1
|
Dinter MC, Bickelmann C, Nickels RM, Menger MD, Laschke MW. Microvascular Fragment-Loaded Platelet-Rich Plasma Dressing Promotes Cutaneous Wound Healing. Adv Wound Care (New Rochelle) 2024. [PMID: 38299944 DOI: 10.1089/wound.2023.0029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2024] Open
Abstract
Objective: Chronic wounds represent a considerable burden for the affected patients and the health care system. To overcome this problem, effective treatment strategies are urgently required. In this study, we tested a novel approach by combining platelet-rich plasma (PRP) and microvascular fragments (MVF) to create a prevascularized gel dressing. Approach: MVF were enzymatically isolated from the epididymal fat pads of transgenic green fluorescent protein (GFP)+ C57BL/6J donor mice. Subsequently, 5,000 MVF were suspended in 10 μL murine PRP as carrier and transferred into full-thickness skin wounds within dorsal skinfold chambers of C57BL/6J wild-type mice (PRP+MVF). Wound healing in comparison to empty wounds (control) and wounds filled with PRP alone was repeatedly analyzed throughout 14 days by means of stereomicroscopy, histology, and immunohistochemistry. Results: Planimetric assessment of the wound size over time revealed a significantly accelerated and improved healing of PRP+MVF-treated wounds when compared with PRP-treated and empty control wounds. These wounds also exhibited a significantly higher density of blood and lymph vessels, which originated from the GFP+ MVF isolates and effectively promoted granulation tissue formation inside the skin defects. Innovation: This study is the first to combine PRP and MVF for the improvement of wound healing. Conclusion: The combination of PRP and MVF represents a promising approach for the future treatment of wounds that do not heal spontaneously due to poor wound-healing conditions.
Collapse
Affiliation(s)
- Melina C Dinter
- Institute for Clinical and Experimental Surgery, Saarland University, Homburg, Germany
| | - Caroline Bickelmann
- Institute for Clinical and Experimental Surgery, Saarland University, Homburg, Germany
| | - Ruth M Nickels
- Institute for Clinical and Experimental Surgery, Saarland University, Homburg, Germany
| | - Michael D Menger
- Institute for Clinical and Experimental Surgery, Saarland University, Homburg, Germany
| | - Matthias W Laschke
- Institute for Clinical and Experimental Surgery, Saarland University, Homburg, Germany
| |
Collapse
|
2
|
Quan Y, Zhang Y, Li J, Lu F, Cai J. Transplantation of in vitro prefabricated adipose organoids attenuates skin fibrosis by restoring subcutaneous fat and inducing dermal adipogenesis. FASEB J 2023; 37:e23076. [PMID: 37432650 DOI: 10.1096/fj.202202117r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 05/31/2023] [Accepted: 06/22/2023] [Indexed: 07/12/2023]
Abstract
Localized scleroderma is a complex autoimmune disease characterized by dermal fibrosis and loss of cutaneous fat. While cytotherapy offers a promising treatment option, stem cell transplantation results in low survival rates and fails in target cell differentiation. In this study, we aimed to prefabricate syngeneic adipose organoids (ad-organoids) using microvascular fragments (MVFs) via three-dimensional (3D) culturing and transplant them beneath the fibrotic skin to restore subcutaneous fat and reverse the pathological manifestation of localized scleroderma. We employed 3D culturing of syngeneic MVFs with stepwise angiogenic and adipogenic induction to produce ad-organoids and evaluated their microstructure and paracrine function in vitro. C57/BL6 mice with induced skin scleroderma were treated with adipose-derived stem cells (ASCs), adipocytes, ad-organoids, and Matrigel, and the therapeutic effect was assessed histologically. Our results showed that ad-organoids derived from MVF contained mature adipocytes and a well-established vessel network, secreted multiple adipokines, promoted adipogenic differentiation of ASCs, and suppressed proliferation and migration of scleroderma fibroblasts. Subcutaneous transplantation of ad-organoids reconstructed the subcutaneous fat layer and stimulated dermal adipocyte regeneration in bleomycin-induced scleroderma skin. It reduced collagen deposition and dermal thickness, attenuating dermal fibrosis. Moreover, ad-organoids suppressed macrophage infiltration and promoted angiogenesis in the skin lesion. In conclusion, 3D culturing of MVFs with stepwise angiogenic and adipogenic induction is an effective strategy for the fabrication of ad-organoids, and the transplantation of prefabricated ad-organoids can improve skin sclerosis by restoring cutaneous fat and attenuating skin fibrosis. These findings offer a promising therapeutic approach for the treatment of localized scleroderma.
