Bioactive starch-based scaffolds and human adipose stem cells are a good combination for bone tissue engineering A.I. Rodrigues, M.E. Gomes, I.B. Leonor ⇑ , R.L. Reis ⇑ 3B’s Research Group – Biomaterials, Biodegradables and Biomimetics, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, University of Minho, AvePark, 4806-909 Taipas, Guimarães, Portugal ICVS/3B’s – PT Government Associate Laboratory, Braga/Guimarães, Portugal article info Article history: Received 30 September 2011 Received in revised form 30 April 2012 Accepted 4 May 2012 Available online 29 May 2012 Keywords: Bone tissue engineering Human adipose stem cells Silanol groups Wet-spinning Flow perfusion bioreactor abstract Silicon is known to have an influence on calcium phosphate deposition and on the differentiation of bone precursor cells. This study explores the effect of the incorporation of silanol (Si–OH) groups into poly- meric scaffolds on the osteogenic differentiation of human adipose stem cells (hASC) cultured under dynamic and static conditions. A blend of corn starch with polycaprolactone (30/70 wt.%, SPCL) was used to produce three-dimensional fibre meshes scaffolds by the wet-spinning technique, and a calcium sili- cate solution was used as a non-solvent to develop an in situ functionalization with Si–OH groups. In vitro assessment, using hASC, of functionalized and non-functionalized scaffolds was evaluated in either a- MEM or osteogenic medium under static and dynamic conditions (provided by a flow perfusion bioreac- tor). The functionalized materials, SPCL–Si, exhibit the capacity to sustain cell proliferation and induce their differentiation into the osteogenic lineage. The formation of mineralization nodules was observed in cells cultured on the SPCL–Si materials. Culturing under dynamic conditions using a flow perfusion bioreactor was shown to enhance the hASC proliferation and differentiation and a better distribution of cells within the material. The present work demonstrates the potential of these functionalized mate- rials for future applications in bone tissue engineering. Additionally, these results highlight the simplicity, economic and reliable production process of those materials. Ó 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. 1. Introduction Tissue engineering (TE) is a promising field for developing bone material capable of substituting for the conventional autogenic or allogenic transplants [1]. Currently, the general strategy for bone TE lies in biocompatible and biodegradable scaffolds seeded with stem cells [2]. However, those scaffolds have limited osteoconduc- tivity and osteoinductivity, which compromise their use in bone TE [3]. Thus, the degree of success of bone TE greatly depends on the intrinsic properties of the material used to obtain a biocompatible and biodegradable scaffold with osteoinductive, osteoconductive and osteogenic properties in order to induce bone regeneration [1,4,5]. Recently, silicate-based materials have been investigated, since they have the ability to activate bone-related gene expression and stimulate osteoblast proliferation and differentiation [6,7]. For instance, bioactive ceramics, containing hydroxyapatite and silica, can degrade in proportion to the rate of new bone formation [8]. Thus, attention is focused on the importance of the chemical com- position of materials, particularly the presence of silicon as a key player in enhancing bone repair. Moreover, culturing cells under dynamic conditions has been revealed to provide an important stimulus for the proliferation and differentiation of cells and, moreover, to mimic in vivo pressure gradients. Previous studies [9–12] showed that the use of a flow perfusion bioreactor enhances calcium deposition and osteogenic differentiation, and improves the cell distribution in a three-dimensional (3-D) scaffold. In this context, the present authors aim to develop a biodegrad- able material with osteo stimulative properties combined with hu- man adipose stem cells (hASC), which in future can serve as a platform for the development of bone implants able to replace the ‘‘gold standard’’ autograft [13,14]. In order to target this ambitious goal, a 3-D scaffold of SPCL (a blend of starch with polycaprolactone) was synthesized, incorpo- rating Si–OH groups by wet-spinning, using a calcium silicate solution as a coagulation bath, as described previously [15,16]. SPCL without Si–OH groups, using methanol as a coagulation bath, was used as control. In vitro studies were performed by seeding and culturing wet-spun fibre mesh scaffolds, both with and 1742-7061/$ - see front matter Ó 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.actbio.2012.05.025 ⇑ Corresponding authors. Address: 3B’s Research Group – Biomaterials, Biode- gradables and Biomimetics, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, University of Minho, AvePark, 4806- 909 Taipas, Guimarães, Portugal. Tel.: +351 253510907. E-mail addresses: belinha@dep.uminho.pt (I.B. Leonor), rgreis@dep.uminho.pt (R.L. Reis). Acta Biomaterialia 8 (2012) 3765–3776 Contents lists available at SciVerse ScienceDirect Acta Biomaterialia journal homepage: www.elsevier.com/locate/actabiomat