title: Hematopoiesis is severely altered in mice with an induced osteoblast deficiency.
abstract: We previously reported a transgenic mouse model expressing herpesvirus thymidine kinase (TK) gene under the control of a 2.3-kilobase fragment of the rat collagen alpha1 type I promoter (Col2.3 Delta TK). This construct confers lineage-specific expression in developing osteoblasts, allowing the conditional ablation of osteoblast lineage after treatment with ganciclovir (GCV). After GCV treatment these mice have profound alterations on bone formation leading to a progressive bone loss. In addition, treated animals also lose bone marrow cellularity. In this report we characterized hematopoietic parameters in GCV-treated Col2.3 Delta TK mice, and we show that after treatment transgenic animals lose lymphoid, erythroid, and myeloid progenitors in the bone marrow, followed by decreases in the number of hematopoietic stem cells (HSCs). Together with the decrease in bone marrow hematopoiesis, active extramedullary hematopoiesis was observed in the spleen and liver, as measured by an increase in peripheral HSCs and active primary in vitro hematopoiesis. After withdrawal of GCV, osteoblasts reappeared in the bone compartment together with a recovery of medullary and decrease in extramedullary hematopoiesis. These observations directly demonstrate the role of osteoblasts in hematopoiesis and provide a model to study the interactions between the mesenchymal and hematopoietic compartments in the marrow.
authors.affiliation: Department of Genetics and Developmental Biolgoy, University of Connecticut Health Center, Farmington, CT 06030, USA.
authors.forename: Dora
authors.initials: D
authors.lastname: Visnjic
authors.forename: Zana
authors.initials: Z
authors.lastname: Kalajzic
authors.forename: David W
authors.initials: DW
authors.lastname: Rowe
authors.forename: Vedran
authors.initials: V
authors.lastname: Katavic
authors.forename: Joseph
authors.initials: J
authors.lastname: Lorenzo
authors.forename: Hector L
authors.initials: HL
authors.lastname: Aguila
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells; D019070:Cell Lineage; D024042:Collagen Type I / Q000235:genetics; D015774:Ganciclovir / Q000494:pharmacology; D005822:Genetic Vectors / Q000494:pharmacology*; D006410:Hematopoiesis; D006411:Hematopoiesis, Extramedullary; D006412:Hematopoietic Stem Cells; D051379:Mice; D008822:Mice, Transgenic; D023421:Models, Animal; D010006:Osteoblasts / Q000378:metabolism / Q000502:physiology*; D011401:Promoter Regions, Genetic; D051381:Rats; D013937:Thymidine Kinase / Q000235:genetics
chemical_list: D024042:Collagen Type I; D013937:Thymidine Kinase; D015774:Ganciclovir