Collapse
Affiliation(s)
- Yuping Quan
- Department of Plastic and Cosmetic Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, P.R. China
- Department of Plastic Surgery and Regenerative Medicine, Fujian Medical University Union Hospital, Fuzhou, P.R. China
| | - Yuteng Zhang
- Department of Plastic and Cosmetic Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, P.R. China
| | - Jian Li
- Department of Plastic and Cosmetic Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, P.R. China
| | - Feng Lu
- Department of Plastic and Cosmetic Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, P.R. China
| | - Junrong Cai
- Department of Plastic and Cosmetic Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, P.R. China
| |
Collapse
|
3
|
Weinzierl A, Harder Y, Schmauss D, Menger MD, Laschke MW. Microvascular Fragments Protect Ischemic Musculocutaneous Flap Tissue from Necrosis by Improving Nutritive Tissue Perfusion and Suppressing Apoptosis. Biomedicines 2023; 11:biomedicines11051454. [PMID: 37239125 DOI: 10.3390/biomedicines11051454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 05/06/2023] [Accepted: 05/12/2023] [Indexed: 05/28/2023] Open
Abstract
Microvascular fragments (MVF) derived from enzymatically digested adipose tissue are functional vessel segments that have been shown to increase the survival rate of surgical flaps. However, the underlying mechanisms have not been clarified so far. To achieve this, we raised random-pattern musculocutaneous flaps on the back of wild-type mice and mounted them into dorsal skinfold chambers. The flaps were injected with MVF that were freshly isolated from green fluorescent protein-positive (GFP+) donor mice or saline solution (control). On days 1, 3, 5, 7, and 10 after surgery, intravital fluorescence microscopy was performed for the quantitative assessment of angiogenesis, nutritive blood perfusion, and flap necrosis. Subsequently, the flaps were analyzed by histology and immunohistochemistry. The injection of MVF reduced necrosis of the ischemic flap tissue by ~20%. When compared to controls, MVF-injected flaps also displayed a significantly higher functional capillary density and number of newly formed microvessels in the transition zone, where vital tissue bordered on necrotic tissue. Immunohistochemical analyses revealed a markedly lower number of cleaved caspase-3+ apoptotic cells in the transition zone of MVF-injected flaps and a significantly increased number of CD31+ microvessels in both the flaps' base and transition zone. Up to ~10% of these microvessels were GFP+, proving their origin from injected MVF. These findings demonstrate that MVF reduce flap necrosis by increasing angiogenesis, improving nutritive tissue perfusion, and suppressing apoptosis. Hence, the injection of MVF may represent a promising strategy to reduce ischemia-induced flap necrosis in future clinical practice.
Collapse
Affiliation(s)
- Andrea Weinzierl
- Institute for Clinical & Experimental Surgery, Saarland University, 66421 Homburg/Saar, Germany
- Department of Plastic Surgery and Hand Surgery, University Hospital Zurich, 8091 Zurich, Switzerland
| | - Yves Harder
- Department of Plastic, Reconstructive and Aesthetic Surgery, Ospedale Regionale di Lugano, Ente Ospedaliero Cantonale (EOC), 6900 Lugano, Switzerland
- Faculty of Biomedical Sciences, Università della Svizzera Italiana, 6900 Lugano, Switzerland
| | - Daniel Schmauss
- Department of Plastic, Reconstructive and Aesthetic Surgery, Ospedale Regionale di Lugano, Ente Ospedaliero Cantonale (EOC), 6900 Lugano, Switzerland
- Faculty of Biomedical Sciences, Università della Svizzera Italiana, 6900 Lugano, Switzerland
| | - Michael D Menger
- Institute for Clinical & Experimental Surgery, Saarland University, 66421 Homburg/Saar, Germany
| | - Matthias W Laschke
- Institute for Clinical & Experimental Surgery, Saarland University, 66421 Homburg/Saar, Germany
| |
Collapse
|
4
|
Später T, Marschall JE, Brücker LK, Nickels RM, Metzger W, Mai AS, Menger MD, Laschke MW. Adipose Tissue-Derived Microvascular Fragments From Male and Female Fat Donors Exhibit a Comparable Vascularization Capacity. Front Bioeng Biotechnol 2021; 9:777687. [PMID: 34778238 PMCID: PMC8578922 DOI: 10.3389/fbioe.2021.777687] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 10/13/2021] [Indexed: 11/13/2022] Open
Abstract
Adipose tissue-derived microvascular fragments (MVF) represent effective vascularization units for tissue engineering. Most experimental studies exclusively use epididymal fat tissue of male donor mice as a source for MVF isolation. However, in future clinical practice, MVF-based approaches may be applied in both male and female patients. Therefore, we herein compared the vascularization capacity of MVF isolated from the epididymal and peri-ovarian fat tissue of male and female donor mice. Freshly isolated MVF from male and female donors did not differ in their number, length distribution, viability and cellular composition. After their assembly into spheroids, they also exhibited a comparable in vitro sprouting activity. Moreover, they could be seeded onto collagen-glycosaminoglycan matrices, which were implanted into full-thickness skin defects within mouse dorsal skinfold chambers. Repetitive intravital fluorescence microscopy as well as histological and immunohistochemical analyses revealed a comparable vascularization and incorporation of implants seeded with MVF of male and female origin. Taken together, these findings demonstrate that the vascularization capacity of MVF is not gender-specific.
