An extended flow cytometry evaluation of ex vivo expanded NK cells using K562.Clone1, a feeder cell line manufactured in Brazil.

BACKGROUND: Natural Killer (NK) cells play a crucial role in the immune system's response against cancer. However, the challenge of obtaining the required quantity of NK cells for effective therapeutic response necessitates the development of strategies for their ex vivo expansion. OBJECTIVE: This study aimed to develop a novel feeder cell line, K562.Clone1, capable of promoting the ex vivo expansion of NK cells while preserving their cytotoxic potential. STUDY DESIGN: The K562 leukemic cell line was transduced with mbIL-21 and 4-1BBL proteins to generate K562.Clone1 cells. NK cells were then co-cultured with these feeder cells, and their expansion rate was monitored over 14 days. The cytotoxic potential of the expanded NK cells was evaluated against acute myeloid leukemia blasts and tumor cell lines of leukemia and glial origin. Statistical analysis was performed to determine the significance of the results. RESULTS: The K562.Clone1 co-cultured with peripheral NK showed a significant increase in cell count, with an approximately 94-fold expansion over 14 days. Expanded NK cells demonstrated cytotoxicity against the tested tumor cell lines, indicating the preservation of their cytotoxic characteristics. Additionally, the CD56, CD16, inhibitory KIRs, and activation receptors were conserved and present in a well-balanced manner. CONCLUSION: The study successfully developed a feeder cell line, K562.Clone1, that effectively promotes the expansion of NK cells ex vivo while maintaining their cytotoxic potential. This development could significantly contribute to the advancement of NK cell therapy, especially in Brazil.

Extracellular vesicles cargo from head and neck cancer cell lines disrupt dendritic cells function and match plasma microRNAs.

Extracellular vesicles (EVs) are mediators of the immune system response. Encapsulated in EVs, microRNAs can be transferred between cancer and immune cells. To define the potential effects of EVs originated from squamous cell carcinoma cells on immune system response, we performed microRNA profiling of EVs released from two distinct cell lines and treated dendritic cells derived from circulating monocytes (mono-DCs) with these EVs. We confirmed the internalization of EVs by mono-DCs and the down-regulation of microRNA mRNA targets in treated mono-DCs. Differences in surface markers of dendritic cells cultivated in the presence of EVs indicated that their content disrupts the maturation process. Additionally, microRNAs known to interfere with dendritic cell function, and detected in EVs, matched microRNAs from squamous cell carcinoma patients' plasma: miR-17-5p in oropharyngeal squamous cell carcinoma, miR-21 in oral squamous cell carcinoma, miR-16, miR-24, and miR-181a circulating in both oral and oropharyngeal squamous cell carcinoma, and miR-23b, which has not been previously described in plasma of head and neck squamous cell carcinoma, was found in plasma from patients with these cancer subtypes. This study contributes with insights on EVs in signaling between cancer and immune cells in squamous cell carcinoma of the head and neck.