Bioengineering of vascularized porcine flaps using perfusion-recellularization.

Large volume soft tissue defects greatly impact patient quality of life and function while suitable repair options remain a challenge in reconstructive surgery. Engineered flaps could represent a clinically translatable option that may circumvent issues related to donor site morbidity and tissue availability. Herein, we describe the regeneration of vascularized porcine flaps, specifically of the omentum and tensor fascia lata (TFL) flaps, using a tissue engineering perfusion-decellularization and recellularization approach. Flaps were decellularized using a low concentration sodium dodecyl sulfate (SDS) detergent perfusion to generate an acellular scaffold with retained extracellular matrix (ECM) components while removing underlying cellular and nuclear contents. A perfusion-recellularization strategy allowed for seeding of acellular flaps with a co-culture of human umbilical vein endothelial cell (HUVEC) and mesenchymal stromal cells (MSC) onto the decellularized omentum and TFL flaps. Our recellularization technique demonstrated evidence of intravascular cell attachment, as well as markers of endothelial and mesenchymal phenotype. Altogether, our findings support the potential of using bioengineered porcine flaps as a novel, clinically-translatable strategy for future application in reconstructive surgery.

Human-Induced Pluripotent Stem Cells in Plastic and Reconstructive Surgery.

A hallmark of plastic and reconstructive surgery is restoring form and function. Historically, tissue procured from healthy portions of a patient's body has been used to fill defects, but this is limited by tissue availability. Human-induced pluripotent stem cells (hiPSCs) are stem cells derived from the de-differentiation of mature somatic cells. hiPSCs are of particular interest in plastic surgery as they have the capacity to be re-differentiated into more mature cells, and cultured to grow tissues. This review aims to evaluate the applications of hiPSCs in the plastic surgery context, with a focus on recent advances and limitations. The use of hiPSCs and non-human iPSCs has been researched in the context of skin, nerve, vasculature, skeletal muscle, cartilage, and bone regeneration. hiPSCs offer a future for regenerated autologous skin grafts, flaps comprised of various tissue types, and whole functional units such as the face and limbs. Also, they can be used to model diseases affecting tissues of interest in plastic surgery, such as skin cancers, epidermolysis bullosa, and scleroderma. Tumorigenicity, immunogenicity and pragmatism still pose significant limitations. Further research is required to identify appropriate somatic origin and induction techniques to harness the epigenetic memory of hiPSCs or identify methods to manipulate epigenetic memory.

Three Ds for diagnosing necrotizing fasciitis by front-line clinicians.

INTRODUCTION: Necrotizing fasciitis (NF) is a life-threatening infection and a surgical emergency. Not all clinicians have the experience or resources to detect NF in its early stages. OBJECTIVE: To develop a diagnostic algorithm for primary care and emergency physicians to identify patients with possible NF, including an initial approach to triaging such individuals. METHODS: Medline was searched to identify studies of validated algorithms for NF diagnosis and/or cohort or case series providing clinical and diagnostic features of NF. Candidate algorithms were validated via application to 3 published cases of initially misdiagnosed NF. We retrospectively reviewed NF cases between 2011 and 2022 at our center to validate our algorithm. RESULTS: The search yielded 540 articles; 109 were included following a review of abstracts. No published validated diagnostic algorithm was identified. Using the reported clinical and diagnostic features of NF, we generated an algorithm of the "3Ds" of NF: Disproportionate pain, Dermatological findings, and Disorganized physiology. A larger number of Ds indicated a greater level of suspicion for NF and prioritization for urgent surgical consultation. In 3 published cases of missed NF, the 3Ds algorithm successfully identified all as having possible NF. On reviewing our cases, we identified 56 patients with NF during an 11 year period. 66% of whom had the 3Ds at their initial presentation. DISCUSSION: The 3Ds algorithm, a simple and easy-to-remember tool can be easily applied in a primary or emergency care setting, and may improve the early diagnosis of NF. Retrospective analysis of NF cases allows for validation of this algorithm. However, this algorithm requires prospective validation.

Grx2 Regulates Skeletal Muscle Mitochondrial Structure and Autophagy.

Glutathione is an important antioxidant that regulates cellular redox status and is disordered in many disease states. Glutaredoxin 2 (Grx2) is a glutathione-dependent oxidoreductase that plays a pivotal role in redox control by catalyzing reversible protein deglutathionylation. As oxidized glutathione (GSSG) can stimulate mitochondrial fusion, we hypothesized that Grx2 may contribute to the maintenance of mitochondrial dynamics and ultrastructure. Here, we demonstrate that Grx2 deletion results in decreased GSH:GSSG, with a marked increase of GSSG in primary muscle cells isolated from C57BL/6 Grx2-/- mice. The altered glutathione redox was accompanied by increased mitochondrial length, consistent with a more fused mitochondrial reticulum. Electron microscopy of Grx2-/- skeletal muscle fibers revealed decreased mitochondrial surface area, profoundly disordered ultrastructure, and the appearance of multi-lamellar structures. Immunoblot analysis revealed that autophagic flux was augmented in Grx2-/- muscle as demonstrated by an increase in the ratio of LC3II/I expression. These molecular changes resulted in impaired complex I respiration and complex IV activity, a smaller diameter of tibialis anterior muscle, and decreased body weight in Grx2 deficient mice. Together, these are the first results to show that Grx2 regulates skeletal muscle mitochondrial structure, and autophagy.