Collapse
Affiliation(s)
- Thomas Später
- Institute for Clinical and Experimental Surgery, Saarland University, Homburg, Germany
| | - Julia E Marschall
- Institute for Clinical and Experimental Surgery, Saarland University, Homburg, Germany
| | - Lea K Brücker
- Institute for Clinical and Experimental Surgery, Saarland University, Homburg, Germany
| | - Ruth M Nickels
- Institute for Clinical and Experimental Surgery, Saarland University, Homburg, Germany
| | - Wolfgang Metzger
- Department of Trauma, Hand and Reconstructive Surgery, Saarland University, Homburg, Germany
| | - Ann-Sophie Mai
- Institute for Clinical and Experimental Surgery, Saarland University, Homburg, Germany
| | - Michael D Menger
- Institute for Clinical and Experimental Surgery, Saarland University, Homburg, Germany
| | - Matthias W Laschke
- Institute for Clinical and Experimental Surgery, Saarland University, Homburg, Germany
| |
Collapse
|
5
|
Laschke MW, Menger MD. The simpler, the better: tissue vascularization using the body's own resources. Trends Biotechnol 2021; 40:281-290. [PMID: 34404555 DOI: 10.1016/j.tibtech.2021.07.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 07/23/2021] [Accepted: 07/23/2021] [Indexed: 12/24/2022]
Abstract
Tissue regeneration is crucially dependent on sufficient vascularization. In regenerative medicine, this can be effectively achieved by autologous vascularization strategies using the body's own resources. These strategies include the administration of blood-derived factor preparations, adipose tissue-based vascularization, and the in situ engineering of vascularized tissue. Due to their simplicity, the translation of these strategies into clinical practice is easier in terms of feasibility, safety requirements, and regulatory hurdles compared with complex and time-consuming procedures involving intensive cell manipulation. Hence, they are close to clinical application or are already being used to successfully treat patients by distinct personalized medicine concepts.
Collapse
Affiliation(s)
- Matthias W Laschke
- Institute for Clinical & Experimental Surgery, Saarland University, 66421 Homburg/Saar, Germany.
| | - Michael D Menger
- Institute for Clinical & Experimental Surgery, Saarland University, 66421 Homburg/Saar, Germany
| |
Collapse
|
6
|
Salamone M, Rigogliuso S, Nicosia A, Campora S, Bruno CM, Ghersi G. 3D Collagen Hydrogel Promotes In Vitro Langerhans Islets Vascularization through ad-MVFs Angiogenic Activity. Biomedicines 2021; 9:biomedicines9070739. [PMID: 34199087 PMCID: PMC8301445 DOI: 10.3390/biomedicines9070739] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 06/22/2021] [Accepted: 06/24/2021] [Indexed: 02/07/2023] Open
Abstract
Adipose derived microvascular fragments (ad-MVFs) consist of effective vascularization units able to reassemble into efficient microvascular networks. Because of their content in stem cells and related angiogenic activity, ad-MVFs represent an interesting tool for applications in regenerative medicine. Here we show that gentle dissociation of rat adipose tissue provides a mixture of ad-MVFs with a length distribution ranging from 33–955 μm that are able to maintain their original morphology. The isolated units of ad-MVFs that resulted were able to activate transcriptional switching toward angiogenesis, forming tubes, branches, and entire capillary networks when cultured in 3D collagen type-I hydrogel. The proper involvement of metalloproteases (MMP2/MMP9) and serine proteases in basal lamina and extracellular matrix ECM degradation during the angiogenesis were concurrently assessed by the evaluation of alpha-smooth muscle actin (αSMA) expression. These results suggest that collagen type-I hydrogel provides an adequate 3D environment supporting the activation of the vascularization process. As a proof of concept, we exploited 3D collagen hydrogel for the setting of ad-MVF–islet of Langerhans coculture to improve the islets vascularization. Our results suggest potential employment of the proposed in vitro system for regenerative medicine applications, such as the improving of the islet of Langerhans engraftment before transplantation.
Collapse
Affiliation(s)
- Monica Salamone
- Abiel s.r.l., c/o Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF) University of Palermo, Viale delle Scienze, Ed. 16, 90128 Palermo, Italy; (M.S.); (S.R.); (C.M.B.)
| | - Salvatrice Rigogliuso
- Abiel s.r.l., c/o Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF) University of Palermo, Viale delle Scienze, Ed. 16, 90128 Palermo, Italy; (M.S.); (S.R.); (C.M.B.)
| | - Aldo Nicosia
- Institute for Biomedical Research and Innovation-National Research Council (IRIB-CNR), Via Ugo La Malfa 153, 90146 Palermo, Italy;
| | - Simona Campora
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF) University of Palermo, Viale delle Scienze, Ed. 16, 90128 Palermo, Italy;
| | - Carmelo Marco Bruno
- Abiel s.r.l., c/o Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF) University of Palermo, Viale delle Scienze, Ed. 16, 90128 Palermo, Italy; (M.S.); (S.R.); (C.M.B.)
| | - Giulio Ghersi
- Abiel s.r.l., c/o Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF) University of Palermo, Viale delle Scienze, Ed. 16, 90128 Palermo, Italy; (M.S.); (S.R.); (C.M.B.)
