Gaps between Asian regulations for eligibility of human mesenchymal stromal cells as starting materials of cell therapy products and comparability of mesenchymal stromal cell-based products subject to changes in their manufacturing process.

Working group 2 (WG2) of the Asia Partnership Conference of Regenerative Medicine has discussed eligibility of mesenchymal stromal cells (MSCs) as starting cells for the manufacture of cell therapy products, and comparability before and after changes in their manufacturing process. Asian countries and regions have their own regulations on the quality of starting cells, and these regulations are not harmonized. As cell therapy products are being developed across countries and regions, we propose a risk-based approach based on donor location, window period of virus test, and additional virus tests on the master cell bank to fill the gaps in regulation while controlling the risk of viral contamination. Moreover, a standard procedure of comparability assessment after changes in the manufacturing process of MSC-based products does not exist. The WG2 discussed points of comparability assessment specifically for MSC-based products considering the similarities and differences with parallel assessments for protein and polypeptide products, which are within the scope of the International Council for Harmonization Q5E guideline. We also summarize possible characterization procedures for MSC-based products and report our discussion on stability evaluations under accelerated and stress conditions for comparability assessment of cell therapy products.