THE STEM CELL NICHE Human Cord Blood CD133 1 Stem Cells Transplanted to Nod-Scid Mice Provide Conditions for Regeneration of Olfactory Neuroepithelium After Permanent Damage Induced by Dichlobenil VALERIA FRANCESCHINI, a SIMONE BETTINI, a SIMONE PIFFERI, b ALFREDO ROSELLINI, c ANNA MENINI, b RICARDO SACCARDI, d EMANUELA OGNIO, e ROSEMARY JEFFERY, f RICHARD POULSOM, f ROBERTO P. REVOLTELLA c a Department of Experimental Evolutionary Biology, University of Bologna, Bologna, Italy; b Neurobiology Sector, International School for Advanced Studies S.I.S.S.A., Italian Institute of Technology, Trieste, Italy; c National Research Council of Italy (CNR) and Foundation ONLUS ‘‘Stem Cells and Life,’’ Pisa, Italy; d Department of Hematology, Bone Marrow Transplantation Center, University Hospital of Careggi, Firenze, Italy; e Animal Model Facility, National Institute for Cancer Research (IST), Genova, Italy; f Histopathology Laboratory, Cancer Research United Kingdom, London Research Institute, London, United Kingdom Key Words. Olfactory neuroepithelium • Dichlobenil • Olfactory tissue regeneration • Cord blood • CD133 1 stem cells • Chimaerism ABSTRACT The herbicide dichlobenil selectively causes necrosis of the dorsomedial part of olfactory neuroepithelium (NE) with permanent damage to the underlying mucosa, whereas the lateral part of the olfactory region and the nasal respiratory mucosa remain undamaged. We investigated here whether human umbilical cord blood CD133 1 stem cells (HSC) injected intravenously to nod-scid mice pretreated with dichlobenil may engraft the olfactory mucosa and contrib- ute to the regeneration of the damaged NE. We tested HLA-DQa1 DNA and three human microsatellites (Com- bined DNA Index System) as indicators of engrafted cells, finding polymerase chain reaction evidence of chimaerism in various tissues of the host, including the olfactory mucosa and bulb, at 7 and 31 days following HSC transplantation. Histology, immunohistochemistry, and lectin staining revealed the morphological recovery of the dorsomedial region of the NE in dichlobenil-treated mice that received HSC, contrasting with the lack of regeneration in similarly injured areas as these remained damaged in control non- transplanted mice. FISH analysis, to detect human genomic sequences from different chromosomes, confirmed persis- tent engraftment of the regenerating olfactory area with chimeric cells. Electro-olfactograms in response to odor- ants, to test the functionality of the olfactory NE, confirmed the functional damage of the dorsomedial area in dichlobe- nil-treated mice and the functional recovery of the same area in transplanted mice. These findings support the con- cept that transplanted HSC migrating to the damaged olfac- tory area provide conditions facilitating the recovery from olfactory receptor cell loss. STEM CELLS 2009;27:825–835 Disclosure of potential conflicts of interest is found at the end of this article. INTRODUCTION The olfactory neuroepithelium (NE) is a pseudostratified epi- thelium, lying in the convoluted turbinates within the poste- rior region of the nasal cavity. From the apical surface to the basal lamina, it is composed of sustentacular cells, mature and immature olfactory neurons, and precursor globose basal cells and horizontal basal cells [1–3]. Sustentacular cells are non-neuronal supporting cells capped by microvilli, which produce a large array of soluble cytokines and growth factors, serve in detoxification of external agents, and also act as phagocytes eliminating dead olfactory neurons and stromal cells [4, 5]. Olfactory receptor cells are elongated, columnar bipolar cells with an apical dendrite ending with knob-bearing cilia. On the surface of these cilia are odorant receptors that are exposed directly to the external environment. The binding odorant molecules to odorant receptors initiate the olfactory transduction cascade that produces a depolarization of the ol- factory receptor neuron [6, 7]. The electrical activity in response to odorants can be recorded at the surface of the ol- factory epithelium from localized populations of olfactory Author contributions: V.F.: conception and design, data analysis and interpretation, financial support, manuscript writing; S.B.: collection and assembly of data, data analysis and interpretation; S.P.: collection and assembly of data, data analysis and interpretation, manuscript writing; A.R.: collection and assembly of data, data analysis and interpretation; A.M.: data analysis and interpretation, financial support, manuscript writing; R.S.: provision of study materials; E.O.: provision of study materials; R.J.: assembly of data, data analysis and interpretation; R.P.: data analysis and interpretation, manuscript writing; R.P.R.: conception and design, data analysis and interpretation, financial support, manuscript writing. Correspondence: Valeria Franceschini, Department of Experimental Evolutionary Biology, University of Bologna, Via Selmi 3, 40126 Bologna, Italy. Telephone: þ39 0512094143; Fax: þ39 0512094286; e-mail: valeria.franceschini@unibo.it; or Roberto P. Revoltella, M.D., Ph.D., Foundation ONLUS: ‘‘Stem Cells and Life,’’ IPCE-CNR, Molecular Modelling Lab., Via G. Moruzzi 1, 56124, Pisa, Italy. Telephone: þ39 3341748107; e-mail: rrevoltella@yahoo.it Received May 23, 2008; accepted for publication December 30, 2008; first published online in STEM CELLS EXPRESS January 15, 2009. V C AlphaMed Press 1066-5099/2009/$30.00/0 doi: 10.1002/stem.11 STEM CELLS 2009;27:825–835 www.StemCells.com