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF) University of Palermo, Viale delle Scienze, Ed. 16, 90128 Palermo, Italy;
- Correspondence:
| |
Collapse
|
7
|
Xu X, Liang C, Gao X, Huang H, Xing X, Tang Q, Yang J, Wu Y, Li M, Li H, Liao L, Tian W. Adipose Tissue-derived Microvascular Fragments as Vascularization Units for Dental Pulp Regeneration. J Endod 2021; 47:1092-1100. [PMID: 33887305 DOI: 10.1016/j.joen.2021.04.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 04/02/2021] [Accepted: 04/09/2021] [Indexed: 02/08/2023]
Abstract
INTRODUCTION The transplantation of dental pulp stem cells (DPSCs) has emerged as a novel strategy for the regeneration of lost dental pulp after pulpitis and trauma. Dental pulp regeneration of the young permanent tooth with a wide tooth apical foramen has achieved significant progress in the clinical trials. However, because of the narrow apical foramen, dental pulp regeneration in adult teeth using stem cells remains difficult in the clinic. Finding out how to promote vascular reconstitution is essential for the survival of stem cells and the regeneration of dental pulp after transplantation into the adult tooth. METHODS Adipose tissue-derived microvascular fragments (ad-MVFs) were isolated from human adipose tissues. The apoptosis and senescence of DPSCs cultured in conditioned media were evaluated to explore the effects of ad-MVFs on DPSCs. DPSCs combined with ad-MVFs were inserted into the human tooth root segments and implanted subcutaneously into immunodeficient mice. Regenerated pulplike tissues were analyzed by hematoxylin and eosin and immunohistochemistry. The vessels in regenerated tissues were analyzed by Micro-CT and immunofluorescence. RESULTS The isolated ad-MVFs contained endothelial cells and pericytes. ad-MVFs effectively prevented the apoptosis and senescence of the transplanted DPSCs both in vivo and in vitro. Combined with DPSCs, ad-MVFs obviously facilitated the formation of vascular networks in the transplants. DPSCs combined with ad-MVFs formed dental pulp-like tissues with abundant cells and matrix after 4 weeks of implantation. The supplementation of ad-MVFs led to more odontoblastlike cells and increased the formation of mineralized substance around the root canal. CONCLUSIONS Cotransplantation with ad-MVFs promotes the angiogenesis and revascularization of transplanted DPSC aggregates, leading to robust regeneration of dental pulp.
Collapse
Affiliation(s)
- Xun Xu
- National Engineering Laboratory for Oral Regenerative Medicine, West China Hospital of Stomatology, Sichuan University, Chengdu, China; State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China; Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Cheng Liang
- National Engineering Laboratory for Oral Regenerative Medicine, West China Hospital of Stomatology, Sichuan University, Chengdu, China; State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China; Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Xin Gao
- National Engineering Laboratory for Oral Regenerative Medicine, West China Hospital of Stomatology, Sichuan University, Chengdu, China; State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China; Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Haisen Huang
- National Engineering Laboratory for Oral Regenerative Medicine, West China Hospital of Stomatology, Sichuan University, Chengdu, China; State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China; Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Xiaotao Xing
- National Engineering Laboratory for Oral Regenerative Medicine, West China Hospital of Stomatology, Sichuan University, Chengdu, China; State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China; Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Qi Tang
- West China School of Public Health and West China Fourth Hospital, Sichuan University, Chengdu, China
| | - Jian Yang
- National Engineering Laboratory for Oral Regenerative Medicine, West China Hospital of Stomatology, Sichuan University, Chengdu, China; State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China; Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Yutao Wu
- National Engineering Laboratory for Oral Regenerative Medicine, West China Hospital of Stomatology, Sichuan University, Chengdu, China; State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China; Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Maojiao Li
- National Engineering Laboratory for Oral Regenerative Medicine, West China Hospital of Stomatology, Sichuan University, Chengdu, China; State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China; Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Huanian Li
- National Engineering Laboratory for Oral Regenerative Medicine, West China Hospital of Stomatology, Sichuan University, Chengdu, China; State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China; Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Li Liao
- National Engineering Laboratory for Oral Regenerative Medicine, West China Hospital of Stomatology, Sichuan University, Chengdu, China; State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China; Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China.
| | - Weidong Tian
- National Engineering Laboratory for Oral Regenerative Medicine, West China Hospital of Stomatology, Sichuan University, Chengdu, China; State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China; Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China.
| |
Collapse
|
8
|
Später T, Worringer DM, Menger MM, Menger MD, Laschke MW. Systemic low-dose erythropoietin administration improves the vascularization of collagen-glycosaminoglycan matrices seeded with adipose tissue-derived microvascular fragments. J Tissue Eng 2021; 12:20417314211000304. [PMID: 33796250 PMCID: PMC7970228 DOI: 10.1177/20417314211000304] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 02/16/2021] [Indexed: 11/24/2022] Open
Abstract
Adipose tissue-derived microvascular fragments (MVF) are used as vascularization
units in tissue engineering. In this study, we investigated whether the
vascularization capacity of MVF can be improved by systemic low-dose
erythropoietin (EPO) administration. MVF were isolated from the epididymal fat
of donor mice and seeded onto collagen-glycosaminoglycan matrices, which were
implanted into full-thickness skin defects within dorsal skinfold chambers of
recipient mice. Both donor and recipient mice were treated daily with either EPO
(500 IU/kg) or vehicle (0.9% NaCl). The implants were analyzed by
stereomicroscopy, intravital fluorescence microscopy, histology, and
immunohistochemistry. EPO-treated MVF contained a comparable number of
proliferating Ki67+ but less apoptotic cleaved caspase-3+
endothelial cells when compared to vehicle-treated controls. Moreover, EPO
treatment accelerated and improved the in vivo vascularization, blood vessel
maturation, and epithelialization of MVF-seeded matrices. These findings
indicate that systemic low-dose EPO treatment is suitable to enhance the
viability and network-forming capacity of MVF.
