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Mayer SA, Thomas B, Heuer M, Brune JC, Eras V, Schuster K, Knoedler L, Schaefer RL, Thiele W, Sleeman JP, Dimmler A, Heimel P, Kneser U, Bigdeli AK, Falkner F. In Vivo Engineering and Transplantation of Axially Vascularized and Epithelialized Flaps in Rats. Tissue Eng Part A 2024. [PMID: 38623816 DOI: 10.1089/ten.tea.2024.0037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2024] Open
Abstract
The arteriovenous loop (AVL) model allows the in vivo engineering of axially vascularized flaps, the so-called AVL flaps. Although AVL flaps can be transplanted microsurgically to cover tissue defects, they lack an epithelial layer on the surface. Therefore, the objective of this study was to engineer axially vascularized AVL flaps with an accompanying epithelial layer for local defect reconstruction. In this study, AVLs were established in 20 male Lewis rats. Minimally invasive injection of keratinocytes onto the surface of the AVL flaps was performed on postoperative day (POD) 21. AVL flaps were explanted from 12 rats on POD 24 or POD 30, then the epithelium formed by the keratinocytes on the surface of the flaps was evaluated using immunofluorescence staining. In six other rats, the AVL flap was locally transposed to cover a critical defect in the rats' leg on POD 30 and explanted for analysis on POD 40. In two control rats, sodium chloride was applied instead of keratinocytes. These control flaps were also transplanted on POD 30 and explanted on POD 40. Our results revealed that 3 days after keratinocyte application, a loose single-layered epithelium was observed histologically on the AVL flaps surface, whereas after 9 days, a multilayered and structured epithelium had grown. The epithelium on the transplanted AVL flaps showed its physiological differentiation when being exposed to an air-liquid interface. Histologically, a layered epithelium identical to the rats' regular skin was formed. In the sodium chloride control group, no epithelium had been grown. This study clearly demonstrates that axially vascularized AVL flaps can be processed in the subcutaneous chamber by minimally invasive injection of keratinocytes. Thus, AVL flaps with an intact epithelial layer were engineered and could be successfully transplanted for local defect coverage in a small animal model.
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Affiliation(s)
- Simon Andreas Mayer
- Department of Hand, Plastic, and Reconstructive Surgery, BG Trauma Center Ludwigshafen, University of Heidelberg, Ludwigshafen, Germany
- Department of Hand, Plastic, and Reconstructive Surgery, University of Heidelberg, Heidelberg, Germany
| | - Benjamin Thomas
- Department of Hand, Plastic, and Reconstructive Surgery, BG Trauma Center Ludwigshafen, University of Heidelberg, Ludwigshafen, Germany
- Department of Hand, Plastic, and Reconstructive Surgery, University of Heidelberg, Heidelberg, Germany
| | - Miriam Heuer
- German Institute for Cell and Tissue Replacement, Berlin, Germany
| | - Jan C Brune
- German Institute for Cell and Tissue Replacement, Berlin, Germany
| | - Volker Eras
- German Institute for Cell and Tissue Replacement, Berlin, Germany
| | - Kilian Schuster
- Department of Hand, Plastic, and Reconstructive Surgery, BG Trauma Center Ludwigshafen, University of Heidelberg, Ludwigshafen, Germany
- Department of Hand, Plastic, and Reconstructive Surgery, University of Heidelberg, Heidelberg, Germany
| | - Leonard Knoedler
- Department of Plastic, Hand and Reconstructive Surgery, University Hospital Regensburg, Regensburg, Germany
- Division of Plastic and Reconstructive Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Rebecca Luisa Schaefer
- Department of Hand, Plastic, and Reconstructive Surgery, University of Freiburg, Freiburg, Germany
| | - Wilko Thiele
- Department of Microvascular Biology and Pathobiology, European Center for Angioscience (ECAS), Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Jonathan P Sleeman
- Department of Microvascular Biology and Pathobiology, European Center for Angioscience (ECAS), Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
- Institute for Biological and Chemical Systems, Karlsruhe Institute of Technology (KIT), Campus North, Karlsruhe, Germany
| | - Arno Dimmler
- Institute of Pathology, Vincentius Kliniken Karlsruhe, Karlsruhe, Germany
| | - Patrick Heimel
- Core Facility Hard Tissue and Biomaterial Research, Karl Donath Laboratory, University Clinic of Dentistry, Medical University of Vienna, Vienna, Austria
- Ludwig Boltzmann Institute for Traumatology the Research Center in Cooperation with AUVA, Vienna, Austria
| | - Ulrich Kneser
- Department of Hand, Plastic, and Reconstructive Surgery, BG Trauma Center Ludwigshafen, University of Heidelberg, Ludwigshafen, Germany
- Department of Hand, Plastic, and Reconstructive Surgery, University of Heidelberg, Heidelberg, Germany
| | - Amir K Bigdeli
- Department of Hand, Plastic, and Reconstructive Surgery, BG Trauma Center Ludwigshafen, University of Heidelberg, Ludwigshafen, Germany
- Department of Hand, Plastic, and Reconstructive Surgery, University of Heidelberg, Heidelberg, Germany
| | - Florian Falkner
- Department of Hand, Plastic, and Reconstructive Surgery, BG Trauma Center Ludwigshafen, University of Heidelberg, Ludwigshafen, Germany
- Department of Hand, Plastic, and Reconstructive Surgery, University of Heidelberg, Heidelberg, Germany
