological activity
• Metabolic function
• Cellular signaling

Evaluation focuses on whether processing alters relevant biological characteristics.

Why This Classification Matters

• Structural tissue: must retain structural characteristics
• Cellular tissue: must retain biological characteristics

This distinction determines how minimal manipulation is applied within regulatory evaluation.

Regulatory Classification Context

• Structural vs cellular classification
• Minimal Manipulation
• Homologous Use
• Combination status
• Systemic effect

These criteria are applied together when determining regulatory classification under Section 361 vs Section 351.

Related Regulatory Topics

• Regulatory Framework Overview
• Minimal Manipulation
• Homologous Use
• Donor Eligibility
• Current Good Tissue Practice (cGTP)

Regulatory Notice

This information is for educational purposes only.

Not evaluated by the FDA. Not intended to diagnose, treat, cure, or prevent any disease.

For use by licensed medical professionals.