Lymphangiogenesis and angiogenesis can occur in a guided manner.These approaches may have a significant impact on the clinical treat-ment of lymphedema.

Endothelial progenitor cells participate inneovascularization and engraftment of culturedskin substitutesSachin S Vaikunth MD, Marwan Marwan MD,Jignesh Parvadia MD, Maria Ripberger BS, Barbara Kalinowska BS,Eva Uzvolgy MD, PhD, Andrew Supp BS, Datis Alaee MS,Steve Boyce PhD, Timothy Crombleholme MD, Dorothy Supp PhDCincinnati Childrens’ Hospital Medical Center, Cincinnati, OH

INTRODUCTION: Bone marrow derived Endothelial ProgenitorCells (EPCs) have been demonstrated to be involved in wound heal-ing and neovascularization. Neovascularization is critical to the en-graftment of Cultured Skin Substitutes (CSS), which are comprisedof keratinocytes and fibroblasts in a biopolymer matrix and used totreat extensive burns. We hypothesize that EPCs are involved in theneovascularization of CSS.

METHODS: Lethally irradiated Balb-C athymic mice were trans-planted with bone marrow from FVBN Tie-2 LacZ mice. Fourweeks after engraftment, human CSS was transplanted onto fullthickness excisional wounds on these mice. CSS were harvested atday 7 (n�4) and day 14 (n�4)and were analyzed for vessel den-sity using CD31 immunostaining, beta-galactosidase (B-gal) ex-pression, and CD133 in situ hybridization for EPC quantifica-tion.

RESULTS: Vessel density analysis revealed that the capillaries werelocated predominantly along the edges of CSS but CD133� EPCswere distributed throughout the CSS, specifically 39.1 � 2.8% atday 7 and 34.1 � 2.5% at day 14 were located near the epidermal-dermal junction of CSS.

CSS

B-gal �cells/HPF

VesselDensity(caps/HPF)

CD133�cells/HPF

% CD133�cells in

superficialdermis

%CD133�cells indeep

dermis

%CD133�cells at

CSSinterface

Day 7 21.7 � 3.8 12.2 � 1.3 9.8 �1.2 39.1� 2.8� 22.1 � 3.1 38.8 � 2.7

Day 14 21.0 � 1.3 8.7 � 1.3 9.3 � 1.5 34.1 � 2.5# 24.6 � 1.0 41.2 � 3.4

� p � 0.006 compared to deep# p � 0.061 compared to deep

CONCLUSIONS: These results show that B-gal� EPCs are re-cruited from the bone marrow to sites of neovascularization in CSS.CD133� cells are more superficial in the dermis compared to theCD31� cells suggesting a possible role of EPCs in orchestratingneovascularization as vessels form from the deep to superficial der-mis. This novel demonstration of EPCs in CSS could lead to betterunderstanding of the EPCs’ contribution in the neovascularizationand engraftment of CSS.

Donor antigen-pulsed host dendritic cells combinedwith transient immunosuppression prolong hind-limb survivalJustin M Sacks MD, Ryosuke Ikeguchi MD, Ali E Aksu MD,Elaine Horibe MD, Jignesh Unadkat MBBS, MRCS,Aurele Taieb MD, Jeremy Breitinger BS, Angus W Thomson PhD,Maryam Feili-Hariri PhD, WP Andrew Lee MDUniversity of Pittsburgh Medical Center, Pittsburgh, PA

INTRODUCTION: Risks of chronic immunosuppression hindercomposite tissue allograft (CTA) transplantation. A novel modalitywas investigated using transient immunosuppression and immaturehost dendritic cells (DC) pulsed with donor antigens (Ag) followingCTA transplantation across a full MHC barrier.

METHODS: Orthotopic hind-limb transplants between Wistar-Furth and Lewis rats were performed. Bone marrow derived DC(BM-DC) were propagated with GM-CSF and pulsed with donorsplenic cell lysate. Recipient groups included: I, control; II, Cy-closporine A (CsA; 10mg/kg/day, day 0-20,i.p.); III, anti-lymphocyte serum (ALS; day - 4, � 1,i.p.) � CsA; and IV,CsA�ALS, combined with donor cell lysate-pulsed BM-DC (day7, 14, 21,i.v.)(n�6-9/group). Epidermolysis defined rejection.Allograft recipients of �100 days received donor and third-partyskin grafts. Biopsies were obtained at 21 days and at rejection. Tcells were stimulated via T-cell receptor or with donor antigens todetermine T-cell function.

RESULTS: Group IV demonstrated mean CTA survival (57.8days) compared to group II (32.8 days,p�0.05) and group I (9.8days,p�0.05). Long-term graft survival (�100 days) in group IVwas observed in 3/9 rats. Muscle component of donor graft ingroup IV showed reduction in mononuclear cell infiltration rela-tive to groups I, II and III (p� 0.05). Donor skin graft wasaccepted, whereas third-party skin was rejected. Analysis of T cellresponses in long-term surviving grafts revealed no donor cellreactivity.

CONCLUSIONS: Donor alloAg-pulsed host BM-DC combinedwith transient immunosuppression prolonged CTA survival.This may represent the basis for a clinically applicable strategypromoting CTA survival with reduced systemic immunosuppres-sion.

Obesity lowers tolerance to ischemia-reperfusion inthe rat abdominal flap: A novel animal model forfree flap breast reconstructionMark E Feldmann MD, Ron Reyna MD, Seung-Jun O MD,Kenneth Chavin MD, PhDMedical University of South Carolina, Charleston, SC

INTRODUCTION: Obesity presents a risk-factor for flap-relatedcomplications in autologous tissue breast reconstruction. A rat modelfor pedicled flaps in the setting of obesity has previously been de-scribed. In this study, we add pedicle cross-clamping to simulate freeflap reconstruction. We hypothesize that obesity reduces the toler-ance of a rat abdominal flap to warm ischemia.

S61Vol. 203, No. 3S, September 2006 Plastic Surgery II