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Falkner F, Mayer SA, Heuer M, Brune J, Helt H, Bigdeli AK, Dimmler A, Heimel P, Thiele W, Sleeman JP, Bergmeister H, Schneider KH, Kneser U, Thomas B. Comparison of Decellularized Human Dermal Scaffolds versus Bovine Collagen/Elastin Matrices for Engineering of Soft-Tissue Flaps. Plast Reconstr Surg 2024; 153:130-141. [PMID: 37014963 DOI: 10.1097/prs.0000000000010511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/06/2023]
Abstract
BACKGROUND Free flap-based soft-tissue reconstruction comes at the price of donor-site morbidity. The arteriovenous loop (AVL) technique can overcome this issue by allowing for the de novo generation of axially vascularized soft-tissue flaps from vein grafts embedded into different matrices. Application of the AVL technique has been limited by insufficient long-term volume retention and poor tissue stability. The authors investigated the suitability of a novel human dermal scaffold to improve volume retention and tissue stability. METHODS AVLs were created in 28 immunocompetent rats and embedded in either decellularized human dermal scaffolds (experimental group, n = 14) (Epiflex) or bovine collagen/elastin matrices (control group, n = 14) (MatriDerm) in subcutaneous polytetrafluoroethylene chambers. The weight and volume of engineered tissues, the extent of angiogenesis, and the proportion of proliferating cells were compared between groups on postoperative days (PODs) 21 and 28 by means of immunohistochemistry and micro-computed tomography. RESULTS On POD 28, both groups displayed homogeneous microvascular networks on histopathology and micro-computed tomography. Mean microvessel counts and surface areas and the percentage of proliferating cells did not differ between the groups. However, the experimental human scaffold group displayed significantly smaller volume loss and significantly less tissue degradation compared with bovine matrix controls (volume retention, 102% ± 5% versus 27% ± 7% on POD 21, and 79% ± 12% versus 12% ± 7% on POD 28, respectively; P < 0.0001). CONCLUSION Compared with bovine matrices, decellularized human scaffolds allow for superior volume retention and tissue stability of de novo engineered soft-tissue AVL flaps in rats. CLINICAL RELEVANCE STATEMENT AVLs allow for the de novo generation of vascularized soft-tissue flaps. However, insufficient long-term volume retention is still an issue. The authors' study shows that decellularized human matrices guarantee superior volume stability of de novo grown soft-tissue flaps in rats.
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Affiliation(s)
- Florian Falkner
- From the Department of Hand, Plastic, and Reconstructive Surgery, BG Trauma Center Ludwigshafen
| | - Simon A Mayer
- From the Department of Hand, Plastic, and Reconstructive Surgery, BG Trauma Center Ludwigshafen
| | - Miriam Heuer
- German Institute for Cell and Tissue Replacement
| | - Jan Brune
- German Institute for Cell and Tissue Replacement
| | - Hannah Helt
- From the Department of Hand, Plastic, and Reconstructive Surgery, BG Trauma Center Ludwigshafen
| | - Amir K Bigdeli
- From the Department of Hand, Plastic, and Reconstructive Surgery, BG Trauma Center Ludwigshafen
| | - Arno Dimmler
- Institute of Pathology, Vincentius Kliniken Karlsruhe
| | - Patrick Heimel
- Core Facility Hard Tissue and Biomaterial Research, Karl Donath Laboratory, University Clinic of Dentistry, Medical University of Vienna
- Ludwig Boltzmann Institute for Experimental and Clinical Traumatology
| | - Wilko Thiele
- Department of Microvascular Biology and Pathobiology, European Center for Angioscience, Medical Faculty Mannheim, University of Heidelberg
- Institute for Biological and Chemical Systems, Karlsruhe Institute of Technology, Campus North
| | - Jonathan P Sleeman
- Department of Microvascular Biology and Pathobiology, European Center for Angioscience, Medical Faculty Mannheim, University of Heidelberg
- Institute for Biological and Chemical Systems, Karlsruhe Institute of Technology, Campus North
| | | | | | - Ulrich Kneser
- From the Department of Hand, Plastic, and Reconstructive Surgery, BG Trauma Center Ludwigshafen
| | - Benjamin Thomas
- From the Department of Hand, Plastic, and Reconstructive Surgery, BG Trauma Center Ludwigshafen
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Tong X, Xiao Z, Li P, Liu X, Wang M, Wen S, Wang N, Liao S, Zhou J. Angiogenesis and flap-related research: A bibliometric analysis. Int Wound J 2023; 20:3057-3072. [PMID: 37312275 PMCID: PMC10502283 DOI: 10.1111/iwj.14181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 03/21/2023] [Accepted: 03/27/2023] [Indexed: 06/15/2023] Open
Abstract
Adequate blood supply, a prerequisite for flap survival after grafting, makes angiogenesis of the flap the biggest problem to be solved. Researches have been conducted around vascularisation in correlation with flap grafting. However, bibliometric analyses systematically examining this research field are lacking. As such, we herein sought to conduct comprehensive comparative analyses of the contributions of different researchers, institutions, and countries to this research space in an effort to identify trends and hotspots in angiogenesis and vascularisation in the context of flap grafting. Publications pertaining to angiogenesis and vascularisation in the context of flap grafting were retrieved from the Web of Science Core Collection. References were then analysed and plotted using Microsoft Excel 2019, VOSviewer, and CiteSpace V. In total, 2234 papers that were cited 40 048 times (17.63 citations/paper) were included in this analysis. The greatest number of studies were from the United States, with these studies exhibiting both the highest number of citations (13 577) and the