A Technique for Generating Artificial Lymph Nodes
Cancer diagnosis and treatment tends to involve the removal of lymph nodes, leading to impaired flow in the lymphatic system and either transient or permanent lymphedema. In aging, lymph nodes become fibrotic and structural disorganized, impairing the ability of immune cells to use the lymphatic system to coordinate a response to infection. One possible approach to these problems is the generation of artificial lymph nodes, or at least suitable arrangements of cells that will form themselves into a functional lymph node and connect to the lymphatic system once implanted into the body. A number of different groups have made progress towards this goal, to the point of demonstrating the creation of partially functional lymph nodes in animal studies; the research program noted here is the most recent.
The increase in cancer incidence has accelerated the need for secondary lymphedema treatments after lymphadenectomy because lymph nodes cannot be regenerated. Recently, many attempts have been made to treat secondary lymphedema by forming lymphatic vessels using three-dimensional cellular structures. Of these, three-dimensional cellular structures composed of lymphatic endothelial cells (LECs) and fibroblasts fabricated using a cell stacking technique by coating functional proteins on the cell surface were reported to form a lymphatic network inside the structures, demonstrating the formation of a lymphatic lumen structure after transplantation in mice. Unfortunately this cellular structure has not been effective for the treatment of secondary lymphedema. Therefore, lymph node regeneration or reconstruction using therapeutic cells has not been achieved, and the development of a better therapeutic method is desired.
This study aims to develop a bioengineered three-dimensional tissue composed of LECs and mesenchymal stem/stromal cells (MSCs), which has immunomodulatory functions and can prolong the survival of transplants for lymph node reconstruction. To fabricate the bioengineered tissue simply, we establish a centrifugal cell stacking technique with no additives. This bioengineered tissue, termed "centrifuge-based bioengineered lymphatic tissue" (CeLyT), forms a lymphatic network inside the tissue during culture for several days. CeLyTs induce the formation of lymph node-like structures, with characteristics similar to lymph nodes, after transplantation into mice, and the formation of this lymph node-like structure suppress edema following lymphadenectomy in mice. Therefore, CeLyTs composed of LECs and MSCs might be a cell-based therapeutic strategy for secondary lymphedema.