The beneficial effect of heparin in preischemic perfusion solutions for cold-stored skin flaps

Improving Research Practice in Rat Orthotopic and Partial Orthotopic Liver Transplantation: A Review, Recommendation, and Publication Guide

Background: Due to a worldwide shortage of donor organs for liver transplantation, alternative approaches, such as split and living donor liver transplantations, were introduced to increase the donor pool and reduce mortality on liver transplant waiting lists. Numerous details concerning the mechanisms and pathophysiology of liver regeneration, small-for-size syndrome, rejection, and tolerance in partial liver transplantation facilitated the development of various animal models. The high number of preclinical animal studies contributed enormously to our understanding of many clinical aspects of living donor and partial liver transplantations. Summary: Microsurgical rat models of partial orthotopic liver transplantation are well established and widely used. Nevertheless, several issues regarding this procedure are controversial, not clarified, or not yet properly standardized (graft rearterialization, size reduction techniques, etc.). The major aim of this literature review is to give the reader a current overview of rat orthotopic liver transplantation models with a special focus on partial liver transplantation. The aspects of model evolution, microsurgical training, and different technical problems are analyzed and discussed in detail. Our further aim in this paper is to elaborate a detailed publication guide in order to improve the quality of reporting in the field of rat liver transplantation according to the ARRIVE guidelines and the 3R principle. Key Messages: Partial orthotopic liver transplantation in rats is an indispensable, reliable, and cost-efficient model for transplantation research. A certain consensus on different technical issues and a significant improvement in scientific reporting are essential to improve transparency and comparability in this field as well as to foster refinement.

Unfavourable results in free tissue transfer

With recent advances in the instrumentation and with increased expertise the results of microvascular surgery are getting better. Complications though, cannot be completely avoided. This paper gives a brief introduction to the possible complications at various stages of free tissue transfer. With careful planning and execution and vigilant postoperative care the overall success rate can be improved.

Vascular anatomy of the hamster retractor muscle with regard to its microvascular transfer

BACKGROUND

The hamster retractor muscle (RET) is used as an in vivo model in studies of skeletal muscle ischemia-reperfusion injury. The RET is unique in that the muscle can be isolated while preserving the primary vascular supply so that its contractile function can be measured simultaneously with local microvascular responses to experimental interventions. The goal of this study was to understand the anatomical origin of the vascular supply to the RET and determine whether the RET can be used as a free flap after surgical isolation of the thoracodorsal vessels.

METHODS

Microdissection was performed to determine the anatomy of the vasculature that supplies and drains the RET.

RESULTS

Distinct numbers and patterns of feed arteries (2-4) and collecting veins (1-3) were identified (n = 26 animals). Dye injection (n = 8) of the thoracodorsal artery demonstrated that the RET remains perfused following its isolation on the thoracodorsal pedicle. Heterotopic allograft transplantation of the RET (n = 2) was performed by anastomosing the thoracodorsal vessels to the femoral vessels using the end-to-side technique.

CONCLUSIONS

The anatomical relationships indicate that the RET can be used as a free flap model for evaluating the effect of preservation strategies and transplantation on skeletal muscle microcirculation and contractile function.

Tissue engineering using autologous microcirculatory beds as vascularized bioscaffolds

Classic tissue engineering paradigms are limited by the incorporation of a functional vasculature and a reliable means for reimplantation into the host circulation. We have developed a novel approach to overcome these obstacles using autologous explanted microcirculatory beds (EMBs) as bioscaffolds for engineering complex three-dimensional constructs. In this study, EMBs consisting of an afferent artery, capillary beds, efferent vein, and surrounding parenchymal tissue are explanted and maintained for 24 h ex vivo in a bioreactor that preserves EMB viability and function. Given the rapidly advancing field of stem cell biology, EMBs were subsequently seeded with three distinct stem cell populations, multipotent adult progenitor cells (MAPCs), and bone marrow and adipose tissue-derived mesenchymal stem cells (MSCs). We demonstrate MAPCs, as well as MSCs, are able to egress from the microcirculation into the parenchymal space, forming proliferative clusters. Likewise, human adipose tissue-derived MSCs were also found to egress from the vasculature and seed into the EMBs, suggesting feasibility of this technology for clinical applications. We further demonstrate that MSCs can be transfected to express a luciferase protein and continue to remain viable and maintain luciferase expression in vivo. By using the vascular network of EMBs, EMBs can be perfused ex vivo and seeded with stem cells, which can potentially be directed to differentiate into neo-organs or transfected to replace failing organs and deficient proteins.

Ex vivo intraoperative angiography for rectus abdominis musculocutaneous free flaps

In this study, the vascular architecture of rectus abdominis free flaps nourished by deep inferior epigastric vessels was investigated using an ex vivo intraoperative angiogram. Oblique rectus abdominis free flaps were elevated and isolated from the donor site. In 11 patients, the vascular architecture of these flaps was analyzed before the flap was thinned. Radiographic study identified an average of 2.1 large deep inferior epigastric arterial perforators in each flap. In nine of the 11 flaps, the axial artery was visible. In four flaps, the axial artery originated from the perforator of the lateral branch of the deep inferior epigastric artery; in five others, it originated from the medial branch. In each flap, the angle of the axial perforator from its anterior rectus sheath in the vertical plane was measured; its mean was 50.6 degrees. All flaps survived, although three showed partial necrosis in the distal portions. In two of these three flaps, the axial artery was not visible in the angiograms, and the third revealed a one-sided distribution of axial flap arteries. Using ex vivo intraoperative angiography, the architecture of the individual flap, its axial perforator, and its connecting axial flap vessel could be investigated. This information can help the surgeon safely thin and separate the flap.