VEGF Over-Expression by Engineered BMSC Accelerates Functional Perfusion, Improving Tissue Density and In-Growth in Clinical-Size Osteogenic Grafts

The first choice for reconstruction of clinical-size bone defects consists of autologous bone flaps, which often lack the required mechanical strength and cause significant donor-site morbidity. We have previously developed biological substitutes in a rabbit model by combining bone tissue engineering and flap pre-fabrication. However, spontaneous vascularization was insufficient to ensure progenitor survival in the core of the constructs. Here, we hypothesized that increased angiogenic stimulation within constructs by exogenous VEGF can significantly accelerate early vascularization and tissue in-growth. Bone marrow stromal cells from NZW rabbits (rBMSC) were transduced with a retroviral vector to express rabbit VEGF linked to a truncated version of rabbit CD4 as a cell-surface marker. Autologous cells were seeded in clinical-size 5.5 cm; 3; HA scaffolds wrapped in a panniculus carnosus flap to provide an ample vascular supply, and implanted ectopically. Constructs seeded with VEGF-expressing rBMSC showed significantly increased progenitor survivival, depth of tissue ingrowth and amount of mineralized tissue. Contrast-enhanced MRI after 1 week; in vivo; showed significantly improved tissue perfusion in the inner layer of the grafts compared to controls. Interestingly, grafts containing VEGF-expressing rBMSC displayed a hierarchically organized functional vascular tree, composed of dense capillary networks in the inner layers connected to large-caliber feeding vessels entering the constructs at the periphery. These data constitute proof of principle that providing sustained VEGF signaling, independently of cells experiencing hypoxia, is effective to drive rapid vascularization and increase early perfusion in clinical-size osteogenic grafts, leading to improved tissue formation deeper in the constructs

Efficacy, safety and complications of autologous fat grafting to healthy breast tissue: a systematic review

Fat grafting for primary breast augmentation is growing in popularity due to its autologous properties and its side benefit of removing unwanted fat from other areas, although volume gain is unpredictable and patient safety remains unclear.; The aim of this study was to provide an evidence-based overview of autologous fat grafting to healthy breast tissue with focus on volume gain, safety and complications.; A systematic review was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines.; The MEDLINE, Cochrane Library and EMBASE databases were searched for clinical studies on autologous fat grafting to healthy breast tissue within the last 30 years.; Clinical articles were evaluated for indication, pre- and postoperative work-up, surgical technique, volume gain (efficacy), complications, radiographic changes and oncological safety. The level of evidence was assessed according to the Oxford Centre for Evidence-based Medicine 2011.; A total of 36 articles involving 1453 patients with a mean follow-up period of 16.3 months (1-156 months) were included. No randomised controlled studies were found. Six percent of the patients undergoing fat grafting to healthy breast tissue experienced major complications requiring a surgical intervention or hospitalisation. Two patients with breast cancer (0.1%) after fat grafting for cosmetic purposes were reported. Average breast volume gain ranged from 55% to 82% relative to the grafted fat volume.; The prevalence of complications and re-operations in fat grafting to healthy breast tissue compared favourably to implant-based breast augmentation. Although no increased incidence of breast cancer was found, long-term breast cancer screening and the implementation of publicly accessible registries are critically important to proving the safety of fat grafting

EPO reverses defective wound repair in hypercholesterolaemic mice by increasing functional angiogenesis

This study aims to elucidate the effect of erythropoietin (EPO) on the microcirculation during wound healing in mice genetically depleted of apolipoprotein E (ApoE(-/-)). The skinfold chamber in mice was used for intravital microscopy, whereby an incisional wound was created within the chamber. Animals received Recormon(®) 1000 U kg(-1) body weight (BW) intra-peritoneally (i.p.) at day 1, 3, 5, 7, 9 and 11 post-wounding at a concentration of 100 Uml(-1) (n=42). Normal healing and vehicle-treated wild type animals (WT) served as controls. The microcirculation of the wound was analysed quantitatively in vivo using epi-illumination intravital fluorescence microscopy. Microtomography (micro-CT) analysis of casted wound microvessels was performed allowing three-dimensional (3D) histomorphometric analysis. Tissue samples were examined ex vivo for wound scoring and for expression analysis of EPO-Receptor (Epo-R) and endothelial nitric oxide synthase (eNOS). Upon EPO treatment, the total wound score in ApoE(-/-) mice was increased by 23% on day 3, by 26% on day 7 and by 18% on day 13 when compared to untreated ApoE(-/-) mice (all P<0.05 vs. vehicle). Improved wound healing was accompanied with a significant increase of functional angiogenetic density and angiogenetic red blood cell perfusion on days 5, 7, 9 and 11 post-wounding. 3D histomorphometric analysis revealed an increase of vessel thickness (1.7-fold), vessel volume (2.4-fold) and vessel surface (1.7-fold) (all P<0.05 vs. vehicle). In addition, improved wound healing was associated with enhanced Epo-R expression (4.6-fold on day 3 and 13.5-fold on day 7) and eNOS expression (2.4-fold on day 7) (all P<0.05 vs. vehicle). Our data demonstrate that repetitive systemic EPO treatment reverses microvascular dysfunction during wound healing in hypercholesterolaemic mice by inducing new vessel formation and by providing the wound with more oxygen

Effects of intersyringe processing on adipose tissue and its cellular components: implications in autologous fat grafting

