*Corresponding author: Caroline Seebach, Department of Trauma Surgery, Johann-Wolfgang-Goethe University Hospital, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany, Tel: +49 6963017110; Fax: +49 6963017108; E-mail: caroline.seebach@kgu.de Citation: Eldesoqi K, Henrich D, El-Kady AM, El-Hady BMA, Sweify KM, et al. (2015) Improved Bone Formation by Differentiated Mesenchymal Stem Cells and Endothelial Progenitor Cells Seeded on High Concentrated Bioglass-Polylactic Acid Composite in Calvarial Rat Bone Defect. J Stem Cell Res Dev Ther 2: 004. Received: February 24, 2015; Accepted: May 07, 2015; Published: May 25, 2015 Introduction Over 2 million bone graf materials are used every year worldwide, thus bone is second only to blood on the list of transplanted materials. With increasing demand and known limitations with traditional bone graf materials, new approaches are developed to provide alternatives for bone regeneration [1-3]. Bone tissue engineering tries to mimic the physiologic situation [4]. Te addition of osteogenic and angiogenic cells to a synthetic biomaterial increases their local density and rely on locally secreted growth and diferentiation factors to induce bone formation. Te biomaterials should present good biocompatibility for cell adhesion and cell viability [5,6] as well as controlled degradation kinetics to match the ratio of replacement by new tissue. Also, the biomaterials should provide an initial biomechanical support until cells generate the extracellular matrix [7,8]. Bioactive Glasses (BG) are a subset of inorganic bioactive materials, which are capable of reacting with physiological fuids to form tenacious bonds to bone through the formation of bone-like hydroxylapatite layers and the biological interaction of collagen with the material surface [9,10]. It has been found that reactions on BG surfaces lead to the release of critical concentrations of soluble Silicon (Si) and Calcium (Ca) ions, which induce favourable intracellular and extracellular responses leading to rapid bone formation [11]. Although BG has traditionally been employed for its osteoconductive and osteostimulative properties, BG also exhibit proangiogenic potential in vitro and in vivo. Soluble dissolution products of BG up-regulate the production of numerous angiogenic factors by stimulated cells providing a potentially promising strategy to enhance early vascularisation and resultant bone formation [12-15]. However, BG, compared to cortical and cancellous bones, usually present low mechanical properties, especially in porous forms [16,17]. Tis disadvantage signifcantly limits the use of these materials in a very broad range of applications. Fortunately, one solution came from mimicking nature, which provides the inspiration to design materials with optimal organized structures under dynamically changing conditions. Many of these structures are composed of an intrinsically complex matrix based on organic and inorganic components which produce a natural hybrid material, usually referred to as composites. By combining two or more materials in a predesigned manner, a biomaterial can be created with properties that are not possible to be attained when considering each of the individual components separately [18]. Seebach C, et al., J Stem Cell Res Dev 2015, 2: 004 DOI: 10.24966/SRDT-2060/100004 HSOA Journal of Stem Cells Research, Development and Therapy Research Article Abstract Objective: New developed composite biomaterials with a Bioglass (BG) and Polylactic Acid (PLA) component are promising candidates for the treatment of bone defects. There is evidence that adding Mesenchymal Stem Cells (MSC) and Endothelial Progenitor Cells (EPC) signifcantly improve new bone formation. Thus, cell adhesion, cell viability and bone formation of these composites, when seeded with undifferentiated or differentiated progenitor cells, respectively were tested. Materials and methods: We investigated newly developed composite material consisting of Polylactic Acid (PLA), PLA and 20% Bioglass (PLA+BG 20%) or PLA and 40% Bioglass (PLA+BG 40%). These materials were seeded with either undifferentiated MSC / EPC or differentiated MSC / EPC and tested for cell adhesion and cell viability in vitro. Moreover, these composites were evaluated for bone formation in vivo. A Critical Size Defect (CSD) was made in each calvarium of 76 rats and composites were implanted. Animals were sacrifced after 14 weeks. Formation of new bone was evaluated by histomorphometry. Results: Cell adhesion and cell viability in vitro is not signifcantly infuenced by our tested composites, but differentiated MSC/EPC seeded onto PLA+BG40 improve signifcantly bone formation in a calvarial rat bone defect in vivo and represent a novel cell-based therapy for bone regeneration. Keywords: Bioglass, Bone tissue engineering, EPC, MSC, PLA Karam Eldesoqi 1,2 , Dirk Henrich 1 *, Abeer M El-Kady 2 , Bothaina M Abd El-Hady 2 , Karima M Sweify 3 , Borna Relja 1 , Christoph Nau 1 , Ingo Marzi 1 and Caroline Seebach 1 * 1 Department of Trauma Surgery, Johann-Wolfgang-Goethe University Hospital, Frankfurt, Germany 2 Department of Biomaterial, National Research Centre, Al-Bohous St. Dokki, Cairo, Egypt 3 Department of Zoology, Women’s College for Arts, Science and Education, Ain Shams University, Cairo, Egypt Improved Bone Formation by Differentiated Mesenchymal Stem Cells and Endothelial Progenitor Cells Seeded on High Concentrated Bioglass-Polylactic Acid Composite in Calvarial Rat Bone Defect