A Mathematical Approach To Model Human Megakaryopoiesis Process in vitro

Megakaryopoiesis is a complex process, which is commenced with the proliferation and the differentiation of hematopoietic stem cells (HSC) into megakaryocytes (Mk), followed by maturation and polyploidy of Mk and ended by platelet biogenesis. An in vitro two-stage protocol including HSC expansion and Mk lineage commitment of human umbilical cord blood cells (hUCB) were established [1]. In the first stage, hUCB CD34+-enriched cells were expanded in co-culture with bone marrow human mesenchymal stem cells (BM hMSC) in a cytokines cocktail pre-optimized for CD34+ expansion. In the second stage, expanded cells were differentiated toward Mk lineage using a cocktail containing TPO and IL-3 in a serum-free medium. Phenotypic characterization of cells was performed by Flow cytometry. In order to describe the fate of HSC during the megakaryopoiesis, a mathematical approach was used based on kinetic modeling of cell expansion and differentiation. This kind of modeling, which computes the concentration of each subset during the time, can provide significant insight into the limiting step involved in the protocol and how the interaction of different factors can affect the outcome of megakaryopoiesis process. A set of ordinary differentiation equation (ODE) were used to analyze the proliferation and differentiation of UCB CD34+ cells, as evaluated by the number of HSC (CD34+ cells), Mk (CD41+ cells) and platelets (CD42b+ cells). These ODEs were solved and a general solution for each subset was fitted to the experimental result, using least square method, to determine the unknown coefficient factors. The establishment of such reliable kinetic model will be useful for development of an efficient bioreactor system devoted for production of specific hematopoietic product.References:1. Hatami J, Andrade PZ, Bacalhau D, Cirurgião F, Ferreira FC, et al. (2014) Proliferation extent of CD34+ cells as a key parameter to maximize megakaryocytic differentiation of umbilical cord blood-derived hematopoietic stem/progenitor cells in a two-stage culture protocol. Biotechnology Reports 4: 50-55.