ORIGINAL PAPER Role of platelet gel embedded within gelatin scaffold on healing of experimentally induced critical-sized radial bone defects in rats Soodeh Alidadi 1 & Ahmad Oryan 1 & Amin Bigham-Sadegh 2 & Ali Moshiri 3 Received: 17 June 2016 /Accepted: 27 December 2016 # SICOT aisbl 2017 Abstract Purpose We investigated the role of human platelet gel (PG) embedded within gelatin (Gel) scaffold on healing of critical- sized radial bone defects in rats. Methods Twenty-five Sprague–Dawley rats were randomly divided into five equal groups. In each animal, critical-sized 5-mm bone defects were created in the radial bones of both forelimbs (n = 10/group). The defects were then either left untreated or filled with autograft, Gel, PG or Gel –PG. Before euthanasia, the healing defects were evaluated radio- logically and clinically. The animals were euthanized after eight weeks and their radial bones evaluated by radiography, computed tomography (CT) scan, histology, biomechanical testing and ultrastructural evaluations. Results PG implantation significantly increased cellular dif- ferentiation, osteoblastic proliferation and consequently new bone formation so that those defects treated with PG showed superior structural and biomechanical properties to the Gel and PG–Gel-treated defects. The PG-treated defects had ra- diological, morphological and mechanical properties closely comparable with those of the autograft group. In contrast, in the PG–Gel group, Gel significantly reduced the beneficial effects of PG on bone healing. Conclusions Human PG had beneficial effects on bone regen- eration, while combination of PG and Gel had no remarkable beneficial effect. Therefore, PG when used alone can be regarded as a promising osteoinductive and osteoconductive option in bone tissue engineering applications. Keywords Gelatin . Platelet-rich plasma . Platelet gel . Long-bone defects . Bone healing . Regeneration Introduction Large bone defects (LBDs) often result from removal of a diseased bone segment [1, 2] and should be reconstructed to prevent malunions and nonunions [1]. Although autologous bone grafts remain the gold standard for such reconstruction, given their limitations, there is need for other therapeutic mo- dalities [2–4]. Tissue engineering has focused on developing synthetic bone grafts with biomimetic properties similar to autografts [2, 5]. Accordingly, a desirable scaffold should be osteogenic, osteoinductive, osteoconductive, bioactive, biode- gradable and biocompatible [2, 4]. Gelatin (Gel) has been widely used in bone tissue engineer- ing because of its key advantages [6, 7] of high bioactivity, biocompatibility and biodegradability, and the osteoconductive Gel scaffolds have good porosity with very low antigenicity [2, 6]. Several growth factors, cytokines and chemokines in platelet granules makes platelet-rich plasma (PRP) an effective osteoinductive vehicle in bone regeneration [8–10], as platelets play critical roles in the initial stages of the healing process [8, 10, 11]. Several studies investigated the effects of PRP on bone regeneration [11–14]. PRP is available as a liquid, hydrogel, sponge or platelet gel (PG) [3, 5, 12, 15]. A major concern with using PRP is maintaining it in the defect sites after application [16]. Therefore, we investigated the role of human pure PG- * Ahmad Oryan Oryan1215@gmail.com 1 Department of Pathology, School of Veterinary Medicine, Shiraz University, Shiraz, Iran 2 Department of Surgery and Radiology, School of Veterinary Medicine, Shahrekord University, Shahrekord, Iran 3 Razi Drug Research Center, Iran University of Medical Sciences, Tehran, Iran International Orthopaedics (SICOT) DOI 10.1007/s00264-016-3393-y