Since the late 1950s when the first experimental and then clinical application of haemopoietic stem cell transplantation (HSCT) were undertaken, haematologists, oncologists and scientists have been fascinated with the potential for generating a new haemopoietic and lymphopoietic system utilizing stem cells either from an autologous source or from allogeneic donors. Today more than 15,000 HSCT are performed annually world-wide. The regenerative power of haemopoietic cells has allowed the safe application of dose intensified therapy for haematologic and non-haematologic malignancies providing cure for patients without otherwise curable options. Whilst allogeneic transplantation also provides an excellent source of engrafting myeloid stem cells, its potency is primarily in regard to the reconstitution of an allogeneic immune system which generates the graft versus tumour affect resulting in improved cure rates for conditions such as acute leukaemia, some forms of lymphoma, myelodysplasia, and myeloproliferative disorders.
The application of HSCT has provided insights into the biology and pathobiology of stem cell engraftment and function in addition to insights into the reconstitution of a functioning immune system. The application of efficient collection systems with the development of stem cell expansion and T-cell expansion technologies has given rise to the advent of a bioengineered stem cell transplants either as supportive care in the setting of expanded committed myeloid progenitors or as an adjunct to the immunotherapy of malignancy.
Despite their substantial and very real promise, all of these approaches have their limitations and the challenges for the future is how best to optimize transplantation techniques to provide all of the potencies which these approaches promise whilst avoiding the undoubted current toxicities.