Collapse
Affiliation(s)
- Thomas Später
- Institute for Clinical & Experimental Surgery, Saarland University, Homburg/Saar, Germany
| | - Denise Ms Worringer
- Institute for Clinical & Experimental Surgery, Saarland University, Homburg/Saar, Germany
| | - Maximilian M Menger
- Institute for Clinical & Experimental Surgery, Saarland University, Homburg/Saar, Germany.,Department of Trauma and Reconstructive Surgery, Eberhard Karls University Tuebingen, BG Trauma Center Tuebingen, Tuebingen, Germany
| | - Michael D Menger
- Institute for Clinical & Experimental Surgery, Saarland University, Homburg/Saar, Germany
| | - Matthias W Laschke
- Institute for Clinical & Experimental Surgery, Saarland University, Homburg/Saar, Germany
| |
Collapse
|
9
|
Nalbach L, Roma LP, Schmitt BM, Becker V, Körbel C, Wrublewsky S, Pack M, Später T, Metzger W, Menger MM, Frueh FS, Götz C, Lin H, EM Fox J, MacDonald PE, Menger MD, Laschke MW, Ampofo E. Improvement of islet transplantation by the fusion of islet cells with functional blood vessels. EMBO Mol Med 2021; 13:e12616. [PMID: 33135383 PMCID: PMC7799357 DOI: 10.15252/emmm.202012616] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 09/25/2020] [Accepted: 09/28/2020] [Indexed: 12/12/2022] Open
Abstract
Pancreatic islet transplantation still represents a promising therapeutic strategy for curative treatment of type 1 diabetes mellitus. However, a limited number of organ donors and insufficient vascularization with islet engraftment failure restrict the successful transfer of this approach into clinical practice. To overcome these problems, we herein introduce a novel strategy for the generation of prevascularized islet organoids by the fusion of pancreatic islet cells with functional native microvessels. These insulin-secreting organoids exhibit a significantly higher angiogenic activity compared to freshly isolated islets, cultured islets, and non-prevascularized islet organoids. This is caused by paracrine signaling between the β-cells and the microvessels, mediated by insulin binding to its corresponding receptor on endothelial cells. In vivo, the prevascularized islet organoids are rapidly blood-perfused after transplantation by the interconnection of their autochthonous microvasculature with surrounding blood vessels. As a consequence, a lower number of islet grafts are required to restore normoglycemia in diabetic mice. Thus, prevascularized islet organoids may be used to improve the success rates of clinical islet transplantation.
Collapse
Affiliation(s)
- Lisa Nalbach
- Institute for Clinical & Experimental SurgerySaarland UniversityHomburg/SaarGermany
| | - Leticia P Roma
- Biophysics DepartmentCenter for Human and Molecular BiologySaarland UniversityHomburg/SaarGermany
| | - Beate M Schmitt
- Institute for Clinical & Experimental SurgerySaarland UniversityHomburg/SaarGermany
| | - Vivien Becker
- Institute for Clinical & Experimental SurgerySaarland UniversityHomburg/SaarGermany
| | - Christina Körbel
- Institute for Clinical & Experimental SurgerySaarland UniversityHomburg/SaarGermany
| | - Selina Wrublewsky
- Institute for Clinical & Experimental SurgerySaarland UniversityHomburg/SaarGermany
| | - Mandy Pack
- Institute for Clinical & Experimental SurgerySaarland UniversityHomburg/SaarGermany
| | - Thomas Später
- Institute for Clinical & Experimental SurgerySaarland UniversityHomburg/SaarGermany
| | - Wolfgang Metzger
- Department of Trauma, Hand and Reconstructive SurgerySaarland UniversityHomburgGermany
| | - Maximilian M Menger
- Institute for Clinical & Experimental SurgerySaarland UniversityHomburg/SaarGermany
- Departement of Trauma and Reconstructive SurgeryEberhar Karls University TuebingenTuebingenGermany
| | - Florian S Frueh
- Division of Plastic Surgery and Hand SurgeryUniversity Hospital ZurichUniversity of ZurichZurichSwitzerland
| | - Claudia Götz
- Medical Biochemistry and Molecular BiologySaarland UniversityHomburgGermany
| | - Haopeng Lin
- Department of PharmacologyAlberta Diabetes InstituteUniversity of AlbertaEdmontonABCanada
| | - Joseline EM Fox
- Department of PharmacologyAlberta Diabetes InstituteUniversity of AlbertaEdmontonABCanada
| | - Patrick E MacDonald
- Department of PharmacologyAlberta Diabetes InstituteUniversity of AlbertaEdmontonABCanada
| | - Michael D Menger
- Institute for Clinical & Experimental SurgerySaarland UniversityHomburg/SaarGermany
| | - Matthias W Laschke
- Institute for Clinical & Experimental SurgerySaarland UniversityHomburg/SaarGermany
| | - Emmanuel Ampofo
- Institute for Clinical & Experimental SurgerySaarland UniversityHomburg/SaarGermany
| |
Collapse
|
10
|
Später T, Ampofo E, Menger MD, Laschke MW. Combining Vascularization Strategies in Tissue Engineering: The Faster Road to Success? Front Bioeng Biotechnol 2020; 8:592095. [PMID: 33364230 PMCID: PMC7752995 DOI: 10.3389/fbioe.2020.592095] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 11/20/2020] [Indexed: 01/08/2023] Open
Affiliation(s)
- Thomas Später
- Institute for Clinical and Experimental Surgery, Saarland University, Homburg, Germany
| | - Emmanuel Ampofo
- Institute for Clinical and Experimental Surgery, Saarland University, Homburg, Germany
| | - Michael D Menger
- Institute for Clinical and Experimental Surgery, Saarland University, Homburg, Germany
| | - Matthias W Laschke
- Institute for Clinical and Experimental Surgery, Saarland University, Homburg, Germany
| |
Collapse
|
11
|
Laschke MW, Später T, Menger MD. Microvascular Fragments: More Than Just Natural Vascularization Units. Trends Biotechnol 2020; 39:24-33. [PMID: 32593437 DOI: 10.1016/j.tibtech.2020.06.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 06/03/2020] [Accepted: 06/04/2020] [Indexed: 12/11/2022]
Abstract
