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.