The Research On The In Vitro Co-culture System Of CD34~+ Cells And Mesenchymal Stem Cell Encapsulated In The Alginate Hydrogel

Attempts to improve the clinical application of hematopoietic stem cell (HSC) have been unsuccessful due to the limited stem cell numbers in the cord blood. Protocols that are based on hematopoietic cytokines have failed to support reliable amplification of immature stem cells in culture, resulting in losing the self-renew ability. Recently, many studies have demonstrated that stromal cells, particularly mesenchymal stem cell (MSC), can significantly promote the in vitro expansion of HSC. And the CD34~+ cells proliferated in this condition have been proved useful in the long-term hematopoiesis in the setting of cord blood transplantation. However, the amplification of CD34~+ cells was affected by co-culture way between CD34~+ cells and MSC.In this research, freshly isolated cord blood CD34~+ cells have been cultured with media at present of serum. The cell seeding ratio and contact way between CD34~+ cells and MSC were studied for the effect on the expansion of CD34~+ cells. It was found that:Expansion fold of total cells and CD34~+ cells increased to 146.7±20.8 fold and 5.3±2.8 fold, more cells entered into S phase when the cell seeding ratio between CD34~+ cells and MSC was 1:5, cultured in indirect contact way.Further, CD34~+ cells were cultured with the MSC encapsulated in the 2.5% alginate hydrogel beads by 5 x 103 cells/bead. The effect of this co-culture system on the expansion of CD34~+ cells was analyzed. It indicated that by using the 2.5% alginate beads encapsulating MSC by 5 x 103 cells/bead to support CD34~+ cells in vitro proliferation, the expansion fold of CD34~+ cells achieved at about 16.0±4.9 fold, significantly higher than control 6.2±3.7 fold at day 14; More cells entered into the S phase with the support of MSC encapsulated in the alginate gel significantly decreasing the apoptosis cells. While, the colony-forming units ability of CD34~+ cells obtained in the alginate co-culture system was improved. The above results were helpful for finding another innovative way researching in the effective ex vivo co-culture system of CD34~+ cells.