greatest overall H-index (60). For The institutions that published the greatest number of studies were WENZHOU MEDICAL UNIVERSITY (681), while UNIVERSITY OF ERLANGEN NUREMBERG has the highest number of citations (1458), and SHANGHAI JIAO TONG UNIVERSITY holds the greatest overall H-index (20). The greatest number of studies in this research space were published by Gao WY, while Horch RE was the most commonly cited researcher in the field. The VOS viewer software clustered relevant keywords into three clusters, with clusters 1, 2, 3, and 4 corresponding to studies in which the keywords 'anatomy', 'survival', 'transplantation', 'therapy' most frequently appeared. The most promising research hotspot-related terms in this field included 'autophagy', 'oxidative stress', 'ischemia/reperfusion injury', which exhibited a most recent average appearing year (AAY) of 2017 and after. Generally speaking, the results of this analysis indicate that the number of articles exploring angiogenesis and flap-related research has risen steadily, with the United States and China being the two countries publishing the greatest proportion of studies in this field. The overall focus of these studies has shifted away from 'infratest and tissue engineering' towards 'mechanisms'. In the future, particular attention should be paid to emerging research hotspots, which include 'ischemia/reperfusion injury' and treatments for promoting vascularization, such as 'platelet-rich plasma'. In light of these findings, funding agencies should continue increasing their investment in the exploration of the concrete mechanisms and interventional therapeutic relevance of angiogenesis during flap transplantation.
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Affiliation(s)
- Xiao‐Fei Tong
- Department of Plastic SurgeryThe Third Xiangya Hospital, Central South UniversityChangshaChina
| | - Zhen‐Yang Xiao
- Department of Plastic SurgeryThe Third Xiangya Hospital, Central South UniversityChangshaChina
| | - Pei‐Ting Li
- Department of Plastic SurgeryThe Third Xiangya Hospital, Central South UniversityChangshaChina
| | - Xin Liu
- Department of Plastic SurgeryThe Third Xiangya Hospital, Central South UniversityChangshaChina
| | - Ming‐Zhu Wang
- Department of Plastic SurgeryThe Third Xiangya Hospital, Central South UniversityChangshaChina
| | - Shi‐Yi Wen
- Department of Plastic SurgeryThe Third Xiangya Hospital, Central South UniversityChangshaChina
| | - Na Wang
- Department of Plastic SurgeryThe Third Xiangya Hospital, Central South UniversityChangshaChina
| | - Shenghui Liao
- School of Computer Science and EngineeringCentral South UniversityChangshaChina
| | - Jian‐Da Zhou
- Department of Plastic SurgeryThe Third Xiangya Hospital, Central South UniversityChangshaChina
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Koepple C, Pollmann L, Pollmann NS, Schulte M, Kneser U, Gretz N, Schmidt VJ. Microporous Polylactic Acid Scaffolds Enable Fluorescence-Based Perfusion Imaging of Intrinsic In Vivo Vascularization. Int J Mol Sci 2023; 24:14813. [PMID: 37834261 PMCID: PMC10573679 DOI: 10.3390/ijms241914813] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 09/29/2023] [Accepted: 09/29/2023] [Indexed: 10/15/2023] Open
Abstract
In vivo tissue engineering (TE) techniques like the AV loop model provide an isolated and well-defined microenvironment to study angiogenesis-related cell interactions. Functional visualization of the microvascular network within these artificial tissue constructs is crucial for the fundamental understanding of vessel network formation and to identify the underlying key regulatory mechanisms. To facilitate microvascular tracking advanced fluorescence imaging techniques are required. We studied the suitability of microporous polylactic acid (PLA) scaffolds with known low autofluorescence to form axial vascularized tissue constructs in the AV loop model and to validate these scaffolds for fluorescence-based perfusion imaging. Compared to commonly used collagen elastin (CE) scaffolds, the total number of vessels and cells in PLA scaffolds was lower. In detail, CE-based constructs exhibited significantly higher vessel numbers on day 14 and 28 (d14: 316 ± 53; d28: 610 ± 74) compared to the respective time points in PLA-based constructs (d14: 144 ± 18; d28: 327 ± 34; each p < 0.05). Analogously, cell counts in CE scaffolds were higher compared to corresponding PLA constructs (d14: 7661.25 ± 505.93 and 5804.04 ± 716.59; d28: 11211.75 + 1278.97 and 6045.71 ± 572.72, p < 0.05). CE scaffolds showed significantly higher vessel densities in proximity to the main vessel axis compared to PLA scaffolds (200-400 µm and 600-800 µm on day 14; 400-1000 µm and 1400-1600 µm on day 28). CE scaffolds had significantly higher cell counts on day 14 at distances from 800 to 2000 µm and at distances from 400 to 1600 µm on day 28. While the total number of vessels and cells in PLA scaffolds were lower, both scaffold types were ideally suited for axial vascularization techniques. The intravascular perfusion of PLA-based constructs with fluorescence dye MHI148-PEI demonstrated dye specificity against vascular walls of low- and high-order branches as well as capillaries and facilitated the fluorescence-based visualization of microcirculatory networks. Fluorophore tracking may contribute to the development of automated quantification methods after 3D reconstruction and image segmentation. These technologies may facilitate the characterization of key regulators within specific subdomains and add to the current understanding of vessel formation in axially vascularized tissue constructs.
