In vitro models for adipose tissue engineering with adipose-derived stem cells using different scaffolds of natural origin.

Soft tissue regeneration with cell and tissue engineering-based approaches has numerous potential applications in plastic and reconstructive surgery. Adipose-derived stem cells (ASC) have been proved as a feasible source for adipose tissue engineering as they possess high proliferative and differentiation capacity. The purpose of our study was to evaluate adipogenic differentiation of human ASC in four different 3D scaffolds of natural origin, namely human platelet-poor plasma, alginate, fibrin gel and collagen sponge, to define their suitability for adipose tissue engineering and potential clinical applications. ASC were isolated from lipoaspirates of three adult female patients, seeded in the scaffolds, and adipogenic differentiation was induced. After two weeks of cultivation, the constructs were assessed for their mechanical and handling properties, cell viability and adipogenic differentiation. Additionally, the expression of vascular endothelial growth factor (VEGF) was analysed in different culture systems. The results indicate that the levels of specific adipogenic markers and VEGF expression were increased in 3D cultures, as compared to 2D culture. Among 3D scaffolds, fibrin gel showed optimal combination of mechanical characteristics and support of adipogenic differentiation; it was easy to handle, allowed high cell viability, and at the same time supported adipogenic differentiation and VEGF expression.

Reconstruction of large upper lip defects by free tissue transfer.

Reconstruction of a large upper lip defect is a demanding procedure and can be performed by a variety of local flaps or by microvascular free tissue transfer. We present our experience in reconstructing near total or total upper lip defects by free tissue transfer. In 11-year period seven patients underwent microvascular reconstruction of upper lip, six with non-innervated radial forearm flap and one with non-innervated anterolateral thigh flap. In all patients good functional and acceptable aesthetic results, with oral competence at rest and during eating and speaking, were achieved. Deglutition and articulation were not affected in any patient. Sensory evaluation of reconstructed upper lips was performed in four patients and in three a reasonable recovery of sensation was recorded. In our opinion subtotal or total upper lip reconstructions with folded thin fascio-cutaneous free flaps produce very good functional and aesthetically acceptable results and avoid additional scars on lower lip and cheek. Further, because the size of the mouth is not altered, microstomia is avoided, which is especially important for patients using dentures. The remaining disadvantage of this method is non-competence of orbicularis oris muscle sphincter.

Arterial anatomy of the lateral orbital and cheek region and arterial supply to the "peri-zygomatic perforator arteries" flap.

Arterial anatomy of the lateral orbital and cheek region and subsequently of the "peri-zygomatic perforator arteries" flap is described, based upon the dissection of the 24 human cadaver head halves. Each specimen was dissected in subdermal, first fascial and deep level. The subdermal vascular network of lateral orbital and cheek region, its orientation and contributing arteries were studied. Origin, perforation sites and diameters of transverse facial, zygomaticoorbital, zygomaticofacial and zygomaticotemporal arteries were also described and measured. Our findings support the view that the cheek island flap used for lower eyelid is a reverse flow axial pattern flap. It includes arterioles of the transverse facial artery, which are part of the subdermal vascular plexus and are uniformly longitudinally oriented. The flap receives its blood supply via perforators of the zygomaticoorbital, zygomaticofacial and zygomaticotemporal arteries, which are connected via their terminal branches with transverse facial artery.

Factors predicting free flap complications in head and neck reconstruction.

In this retrospective study, all free flap transfers used for reconstruction following ablation of head and neck tumors in University Medical Centre Ljubljana between the years 1989 and 1999 were analysed. The data taken from the patients' charts covered the demographic profile, the tumor and free flap details (44 variables for each patient). Logistic regression model was used to identify factors associated with free flap failure and complications. One hundred and sixty-two patients with head and neck tumors underwent microsurgical reconstruction. One hundred and ninety-four free flaps were performed with an overall success rate of 85%. Two significant predictors of free flap complication were identified: diabetes and salvage free flap transfer. Patients with diabetes were five times more likely to develop complications associated with free flaps (p = 0.02). Free flap complications were four times more likely to develop after salvage free flap transfer (p = 0.04). In addition, two significant factors predicting free flap failure were identified: salvage free flap transfer (p = 0.019) and use of interposition vein grafts (p = 0.032). After this study we changed our strategy of free flap selection and preoperative evaluation of the patients with head and neck tumors requiring free tissue transfer. Between January 2000 and January 2005 we performed additional 105 free flaps for head and neck reconstruction after tumor resection in 101 patients and our success rate improved to 94.3%.

Predicting patient's long-term clinical status after hip arthroplasty using hierarchical decision modelling and data mining.

Construction of a prognostic model is presented for the long-term outcome after femoral neck fracture treatment with implantation of hip endoprosthesis. While the model is induced from the follow-up data, we show that the use of additional expert knowledge is absolutely crucial to obtain good predictive accuracy. A schema is proposed where domain knowledge is encoded as a hierarchical decision model of which only a part is induced from the data while the rest is specified by the expert. Although applied to hip endoprosthesis domain, the proposed schema is general and can be used for the construction of other prognostic models where both follow-up data and human expertise is available.