Autologous fat grafting is a popular technique in plastic surgery. A mechanical processing method is used to facilitate fat injection. No study has investigated whether this process affects cell quality and preservation of biological functionality. This study analyzed the influence of quick mechanical processing through two interconnected small-diameter syringes ("shuffling") on both structure and viability of fat tissue, and on viability, clonogenicity, and differentiation of the freshly isolated stromal vascular fraction.; Lipoaspiration was performed in six healthy donors, followed by shuffling the fat either zero, five, or 30 times between two 10-cc syringes. Thereafter, fat was applied through a 1.5-mm cannula as in a clinical setting for autologous fat grafting. Analysis of different treatment conditions was conducted. Immunofluorescent staining allowed assessment of morphology, viability, composition, and damage of the tissue. The stromal vascular fraction was examined for isolation yield, viability, clonogenicity, and differentiation capacity.; The process of shuffling changed the macroscopic but not the microscopic structure of the lipoaspirated fat. No difference in cell number, viability, number of lipid droplets, vascular architecture, or ratio of cell composition was found. Analysis of the stromal vascular fraction, apart from large interdonor variability, did not show a significant change in isolation yield, viability, clonogenicity, or adipogenic differentiation capacity of the expanded cells.; The mechanical procedure of shuffling lipoaspirated fat does not alter its tissue viability or its microscopic structure. The absence of impact on the stromal vascular fraction in the assessed parameters suggests that shuffling can be executed according to surgical needs

Harnessing the synergy of perfusable muscle flap matrix and adipose-derived stem cells for prevascularization and macrophage polarization to reconstruct volumetric muscle loss

Muscle flaps must have a strong vascular network to support a large tissue volume and ensure successful engraftment. We developed porcine stomach musculofascial flap matrix (PDSF) comprising extracellular matrix (ECM) and intact vasculature. PDSF had a dominant vascular pedicle, microcirculatory vessels, a nerve network, well-retained 3-dimensional (3D) nanofibrous ECM structures, and no allo- or xenoantigenicity. In-depth proteomic analysis demonstrated that PDSF was composed of core matrisome proteins (e.g., collagens, glycoproteins, proteoglycans, and ECM regulators) that, as shown by Gene Ontology term enrichment analysis, are functionally related to musculofascial biological processes. Moreover, PDSF−human adipose-derived stem cell (hASC) synergy not only induced monocytes towards IL-10−producing M2 macrophage polarization through the enhancement of hASCs' paracrine effect but also promoted the proliferation and interconnection of both human skeletal muscle myoblasts (HSMMs) and human umbilical vein endothelial cells (HUVECs) in static triculture conditions. Furthermore, PDSF was successfully prevascularized through a dynamic perfusion coculture of hASCs and HUVECs, which integrated with PDSF and induced the maturation of vascular networks in vitro. In a xenotransplantation model, PDSF demonstrated myoconductive and immunomodulatory properties associated with the predominance of M2 macrophages and regulatory T cells. In a volumetric muscle loss (VML) model, prevascularized PDSF augmented neovascularization and constructive remodeling, which was characterized by the predominant infiltration of M2 macrophages and significant musculofascial tissue formation. These results indicate that hASCs' integration with PDSF enhances the cells’ dual function in immunomodulation and angiogenesis. Owing in part to this PDSF-hASC synergy, our platform shows promise for vascularized muscle flap engineering for VML reconstruction

The lateral forearm flap versus traditional upper extremity flaps: A comparison of donor site morbidity and flap thickness

INTRODUCTIONThe lateral forearm flap (LFF) is a thin fasciocutaneous flap with a donor site that can be closed primarily. METHODSA retrospective analysis of donor site morbidity and hand function was performed in patients who underwent a radial forearm flap (RFF), ulnar artery perforator flap (UAPF), or LFF. Flap thickness was evaluated radiographically in 50 control patients. RESULTSOf 134 patients (lateral forearm flap: n = 49, RFF: n = 47, UAPF: n = 38), the LFF demonstrated significantly faster return to baseline hand grip strength (3 months vs. 12 months in RFF and UAPF; p < 0.001), had significantly fewer donor site complications (6.1% compared to 6.4% in RFF and 28.9% in UAPF; p = 0.003) and fewer sensory deficits (2.0% compared to 6.4% in RFF and 15.8% in UAPF sites; p = 0.013). The radiographic study confirmed the LFF to be the thinnest of all upper extremity flap options. CONCLUSIONSThe LFF is an excellent forearm-based flap option with thin, pliable tissue and low donor site morbidity

Immediate Reconstruction of Complex Spinal Wounds Is Associated with Increased Hardware Retention and Fewer Wound-related Complications: A Systematic Review and Meta-analysis

Background:. Patients undergoing surgeries involving extensive posterior spine instrumentation and fusion often have multiple risk factors for wound healing complications. We performed a systematic review and meta-analysis of the available evidence on immediate (proactive/prophylactic) and delayed (reactive) spinal wound reconstruction. We hypothesized that immediate soft-tissue reconstruction of extensive spinal wounds would be associated with fewer postoperative surgicalsite complications than delayed reconstruction. Methods:. In accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, a PubMed database search was performed to identify English-language, human-subject literature published between 2003 and 2018. Data were summarized, and the pooled prevalence of various wound complications was calculated, weighted by study size, using the generic inverse variance method. A subgroup analysis of all studies with a comparison group (Oxford Centre for Evidence-based Medicine level 3 or better) was performed, and Forest plots were created. Results:. The database search yielded 16 articles including 828 patients; 428 (51.7%) received an immediate spinal wound reconstruction and 400 (48.3%) had a delayed reconstruction. Spinal neoplasm was the most common index diagnosis. Paraspinous muscle flap reconstruction was performed in the majority of cases. Pooled analysis of all studies revealed immediate reconstruction to be associated with decreased rates of overall wound complications (28.5% versus 18.8%), hardware loss (10.7% versus 1.8%), and wound infections (10.7% versus 7.6%) compared with delayed reconstruction. Conclusions:. Immediate soft-tissue reconstruction of high-risk spinal wounds is associated with fewer wound healing complications and increased hardware retention