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Affiliation(s)
- Christoph Koepple
- Department for Hand-, Plastic- and Reconstructive Surgery, BG Trauma Center Ludwigshafen, Heidelberg University, 67071 Ludwigshafen, Germany; (L.P.); (N.S.P.); (M.S.); (U.K.)
| | - Lukas Pollmann
- Department for Hand-, Plastic- and Reconstructive Surgery, BG Trauma Center Ludwigshafen, Heidelberg University, 67071 Ludwigshafen, Germany; (L.P.); (N.S.P.); (M.S.); (U.K.)
| | - Nicola Sariye Pollmann
- Department for Hand-, Plastic- and Reconstructive Surgery, BG Trauma Center Ludwigshafen, Heidelberg University, 67071 Ludwigshafen, Germany; (L.P.); (N.S.P.); (M.S.); (U.K.)
| | - Matthias Schulte
- Department for Hand-, Plastic- and Reconstructive Surgery, BG Trauma Center Ludwigshafen, Heidelberg University, 67071 Ludwigshafen, Germany; (L.P.); (N.S.P.); (M.S.); (U.K.)
| | - Ulrich Kneser
- Department for Hand-, Plastic- and Reconstructive Surgery, BG Trauma Center Ludwigshafen, Heidelberg University, 67071 Ludwigshafen, Germany; (L.P.); (N.S.P.); (M.S.); (U.K.)
| | - Norbert Gretz
- Medical Research Center, Medical Faculty Mannheim, University of Heidelberg, 68167 Mannheim, Germany;
| | - Volker J. Schmidt
- Department of Plastic Surgery and Hand Surgery, Kantonsspital St. Gallen, 9007 St. Gallen, Switzerland;
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Falkner F, Mayer SA, Thomas B, Zimmermann SO, Walter S, Heimel P, Thiele W, Sleeman JP, Bigdeli AK, Kiss H, Podesser BK, Kneser U, Bergmeister H, Schneider KH. Acellular Human Placenta Small-Diameter Vessels as a Favorable Source of Super-Microsurgical Vascular Replacements: A Proof of Concept. Bioengineering (Basel) 2023; 10:337. [PMID: 36978728 PMCID: PMC10045636 DOI: 10.3390/bioengineering10030337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 02/19/2023] [Accepted: 02/27/2023] [Indexed: 03/30/2023] Open
Abstract
In this study, we aimed to evaluate the human placenta as a source of blood vessels that can be harvested for vascular graft fabrication in the submillimeter range. Our approach included graft modification to prevent thrombotic events. Submillimeter arterial grafts harvested from the human placenta were decellularized and chemically crosslinked to heparin. Graft performance was evaluated using a microsurgical arteriovenous loop (AVL) model in Lewis rats. Specimens were evaluated through hematoxylin-eosin and CD31 staining of histological sections to analyze host cell immigration and vascular remodeling. Graft patency was determined 3 weeks after implantation using a vascular patency test, histology, and micro-computed tomography. A total of 14 human placenta submillimeter vessel grafts were successfully decellularized and implanted into AVLs in rats. An appropriate inner diameter to graft length ratio of 0.81 ± 0.16 mm to 7.72 ± 3.20 mm was achieved in all animals. Grafts were left in situ for a mean of 24 ± 4 days. Decellularized human placental grafts had an overall patency rate of 71% and elicited no apparent immunological responses. Histological staining revealed host cell immigration into the graft and re-endothelialization of the vessel luminal surface. This study demonstrates that decellularized vascular grafts from the human placenta have the potential to serve as super-microsurgical vascular replacements.
