A new study that has appeared in the journal STEM CELLS Translational Medicine demonstrates the potential of a subset of stem cells called CD34+ in treating stubborn bone fractures that prove hard to heal.
The body has mechanisms for the repair of broken bones. Consequently, most patients recover from broken bones with little or no complication. However, up to 10 percent of all fracture patients experience fractures that refuse to heal. Such heard to heal fractures can lead to several debilitating side effects that include infection and bone loss, and the healing of hard to heal fractures often requires extensive treatment that includes multiple operations and prolonged hospitalization as well as long-term disability.
Regenerating broken bones with stem cells could offer an answer to this medical conundrum. Adult human peripheral blood CD34+ cells have been shown to contain a robust population of endothelial progenitor cells (EPCs) and hematopoietic stem cells, which give rise to all types of blood cells. These two types of stem cells might be good candidates for this therapy.
However, while other types of stem cells have been tested for their bone regeneration potential, the ability of CD34+ stem cells to facilitate bone healing has not been examined; that is until now. A phase I/II clinical study that evaluated the capacity of CD34+ to stimulate bone regeneration was published in the current edition of STEM CELLS Translational Medicine. This study was conducted by researchers at Kobe University Graduate School of Medicine, led by Tomoyuki Matsumoto, M.D., and Ryosuke Kuroda, M.D., members of the university’s department of orthopedic surgery and its Institute of Biomedical Research and Innovation (IBRI).
Matsumoto’s and Kuroda’s study was designed to evaluate the safety, feasibility and efficacy of autologous and G-CSF-mobilized CD34+cells in patients with non-healing leg bone breaks that had not healed in nine months. Seven patients were treated with CD34+ stem cells after receiving bone grafts.
In case you were wondering, G-CSF is a drug that releases stem cells from the bone marrow into the blood. It is given by injection or intravenously, and works rather well to mobilize bone marrow stem cells into the peripheral circulation. It has clinical uses for patients recovering from chemotherapy. Filgrastim (Neupogen) and PEG-filgrastim (Neulasta) are two commercially-available forms of recombinant G-CSF.
“Bone union was successfully achieved in every case, confirmed as early as 16.4 weeks on average after treatment,” Dr. Kuroda said.
Dr. Matsumoto added, “Neither deaths nor life-threatening adverse events were observed during the one year follow-up after the cell therapy. These results suggest feasibility, safety and potential effectiveness of CD34+ cell therapy in patients with nonunion.”
Atsuhiko Kawamoto, MD, Ph.D., a collaborator in IBRI, said, “Our team has been conducting translational research of CD34+ cell-based vascular regeneration therapy mainly in cardiovascular diseases. This promising outcome in bone fracture opens a new gate of the bone marrow-derived stem cell application to other fields of medicine.”
Although the study documents a relatively small number of patients, the results suggest the feasibility, safety and potential effectiveness of CD34+ cell therapy in patients with non-healing breaks,” said Anthony Atala, M.D., editor of STEM CELLS Translational Medicine and director of the Wake Forest Institute for Regenerative Medicine.