Table 1.

Challenges faced during CGT product manufacturing that may affect their clinical use

Type of therapy	Type of cell or vector	Points to consider during the manufacturing process
Cell-based therapy	MSCs	Quality of the tissue source (starting material) Duration of cell cultivation Presence of residual xenogeneic serum
Gene-based therapy	AAV	Separation of empty from full AAV capsids
	LV	Presence of residual impurities (including xenogeneic serum) Optimization of transfection conditions Development of (a) stable producer cell line(s)
Cell-based gene therapy	CAR-T cells	Quality of leukapheresis material Impurities Complex, multistep procedures

Abbreviations: CGT, cell and gene therapy; MSCs, mesenchymal stem cells; AAV, adeno-associated virus; LV, lentiviral vector; CAR-T, chimeric antigen receptor T.