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Affiliation(s)
- Florian Falkner
- Department of Hand, Plastic and Reconstructive Surgery, BG Trauma Center Ludwigshafen, University of Heidelberg, 69117 Heidelberg, Germany
| | - Simon Andreas Mayer
- Department of Hand, Plastic and Reconstructive Surgery, BG Trauma Center Ludwigshafen, University of Heidelberg, 69117 Heidelberg, Germany
| | - Benjamin Thomas
- Department of Hand, Plastic and Reconstructive Surgery, BG Trauma Center Ludwigshafen, University of Heidelberg, 69117 Heidelberg, Germany
| | - Sarah Onon Zimmermann
- Center for Biomedical Research and Translational Surgery, Medical University of Vienna, 1090 Vienna, Austria
| | - Sonja Walter
- Department of Hand, Plastic and Reconstructive Surgery, BG Trauma Center Ludwigshafen, University of Heidelberg, 69117 Heidelberg, Germany
| | - Patrick Heimel
- Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, 1200 Vienna, Austria
- Core Facility Hard Tissue and Biomaterial Research, Karl Donath Laboratory, University Clinic of Dentistry, Medical University of Vienna, 1090 Vienna, Austria
| | - Wilko Thiele
- Department of Microvascular Biology and Pathobiology, European Center for Angioscience (ECAS), Medical Faculty Mannheim, University of Heidelberg, 68167 Mannheim, Germany
| | - Jonathan Paul Sleeman
- Department of Microvascular Biology and Pathobiology, European Center for Angioscience (ECAS), Medical Faculty Mannheim, University of Heidelberg, 68167 Mannheim, Germany
- Institute for Biological and Chemical Systems, Karlsruhe Institute of Technology, Campus North, 76131 Karlsruhe, Germany
| | - Amir Khosrow Bigdeli
- Department of Hand, Plastic and Reconstructive Surgery, BG Trauma Center Ludwigshafen, University of Heidelberg, 69117 Heidelberg, Germany
| | - Herbert Kiss
- Department of Obstetrics and Gynecology, Division of Obstetrics and Feto-Maternal Medicine, Medical University of Vienna, 1090 Vienna, Austria
| | - Bruno Karl Podesser
- Center for Biomedical Research and Translational Surgery, Medical University of Vienna, 1090 Vienna, Austria
- Department of Obstetrics and Gynecology, Division of Obstetrics and Feto-Maternal Medicine, Medical University of Vienna, 1090 Vienna, Austria
| | - Ulrich Kneser
- Department of Hand, Plastic and Reconstructive Surgery, BG Trauma Center Ludwigshafen, University of Heidelberg, 69117 Heidelberg, Germany
| | - Helga Bergmeister
- Center for Biomedical Research and Translational Surgery, Medical University of Vienna, 1090 Vienna, Austria
- Ludwig Boltzmann Institute for Cardiovascular Research, 1090 Vienna, Austria
- Austrian Cluster for Tissue Regeneration, 1200 Vienna, Austria
| | - Karl Heinrich Schneider
- Center for Biomedical Research and Translational Surgery, Medical University of Vienna, 1090 Vienna, Austria
- Ludwig Boltzmann Institute for Cardiovascular Research, 1090 Vienna, Austria
- Austrian Cluster for Tissue Regeneration, 1200 Vienna, Austria
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Prefabrication-a Vascularized Skin Flap Using an Arteriovenous LoopPrefabricated Flap With Arteriovenous Loop: An Experimental Study in Minipigs. J Craniofac Surg 2023; 34:e255-e259. [PMID: 36727988 DOI: 10.1097/scs.0000000000009172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 11/13/2022] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND Arteriovenous loops have a high potency to induce angiogenesis and are promising to solve the problem of scarce implanted pedicle sources and insufficient neovascularization in flap prefabrication. But there is a lack of large animal experiments to support their clinical application. Therefore, we aimed to explore the feasibility of prefabricating large flaps based on arteriovenous loops in pigs. METHODS Five minipigs were used. In the experimental group, a 10-cm-long ear vein graft was microanastomosed with the saphenous artery and vein to form an arteriovenous loop and implanted under the medial thigh flap. A month later, a 10×10 cm prefabricated flap pedicled with the arteriovenous loop was elevated and sutured in situ. In the control group, a 10×10 cm flap with no vascular pedicle was elevated completely and sutured in situ in the same position. The patency of the arteriovenous loop was evaluated by angiography 30 days after implantation, and the viability of flaps was assessed by macroscopic analysis 10 days after elevation. Three animals received arteriovenous loop flaps unilaterally and no-pedicle flaps unilaterally. Two animals received arteriovenous loop flaps bilaterally. RESULTS In the experimental group, no thrombi were exhibited in any arteriovenous loop. All 7 prefabricated flaps survived uneventfully. In the control group, 3 flaps were completely necrotic. CONCLUSION The arteriovenous loops with long interpositional venous grafts can be used as vascular pedicles to prefabricated large area and well-vascularized flaps. This approach can greatly expand the application of flap prefabrication.
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Enrichment of Nanofiber Hydrogel Composite with Fractionated Fat Promotes Regenerative Macrophage Polarization and Vascularization for Soft-Tissue Engineering. Plast Reconstr Surg 2022; 149:433e-444e. [PMID: 35196680 DOI: 10.1097/prs.0000000000008872] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND Fractionated fat has been shown to promote dermal regeneration; however, the use of fat grafting for reconstruction of soft-tissue defects is limited because of volume loss over time. The authors have developed a novel approach for engineering of vascularized soft tissue using an injectable nanofiber hydrogel composite enriched with fractionated fat. METHODS Fractionated fat was generated by emulsification of groin fat pads from rats and mixed in a 3:1 ratio with nanofiber hydrogel composite (nanofiber hydrogel composite with fractionated fat). Nanofiber hydrogel composite with fractionated fat or nanofiber hydrogel composite alone was placed into isolation chambers together with arteriovenous loops, which were subcutaneously implanted into the groin of rats (n = 8 per group). After 21 days, animals were euthanized and systemically perfused with ink, and tissue was explanted for histologic analysis. Immunofluorescent staining and confocal laser scanning microscopy were used to quantify CD34+ progenitor cell and macrophage subpopulations. RESULTS Nanofiber hydrogel composite with fractionated fat tissue maintained its shape without shrinking and showed a significantly stronger functional vascularization compared to composite alone after 21 days of implantation (mean vessel count, 833.5 ± 206.1 versus 296.5 ± 114.1; p = 0.04). Tissue heterogeneity and cell count were greater in composite with fractionated fat (mean cell count, 49,707 ± 18,491 versus 9263 ± 3790; p = 0.005), with a significantly higher number of progenitor cells and regenerative CD163+ macrophages compared to composite alone. CONCLUSIONS Fractionated fat-enriched nanofiber hydrogel composite transforms into highly vascularized soft tissue over 21 days without signs of shrinking and promotes macrophage polarization toward regenerative phenotypes. Enrichment of injectable nanofiber hydrogel composite with fractionated fat represents a promising approach for durable reconstruction of soft-tissue defects. CLINICAL RELEVANCE STATEMENT The authors' approach for tissue engineering may ultimately lay the groundwork for clinically relevant applications with the goal of generating large volumes of vascularized soft tissue for defect reconstruction without donor site morbidity.
