The following research examines the creation of a new small-diameter bypass graft. It is clinically relevant to patients who need distal arterial bypass, coronary artery bypass, or hemodialysis access, but who do not have adequate autologous vein for their surgeries. Future investigations will involve further tissue engineering of this vascular scaffold (eg, autologous endothelial seeding of its lumen) and testing the clinical usefulness of the completed graft.

Adipose-derived stem cells (ASCs) possess significant therapeutic potential for tissue engineering and regeneration. This study investigates the endothelial differentiation and functional capacity of ASCs isolated from elderly patients. Isolation of ASCs from 53 patients (50-89 years) revealed that advanced age or comorbidity did not negatively impact stem cell harvest; rather, higher numbers were observed in older donors (>70 years) than in younger. ASCs cultured in endothelial growth medium-2 for up to 3 weeks formed cords upon Matrigel and demonstrated acetylated-low-density lipoprotein and lectin uptake. Further stimulation with vascular endothelial growth factor and shear stress upregulated endothelial cell-specific markers (CD31, von Willebrand factor, endothelial nitric oxide synthase, and VE-cadherin). Inhibition of the PI 3 K but not mitogen-activated protein kinase pathway blocked the observed endothelial differentiation. Shear stress promoted an antithrombogenic phenotype as demonstrated by production of tissue-plasminogen activator and nitric oxide, and inhibition of plasminogen activator inhibitor-1. Shear stress augmented integrin a 5 b 1 expression and subsequently increased attachment of differentiated ASCs to basement membrane components. Finally, ASCs seeded onto a decellularized vein graft resisted detachment despite application of shear force up to 9 dynes. These results suggest that (1) advanced age and comorbidity do not negatively impact isolation of ASCs, and (2) these stem cells retain significant capacity to acquire key endothelial cell traits throughout life. As such, adipose tissue is a practical source of autologous stem cells for vascular tissue engineering. IntroductionU se of adult stem cells for vascular tissue engineering and regeneration continues to gain momentum as research reveals their improved potency and function. The majority of work involves mesenchymal stem cells (MSCs) derived from bone marrow aspiration and endothelial progenitor cells (EPCs) obtained from blood. Each of these cell types have been used to line vascular scaffolds in the creation of a tissue engineered bypass graft [1][2][3], as well as in various strategies to promote therapeutic angiogenesis in the coronary and peripheral circulations [4][5][6][7]. Although these cells are appropriate for vascular tissue engineering, their availability in patients most likely to benefit from this technology raises practical concerns. The number of stem and progenitor cells derived from bone marrow and blood decrease significantly with age and patient comorbidity [8][9][10]. Further, it has also been suggested that differentiation potential of bone-marrow-derived MSCs decreases with age [11]. Recent data also indicate that EPC function is diminished in patients with severe vascular disease and multiple coronary risk factors [12,13].An alternative source for autologous adult stem cells is adipose tissue. Adipose-derived stem cells (ASCs) are multipotent, with the capacity to differentiate into adipocytes, chondrocytes,...

With increasingly complex spine surgeries now being performed on a more comorbid patient population, the reconstruction of midline back wounds from these procedures is becoming a frequent dilemma encountered by plastic surgery. The purpose of this study is to examine the effect of various preoperative risk factors on postoperative wound healing complications after paraspinous muscle flap reconstruction of midline back defects. An Institutional Review Board-approved, 11-year, retrospective, office and hospital chart review was conducted. All adult patients who underwent paraspinous muscle flap reconstruction during the study period were included. There were 92 patients in the study, representing the largest reported series to-date for the paraspinous muscle flap procedure. Mean follow-up was 120 days. Several wound-healing risk factors were present in this patient population: 72% were malnourished, 41% had hypertension, 37% were obese, 34% had a history of smoking, 32% had diabetes, 16% were on chronic steroids, 14% had a history of more than 2 previous spine surgeries, and 9% had a history of radiation to the wound area. Factors significantly (P < 0.05) associated with postreconstruction wound complications included history of traumatic spine injury, prereconstruction hardware removal, a history of more than 2 spine surgeries, hypertension, and lumbar wound location. This patient population possesses multiple comorbidities making complex wound healing difficult. Several specific risk factors are associated with an increased rate of postreconstruction wound complications after paraspinous muscle flaps. The paraspinous muscle flap remains an important tool for spinal wound reconstruction in the reconstructive surgeon's armamentarium.

Background-Most research evaluating adipose-derived stem cells (ASC) uses tissue obtained from young, healthy patients undergoing plastic surgical procedures. Given the propensity of other adult stem cell lines to diminish with increasing patient age and co-morbidities, we assess the availability of ASC in elderly patients undergoing vascular surgical procedures, and evaluate their acquisition of endothelial cell (EC) traits to define their potential use in vascular tissue engineering.

The gold standard conduit for bypass of diseased small-diameter arteries remains autologous vascular tissue. In the absence of such tissue, patients are offered bypass with prosthetic material, with far less durable results. Vascular tissue engineering, the creation of a vascular conduit by seeding a tubular scaffold with various cells, may offer an alternative approach to this difficult situation. Herein we review some of the significant challenges that remain in designing an ideal vascular conduit and outline potential solutions offered by a graft created by seeding natural vascular tissue (decellularized vein allograft) with readily available autologous cells (adipose-derived stem cells).