Adipose tissue-derived microvascular fragments serve as natural vascularization units in angiogenesis research and tissue engineering due to their ability to rapidly reassemble into microvascular networks. Recent studies indicate that they exhibit additional unique properties that may be beneficial for a wide range of future biomedical applications. Their angiogenic activity can be increased during short-term cultivation as a means of adapting their vascularization capacity to patient-specific needs. Moreover, they are a source of endothelial progenitor cells, multipotent mesenchymal stromal cells, and lymphatic vessel fragments. Finally, they exert immunomodulatory effects, determining the tissue integration of implanted biomaterials. Hence, microvascular fragments represent versatile building blocks for the improvement of vascularization, organotypic tissue formation, lymphatic regeneration, and implant integration.
Collapse
Affiliation(s)
- Matthias W Laschke
- Institute for Clinical & Experimental Surgery, Saarland University, 66421 Homburg/Saar, Germany.
| | - Thomas Später
- Institute for Clinical & Experimental Surgery, Saarland University, 66421 Homburg/Saar, Germany
| | - Michael D Menger
- Institute for Clinical & Experimental Surgery, Saarland University, 66421 Homburg/Saar, Germany
| |
Collapse
|
12
|
Abstract
Porous polyethylene (pPE) is a frequently implanted biomaterial in craniofacial reconstructive surgery. Its rapid vascularization and tissue incorporation are major prerequisites to prevent complications, such as material infection, migration, and extrusion. To achieve this, several sophisticated strategies have been introduced and evaluated during the last 20 years. These include (i) the angiogenic stimulation of the host tissue with epidermal growth factor, basic fibroblast growth factor or macrophage-activating lipopeptide-2, (ii) material modifications, such as increase of surface roughness and incorporation of bioactive glass particles, (iii) surface coatings with growth factors, glycoproteins, acrylic acid, arginine/glycine/aspartic acid peptide as well as components of the plasminogen activation system and autologous clotted blood or serum, and (iv) the seeding with fibroblasts, chondrocytes, stem cells, or adipose-tissue-derived microvascular fragments. The majority of these approaches showed promising results in experimental studies and, thus, may be capable of improving the success rates after pPE implantation in future clinical practice.
Collapse
Affiliation(s)
- Thomas Später
- Institute for Clinical & Experimental Surgery, Saarland University, Homburg, Germany
| | - Michael D Menger
- Institute for Clinical & Experimental Surgery, Saarland University, Homburg, Germany
| | - Matthias W Laschke
- Institute for Clinical & Experimental Surgery, Saarland University, Homburg, Germany
| |
Collapse
|
13
|
Kamat P, Frueh FS, McLuckie M, Sanchez-Macedo N, Wolint P, Lindenblatt N, Plock JA, Calcagni M, Buschmann J. Adipose tissue and the vascularization of biomaterials: Stem cells, microvascular fragments and nanofat-a review. Cytotherapy 2020; 22:400-411. [PMID: 32507607 DOI: 10.1016/j.jcyt.2020.03.433] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 02/27/2020] [Accepted: 03/12/2020] [Indexed: 12/13/2022]
Abstract
Tissue defects in the human body after trauma and injury require precise reconstruction to regain function. Hence, there is a great demand for clinically translatable approaches with materials that are both biocompatible and biodegradable. They should also be able to adequately integrate within the tissue through sufficient vascularization. Adipose tissue is abundant and easily accessible. It is a valuable tissue source in regenerative medicine and tissue engineering, especially with regard to its angiogenic potential. Derivatives of adipose tissue, such as microfat, nanofat, microvascular fragments, stromal vascular fraction and stem cells, are commonly used in research, but also clinically to enhance the vascularization of implants and grafts at defect sites. In plastic surgery, adipose tissue is harvested via liposuction and can be manipulated in three ways (macro-, micro- and nanofat) in the operating room, depending on its ultimate use. Whereas macro- and microfat are used as a filling material for soft tissue injuries, nanofat is an injectable viscous extract that primarily induces tissue remodeling because it is rich in growth factors and stem cells. In contrast to microfat that adds volume to a defect site, nanofat has the potential to be easily combined with scaffold materials due to its liquid and homogenous consistency and is particularly attractive for blood vessel formation. The same is true for microvascular fragments that are easily isolated from adipose tissue through collagenase digestion. In preclinical animal models, it has been convincingly shown that these vascular fragments inosculate with host vessels and subsequently accelerate scaffold perfusion and host tissue integration. Adipose tissue is also an ideal source of stem cells. It yields larger quantities of cells than any other source and is easier to access for both the patient and doctor compared with other sources such as bone marrow. They are often used for tissue regeneration in combination with biomaterials. Adipose-derived stem cells can be applied unmodified or as single cell suspensions. However, certain pretreatments, such as cultivation under hypoxic conditions or three-dimensional spheroids production, may provide substantial benefit with regard to subsequent vascularization in vivo due to induced growth factor production. In this narrative review, derivatives of adipose tissue and the vascularization of biomaterials are addressed in a comprehensive approach, including several sizes of derivatives, such as whole fat flaps for soft tissue engineering, nanofat or stem cells, their secretome and exosomes. Taken together, it can be concluded that adipose tissue and its fractions down to the molecular level promote, enhance and support vascularization of biomaterials. Therefore, there is a high potential of the individual fat component to be used in regenerative medicine.
