273 Buletin USAMV-CN, 63/2006 (273-277) ISSN 1454-2382 MESENCHYMAL STEM CELLS – A BIOLOGICAL ALTERNATIVE IN OSTEOARTICULAR RECONSTRUCTION IN DOGS Igna, C.*, Gabriela Tanasie**, Simona Anghel**, Violeta Paunescu**, Steliana Telteu*, M. Sabau*, Larisa Schuszler*, A. Sala*, Roxana Dascalu* * Facultatea de Medicină Veterinară, Timioara ** Universitatea de Medicină Victor Babe, Timioara USAMVB, Timioara Facultatea de Medicină Veterinară Clinica de Chirurgie Calea Aradului, nr.119 Fax: 0256 277118 E-mail: ignacornel@gmail.com Key words: mesenchymal stem cells, ceramic scaffolds, critical space defects, osteoinductive, osteoconductive materials Abstract. Mesenchymal stem cells (MSC) posses the ability to differentiate into any type of somatic cells if properly stimulated. This study documented the effects of using mesenchymal stem cells loaded scaffolds in repairing large bone and cartiladge defects in dogs. The innovative aproach to osteoarticular reconstruction in dogs by using auto- or alogenic MSC loaded scaffolds, opens up new possibilities for treating diverse conditions with bioreactive materials and cells. The MSC were obtained from the humeral bone marrow aspirates. The multipotent cells underwent a specific cultivation and differentiation protocol, derived from the standard procedure. The protocol was altered to best fit the cells behaviour as it follows: the cultivation period needed to reach the 60-80% junction point, differed from dog to dog as well as the potency of the cell cultures, this determining the moment of their passage; the MSC were poured on the scaffolds and only then the diffentiation medium was added, this allowing the cells to differentiate on the osteogenic and osteoinductive material, thus obtaining a better cell load and disposition of the bioactive scaffold. INTRODUCTION The work initiated by Friedenstein and collaborators, cited by Bruder, Scott P., Fox, Barbara S.(2), provided definitive evidence that bone marrow contains, in addition to the hematopoietic progenitors, a population of spindle-shaped clonogenic fibroblast precursor cells or fibroblast colony-forming units (CFU-F). These cells, which were defined in vivo as quiescent resting cells, after proper in vitro stimulation can enter the cell cycle and develop colonies that resemble small deposits of bone or cartilage. Since CFU-F exhibit a high ability for self-renewal and multipotentiality, it was speculated that these marrow stromal stem cells were the precursors of a number of different mesenchymal cell lineages. Thus, the concept that the marrow stromal moiety was part of a wider stromal mesenchymal system in adult organisms was developed (2). Bone marrow has been shown to contain a population of rare cells capable of differentiating to the cells that form various tissues. These cells, referred to as mesenchymal stem cells (MSCs), are capable of forming bone when implanted ectopically in an appropriate scaffold (3).