Natural killer cells as a promising tool to tackle cancer—A review of sources, methodologies, and potentials

ABSTRACT

Immune cell-based therapies are emerging as a promising tool to tackle malignancies, both solid tumors and selected hematological tumors. Vast experiences in literature have documented their safety and added survival benefits when such cell-based therapies are combined with the existing treatment options. Numerous methodologies of processing and in vitro expansion protocols of immune cells, such as the dendritic cells, natural killer (NK) cells, NKT cells, αβ T cells, so-called activated T lymphocytes, γδ T cells, cytotoxic T lymphocytes, and lymphokine-activated killer cells, have been reported for use in cell-based therapies. Among this handful of immune cells of significance, the NK cells stand apart from the rest for not only their direct cytotoxic ability against cancer cells but also their added advantage, which includes their capability of (i) action through both innate and adaptive immune mechanism, (ii) tackling viruses too, giving benefits in conditions where viral infections culminate in cancer, and (iii) destroying cancer stem cells, thereby preventing resistance to chemotherapy and radiotherapy. This review thoroughly analyses the sources of such NK cells, methods for expansion, and the future potentials of taking the in vitro expanded allogeneic NK cells with good cytotoxic ability as a drug for treating cancer and/or viral infection and even as a prophylactic tool for prevention of cancer after initial remission.

KEYWORDS:

• Natural killer cells
• immune cell therapy
• in vitro expansion
• cancer treatment

Acknowledgments

The authors acknowledge (1) Thangavelu Srinivasan for his assistance in the preparation of this manuscript; (2) M/s Chennai Cell Cluster (CCC) for technical advice; And (3) Loyola ICAM College of Engineering Technology (LICET) and Loyola Institute of Frontier Energy (LIFE), Chennai, India for their support in our research work.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the article.