Three-dimensional culture of mouse bone marrow cells within a porous polymer scaffold: effects of oxygen concentration and stromal layer on expansion of haematopoietic progenitor cells.

To establish an ex vivo expansion method of haematopoietic progenitor cells (HPCs) and erythroid cells, three-dimensional (3D) cultures of mouse bone marrow cells were performed, employing a porous polyvinyl formal (PVF) resin as a scaffold. In these cultures, the effects of oxygen concentration and co-cultures with stromal cells on the expansion of HPCs and erythroid cells were investigated. When bone marrow cells were cultured under 3D conditions, HPCs and erythroid cells expanded without supplementation of exogenous cytokines, irrespective of the presence of stromal cells. On the contrary, slight expansion of HPCs or erythroid cells was observed in monolayer cultures as controls, indicating that the 3D cultures using the PVF scaffold were far better in expanding HPCs and erythroid cells than the monolayer cultures. Under hypoxic conditions, bone marrow stromal cells allowed for a 3D culture of erythroid cells and HPCs at higher cell densities compared to cultures without stromal cells, and the duration of the expansion of HPCs and erythroid cells after initiating the 3D co-cultures was prolonged. The number of these cells increased throughout the culture period up to 3 weeks under hypoxic conditions, although the number decreased after 2 weeks under normoxic conditions. In conclusion, the 3D co-culture method of haematopoietic cells with stromal cells under hypoxic conditions was confirmed to be effective in expanding HPCs and erythroid cells, and this method seemed to be useful for developing an ex vivo expansion method for haematopoietic cells.