In vivo evaluation of bioprinted prevascularized bone tissue.

Bioprinting can be considered as a progression of the classical tissue engineering approach, in which cells are randomly seeded into scaffolds. Bioprinting offers the advantage that cells can be placed with high spatial fidelity within three-dimensional tissue constructs. A decisive factor to be addressed for bioprinting approaches of artificial tissues is that almost all tissues of the human body depend on a functioning vascular system for the supply of oxygen and nutrients. In this study, we have generated cuboid prevascularized bone tissue constructs by bioprinting human adipose-derived mesenchymal stem cells (ASCs) and human umbilical vein endothelial cells (HUVECs) by extrusion-based bioprinting and drop-on-demand (DoD) bioprinting, respectively. The computer-generated print design could be verified in vitro after printing. After subcutaneous implantation of bioprinted constructs in immunodeficient mice, blood vessel formation with human microvessels of different calibers could be detected arising from bioprinted HUVECs and stabilization of human blood vessels by mouse pericytes was observed. In addition, bioprinted ASCs were able to synthesize a calcified bone matrix as an indicator of ectopic bone formation. These results indicate that the combined bioprinting of ASCs and HUVECs represents a promising strategy to produce prevascularized artificial bone tissue for prospective applications in the treatment of critical-sized bone defects.

Co-culture of adipose-derived stem cells and endothelial cells in fibrin induces angiogenesis and vasculogenesis in a chorioallantoic membrane model.

Neovascularization of adipose tissue equivalents is a crucial step in successful adipose tissue engineering, since insufficient vascularization results in graft resorption in an in vivo situation. A possible cellular approach to overcome this limitation is the co-implantation of adipose-derived stem cells (ASCs) with endothelial cells to stimulate the formation of a vascular network. We investigated the potential of ASCs derived from human abdominal fat tissue co-cultured with endothelial progenitor cells (EPCs) from human peripheral blood to stimulate neovascularization of fibrin constructs on the chorioallantoic membrane (CAM) of fertilized chicken eggs, in direct comparison to human umbilical vein endothelial cells (HUVECs). After 9 days of incubation, cell-fibrin constructs were explanted and histologically evaluated with respect to ingrowth of avian blood vessels into the construct and formation of human blood vessels by co-implanted endothelial cells. When administered on the CAM, ASCs successfully guided host vasculature into the construct (angiogenesis) and guided formation of capillary-like structures by co-implanted human endothelial cells (vasculogenesis), with HUVECs being superior to EPCs, leading to a perfused avian and human capillary network within the fibrin construct. However, the results also showed that perfused human blood vessels were only observed near the CAM compared to unperfused capillary-like structures near the top of the construct, indicating that perfusion of the cell-fibrin construct takes longer than 9 days. In conclusion, as blood vessel formation is an essential step during adipogenic differentiation, the data support our hypothesis that cellular communication between transplanted ASCs and endothelial cells is beneficial for vasculogenesis. Copyright © 2013 John Wiley & Sons, Ltd.

Pentameric CRP attenuates inflammatory effects of mmLDL by inhibiting mmLDL--monocyte interactions.

Previous studies have reported that C-reactive protein (CRP) interacting with low-density lipoproteins (LDL) affects macrophage activation and LDL uptake. However, the physiological relevance of CRP-LDL interaction with circulating monocytes remains elusive. Moreover, recent studies have shown that CRP exists in two isoforms with partly opposing characteristics pentameric (pCRP) and monomeric CRP (mCRP). Here we investigated the effects of CRP interacting with minimally modified low-density lipoprotein (mmLDL) interaction in regard to events involved in formation of atherosclerotic plaque. We analyzed the effect of mmLDL on human monocytes and found a substantial increase in monocyte activation as evaluated by CD11b/CD18 expression and increased monocyte adhesion under static and under shear flow conditions to human endothelial cells. Monocyte adhesion and activation was attenuated by pCRP via the prevention of mmLDL binding to monocytes. These anti-inflammatory properties of pCRP were lost when it dissociates to the monomeric form. Our results elucidate the physiological relevance of the CRP-mmLDL interaction and furthermore confirm the importance of the previously described pCRP dissociation to mCRP as a localized inflammatory "activation" mechanism.

[Soft tissue reconstruction with a temporoparietal fascial flap (TPFF)]. / Der temporoparietale Faszienlappen zur Rekonstruktion von Weichteildefekten.

OBJECTIVE: Soft tissue reconstruction with a temporoparietal fascial flap (TPFF). INDICATIONS: Defect coverage with thin, pliable, and well-vascularized tissue. A bilayered TPFF provides a gliding surface in tendon reconstruction. Further options include TPFF harvest with overlying skin or subjacent bone for composite tissue reconstruction or the application as a sensate local fascial flap. Maximum defect dimensions: 17 × 14 cm. CONTRAINDICATIONS: Absolute: prior injury to the flap or flap pedicle, temporal arteritis, Moyamoya syndrome, defects with volume deficit. Relative: alopecia along the planned incision. SURGICAL TECHNIQUE: Pedicle location is outlined using Doppler ultrasound. Injection of the incision line with diluted epinephrine solution. Skin incision with subsequent visualization of the temporoparietal fascia and supplying vessels. Skin flaps are raised carefully paying special attention to the hair follicles (CAVE: postoperative alopecia). Primary closure of the donor site. Defect coverage with pedicled or free TPFF with subsequent full or split-thickness skin grafting. Dressing: Bolster or V.A.C. POSTOPERATIVE MANAGEMENT: Immobilization/elevation in the setting of extremity reconstruction. Removal of bolster dressing or V.A.C. on postoperative day 5. Dangling protocol instituted on postoperative day 7. Removal of sutures/staples at the donor site on postoperative day 5-7 and at the recipient site on postoperative day 12-14. RESULTS: The TPFF was utilized for soft tissue reconstruction in 8 patients. A pedicled TPFF was used in 2 patients. Mean time to healing was 16.3 days. Mean follow-up was 13.4 months. Successful reconstructive results with satisfactory functional and aesthetic appearance were obtained in all patients. Complications were encountered in 3 patients and included alopecia at the donor site and iatrogenic injury to the frontal branch of the facial nerve. Vascular compromise was observed in the early postoperative period in a third patient. However, operative revision resulted in successful flap salvage.

Endoscopic transaxillary subpectoral augmentation mammaplasty: a safe and predictable procedure.

During the last decades breast augmentation has gained worldwide acceptance. In addition to the inframammary and periareolar approach for augmentation mammaplasty, the transaxillary route provides an elegant means of retaining the integrity of the breast mound by avoiding visible scars. Due to concerns as to the safety of this technique we analysed 47 patients who underwent endoscopy-assisted transaxillary submuscular augmentation mammaplasty in our department from 1999 to 2004. The inclusion criteria were aesthetic breast augmentation due to breast hypoplasia. Patients with a history of breast cancer, other malignancies, or previously performed mastectomy were excluded. Procedures for tuberous breast deformity as well as concomitantly performed mastopexy were also excluded. No complications were observed impairing final outcome or requiring early operative intervention, such as infection or haematoma. This technique is suitable for patients who prefer a hidden incision at a distant site, and provides predictability of aesthetic outcome and is safe.