Hematopoietic stem cells (HSCs) in the bone marrow are the stem cells producing all types of blood cells and supplying the organism with new blood cells. There is a high clinical interest in being able to maintain and expand hHSCs in vitro as this could be applied to treat a large number of haematological malignancies. In vivo, they expand in the hematopoietic niche but recapitulating an artificial niche for ex vivo hHSC maintenance and expansion remains challenging. Microengineering biomimetic three dimensional environments provides a realistic environment of an artificial stem cell niche. For this purpose, microfluidic lab-on-a-chip technologies provide a new unique advantages to mimic complex physiological microenvironments in vitro. Here, a droplet-based microfluidic device able to generate double layered three-dimensional hydrogel environments to maintain hHScs ex vivo is presented