Overview of Strategies to Improve Therapy against Tumors Using Natural Killer Cell

Table 1

The advantages and disadvantages of different sources of NK cells.

Sources of NK cells	Advantages	Disadvantages
Peripheral blood	Safe; conveniently collected; strong ability to kill tumor cells	Low numbers in patients; time-consuming and costly
Umbilical cord blood	Available; off-the-shelf; UCB-derived CD34+ cells have translated to the clinic; frozen for a long time	Only one time to get access to the umbilical cord blood
Human embryonic stem cells or induced pluripotent cell	Homogenous NK cell product; easy to amplify large numbers of NK cells	Need to induce iPSC into NK cells
Bone marrow	From patients	Invasive operation
NK cell line (i.e., NK-92 and NK-92MI)	Off-the-shelf; easy to amplify; lack most inhibitory receptors compared to naïve NK cells	Potential tumorigenicity