Duke University Medical Center researchers claim that the naturally secreted growth factor pleiotrophin could provide a useful new tool in the drive to develop hematopoietic stem cell (HSC) therapies. They further suggest that the neurite outgrowth factor could represent the answer to a major stumbling block currently preventing the widespread use of umbilical cord blood as a source of stem cell based transplants.
The study is published in Nature Medicine in a paper titled “Pleiotrophin regulates the expansion and regeneration of hematopoietic stem cells.”
Umbilical cord blood has long been mooted as a potential universal source of stem cells for transplantation therapy, points out lead author, John Chute, M.D., a stem cell transplant physician. However, the limited number of stem cells in cord blood means a reliable method for expanding the cells to generate sufficient numbers is needed. “Unfortunately, there are no soluble growth factors identified to date that have been proven to expand human stem cells for therapeutic purposes.”
Dr. Chute and his group found that adding pleiotrophin to cultured mouse bone marrow cells triggered a 10-fold expansion in the number of cells. The growth factor also boosted the number of human cord blood stem cells capable of engraftment in immunodeficient mice. Subsequent studies confirmed that systemic administration of pleiotrophin to irradiated mice caused a pronounced expansion of bone marrow stem and progenitor cells in vivo.
The Duke team suggests that the use of pleiotrophin could mean the broader use of therapeutic cord blood transplants in humans is now feasible. “Here, we show that the soluble growth factor pleiotrophin acts on both mouse and human hematopoietic stem cells and can induce long-term HSC expansion ex vivo and HSC regeneration in vivo,” the authors state. “Perhaps more importantly systemic treatment with pleiotrophin may have the potential to accelerate recovery of the blood and immune system in patients undergoing chemotherapy or radiotherapy.”