Table 1.

Comparison between main ex vivo and in vivo editing features

Criteria	Ex vivo engineering	In vivo engineering
Patient convenience	may require cell collection from patient, waiting times	no need for cell collection, timely availability
Preconditioning	preconditioning regimen is recommended	may bypass the need for preconditioning
Precision & control	high precision in manufacturing, quality checks	high percision in delivery vector design
Validation & efficiency	clinically validated, high editing efficiency	still under validation, varying efficiency
Manufacturing & logistics	complex and lengthy process, logistical burden	simplified process, minimal logistics
Cost & infrastructure	high cost, complex infrastructure required	generally reduced cost and infrastructure needs
Cell fitness considerations	possibility of reduced cell fitness due to ex vivo culturing	possibility of preserved cell fitness due to direct in vivo editing
Toxicity risks	controlled ex vivo editing, potential risks of toxicity and off-target effects	uncontrolled in vivo editing, increased risk of toxicity and off-target effects
Immunogenicity	potential risks of immunogenic responses, method-dependent	higher risk of immunogenicity