Haematopoietic stem cells (HSCs) are commonly used to reconstitute the bone marrow and
blood of patients suffering from diseases such as leukaemias, lymphomas and non-malignant conditions
like severe bone marrow aplasia and thalassemia major. The mature progeny of HSCs, especially
erythrocytes and platelets, are used regularly for rapid transfusion into patients with acute conditions
like life-threatening bleeding. For HSC transplantation (HSCT), cells must originate from an
immunologically matched donor, and the chronic lack of supply of suitable cells drives the search for
alternate HSC sources. Human embryonic stem cells (hESCs) hold the promise for development into
every tissue type. Multiple laboratory based studies have demonstrated the careful, ontological
approach to HSC differentiation from hESCs, leading to the differentiation of cells which are similar to
bone marrow HSCs. Significant challenges remain in achieving HSC replicas, primarily improvement
to both efficiency of HSC generation and sustained engraftment in vivo. The differentiation of mature
blood cells from hESCs, in order to generate large numbers of “off the shelf” cells for transfusions, has
been successful with the production of seemingly fully mature and functional cells, albeit in low
numbers. Concerns about the need for immunosuppression after hESC transplantation, has meant that
the development of patient-specific induced pluripotent stem cells, which have also been differentiated
into blood cells, also has enormous potential for use in the clinic. Presently, these cell products have
significant barriers to overcome before clinical translation, such as efficient in vivo function, large-scale
manufacture of consistent cell products and short- and long-term safety issues.
Keywords: Haematopoietic stem cells, embryonic stem cells, immunosuppression, transpalantion.
