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

ABSTRACT

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. 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. 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. 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