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Introduction: For the regeneration of large volume tissue defects, the interaction between angiogenesis and osteogenesis is a crucial prerequisite. The surgically induced angiogenesis by means of a...

Abdominal free flaps such as the muscle sparing transverse rectus abdominis myocutaneous (ms-TRAM) or deep inferior epigastric artery perforator (DIEP) flap represent the gold standard in autologous breast reconstruction. We describe a salvage procedure during bilateral free flap breast reconstruction due to insufficient venous drainage using a venous cross-over bypass. A 54-year-old woman with a thrombosis of the left subclavian port-system in the medical history was elected for simultaneous bilateral breast reconstruction with ms-TRAM and DIEP flaps. Intraoperatively, a venous congestion of the DIEP flap, which was connected to the left cranial internal mammary vessels, appeared. In the absence of sufficient ipsilateral venous recipient vessels, we performed a salvage procedure requiring a 15 cm small saphenous vein graft and presternal subcutaneous tunneling. The flap vein was anastomosed end-to-end with the contralateral caudal internal mammary vein using a coupler system. The postoperative course was uneventful and both flaps survived. We describe the cross-over venous emergency bypass as a useful tool in unexpected venous thrombosis during bilateral free flap breast reconstruction.

Background: Breast cancer is the most common malignancy in women. The interdisciplinary treatment is based on the histological tumor type, the TNM classification, and the patient's wishes. Following tumor resection and (neo-) adjuvant therapy strategies, breast reconstruction represents the final step in the individual interdisciplinary treatment plan. Although manifold flaps have been described, abdominal free flaps, such as the deep inferior epigastric artery perforator (DIEP) or the muscle-sparing transverse rectus abdominis myocutaneous (ms-TRAM) flap, are the current gold standard for autologous breast reconstruction. This retrospective study focuses on the safety of autologous breast reconstruction upon mastectomy using abdominal free flaps. Methods: From April 2012 until December 2018, 193 women received 217 abdominal free flaps for autologous breast reconstruction at the University Hospital of Erlangen. For perforator mapping, we performed computed tomography angiography (CTA). Venous anastomosis was standardized using a ring pin coupler system, and flap perfusion was assessed with fluorescence angiography. A retrospective analysis was performed based on medical records, the surgery report, and follow-up of outpatient course. Results: In most cases, autologous breast reconstruction was performed as a secondary reconstructive procedure after mastectomy and radiotherapy. In total, 132 ms1-TRAM, 23 ms2-TRAM, and 62 DIEP flaps were performed with 21 major complications (10%) during hospital stay including five free flap losses (2.3%). In all cases of free flap loss, we found an arterial thrombosis as the main cause. In 24 patients a bilateral breast reconstruction was performed without free flap loss. The majority of free flaps (96.7%) did not need additional supercharging or turbocharging to improve venous outflow. Median venous coupler size was 2.5 mm (range, 1.5–3.5 mm). Conclusion: Using CTA, intraoperative fluorescence angiography, titanized hernia meshes for rectus sheath reconstruction, and venous coupler systems, autologous breast reconstruction with DIEP or ms-TRAM free flaps is a safe and standardized procedure in high-volume microsurgery centers.

Vascularization of bioartificial tissues can be significantly enhanced by the generation of an arteriovenous (AV) loop. Besides the surgical vascularization, the choice of the scaffold and the applied cells are indispensable cofactors. The combination of alginate dialdehyde and gelatin (ADA-GEL) and mesenchymal stem cells (MSCs) is a promising approach with regard to biocompatibility, biodegradation, as well as de novo tissue formation. In this study, we targeted the investigation of the vascularization of ADA-GEL with and in the absence of encapsulated MSCs in the AV loop model. A Teflon chamber filled with ADA-GEL microcapsules was placed in the groin of Lewis rats and an AV loop was placed into the chamber. Group A encompassed the ADA-GEL without MSCs, whereas group B contained 2 × 10

