In this study, we aimed at generating osteogenic and vasculogenic constructs starting from the stromal vascular fraction (SVF) of human adipose tissue as a single cell source. SVF cells from human lipoaspirates were seeded and cultured for 5 days in porous hydroxyapatite scaffolds by alternate perfusion through the scaffold pores, eliminating standard monolayer (two-dimensional [2D]) culture. The resulting cell-scaffold constructs were either enzymatically treated to extract and characterize the cells or subcutaneously implanted in nude mice for 8 weeks to assess the capacity to form bone tissue and blood vessels. SVF cells were also expanded in 2D culture for 5 days and statically loaded in the scaffolds. The SVF yielded 5.9 ؎ 3.5 ؋ 10 5 cells per milliliter of lipoaspirate containing both mesenchymal progenitors (5.2% ؎ 0.9% fibroblastic colony forming units) and endothelial-lineage cells (54% ؎ 6% CD34 ؉ /CD31 ؉ cells). After 5 days, the total cell number was 1.8-fold higher in 2D than in three-dimensional (3D) cultures, but the percentage of mesenchymaland endothelial-lineage cells was similar (i.e., 65%-72% of CD90 ؉ cells and 7%-9% of CD34 ؉ /CD31 ؉ cells). After implantation, constructs from both conditions contained blood vessels stained for human CD31 and CD34, functionally connected to the host vasculature. Importantly, constructs generated under 3D perfusion, and not those based on 2D-expanded cells, reproducibly formed bone tissue. In conclusion, direct perfusion of human adiposederived cells through ceramic scaffolds establishes a 3D culture system for osteoprogenitor and endothelial cells and generates osteogenic-vasculogenic constructs. It remains to be tested whether the presence of endothelial cells accelerates construct vascularization and could thereby enhance implanted cell survival in larger size implants.

Biological substitutes for autologous bone flaps could be generated by combining flap pre-fabrication and bone tissue engineering concepts. Here, we investigated the pattern of neotissue formation within large pre-fabricated engineered bone flaps in rabbits. Bone marrow stromal cells from 12 New Zealand White rabbits were expanded and uniformly seeded in porous hydroxyapatite scaffolds (tapered cylinders, 10–20 mm diameter, 30 mm height) using a perfusion bioreactor. Autologous cell-scaffold constructs were wrapped in a panniculus carnosus flap, covered by a semipermeable membrane and ectopically implanted. Histological analysis, substantiated by magnetic resonance imaging (MRI) and micro-computerized tomography scans, indicated three distinct zones: an outer one, including bone tissue; a middle zone, formed by fibrous connective tissue; and a central zone, essentially necrotic. The depths of connective tissue and of bone ingrowth were consistent at different construct diameters and significantly increased from respectively 3.1 ± 0.7 mm and 1.0 ± 0.4 mm at 8 weeks to 3.7± 0.6 mm and 1.4 ± 0.6 mm at 12 weeks. Bone formation was found at a maximum depth of 1.8 mm after 12 weeks. Our findings indicate the feasibility of ectopic pre-fabrication of large cell-based engineered bone flaps and prompt for the implementation of strategies to improve construct vascularization, in order to possibly accelerate bone formation towards the core of the grafts.

Background The role of laparoscopy in the setting of perforated appendicitis remains controversial. A retrospective study was conducted to evaluate the early postoperative outcomes of laparoscopic appendectomy (LA) compared to open appendectomy (OA) in patients with perforated appendicitis. Methods A total of 1,032 patients required an appendectomy between January 2005 and December 2009. Among these patients, 169 presented with perforated appendicitis. Operation times, length of hospital stay, overall complication rates within 30 days, and surgical site infection (SSI) rates were analyzed. Results Out of the 169 evaluated patients, 106 required LA and 63 OA. Although operation times were similar in both groups (92 ± 31 min for LA vs. 98 ± 45 for OA, p = 0.338), length of hospital stay was shorter in the LA group (6.9 ± 3.8 days vs. 11.5 ± 9.2, p \ 0.001). Overall complication rates were significantly lower in the LA group (32.1 vs. 52.4 %, p \ 0.001), as were incisional SSI (1.9 vs. 22.2 %, p \ 0.001). Organ/space SSI rates were similar in both groups (23.6 % after LA vs. 20.6 % after OA, p = 0.657). Conclusions For perforated appendicitis, LA results in a significantly shorter hospital stay, fewer overall postoperative complications, and fewer wound infections compared to OA. Organ/space SSI rates were similar for both procedures. LA provides a safe option for treating patients with perforated appendicitis.Keywords Adult Á Laparoscopy Á Organ space infection Á Perforated appendicitis Appendicitis is one of the most common causes for emergency abdominal surgery, with a reported lifetime incidence of approximately 7 % [1]. Laparoscopic appendectomy (LA) has gradually become a routine procedure, although its efficacy and superiority remain a matter of debate. Several reports suggest that LA provides advantages in terms of shorter hospital stay, less postoperative pain, faster recovery time, and reduced morbidity rate at the expense of longer operating times [2][3][4][5]. However, other studies reported no significant advantages for LA compared to open appendectomy (OA), stating that choice of the operative approach should be based on surgeon and patient preference [6,7].One of the main controversies lies within the application of LA in the setting of perforation. Perforated appendicitis is inevitably associated with higher postoperative morbidity and mortality rates [8], with one of the most feared postoperative complications being an intra-abdominal abscess. Previous studies have demonstrated that LA for complicated appendicitis may be associated with an increased rate of abscess formation when compared to OA, suggesting caution when using the laparoscopic approach in this group of patients [9][10][11][12].