Collapse
Affiliation(s)
- Pranitha Kamat
- Department of Plastic Surgery and Hand Surgery, University Hospital Zurich, Zurich, Switzerland; Department of Plastic Surgery and Hand Surgery, University of Zurich, Zurich, Switzerland
| | - Florian S Frueh
- Department of Plastic Surgery and Hand Surgery, University Hospital Zurich, Zurich, Switzerland
| | - Michelle McLuckie
- Department of Plastic Surgery and Hand Surgery, University Hospital Zurich, Zurich, Switzerland
| | - Nadia Sanchez-Macedo
- Department of Plastic Surgery and Hand Surgery, University Hospital Zurich, Zurich, Switzerland
| | - Petra Wolint
- Department of Plastic Surgery and Hand Surgery, University Hospital Zurich, Zurich, Switzerland
| | - Nicole Lindenblatt
- Department of Plastic Surgery and Hand Surgery, University Hospital Zurich, Zurich, Switzerland
| | - Jan A Plock
- Department of Plastic Surgery and Hand Surgery, University Hospital Zurich, Zurich, Switzerland; Department of Plastic Surgery and Hand Surgery, University of Zurich, Zurich, Switzerland
| | - Maurizio Calcagni
- Department of Plastic Surgery and Hand Surgery, University Hospital Zurich, Zurich, Switzerland
| | - Johanna Buschmann
- Department of Plastic Surgery and Hand Surgery, University Hospital Zurich, Zurich, Switzerland.
| |
Collapse
|
14
|
Später T, Menger MM, Nickels RM, Menger MD, Laschke MW. Macrophages promote network formation and maturation of transplanted adipose tissue-derived microvascular fragments. J Tissue Eng 2020; 11:2041731420911816. [PMID: 32313616 PMCID: PMC7153185 DOI: 10.1177/2041731420911816] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 02/18/2020] [Indexed: 12/12/2022] Open
Abstract
Adipose tissue–derived microvascular fragments rapidly reassemble into microvascular networks within implanted scaffolds. Herein, we analyzed the contribution of macrophages to this process. C57BL/6 mice received clodronate (clo)-containing liposomes for macrophage depletion, whereas animals treated with phosphate-buffered-saline-containing liposomes served as controls. Microvascular fragments were isolated from clo- and phosphate-buffered-saline-treated donor mice and seeded onto collagen–glycosaminoglycan matrices, which were implanted into dorsal skinfold chambers of clo- and phosphate-buffered-saline-treated recipient mice. The implants’ vascularization and incorporation were analyzed by stereomicroscopy, intravital fluorescence microscopy, histology, and immunohistochemistry. Compared to controls, matrices within clo-treated animals exhibited a significantly reduced functional microvessel density. Moreover, they contained a lower fraction of microvessels with an α-smooth muscle actin (SMA)+ cell layer, indicating impaired vessel maturation. This was associated with a deteriorated implant incorporation. These findings demonstrate that macrophages not only promote the reassembly of microvascular fragments into microvascular networks, but also improve their maturation during this process.
