Polycaprolactone/Hydroxyapatite composite scaffolds: Preparation, characterization, and in vitro and in vivo biological responses of human primary bone cells Boontharika Chuenjitkuntaworn, 1 Wipawan Inrung, 2 Damrong Damrongsri, 1 Kongkwan Mekaapiruk, 1 Pitt Supaphol, 2 Prasit Pavasant 1 1 Faculty of Dentistry, Department of Anatomy, Chulalongkorn University, Pathumwan, Bangkok 10330, Thailand 2 The Petroleum and Petrochemical College and The Center for Petroleum, Petrochemicals and Advanced Materials, Chulalongkorn University, Pathumwan, Bangkok 10330, Thailand Received 27 April 2009; revised 24 August 2009; accepted 22 September 2009 Published online 17 February 2010 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/jbm.a.32657 Abstract: Polycaprolactone (PCL) is a synthetic biode- gradable polymer that has been approved for use as bone graft substitutes. In this study, PCL scaffolds incorporating hydroxyapatite (HAp) particles were fabricated by com- bined solvent casting and particulate leaching techniques. The average pore dimension was in the range of about 480–500 lm. The porosity, water absorption, and compres- sive modulus of the scaffold were evaluated. The responses of primary bone cells cultured on the PCL and PCL/HAp scaffolds were examined both in vitro and in vivo. In comparison with the cells grown on the PCL scaffold, those cultured on the PCL/HAp counterpart posi- tively expressed the markers of osteogenic differentiation. Cells increased the mRNA expressions of type I collagen and osteocalcin on day 10 and demonstrated a significant increase in calcium deposition. In coherence with the in vitro appearance, histomorphometric analysis in a mouse calvarial model showed a significantly greater amount of new bone formation. The results demonstrated that the prepared PCL/HAp scaffold could be a good can- didate as synthetic substitute for bone tissue engineering. Ó 2010 Wiley Periodicals, Inc. J Biomed Mater Res 94A: 241–251, 2010 Key words: bone tissue engineering; polycaprolactone; 3D scaffold; osteoblasts; osteogenic markers INTRODUCTION Some of the common practices that are used to repair bony skeletal defects caused by congenital abnormalities, diseases, injuries, or traumas are auto- grafts, allografts, or synthetic implanting materials. Yet, there persist imperfections in these methods; namely, limited availability of the harvesting sites, the possibility of disease transmission, poor biocom- patibility, and the risk of prosthetic implantation fail- ure. Therefore, the need for alternative strategies such as tissue engineering approaches is required to improve the treatment and quality of life for all of the patients. 1–4 The use of a synthetic polymer in bone tissue engi- neering is an alternative strategy extensively used nowadays. The most commonly used synthetic poly- mers for this purpose are polycaprolactone (PCL), polyglycolide (PGA), polylactide (PLA), and their corresponding copolymers. PCL, a US food and drug administration (FDA)-approved material for craniofacial indications, is a biocompatible and bio- degradable aliphatic polyester, having a low melting point. PCL dissolves well in common organic sol- vents, hence, it is a prime candidate to be used in bone scaffolding applications. 5 Both mechanical and biological (in terms of osteoconductivity and osteoinductivity) properties of a PCL scaffold can be improved by the addition of bioactive materials. Hydroxyapatite [HAp: Ca 10 (PO 4 ) 6 (OH) 2 ] is a biocer- amic which has the same chemical composition (Ca/P 5 1.67) as that of the bone mineral. Despite its inherent osteoconductivity, HAp has some undesirable traits, such as brittleness and Correspondence to: P. Pavasant; e-mail: prasit215@gmail. com or P. Supaphol; e-mail: pitt.s@chula.ac.th Contract grant sponsors: The 90th and 100th Anniver- sary of Chulalongkorn University Research Fund, Ratcha- daphiseksomphot Endowment, and Government Research Fund; contract grant number: GRB_051_52_30_21 Ó 2010 Wiley Periodicals, Inc.