Speaker
Description
Introduction
Natural biomaterials have opened promising avenues in bioprinting and tissue engineering by providing native-like environments for regenerative therapies. These materials offer significant biological advantages but also introduce challenges related to variability, immunogenicity, and contamination risks [1]. The regulatory framework is gradually evolving to address these concerns, but remains insufficient, particularly for decellularized extracellular matrix (dECM) from animal sources. The lack of standardized regulations and acceptance criteria for dECM hinders the clinical translation of dECM-based bioinks and related constructs.
Safety criteria
Effective decellularization is commonly defined as <5 ng DNA/mg dry weight, DNA fragments <200 bp, and absence of visible nuclear material [2]. Ensuring cell removal and biocompatibility is critical for dECM safety, as it prevents immune responses. ISO 10993 provides comprehensive biological evaluation guidelines for medical devices. Safety criteria also include the removal of microbial and viral contaminants, immunogenic epitopes, and residual chemicals. Sterility validation should follow Ph.Eur. 2.6.1 and ISO 11737, requiring a sterility assurance level (SAL) of 10⁻⁶. Endotoxin testing must comply with Ph.Eur. 2.6.14 and USP <85>, with a limit of <0.5 EU/mL. ISO 22442 guides sourcing and evaluation of animal-derived materials to mitigate zoonotic risks. Xenogeneic scaffolds must also exclude species-specific antigens (e.g. α-gal), although standardized detection and removal criteria remain undefined. Chemicals, especially detergents, are widely used in decellularization protocols, and their residues must be minimized, yet specific thresholds are lacking. Recent data indicate that Triton X-100 concentrations in influenza vaccines are considered acceptable below 0.05% v/v [3].
Quality, functionality and consistency
The dECM should be evaluated for the preservation of key structural and functional ECM components (e.g. collagen, elastin, GAGs, and growth factors). An often overlooked parameter in dECM characterization is lipid content, which can impair hydrogel formulation. We have defined <4% as the acceptable fat concentration. Functional assessment should also include mechanical testing and in vitro bioactivity assays. Variability in tissue sourcing and processing can impact outcomes, making standardized protocols essential. Batch consistency, reproducibility and regulatory compliance can be supported by GMP practices and ISO 13485, ASTM (F3354-19) standards. From a clinical perspective, implanted dECM-based products should be assigned to Class III medical devices or ATMPs, depending on their composition and function.
Discussion
Despite advances in natural biomaterials preparation and evaluation, regulatory clarity remains limited. Current practices often rely on widely cited but non-binding criteria. DNA thresholds, although frequently referenced, are not officially standardized, and some studies report their exceedance in commercial dECM products with favorable clinical outcomes [4,5]. The use of detergents, particularly Triton X-100 - classified by ECHA as a Substance of Very High Concern due to its environmental impact - highlights the need for safer, more sustainable alternatives. Detergent-free approaches offer potential but often exhibit reduced efficacy. Source materials variability and species-specific risks further hinder standardization. Establishing unified, tissue-specific standards encompassing safety, quality and batch consistency is essential. Moreover, integrating sustainable processing methods and validated quality benchmarks will support regulatory alignment and facilitate clinical translation of dECM-based products.
References:
1. doi.org/10.3389/fimmu.2023.1269960
2. doi.org/10.1007/s10439-019-02408-9
3. doi.org/10.3389/fbioe.2023.1097349
4. doi.org/10.1111/aor.14126
5. doi.org/10.1159/000455070
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