Helen Claire O'Neill

Bone marrow is the main site for hematopoiesis in adults. It acts as a niche for hematopoietic stem cells (HSCs) and contains non‐hematopoietic cells that contribute to stem cell dormancy, quiescence, self‐renewal, and differentiation. HSC also exist in resting spleen of several species, although their contribution to hematopoiesis under steady‐state conditions is unknown. The spleen can however undergo extramedullary hematopoiesis (EMH) triggered by physiological stress or disease. With the loss of bone marrow niches in aging and disease, the spleen as an alternative tissue site for hematopoiesis is an important consideration for future therapy, particularly during HSC transplantation. In terms of harnessing the spleen as a site for hematopoiesis, here the remarkable regenerative capacity of the spleen is considered with a view to forming additional or ectopic spleen tissue through cell engraftment. Studies in mice indicate the potential for such grafts to support the influx of hematopoietic cells leading to the development of normal spleen architecture. An important goal will be the formation of functional ectopic spleen tissue as an aid to hematopoietic recovery following clinical treatments that impact bone marrow. For example, expansion or replacement of niches could be considered where myeloablation ahead of HSC transplantation compromises treatment outcomes.

The year 2018 was the 40th anniversary of the birth of Louise Joy Brown, marking four decades of clinical in vitro fertilization and embryo transfer. Though this milestone, reached first by Steptoe and Edwards in the United Kingdom, is well acknowledged through Nobel accolade, the achievement was not entirely celebrated at the time. Global contention was not just moral, but political and legislative. In the United States, the achievement led in 1978 to the freezing of federal funds by the National Institute of Health for research on human embryos and oocytes.A report published on May 4, 1979, by the Ethics Advisory Board of the Department of Health...