NK cells are heterogeneous lymphocyte subpopulations originated from bone marrow HSCs and play an important role in both innate and adaptive immune response via receptor-ligand- or cytokine-mediated cytotoxicity effects and paracrine effects such as secreting perforin and granzyme, antibody-dependent cytotoxicity (ADCC) dispense with antigen presentation [
1,
3,
6,
24]. In particular, the ADCC process, medicated by the therapeutic monoclonal antibodies (mAbs) and facilitated by the activating Fc receptor CD16a, has been recognized as an important effector mechanism of NK cells [
23,
24]. Herein, by utilizing the “3IL”-based strategy, we efficiently derived UC-NKs and P-NKs from the corresponding MNCs with high level of CD16 expression within 14 days without gene editing. Considering the large amount of the “discarded” perinatal blood, our findings demonstrate the feasibility of exploiting umbilical cord blood and placental blood as splendid renewable sources for ex vivo expansion and activation of functionally mature NK cells with high-affinity CD16-mediated enhanced ADCC property against multiple cancers. Meanwhile, the natural cytotoxicity and cytokine production are also of great importance for mediating the functionality of NK cells. Therewith, it will be interesting to test the potential role of CD16a-associated ADCC for NK cells of both origins (UC-NK cells, P-NK cells) against a Her2/Neu breast cancer cell line or other tumor cell lines (e.g., melanoma, colon cancer cell lines) in the presence of trastuzumab or equivalent drugs in future.
For decades, numerous strategies have been developed to fulfill the clinical needs of NK cell or CAR-NK cell-based immunotherapy [
8,
12,
13]. On the one hand, pioneering investigators focus on screening suitable cell sources for NK cell generation among peripheral blood (PB), NK cell lines (e.g., NK-92, NK-YS, KHYG-1), umbilical cord blood (UCB), placental blood and stem cells (HSPCs, hiPSCs, hESCs) [
1,
2,
8,
11]. Generally, considering the limitation of PB-NKs and UCB-NKs in ex vivo expansion potential together with the intrinsic nature of NK-92 cells derived from Hodgkin’s lymphoma, we speculate that placenta perfusate and hPSCs hold the promising potential for large-scale clinical-grade NK cell generation [
4,
25‐
29]. For instance, Kang et al.reported the characterization and miRNA profiling of P-NKs from placenta-derived stem cells for cancer immunotherapy, yet the systematical and detailed information of P-NKs and UC-NKs remains largely unknown [
4]. Herein, we for the first time illuminated the similarities and diversities of the indicated NKs in biological phenotypes and transcriptome phenotypes. On the other hand, we and other investigators have been dedicating to develop high-efficient and cost-effective procedures for large quantities of functional NK cell generation such as feeder cell stimulation (irradiated K562 cells, K562-mbIL15-41BBL), cytokine cocktail stimulation (e.g., IL-2, IL-15, IL-18, IL-21) and even physicochemical irritation (e.g., bioreactor, culture vessels) [
29‐
31]. In particular, NK cell expansion and functionality are largely affected by the culture medium, and thus the effects of different culture media and human serum supplementation on CB-NK or P-NK cell expansion and functionality as well as relevant cellular vitality (e.g., high dose of cytokine stimulation for activation-induced cell death) are also of great importance. For instance, Moseman and Koh reported the variations in the expansion and cytotoxicity of NK cells due to the culture medium used between the serum-free and serum-containing media formulations, respectively [
32,
33]. Simultaneously, Shah et al. reported the artificial antigen presenting cell (aAPC)-mediated log-scale expansion of UC-NKs from both fresh and cryopreserved CB units with anti-myeloma activity [
12]. However, mature NK cells have multiple disadvantages such as short lifespan and poor in vivo persistence [
1,
34]. It’s noteworthy that Sliz and the colleagues recently reported the pivotal role of Gab3 in IL-2 and IL-15-mediated NK cell priming and expansion, together with the elimination and recognition of “missing-self” and antitumor responses, which indicated the possibility of lifespan intervention of ex vivo expanded NK cells [
35]. Above all, we systematically and meticulously dissected the similarities and differences of UC-NKs and P-NKs in biological signatures, gene expression profiling and the recommended cytotoxic activity assessment for the first time. Additionally, considering the nearly 20% of total T cells remaining in the cultures at day 14, and thus all these cells would have to be removed before administration of the NK cells to the patient. Collectively, our studies would benefit the fundamental research and clinical practice of NK cell-based immunotherapy in future.