The surgically induced angiogenesis by means of arteriovenous (AV) loops represents a powerful method to significantly enhance vascularization of biomaterials. Regarding tissue engineering applications, spider silk is a promising biomaterial with a good biocompatibility and slow biodegradation. This study aims at investigating vascularization as well as

Vascularization is important for bone development, fracture healing and engineering of artificial bone tissue. In the context of bone tissue engineering, it was shown that coimplantation of human primary umbilical vein endothelial cells (HUVECs) and human osteoblasts (hOBs) results in the formation of functional blood vessels and enhanced bone regeneration. Implanted endothelial cells do not only contribute to blood vessel formation, but also support proliferation, cell survival and osteogenic differentiation of coimplanted hOBs. These effects are partially mediated by direct heterotypic cell contacts. In a previous report we could show that cocultivated hOBs strongly increase the expression of genes involved in extracellular matrix (ECM) formation in HUVECs, suggesting that ECM may be involved in the intercellular communication between hOBs and HUVECs. The present study aimed at investigating whether comparable changes occur in hOBs. We therefore performed a microarray analysis of hOBs cultivated in direct contact with HUVECs, revealing 1,004 differentially expressed genes. The differentially expressed genes could be assigned to the functional clusters ECM, proliferation, apoptosis and osteogenic differentiation. The microarray data could be confirmed by performing quantitative real time RT-PCR on selected genes. Furthermore, we could show that the ECM produced by HUVECs increased the expression of the osteogenic differentiation marker alkaline phosphatase (ALP) in hOBs. In summary, our data demonstrate that HUVECs provoke complex changes in gene expression patterns in cocultivated hOBs and that ECM plays and important role in this interaction. J. Cell. Biochem. 117: 1869-1879, 2016. © 2016 Wiley Periodicals, Inc.

Integrating bioartificial tissues into the host vasculature is a prerequisite for tissue engineering applications. Endothelial progenitor cells (EPCs) display a high angiogenic potential and a low donor-site morbidity, making them ideal for tissue engineering applications. In our study we used a murine EPC cell line (T17b) and rat mesenchymal stem cells (MSCs) for cocultivation experiments. MSCs were cocultured with increasing T17b EPC amounts. Furthermore, MSCs in monoculture were treated with conditioned medium (CM) from T17b EPCs and T17b EPCs were treated with CM from MSCs. Proliferation and apoptosis were quantified with a bromodeoxyuridine ELISA and a DNA fragmentation ELISA, respectively. Osteogenic differentiation was detected with an alkaline phosphatase assay and bone morphogenetic protein-2 ELISA. The production of proangiogenic molecules was measured with a matrix metalloproteinase-3 and vascular endothelial growth factor ELISA as well as nitric oxide assay. We could show that T17b EPCs stimulated MSC proliferation but not vice versa. On the other hand, MSCs promoted the cell survival of EPCs. The growth-inducing and antiapoptotic effects were dependent on heterotypic cell contacts and paracrine mediators. Moreover, proangiogenic growth factors were found in the coculture. Collectively, our results indicate that the coapplication of MSCs and T17b EPCs provides new perspectives for tissue engineering applications.

Scalp reconstruction is a challenging task for the reconstructive surgeon. In consideration of the anatomical and cosmetic characteristics, the defect depth and size, an armamentarium of reconstructive procedures ranging from skin grafts over local flaps to free tissue transfer has been described. In this 10-year retrospective study, 85 operative procedures for scalp reconstruction were performed at our department. The underlying entity, defect size/depth, reconstructive procedure, complications, and mean hospital stay were analyzed. In most cases, scalp reconstruction was necessary after oncologic resection (67%) or radiation therapy (16%). A total of 85 operative procedures were performed for scalp reconstruction including local flaps (n = 50), free tissue transfer (n = 18), and skin grafts (n = 17). Regarding the complication rate, we could detect an overall major complication rate of 16.5% with one free flap loss. Briefly, local flaps are an adequate and safe procedure for limited scalp defects. In the case of extensive scalp defects affecting the calvarium, prior multiple surgical interventions and/or radiation, we prefer free tissue transfer.