Challenges in the Development of a Reference Standard and Potency Assay for the Clinical Production of RAFT Tissue Equivalents for the Cornea

Abstract

Aim: To develop a reference standard and potency assay for Real Architecture For 3D Tissues (RAFT) tissue equivalents intended for use in limbal epithelial stem cell (LESC) therapy for the cornea. Methods: RAFT, a cell-seeded plastic compressed collagen construct with LESCs cultured on the surface, was manufactured with the goal of achieving GMP compliance. RAFTs were tested for reproducibility of manufacture (reference standard) and subsequently wounded and monitored for re-epithelialization (potency assay). Results: RAFT tissue equivalents produced with cells from different biological donors were capable of supporting multilayered epithelium in culture. The potency assay demonstrated re-epithelialization following wounding, indicating the potential efficacy of RAFT constructs. Conclusion: We have presented our attempts at creating a reference standard and potency assay for the clinical manufacture of RAFT for the treatment of LESC deficiency. However, it remains challenging for adult stem cell therapies (including LESC therapy) to fully meet regulatory requirements when dealing with a limited source of autologous cells with inherent biological variation between donors.

Keywords::

• cell therapy
• cornea
• GMP
• limbal epithelial stem cells
• potency assay
• RAFT
• reference standard

Financial & competing interests disclosure

The authors are grateful to the Technology Strategy Board for funding this study, in addition to part-funding by the National Institute for Health Research (NIHR) Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology. RAL Drake and JT Daniels hold peer-reviewed funding for development of the RAFT process. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.

Ethical conduct of research

The authors state that they have obtained appropriate institutional review board approval or have followed the principles outlined in the Declaration of Helsinki for all human or animal experimental investigations. In addition, for investigations involving human subjects, informed consent has been obtained from the participants involved.

Additional information

Funding

The authors are grateful to the Technology Strategy Board for funding this study, in addition to part-funding by the National Institute for Health Research (NIHR) Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology. RAL Drake and JT Daniels hold peer-reviewed funding for development of the RAFT process. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed. No writing assistance was utilized in the production of this manuscript.