title: Transient Canonical Wnt Stimulation Enriches Human Bone Marrow Mononuclear Cell Isolates for Osteoprogenitors.
abstract: Activation of the canonical Wnt signaling pathway is an attractive anabolic therapeutic strategy for bone. Emerging data suggest that activation of the Wnt signaling pathway promotes bone mineral accrual in osteoporotic patients. The effect of Wnt stimulation in fracture healing is less clear as Wnt signaling has both stimulatory and inhibitory effects on osteogenesis. Here, we tested the hypothesis that transient Wnt stimulation promotes the expansion and osteogenesis of a Wnt-responsive stem cell population present in human bone marrow. Bone marrow mononuclear cells (BMMNCs) were isolated from patients undergoing hip arthroplasty and exposed to Wnt3A protein. The effect of Wnt pathway stimulation was determined by measuring the frequency of stem cells within the BMMNC populations by fluorescence-activated cell sorting and colony forming unit fibroblast (CFU-F) assays, before determining their osteogenic capacity in in vitro differentiation experiments. We found that putative skeletal stem cells in BMMNC isolates exhibited elevated Wnt pathway activity compared with the population as whole. Wnt stimulation resulted in an increase in the frequency of skeletal stem cells marked by the STRO-1(bright) /Glycophorin A(-) phenotype. Osteogenesis was elevated in stromal cell populations arising from BMMNCs transiently stimulated by Wnt3A protein, but sustained stimulation inhibited osteogenesis in a concentration-dependent manner. These results demonstrate that Wnt stimulation could be used as a therapeutic approach by transient targeting of stem cell populations during early fracture healing, but that inappropriate stimulation may prevent osteogenesis.
authors.affiliation: Centre for Human Development, Stem Cells and Regeneration, University of Southampton, Southampton, United Kingdom.|Bone and Joint Research Group, Human Development and Health Academic Unit, Institute for Developmental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom.|Institute for Life Sciences, University of Southampton, Southampton, United Kingdom.
authors.forename: Agnieszka A
authors.initials: AA
authors.lastname: Janeczek
authors.affiliation: Centre for Human Development, Stem Cells and Regeneration, University of Southampton, Southampton, United Kingdom.|Bone and Joint Research Group, Human Development and Health Academic Unit, Institute for Developmental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom.|Institute for Life Sciences, University of Southampton, Southampton, United Kingdom.
authors.forename: Rahul S
authors.initials: RS
authors.lastname: Tare
authors.affiliation: Centre for Human Development, Stem Cells and Regeneration, University of Southampton, Southampton, United Kingdom.|Bone and Joint Research Group, Human Development and Health Academic Unit, Institute for Developmental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom.|Institute for Life Sciences, University of Southampton, Southampton, United Kingdom.
authors.forename: Edoardo
authors.initials: E
authors.lastname: Scarpa
authors.affiliation: Centre for Human Development, Stem Cells and Regeneration, University of Southampton, Southampton, United Kingdom.|Bone and Joint Research Group, Human Development and Health Academic Unit, Institute for Developmental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom.|Institute for Life Sciences, University of Southampton, Southampton, United Kingdom.
authors.forename: Ines
authors.initials: I
authors.lastname: Moreno-Jimenez
authors.affiliation: Microbiology group, Chemical, Biological and Radiological Division, Salisbury, United Kingdom.
authors.forename: Caroline A
authors.initials: CA
authors.lastname: Rowland
authors.affiliation: Microbiology group, Chemical, Biological and Radiological Division, Salisbury, United Kingdom.
authors.forename: Dominic
authors.initials: D
authors.lastname: Jenner
authors.affiliation: Clinical and Experimental Sciences, Faculty of Medicine, Institute for Life Sciences, University of Southampton, Southampton, United Kingdom.
authors.forename: Tracey A
authors.initials: TA
authors.lastname: Newman
authors.affiliation: Centre for Human Development, Stem Cells and Regeneration, University of Southampton, Southampton, United Kingdom.|Bone and Joint Research Group, Human Development and Health Academic Unit, Institute for Developmental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom.|Institute for Life Sciences, University of Southampton, Southampton, United Kingdom.
authors.forename: Richard O C
authors.initials: RO
authors.lastname: Oreffo
authors.affiliation: Centre for Human Development, Stem Cells and Regeneration, University of Southampton, Southampton, United Kingdom.|Bone and Joint Research Group, Human Development and Health Academic Unit, Institute for Developmental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom.|Institute for Life Sciences, University of Southampton, Southampton, United Kingdom.
authors.forename: Nicholas D
authors.initials: ND
authors.lastname: Evans
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip; D001854:Bone Marrow Cells / Q000166:cytology / Q000378:metabolism*; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000166:cytology / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010012:Osteogenesis; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism*; D017154:Stromal Cells / Q000166:cytology / Q000378:metabolism; D060449:Wnt Signaling Pathway; D060509:Wnt3A Protein / Q000378:metabolism*
chemical_list: C555510:WNT3A protein, human; D060509:Wnt3A Protein
keywords: Fracture healing; Marrow stromal cells/mesenchymal stem cells; Osteoprogenitors; Stem cells; Wnt signaling