Reconstruction of large bone defects is still a major problem. Tissue-engineering approaches have become a focus in regeneration of bone. In particular, critical-sized defects do not ossify spontaneously. The use of electrospinning is attracting increasing attention in the preparation of tissue-engineering scaffolds. Recently, acellular scaffolds carrying bioactive agents have been used as scaffolds in "in situ" tissue engineering for soft and hard tissue repair. Poly(epsilon-caprolactone) (PCL) with two different molecular weights were synthesized, and the blends of these two were electrospun into nonwoven membranes composed of nanofibers/micropores. To stimulate bone formation, an active drug, "simvastatin" was loaded either after the membranes were formed or during electrospinning. The matrices were then spiral-wound to produce scaffolds with 3D-structures having both macro- and microchannels. Eight-millimeter diameter critical size cranial defects were created in rats. Scaffolds with or without simvastatin were then implanted into these defects. Samples from the implant sites were removed after 1, 3, and 6 months postimplantation. Bone regeneration and tissue response were followed by X-ray microcomputed tomography and histological analysis. These in vivo results exhibited osseous tissue integration within the implant and mineralized bone restoration of the calvarium. Both microCT and histological data clearly demonstrated that the more successful results were observed with the "simvastatin-containing PCL scaffolds," in which simvastatin was incorporated into the PCL scaffolds during electrospinning. For these samples, bone mineralization was quite significant when compared with the other groups.

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The loss of cartilage tissue due to trauma, tumour surgery or congenital defects, such as microtia and anotia, is one of the major concerns in head and neck surgery. Recently tissue‐engineering approaches, including gene delivery, have been proposed for the regeneration of cartilage tissue. In this study, primary chondrocytes were genetically modified with plasmid‐encoding bone morphogenetic protein‐7 (BMP‐7) via the commercially available non‐viral Turbofect vector, with the aim of bringing ex vivo transfected chondrocytes to resynthesize BMP‐7 in vitro as they would in vivo. Genetically modified cells were implanted into gelatin–oxidized dextran scaffolds and cartilage tissue formation was investigated in 15 × 15 mm auricular cartilage defects in vivo in 48 New Zealand (NZ) white rabbits for 4 months. The results were evaluated via histology and early gene expression. Early gene expression results indicated a strong effect of exogenous BMP‐7 on matrix synthesis and chondrocyte growth. In addition, histological analysis results exhibited significantly better cartilage healing with BMP‐7‐modified (transfected) cells than in the non‐modified (non‐transfected) group and as well as the control. Copyright © 2012 John Wiley & Sons, Ltd.

Cranial bone repair and regeneration via tissue engineering principles has attracted a great deal of interest from researchers during last decade. Here, within this study, 6 mm critical-sized bone defect regeneration via genetically modified mesenchymal stem cells (MSC) were monitored up to 4 months. Cranial bone repair and new bone formations were evaluated by histological staining and real time PCR analysis in five different groups including autograft and bone morphogenetic protein-2 (BMP-2) transfected MSC groups. Results presented here indicate a proper cranial regeneration in autograft groups and a prospering regeneration for hBMP-2 encoding mesenchymal stem cells.