Figure 1.

In vitro erythropoiesis performed at 3% O₂ results in a lower erythroid yield and cell volume compared to cultures at 20% O₂. (A) Cumulative growth curve of erythroid cultures from PBMC to enucleated reticulocytes (day 26). Grey dashed line indicates the change from the expansion phase to the differentiation culture condition (day 13 = day 0 differentiation), as outlined in Materials and Methods. (B) Mean cell volume throughout erythroid cultures was significantly lower in cells at 3% O₂ during expansion but not during differentiation. (C) High altitude (20% O₂ JJ) cultures resulted in an increased erythroid yield compared to pre-altitude (20% O₂) samples. (D) Analysis of CD34+ cells revealed a higher percentage of HSPC circulating in peripheral blood at high altitude. These measurements were performed on all 12 volunteers involved in the high-altitude study. (E) Mean cell volume between 20% O₂ and 20% O₂ JJ samples was comparable. Data on cultures represent results of 5 of the volunteers involved in the high-altitude study (Materials and Methods). Statistical significance was determined using unpaired student t-test, with * = p < 0.05, ** = p < 0.01 and *** = p < 0.001.