Table 6.

Overview of key evaluation parameters, methods, and regulatory considerations for cell-based and non-cell-based adhesive hydrogel scaffolds in cartilage repair.

Consideration	Device Category	Description	Evaluation Method	Standards/References
Biocompatibility Assessment	Cell-Based	- Assessment of cell viability, proliferation, and differentiation within the hydrogel scaffold in vitro. - Evaluation of host immune response and tissue integration post-implantation.	- Live/dead staining, MTT assay, Alamar Blue assay for cell viability. - Immunohistochemistry for cell-specific markers (e.g., collagen type II, aggrecan) for differentiation. - ELISA for evaluation of inflammatory cytokines (e.g., TNF-α, IL-6) post-implantation.	- ISO 10993 series for biocompatibility testing. - ASTM F1903-98 for evaluation of tissue-engineered cartilage constructs.
	Non-Cell-Based	- Examination of tissue response and integration without cellular components. - Focus on minimizing inflammatory reactions and promoting tissue regeneration.	- Histological analysis (e.g., H and E staining) for tissue response and integration. - Immunohistochemistry for ECM components (e.g., collagen type II, glycosaminoglycans).	- ISO 10993 series for biocompatibility testing. - ASTM F2150-18 for standard guide for tissue-engineered medical products (TEMPs).
Preclinical Efficacy Studies	Cell-Based	- Demonstration of chondrogenic potential and matrix synthesis by seeded cells. - Evaluation of scaffold degradation and tissue remodeling.	- Immunohistochemistry for chondrogenic markers (e.g., collagen type II, aggrecan). - Biochemical assays (e.g., GAG/DNA content, hydroxyproline assay) for matrix synthesis. - SEM and mechanical testing for scaffold degradation and mechanical properties.	- ASTM F2451-05 for testing the mechanical properties of hydrogels for cartilage repair. - ISO 10993 series for biocompatibility testing.
	Non-Cell-Based	- Emphasis on scaffold stability, mechanical properties, and biodegradation characteristics. - Assessment of tissue ingrowth and integration with surrounding cartilage.	- Mechanical testing (e.g., tensile, compressive, shear) for scaffold stability and properties. - Histomorphometry for tissue ingrowth and integration.	- ASTM F2451-05 for testing the mechanical properties of hydrogels for cartilage repair. - ISO 10993 series for biocompatibility testing.
Clinical Trial Design	Cell-Based	- Consideration of cell sourcing, expansion, and delivery methods. -Evaluation of cell retention, survival, and functionality post-implantation.	- In vivo imaging techniques (e.g., MRI, CT) for cell tracking and localization. - Biopsies for histological evaluation of cell survival and phenotype. - Functional assessments (e.g., joint function scores, pain scales) for therapeutic outcomes.	- FDA Guidance for Industry: Preclinical Assessment of Investigational Cellular and Gene Therapy Products (FDA-2012-D-1038). - EMA Guideline on Human Cell-Based Medicinal Products [132].
	Non-Cell-Based	- Simplified trial design without the complexity of cell handling and processing. - Focus on scaffold delivery, integration, and therapeutic outcomes.	- In vivo imaging techniques (e.g., MRI, CT) for scaffold localization and integration. - Functional assessments (e.g., joint function scores, pain scales) for therapeutic outcomes.	- FDA Guidance for Industry: Considerations for the Design of Early-Phase Clinical Trials of Cellular and Gene Therapy Products. - Regulation (EU) 2017/745: New Medical Device Regulation (MDR).
Regulatory Approval Pathway	Cell-Based	- Additional regulatory scrutiny for cell sourcing, processing, and manipulation. - Compliance with Good Manufacturing Practice (GMP) standards for cell-based therapies.	- Adherence to GMP regulations for cell isolation, expansion, and manipulation. - Documentation of cell identity, purity, and potency. - Validation of manufacturing processes and quality control measures.	- FDA Guidance for Industry: CGMP for Phase 1 Investigational Drug and Biological Products. - EMA Guidelines on Good Manufacturing Practice Specific to Advanced Therapy Medicinal Products [133].
	Non-Cell-Based	- Streamlined regulatory pathway focusing on scaffold composition, manufacturing, and performance. - Emphasis on biocompatibility, safety, and efficacy of the scaffold material.	- Compliance with regulatory guidelines for medical devices (e.g., ISO 13485). - Documentation of material characterization, sterilization, and biocompatibility testing.	- FDA Guidance for Premarket Approval (PMA) or Premarket Notification 510(k) depending on device classification. - ISO 13485:2016 for quality management systems for medical devices.