3D bioprinting reveals a new approach for killing solid cancer tumors

3D bioprinting keeps NK cells viable 

Natural killer cells are leukocytes or white blood cells that protect our body from infections and diseases by selectively killing disease-carrying cells and tumor formations that may cause any harm. 

When these leukocytes are used to target cancer cells via intravenous injections, they do wipe out small tumors and prevent the spread of cancer. However, they are not that effective against large solid tumors. “This is because NK cells are incapable of retaining an appropriate level of viability,” the researchers note.

Standard immunotherapy has two major limitations; there is no scope for cell expansion due to the lack of cell-to-cell interaction within the immunotherapy system, and there is no mechanism to directly target the tumors. 

This is why Korean researchers adopted a different approach to using NK cells against cancer. They 3D bio-printed micro-macro porous hydrogels using organic compounds like gelatin and sodium alginate (NaC6H7O6). 

Unlike regular 3D printing which uses plastic or metals to print objects, 3D bioprinting is a more advanced additive manufacturing technique that utilizes living cells and biomaterials to produce artificial 3D structures that look and function like natural tissues and organs.

The researchers successfully encapsulated NK cells in the hydrogels. The micropores allowed the cells to perform natural functions like cytokinesis (cell division) and cell death, and hence they were able to retain their viability.

The macropores on the other side enabled the leukocytes to receive nutrients, oxygen, and various other supplies that ensured their survival and growth. The micro-macro pore environment basically solves the two problems that scientists face with standard NK cell immunotherapy.

Finally, when the researchers attacked cancer cells using these NK cells in an in-vitro model, the majority of the leukocytes successfully targeted solid tumors. 

“We demonstrated that the hydrogel encapsulating NK cells created an appropriate micro–macro environment for clinical applications of NK cell therapy for both leukemia and solid tumors via 3D bioprinting,” said the study authors. 

Such a feat could never be achieved with the conventional immunotherapy setup, and a big credit for this also goes to the 3D bioprinting technique. As “3D bioprinting makes macro-scale clinical applications possible, and the automatic process shows potential for development as an off-the-shelf immunotherapy product,” they added.

Hopefully, this immunotherapy approach will soon emerge as an effective clinical strategy for avoiding tumor recurrence and metastasis following tumor excision in cancer patients.

The study is published in the journal Biomaterials Research.

Study Abstract:

Patients face a serious threat if a solid tumor leaves behind partial residuals or cannot be completely removed after surgical resection. Immunotherapy has attracted attention as a method to prevent this condition. However, the conventional immunotherapy method targeting solid tumors, that is, intravenous injection, has limitations in homing in on the tumor and in vivo expansion and has not shown effective clinical results. To overcome these limitations, NK cells (Natural killer cells) were encapsulated in micro/macropore-forming hydrogels using 3D bioprinting to target solid tumors.