Collapse
Affiliation(s)
- Thomas Später
- Institute for Clinical & Experimental Surgery, Saarland University, Homburg, Germany
| | - Maximilian M Menger
- Institute for Clinical & Experimental Surgery, Saarland University, Homburg, Germany.,Department of Trauma, Hand and Reconstructive Surgery, Saarland University, Homburg, Germany
| | - Ruth M Nickels
- Institute for Clinical & Experimental Surgery, Saarland University, Homburg, Germany
| | - Michael D Menger
- Institute for Clinical & Experimental Surgery, Saarland University, Homburg, Germany
| | - Matthias W Laschke
- Institute for Clinical & Experimental Surgery, Saarland University, Homburg, Germany
| |
Collapse
|
15
|
Laschke MW, Kontaxi E, Scheuer C, Heß A, Karschnia P, Menger MD. Insulin-like growth factor 1 stimulates the angiogenic activity of adipose tissue-derived microvascular fragments. J Tissue Eng 2019; 10:2041731419879837. [PMID: 31632630 PMCID: PMC6767710 DOI: 10.1177/2041731419879837] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 09/12/2019] [Indexed: 02/06/2023] Open
Abstract
Angiogenesis in adipose tissue is promoted by insulin-like growth factor 1 signaling. We analyzed whether this regulatory mechanism also improves the angiogenic activity of adipose tissue-derived microvascular fragments. Murine adipose tissue-derived microvascular fragments were cultivated for 24 h in the University of Wisconsin (UW) solution supplemented with vehicle, insulin-like growth factor 1, or a combination of insulin-like growth factor 1 and insulin-like growth factor-binding protein 4. Subsequently, we assessed their cellular composition, viability, proliferation, and growth factor expression. Moreover, cultivated adipose tissue-derived microvascular fragments were seeded onto collagen-glycosaminoglycan scaffolds, which were implanted into dorsal skinfold chambers to study their vascularization and incorporation. Insulin-like growth factor 1 increased the viability and growth factor expression of adipose tissue-derived microvascular fragments without affecting their cellular composition and proliferation. Accordingly, scaffolds containing insulin-like growth factor 1-stimulated adipose tissue-derived microvascular fragments exhibited an enhanced in vivo vascularization and incorporation. These positive insulin-like growth factor 1 effects were reversed by additional exposure of adipose tissue-derived microvascular fragments to insulin-like growth factor-binding protein 4. Our findings indicate that insulin-like growth factor 1 stimulation of adipose tissue-derived microvascular fragments is suitable to improve their vascularization capacity.
Collapse
Affiliation(s)
- Matthias W Laschke
- Institute for Clinical & Experimental Surgery, Saarland University, Homburg/Saar, Germany
| | - Elena Kontaxi
- Institute for Clinical & Experimental Surgery, Saarland University, Homburg/Saar, Germany
| | - Claudia Scheuer
- Institute for Clinical & Experimental Surgery, Saarland University, Homburg/Saar, Germany
| | - Alexander Heß
- Institute for Clinical & Experimental Surgery, Saarland University, Homburg/Saar, Germany
| | - Philipp Karschnia
- Institute for Clinical & Experimental Surgery, Saarland University, Homburg/Saar, Germany
| | - Michael D Menger
- Institute for Clinical & Experimental Surgery, Saarland University, Homburg/Saar, Germany
| |
Collapse
|
16
|
Ruehle MA, Krishnan L, Vantucci CE, Wang Y, Stevens HY, Roy K, Guldberg RE, Willett NJ. Effects of BMP-2 dose and delivery of microvascular fragments on healing of bone defects with concomitant volumetric muscle loss. J Orthop Res 2019; 37:553-561. [PMID: 30648751 DOI: 10.1002/jor.24225] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Accepted: 01/11/2019] [Indexed: 02/04/2023]
Abstract
Traumatic composite bone-muscle injuries, such as open fractures, often require multiple surgical interventions and still typically result in long-term disability. Clinically, a critical indicator of composite injury severity is vascular integrity; vascular damage alone is sufficient to assign an open fracture to the most severe category. Challenging bone injuries are often treated with bone morphogenetic protein 2 (BMP-2), an osteoinductive growth factor, delivered on collagen sponge. Previous studies in a composite defect model found that a minimally bridging dose in the segmental defect model was unable to overcome concomitant muscle damage, but the effect of BMP dose on composite injuries has not yet been studied. Here, we test the hypotheses that BMP-2-mediated functional regeneration of composite extremity injuries is dose dependent and can be further enhanced via co-delivery of adipose-derived microvascular fragments (MVF), which have been previously shown to increase tissue vascular volume. Although MVF did not improve healing outcomes, we observed a significant BMP-2 dose-dependent increase in regenerated bone volume and biomechanical properties. This is the first known report of an increased BMP-2 dose improving bone healing with concomitant muscle damage. While high dose BMP-2 delivery can induce heterotopic ossification (HO) and increased inflammation, the maximum 10 μg dose used in this study did not result in HO and was associated with a lower circulating inflammatory cytokine profile than the low dose (2.5 μg) group. These data support the potential benefits of an increased, though still moderate, BMP-2 dose for treatment of bone defects with concomitant muscle damage. Published 2019. This article is a U.S. Government work and is in the public domain in the USA. J Orthop Res.
Collapse
Affiliation(s)
- Marissa A Ruehle
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia.,Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology & Emory University, Atlanta, Georgia
| | - Laxminarayanan Krishnan
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia
| | - Casey E Vantucci
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia.,Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology & Emory University, Atlanta, Georgia
| | - Yuyan Wang
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia
| | - Hazel Y Stevens
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia
| | - Krishnendu Roy
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia.,Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology & Emory University, Atlanta, Georgia
| | - Robert E Guldberg
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia.,Knight Campus for Accelerating Scientific Impact, University of Oregon, Eugene, Oregon
| | - Nick J Willett
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia.,Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology & Emory University, Atlanta, Georgia.,Research Service, Atlanta VA Medical Center, Decatur, Georgia.,Division of Orthopaedics, Emory University School of Medicine, 1670 Clairmont Rd, Room 5A125, Decatur 30033, Georgia
| |
Collapse
|