Design and Validation of an Automated Process for the Expansion of Peripheral Blood-Derived CD34+ Cells for Clinical Use After Myocardial Infarction

Abstract

We previously demonstrated that intracardiac delivery of autologous peripheral blood‐derived CD34+ stem cells (SCs), mobilized by granulocyte‐colony stimulating factor (G‐CSF) and collected by leukapheresis after myocardial infarction, structurally and functionally repaired the damaged myocardial area. When used for cardiac indication, CD34+ cells are now considered as Advanced Therapy Medicinal Products (ATMPs). We have industrialized their production by developing an automated device for ex vivo CD34+‐SC expansion, starting from a whole blood (WB) sample. Blood samples were collected from healthy donors after G‐CSF mobilization. Manufacturing procedures included: (a) isolation of total nuclear cells, (b) CD34+ immunoselection, (c) expansion and cell culture recovery in the device, and (d) expanded CD34+ cell immunoselection and formulation. The assessment of CD34+ cell counts, viability, and immunophenotype and sterility tests were performed as quality tests. We established graft acceptance criteria and performed validation processes in three cell therapy centers. 59.4 × 106 ± 36.8 × 106 viable CD34+ cells were reproducibly generated as the final product from 220 ml WB containing 17.1 × 106 ± 8.1 × 106 viable CD34+ cells. CD34+ identity, genetic stability, and telomere length were consistent with those of basal CD34+ cells. Gram staining and mycoplasma and endotoxin analyses were negative in all cases. We confirmed the therapeutic efficacy of both CD34+‐cell categories in experimental acute myocardial infarct (AMI) in immunodeficient rats during preclinical studies. This reproducible, automated, and standardized expansion process produces high numbers of CD34+ cells corresponding to the approved ATMP and paves the way for a phase I/IIb study in AMI, which is currently recruiting patients. Stem Cells Translational Medicine 2019;8:822&832

Evaluation of expanded peripheral blood derived CD34+ cells for the treatment of moderate knee osteoarthritis

“…ProtheraCytes ® were obtained after expansion of mobilized CD34+ cells from frozen healthy donors (Lonza, NC, United States) as previously described ( Saucourt et al, 2019 ). ProtheraCytes ® were conditioned in 2% human serum albumin (HSA) in phosphate buffered saline (PBS) in sterile prelabelled syringes and shipped the same day in a refrigerated box to the Cartilage Engineering laboratory at the University Hospital Basel for analysis.…”

“…In particular, ProtheraCytes ® , an advanced therapeutic medicinal product (ATMP) derived from autologous expanded CD34+ cells can represent a novel source for the treatment of OA cartilage lesion. ProtheraCytes ® have regenerative properties and have shown to improve global cardiac function in post-acute myocardial infarction ( Saucourt et al, 2019 ). In a pilot clinical study, we showed that intramyocardial delivery of human CD34+ cells in post-acute myocardial infarction (AMI) patients is safe and leads to long term improvement ( Pasquet et al, 2009 ).…”

A preview of selected articles

“…A pilot study carried out by researchers from the group of Claire Saucourt (CellProthera, Mulhouse, France) demonstrated that the direct intracardiac injection of autologous peripheral blood‐derived CD34+ stem cells, 18 mobilized by granulocyte colony‐stimulating factor treatment and collected by leukapheresis, prompted the long‐term functional and structural regeneration of cardiac lesions following AMI 19 . In the hope of expanding this cell therapy to a greater number of patients, the team next endeavored to simplify and standardize the production of peripheral blood‐derived CD34+ stem cells, as described in a recently published STEM CELLS Translational Medicine article 6 . The authors developed an automated device named StemXpand that permitted the reproducible expansion of CD34+ stem cells derived from mobilized peripheral blood under good manufacturing practice conditions.…”

“…In our first Featured Article published this month in STEM CELLS , Carlone et al link the temporally‐regulated expression of Tert in SSCs with a discrete transitional growth phase that occurs between rapid bone growth and maintenance 5 . In a Related Article published recently in STEM CELLS Translational Medicine , Saucourt et al described a simplified and standardized expansion protocol that yields elevated numbers of CD34+ stem cells from whole blood, which display genetic stability and telomere lengths consistent with basal CD34+ stem cells, for use in the treatment of acute myocardial infarction (AMI) 6 …”

Key Success Factors for Regenerative Medicine in Acquired Heart Diseases

“…The best way to harvest a large number of CD34 + cells has been, up to now, to perform LKP after G-CSF mobilization. However, we have developed a proprietary expansion process that allows GMP production of up to 150 × 10 6 CD34 + stem cells capable of both long-term self-renewal and lineage differentiation, starting from a simple autologous blood draw [144].…”