Patent ID: 7955852

Claim:
A method of expanding a population of CD34+ hematopoietic stem cells ex-vivo, while at the same time, inhibiting differentiation of the stem cells ex-vivo, the method comprising: (a) culturing said CD34+ hematopoietic stem cells ex-vivo under conditions allowing for cell proliferation, said conditions which comprise providing nutrients, serum and a combination of cytokines including each of stem cell factor, thrombopoietin, FLt3 ligand, and IL-6 and optionally IL-3 and, (b) in the same culture medium providing nicotinamide in an amount between 1.0 mM to 10 mM, wherein culturing said cells for a culture period of three weeks results in expanding the population of CD34+ hematopoietic stem cells while inhibiting differentiation of said CD34+ hematopoietic stem cells ex-vivo to produce an expanded CD34+ hematopoietic stem cell population with an increased proportion of CD34+/Lin− and CD34+/CD38− cells in the expanded culture as compared to CD34+ cells cultured in the presence of cytokines and nutrients without exogenously added nicotinamide.