Vascularization is the cornerstone of wound healing. We introduced human blood outgrowth endothelial cells (hBOEC) in a self-assembled human dermal fibroblast sheet (hDFS), intended as a tissue-engineered dermal substitute with inherent vascular potential. hBOEC were functionally and molecularly different from early endothelial progenitor cells and human umbilical vein endothelial cells (HUVEC). hBOEC alone, unlike HUVEC, efficiently revascularized and re-oxygenated the wound bed, both by active incorporation into new vessels and by trophic stimulation of host angiogenesis in a dose-dependent manner. Furthermore, hBOEC alone, but not HUVEC, accelerated epithelial coverage and matrix organization of the wound bed. In addition, integration of hBOEC in hDFS not only further improved vascularization, epithelial coverage and matrix organization but also prevented excessive wound contraction. In vitro analyses with hBOEC, fibroblasts and keratinocytes revealed that these effects were both due to growth factor crosstalk and to short cutting hypoxia. Among multiple growth factors secreted by hBOEC, placental growth factor mediated at least in part the beneficial effects on keratinocyte migration and proliferation. Overall, this combined tissue engineering approach paves the way for clinical development of a fully autologous vascularized dermal substitute for patients with large skin defects that do not heal properly.

Aims/hypothesis As current islet-transplantation protocols suffer from significant graft loss and dysfunction, strategies to sustain the long-term benefits of this therapy are required. Rapid and adequate oxygen and nutrient delivery by blood vessels improves islet engraftment and function. The present report evaluated a potentially beneficial effect of adult human blood outgrowth endothelial cells (BOEC) on islet graft vascularisation and function. Methods Human BOEC, 5×10 5 , were co-transplanted with a rat marginal-islet graft under the kidney capsule of hyperglycaemic NOD severe combined immunodeficiency (SCID) mice, and the effect on metabolic outcome was evaluated. Results Although vessel density remained unaffected, cotransplantation of islets with BOEC resulted in a significant and specific improvement of glycaemia and increased plasma C-peptide. Moreover, in contrast to control mice, BOEC recipients displayed reduced beta cell death and increases in body weight, beta cell proliferation and graft-vessel and beta cell volume. In vivo cell tracing demonstrated that BOEC remain at the site of transplantation and do not expand. The potential clinical applicability was underscored by the observed metabolic benefit of co-transplanting islets with BOEC derived from a type 1 diabetes patient. Conclusions/interpretation The present data support the use of autologous BOEC in translational studies that aim to improve current islet-transplantation protocols for the treatment of brittle type 1 diabetes.

In a search for the optimal nonviral gene transfer technique in epidermal and dermal supportive extracellular matrix studies, we investigated the efficiency of late generation liposomal transfection reagents and nucleofection of fibroblasts (FBs), endothelial progenitor cells (EPCs), and keratinocytes (KCs) as essential indicators of healing skin wounds. FBs, KCs, and EPCs were grown under serum-reduced conditions and manipulated according to optimized in vitro manufacturer protocols. Fugene HD, Effectene, PEI, and Lipofectin were compared to Amaxa Nucleofection. A green fluorescent protein (GFP)-encoded reporter gene plasmid was transfected, and transfection efficiencies were determined by green-fluorescence-activated cell sorting. Normal cell morphologies were observed after either transfection or nucleofection. For KC cell cultures, Fugene HD resulted in the highest transfection efficiency in human (41%) and porcine (42%) KCs. For EPCs, Effectene was optimal for human-derived cells (42%), whereas nucleofection was optimal (32%) for porcine cells. For FBs, however, nucleofection resulted in the highest transfection rates in human (46%) and porcine (60%) FBs. For specific epidermal cell studies, Fugene HD was the preferred gene transfer method, whereas Effectene appeared to be the optimal reagent for pro-angiogenic studies. Nucleofection in combination with FBs is the best combination to achieve the highest overall transfection rate and is thus the optimal combination for use in ex vivo gene transfer strategies of wound healing or skin tissue engineering.

BackgroundBlood outgrowth endothelial cells (BOECs) mediate therapeutic neovascularization in experimental models, but outgrowth characteristics and functionality of BOECs from patients with ischemic cardiomyopathy (ICMP) are unknown. We compared outgrowth efficiency and in vitro and in vivo functionality of BOECs derived from ICMP with BOECs from age‐matched (ACON) and healthy young (CON) controls.Methods and ResultsWe isolated 3.6±0.6 BOEC colonies/100×106 mononuclear cells (MNCs) from 60‐mL blood samples of ICMP patients (n=45; age: 66±1 years; LVEF: 31±2%) versus 3.5±0.9 colonies/100×106 MNCs in ACON (n=32; age: 60±1 years) and 2.6±0.4 colonies/100×106 MNCs in CON (n=55; age: 34±1 years), P=0.29. Endothelial lineage (VEGFR2+/CD31+/CD146+) and progenitor (CD34+/CD133−) marker expression was comparable in ICMP and CON. Growth kinetics were similar between groups (P=0.38) and not affected by left ventricular systolic dysfunction, maladaptive remodeling, or presence of cardiovascular risk factors in ICMP patients. In vitro neovascularization potential, assessed by network remodeling on Matrigel and three‐dimensional spheroid sprouting, did not differ in ICMP from (A)CON. Secretome analysis showed a marked proangiogenic profile, with highest release of angiopoietin‐2 (1.4±0.3×105 pg/106 ICMP‐BOECs) and placental growth factor (5.8±1.5×103 pg/106 ICMP BOECs), independent of age or ischemic disease. Senescence‐associated β‐galactosidase staining showed comparable senescence in BOECs from ICMP (5.8±2.1%; n=17), ACON (3.9±1.1%; n=7), and CON (9.0±2.8%; n=13), P=0.19. High‐resolution microcomputed tomography analysis in the ischemic hindlimb of nude mice confirmed increased arteriogenesis in the thigh region after intramuscular injections of BOECs from ICMP (P=0.025; n=8) and CON (P=0.048; n=5) over vehicle control (n=8), both to a similar extent (P=0.831).Conclusions BOECs can be successfully culture‐expanded from patients with ICMP. In contrast to impaired functionality of ICMP‐derived bone marrow MNCs, BOECs retain a robust proangiogenic profile, both in vitro and in vivo, with therapeutic potential for targeting ischemic disease.