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Hancock PC, Koduru SV, Sun M, Ravnic DJ. Induction of scaffold angiogenesis by recipient vasculature precision micropuncture. Microvasc Res 2021; 134:104121. [PMID: 33309646 DOI: 10.1016/j.mvr.2020.104121] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 11/12/2020] [Accepted: 12/08/2020] [Indexed: 12/01/2022]
Abstract
The success of engineered tissues continues to be limited by time to vascularization and perfusion. Here, we studied the effects of precision injury to a recipient macrovasculature in promoting neovessel formation in an adjacently placed scaffold. Segmental 60 μm diameter micropunctures (MP) were created in the recipient rat femoral artery and vein followed by coverage with a simple collagen scaffold. Scaffolds were harvested at 24, 48, 72, and 96 h post-implantation for detailed analysis. Those placed on top of an MP segment showed an earlier and more robust cellular infiltration, including both endothelial cells (CD31) and macrophages (F4/80), compared to internal non-micropunctured control limbs (p < 0.05). At the 96-hour timepoint, MP scaffolds demonstrated an increase in physiologic perfusion (p < 0.003) and a 2.5-fold increase in capillary network formation (p < 0.001). These were attributed to an overall upsurge in small vessel quantity. Furthermore, MP positioned scaffolds demonstrated significant increases in many modulators of angiogenesis, including VEGFR2 and Tie-2 despite a decrease in HIF-1α at all timepoints. This study highlights a novel microsurgical approach that can be used to rapidly vascularize or inosculate contiguously placed scaffolds and grafts. Thereby, offering an easily translatable route towards the creation of thicker and more clinically relevant engineered tissues.
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Affiliation(s)
- Patrick C Hancock
- Irvin S. Zubar Plastic Surgery Research Laboratory, Penn State College of Medicine, Hershey, PA, USA
| | - Srinivas V Koduru
- Irvin S. Zubar Plastic Surgery Research Laboratory, Penn State College of Medicine, Hershey, PA, USA; Department of Surgery, Penn State Health Milton S. Hershey Medical Center, Hershey, PA, USA; Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, PA, USA
| | - Mingjie Sun
- Irvin S. Zubar Plastic Surgery Research Laboratory, Penn State College of Medicine, Hershey, PA, USA; Department of Surgery, Penn State Health Milton S. Hershey Medical Center, Hershey, PA, USA
| | - Dino J Ravnic
- Irvin S. Zubar Plastic Surgery Research Laboratory, Penn State College of Medicine, Hershey, PA, USA; Department of Surgery, Penn State Health Milton S. Hershey Medical Center, Hershey, PA, USA.
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Henn D, Chen K, Fischer K, Rauh A, Barrera JA, Kim YJ, Martin RA, Hannig M, Niedoba P, Reddy SK, Mao HQ, Kneser U, Gurtner GC, Sacks JM, Schmidt VJ. Tissue Engineering of Axially Vascularized Soft-Tissue Flaps with a Poly-(ɛ-Caprolactone) Nanofiber-Hydrogel Composite. Adv Wound Care (New Rochelle) 2020; 9:365-377. [PMID: 32587789 DOI: 10.1089/wound.2019.0975] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2019] [Accepted: 12/18/2019] [Indexed: 11/12/2022] Open
Abstract
Objective: To develop a novel approach for tissue engineering of soft-tissue flaps suitable for free microsurgical transfer, using an injectable nanofiber hydrogel composite (NHC) vascularized by an arteriovenous (AV) loop. Approach: A rat AV loop model was used for tissue engineering of vascularized soft-tissue flaps. NHC or collagen-elastin (CE) scaffolds were implanted into isolation chambers together with an AV loop and explanted after 15 days. Saphenous veins were implanted into the scaffolds as controls. Neoangiogenesis, ultrastructure, and protein expression of SYNJ2BP, EPHA2, and FOXC1 were analyzed by immunohistochemistry and compared between the groups. Rheological properties were compared between the two scaffolds and native human adipose tissue. Results: A functional neovascularization was evident in NHC flaps with its amount being comparable with CE flaps. Scanning electron microscopy revealed a strong mononuclear cell infiltration along the nanofibers in NHC flaps and a trend toward higher fiber alignment compared with CE flaps. SYNJ2BP and EPHA2 expression in endothelial cells (ECs) was lower in NHC flaps compared with CE flaps, whereas FOXC1 expression was increased in NHC flaps. Compared with the stiffer CE flaps, the NHC flaps showed similar rheological properties to native human adipose tissue. Innovation: This is the first study to demonstrate the feasibility of tissue engineering of soft-tissue flaps with similar rheological properties as human fat, suitable for microsurgical transfer using an injectable nanofiber hydrogel composite. Conclusions: The injectable NHC scaffold is suitable for tissue engineering of axially vascularized soft-tissue flaps with a solid neovascularization, strong cellular infiltration, and biomechanical properties similar to human fat. Our data indicate that SYNJ2BP, EPHA2, and FOXC1 are involved in AV loop-associated angiogenesis and that the scaffold material has an impact on protein expression in ECs.
