title: Recruitment of a host's osteoprogenitor cells using exogenous mesenchymal stem cells seeded on porous ceramic.
abstract: The contribution of the host's circulating progenitor cells after implantation of mesenchymal stem cells (MSC)/bioscaffold combinations for repairing bone defects has not been elucidated, although this issue affects the clinical application of the tissue engineering approach. We implanted blocks of hydroxyapatite loaded with murine MSCs into syngenic, allogenic, and immunocompromised recipients. After 8 weeks, we found that bone tissue was formed in syngenic and immunocompromised animals. The implanted cells appeared pivotal in the early stages of tissue development, but cells of the recipient's origin finally made bone. In this system, osteoprogenitors migrated from the recipient to the implant, whereas the implanted cells left the scaffold and entered the circulatory flow. We observed rapid destruction of implanted cells when allogenic MSC/bioscaffold combinations were grafted onto immunocompetent recipients without immunosuppressant therapy. This destruction blocked the recruitment process and did not allow the formation of new bone tissue. The possibility that the implanted exogenous MSCs could engage the host's osteoprogenitor cells to form new bone tissue could open new perspectives for the tissue engineering approach to bone repair, including the opportunity of using allogenic cells combined with a temporary immunosuppressant therapy, stimulating the replacement of the exogenous cells with autologous cells.
authors.affiliation: Department of Oncology, Biology, and Genetics, University of Genova , Genova, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Tasso
authors.forename: Andrea
authors.initials: A
authors.lastname: Augello
authors.forename: Simona
authors.initials: S
authors.lastname: Boccardo
authors.forename: Sandra
authors.initials: S
authors.lastname: Salvi
authors.forename: Michela
authors.initials: M
authors.lastname: Caridà
authors.forename: Fabio
authors.initials: F
authors.lastname: Postiglione
authors.forename: Franco
authors.initials: F
authors.lastname: Fais
authors.forename: Mauro
authors.initials: M
authors.lastname: Truini
authors.forename: Ranieri
authors.initials: R
authors.lastname: Cancedda
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Pennesi
mesh_terms: D000818:Animals; D002516:Ceramics / Q000494:pharmacology*; D006084:Graft Rejection; D007121:Immunocompetence; D016130:Immunophenotyping; D020007:Implants, Experimental; D045164:Mesenchymal Stem Cell Transplantation; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000187:drug effects*; D051379:Mice; D008810:Mice, Inbred C57BL; D018919:Neovascularization, Physiologic / Q000187:drug effects; D010012:Osteogenesis / Q000187:drug effects; D016062:Porosity / Q000187:drug effects; D054457:Tissue Scaffolds; D014184:Transplantation, Homologous