Table 1.

Quality controls performed at (a) the different steps of the culture and their impact on batch validation and quality controls performed at (b) the thawing of the cells and their impact on batch validation

Test	Culture step	Material	Method	Specifications	Release criteria for downstream manufacture
(a) MSC quality controls
Cell count	P1, P2, Harvest	Cell suspension	Cell counting (Neubauer cell counting chamber)	None	Informative
Cell viability	P1, P2, Harvest	Cell suspension	Trypan blue exclusion (Neubauer cell counting chamber)	None	Informative
Morphology	P1, P2, Harvest	Cell suspension	Microscope observation	Fibroblastic	Release criteria for batch validation
Aspect	P1, P2, Harvest	Cell suspension	Microscope observation	Cell suspension without aggregates	Release criteria for batch validation (harvest only)
Sterility	P0, P2 and harvest	Culture supernatant	BactAlertR	Sterile	Release criteria for batch validation (P2 and harvest)
Mycoplasma	P2 and harvest	Culture supernatant	Biochemical test (detection of mycoplasma enzymes by bioluminescence)	Absence of mycoplasma	Release criteria for batch validation
Endotoxin	P2 and harvest	Culture supernatant	LAL (limulus amebocyte lysate) detection E.P. 2.6.14.	Endotoxin level <2.5 U.I./ml	Release criteria for batch validation
Cell identity and purity (phenotype)	P2 and harvest	Cell suspension	Facs analysis	CD90 > 70 % CD105 > 70 % CD73 > 70 % CD14 < 5 % CD34 < 5 % CD45 < 5 % CD3 < 1 %	Release criteria for batch validation
Karyotype	P2 and harvest	Cell culture	Chromosome analysis	Absence of abnormal chromosomal structure and/or number	Release criteria for batch validation
Immunosuppressive properties	Harvest	Cell culture	MLR with stimulated PBMC-cell cycle analysis	>25 % Inhibition of PBMC-induced proliferation (10/1 ratio)	Release criteria for batch validation
(b) Post-thaw MSC quality controls
Cell count	Thawing	Cell suspension	Cell counting (Neubauer cell counting chamber)	Yes, cell number should be > × 10E6 and < × 10E6 cells/kg recipient According to the clinical protocol	Release criteria
Viability	Thawing	Cell suspension	Trypan blue exclusion (Neubauer cell counting chamber)	50 %	Release criteria
Sterility	Thawing	Thawed cell product	BactAlertR	Sterile	No, results are not known at the time of infusion. Cells are released according to sterility results at harvest