3D culture of umblical cord blood-drived CD34+ cells on a DBM scaffold coated by cord blood–derived unrestricted somatic stem cells (USSC)

Objective: Allogeneic transplantation with umbilical cord blood (UCB) in adult recipients is limited mainly by a low CD34+ cell dose. To overcome this shortcoming, human placenta as a novel source of human mesenchymal progenitor cell (MPC)- unrestricted somatic stem cells (USSC)- was incorporated in an attempt to expand CD34+ cells from UCB. To provide a similar environment in vitro, we coated DBM scaffold with USSC cells as the matrix for support UCB-CD34+ cells growth.
Materials and Methods: Human placenta USSC was isolated and characterized by morphologic and immunophenotypical analysis. UCB CD34+ cells were expanded by coculture with placental USSC in 2D and 3D environment. Suitable aliquots of cells were used to monitor cell production, clonogenic activity, and long-term culture-initiating culture (LTC-IC) output.
Results: Ex vivo expansion of UCB hematopoietic cells, when cultured in different 2D conditions and 3D condition for 3 weeks, was significantly enhanced, the total cell count increased within the 28-day period. For total CFC, the highest CFC expansion was observed at day 14. Flow cytometry analysis of the percentage of CD34+ cells showed a decline in USSC cocultures in 2D and 3D condition at 3 weeks.
Conclusion: These results strongly suggest that human USSC may be a suitable feeder layer for expansion of hematopoietic progenitors from UCB in vitro and USSC- coated DBM can therefore provide an ex vivo mimicry of bone marrow by enhancing of surface/ volume ratio and feeder layers,recapitulate the desired niche, and provide a suitable environment for stem cell expansion and differentiation.