GMP-based CD133+ cells isolation maintains progenitor angiogenic properties and enhances standardization in cardiovascular cell therapy

The aim of the present study was to develop and validate a good manufacturing practice (GMP) compliant procedure for the preparation of bone marrow (BM) derived CD133(+) cells for cardiovascular repair. Starting from available laboratory protocols to purify CD133(+) cells from human cord blood, we implemented these procedures in a GMP facility and applied quality control conditions defining purity, microbiological safety and vitality of CD133(+) cells. Validation of CD133(+) cells isolation and release process were performed according to a two-step experimental program comprising release quality checking (step 1) as well as 'proofs of principle' of their phenotypic integrity and biological function (step 2). This testing program was accomplished using in vitro culture assays and in vivo testing in an immunosuppressed mouse model of hindlimb ischemia. These criteria and procedures were successfully applied to GMP production of CD133(+) cells from the BM for an ongoing clinical trial of autologous stem cells administration into patients with ischemic cardiomyopathy. Our results show that GMP implementation of currently available protocols for CD133(+) cells selection is feasible and reproducible, and enables the production of cells having a full biological potential according to the most recent quality requirements by European Regulatory Agencies.