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Affiliation(s)
- Dominic Henn
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford University, Stanford, California
- Department of Hand, Plastic, and Reconstructive Surgery, BG Trauma Center Ludwigshafen, Ruprecht-Karls-University of Heidelberg, Heidelberg, Germany
| | - Kellen Chen
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford University, Stanford, California
| | - Katharina Fischer
- Department of Hand, Plastic, and Reconstructive Surgery, BG Trauma Center Ludwigshafen, Ruprecht-Karls-University of Heidelberg, Heidelberg, Germany
| | - Annika Rauh
- Department of Hand, Plastic, and Reconstructive Surgery, BG Trauma Center Ludwigshafen, Ruprecht-Karls-University of Heidelberg, Heidelberg, Germany
| | - Janos A. Barrera
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford University, Stanford, California
| | - Yoo-Jin Kim
- Institute of Pathology, Kaiserslautern, Germany
| | - Russell A. Martin
- Department of Materials Science and Engineering, Whiting School of Engineering, and Institute for NanoBioTechnology, Johns Hopkins University, Baltimore, Maryland
- Translational Tissue Engineering Center and Department of Biomedical Engineering, Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Matthias Hannig
- Clinic of Operative Dentistry, Periodontology and Preventive Dentistry, Saarland University, Homburg, Germany
| | - Patricia Niedoba
- Department of Hand, Plastic, and Reconstructive Surgery, BG Trauma Center Ludwigshafen, Ruprecht-Karls-University of Heidelberg, Heidelberg, Germany
| | - Sashank K. Reddy
- Department of Plastic and Reconstructive Surgery, Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Hai-Quan Mao
- Department of Materials Science and Engineering, Whiting School of Engineering, and Institute for NanoBioTechnology, Johns Hopkins University, Baltimore, Maryland
- Translational Tissue Engineering Center and Department of Biomedical Engineering, Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Ulrich Kneser
- Department of Hand, Plastic, and Reconstructive Surgery, BG Trauma Center Ludwigshafen, Ruprecht-Karls-University of Heidelberg, Heidelberg, Germany
| | - Geoffrey C. Gurtner
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford University, Stanford, California
| | - Justin M. Sacks
- Department of Plastic and Reconstructive Surgery, Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Volker J. Schmidt
- Department of Hand, Plastic, and Reconstructive Surgery, BG Trauma Center Ludwigshafen, Ruprecht-Karls-University of Heidelberg, Heidelberg, Germany
- Department for Plastic and Breast Surgery, Zealand University Hospital Roskilde, Roskilde, Denmark
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Micro-RNA-Regulated Proangiogenic Signaling in Arteriovenous Loops in Patients with Combined Vascular and Soft-Tissue Reconstructions: Revisiting the Nutrient Flap Concept. Plast Reconstr Surg 2019; 142:489e-502e. [PMID: 29979372 DOI: 10.1097/prs.0000000000004750] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND The placement of arteriovenous loops can enable microvascular anastomoses of free flaps when recipient vessels are scarce. In animal models, elevated fluid shear stress in arteriovenous loops promotes neoangiogenesis. Anecdotal reports in patients indicate that vein grafts used in free flap reconstructions of ischemic lower extremities are able to induce capillary formation. However, flow-stimulated angiogenesis has never been systematically investigated in humans, and it is unclear whether shear stress alters proangiogenic signaling pathways within the vascular wall of human arteriovenous loops. METHODS Eight patients with lower extremity soft-tissue defects underwent two-stage reconstruction with arteriovenous loop placement, and free flap anastomoses to the loops 10 to 14 days later. Micro-RNA (miRNA) and gene expression profiles were determined in tissue samples harvested from vein grafts of arteriovenous loops by microarray analysis and quantitative real-time polymerase chain reaction. Samples from untreated veins served as controls. RESULTS A strong deregulation of miRNA and gene expression was detected in arteriovenous loops, showing an overexpression of angiopoietic cytokines, oxygenation-associated genes, vascular growth factors, and connexin-43. The authors discovered inverse correlations along with validated and bioinformatically predicted interactions between angiogenesis-regulating genes and miRNAs in arteriovenous loops. CONCLUSIONS The authors' findings demonstrate that elevated shear stress triggers proangiogenic signaling pathways in human venous tissue, indicating that arteriovenous loops may have the ability to induce neoangiogenesis in humans. The authors' data corroborate the nutrient flap hypothesis and provide a molecular background for arteriovenous loop-based tissue engineering with potential clinical applications for soft-tissue defect reconstruction.
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Henn D, Abu-Halima M, Wermke D, Falkner F, Thomas B, Köpple C, Ludwig N, Schulte M, Brockmann MA, Kim YJ, Sacks JM, Kneser U, Keller A, Meese E, Schmidt VJ. MicroRNA-regulated pathways of flow-stimulated angiogenesis and vascular remodeling in vivo. J Transl Med 2019; 17:22. [PMID: 30635008 PMCID: PMC6330440 DOI: 10.1186/s12967-019-1767-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2018] [Accepted: 01/02/2019] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Vascular shear stress promotes endothelial cell sprouting in vitro. The impact of hemodynamic forces on microRNA (miRNA) and gene expression within growing vascular networks in vivo, however, remain poorly investigated. Arteriovenous (AV) shunts are an established model for induction of neoangiogenesis in vivo and can serve as a tool for analysis of hemodynamic effects on miRNA and gene expression profiles over time. METHODS AV shunts were microsurgically created in rats and explanted on postoperative days 5, 10 and 15. Neoangiogenesis was confirmed by histologic analysis and micro-computed tomography. MiRNA and gene expression profiles were determined in tissue specimens from AV shunts by microarray analysis and quantitative real-time polymerase chain reaction and compared with sham-operated veins by bioinformatics analysis. Changes in protein expression within AV shunt endothelial cells were determined by immunohistochemistry. RESULTS Samples from AV shunts exhibited a strong overexpression of proangiogenic cytokines, oxygenation-associated genes (HIF1A, HMOX1), and angiopoetic growth factors. Significant inverse correlations of the expressions of miR-223-3p, miR-130b-3p, miR-19b-3p, miR-449a-5p, and miR-511-3p which were up-regulated in AV shunts, and miR-27b-3p, miR-10b-5p, let-7b-5p, and let-7c-5p, which were down-regulated in AV shunts, with their predicted interacting targets C-X-C chemokine receptor 2 (CXCR2), interleukin-1 alpha (IL1A), ephrin receptor kinase 2 (EPHA2), synaptojanin-2 binding protein (SYNJ2BP), forkhead box C1 (FOXC1) were present. CXCL2 and IL1A overexpression in AV shunt endothelium was confirmed at the protein level by immunohistochemistry. CONCLUSIONS Our data indicate that flow-stimulated angiogenesis is determined by an upregulation of cytokines, oxygenation associated genes and miRNA-dependent regulation of FOXC1, EPHA2 and SYNJ2BP.
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Affiliation(s)
- Dominic Henn
- Department of Hand, Plastic and Reconstructive Surgery, University of Heidelberg, BG Trauma Center Ludwigshafen, Ludwig-Guttmann Str. 13, 67071, Ludwigshafen, Germany
| | - Masood Abu-Halima
- Institute of Human Genetics, Saarland University, Homburg-Saar, Germany
| | - Dominik Wermke
- Institute of Clinical Bioinformatics, Saarland University, Saarbruecken, Germany
| | - Florian Falkner
- Department of Hand, Plastic and Reconstructive Surgery, University of Heidelberg, BG Trauma Center Ludwigshafen, Ludwig-Guttmann Str. 13, 67071, Ludwigshafen, Germany
| | - Benjamin Thomas
- Department of Hand, Plastic and Reconstructive Surgery, University of Heidelberg, BG Trauma Center Ludwigshafen, Ludwig-Guttmann Str. 13, 67071, Ludwigshafen, Germany
| | - Christoph Köpple
- Department of Hand, Plastic and Reconstructive Surgery, University of Heidelberg, BG Trauma Center Ludwigshafen, Ludwig-Guttmann Str. 13, 67071, Ludwigshafen, Germany
| | - Nicole Ludwig
- Institute of Human Genetics, Saarland University, Homburg-Saar, Germany
| | - Matthias Schulte
- Department of Hand, Plastic and Reconstructive Surgery, University of Heidelberg, BG Trauma Center Ludwigshafen, Ludwig-Guttmann Str. 13, 67071, Ludwigshafen, Germany
| | - Marc A Brockmann
- Department of Neuroradiology, University Medical Center Mainz, Mainz, Germany
| | - Yoo-Jin Kim
- Institute of Pathology, Kaiserslautern, Germany
| | - Justin M Sacks
- Department of Plastic and Reconstructive Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Ulrich Kneser
- Department of Hand, Plastic and Reconstructive Surgery, University of Heidelberg, BG Trauma Center Ludwigshafen, Ludwig-Guttmann Str. 13, 67071, Ludwigshafen, Germany
| | - Andreas Keller
- Institute of Clinical Bioinformatics, Saarland University, Saarbruecken, Germany
| | - Eckart Meese
- Institute of Human Genetics, Saarland University, Homburg-Saar, Germany
| | - Volker J Schmidt
- Department of Hand, Plastic and Reconstructive Surgery, University of Heidelberg, BG Trauma Center Ludwigshafen, Ludwig-Guttmann Str. 13, 67071, Ludwigshafen, Germany.
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Yap KK, Yeoh GC, Morrison WA, Mitchell GM. The Vascularised Chamber as an In Vivo Bioreactor. Trends Biotechnol 2018; 36:1011-1024. [DOI: 10.1016/j.tibtech.2018.05.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Revised: 05/25/2018] [Accepted: 05/29/2018] [Indexed: 02/06/2023]
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