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Effects of crystalloids and colloids on microcirculation, central venous oxygen saturation, and central venous-to-arterial carbon dioxide gap in a rabbit model of hemorrhagic shock. J Anesth 2018; 33:108-117. [DOI: 10.1007/s00540-018-2594-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2018] [Accepted: 11/30/2018] [Indexed: 10/27/2022]
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A stimuli responsive liposome loaded hydrogel provides flexible on-demand release of therapeutic agents. Acta Biomater 2017; 48:110-119. [PMID: 27773752 DOI: 10.1016/j.actbio.2016.10.001] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Revised: 09/29/2016] [Accepted: 10/02/2016] [Indexed: 12/22/2022]
Abstract
Lysolipid-based thermosensitive liposomes (LTSL) embedded in a chitosan-based thermoresponsive hydrogel matrix (denoted Lipogel) represents a novel approach for the spatiotemporal release of therapeutic agents. The entrapment of drug-loaded liposomes in an injectable hydrogel permits local liposome retention, thus providing a prolonged release in target tissues. Moreover, release can be controlled through the use of a minimally invasive external hyperthermic stimulus. Temporal control of release is particularly important for complex multi-step physiological processes, such as angiogenesis, in which different signals are required at different times in order to produce a robust vasculature. In the present work, we demonstrate the ability of Lipogel to provide a flexible, easily modifiable release platform. It is possible to tune the release kinetics of different drugs providing a passive release of one therapeutic agent loaded within the gel and activating the release of a second LTSL encapsulated agent via a hyperthermic stimulus. In addition, it was possible to modify the drug dosage within Lipogel by varying the duration of hyperthermia. This can allow for adaption of drug dosing in real time. As an in vitro proof of concept with this system, we investigated Lipogels ability to recruit stem cells and then elevate their production of vascular endothelial growth factor (VEGF) by controlling the release of a pro-angiogenic drug, desferroxamine (DFO) with an external hyperthermic stimulus. Initial cell recruitment was accomplished by the passive release of hepatocyte growth factor (HGF) from the hydrogel, inducing a migratory response in cells, followed by the delayed release of DFO from thermosensitive liposomes, resulting in a significant increase in VEGF expression. This delayed release could be controlled up to 14days. Moreover, by changing the duration of the hyperthermic pulse, a fine control over the amount of DFO released was achieved. The ability to trigger the release of therapeutic agents at a specific timepoint and control dosing level through changes in duration of hyperthermia enables sequential multi-dose profiles. STATEMENT OF SIGNIFICANCE This paper details the development of a heat responsive liposome loaded hydrogel for the controlled release of pro-angiogenic therapeutics. Lysolipid-based thermosensitive liposomes (LTSLs) embedded in a chitosan-based thermoresponsive hydrogel matrix represents a novel approach for the spatiotemporal release of therapeutic agents. This hydrogel platform demonstrates remarkable flexibility in terms of drug scheduling and sequencing, enabling the release of multiple agents and the ability to control drug dosing in a minimally invasive fashion. The possibility to tune the release kinetics of different drugs independently represents an innovative platform to utilise for a variety of treatments. This approach allows a significant degree of flexibility in achieving a desired release profile via a minimally invasive stimulus, enabling treatments to be tuned in response to changing symptoms and complications.
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O'Neill HS, Gallagher LB, O'Sullivan J, Whyte W, Curley C, Dolan E, Hameed A, O'Dwyer J, Payne C, O'Reilly D, Ruiz-Hernandez E, Roche ET, O'Brien FJ, Cryan SA, Kelly H, Murphy B, Duffy GP. Biomaterial-Enhanced Cell and Drug Delivery: Lessons Learned in the Cardiac Field and Future Perspectives. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2016; 28:5648-5661. [PMID: 26840955 DOI: 10.1002/adma.201505349] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 12/04/2015] [Indexed: 06/05/2023]
Abstract
Heart failure is a significant clinical issue. It is the cause of enormous healthcare costs worldwide and results in significant morbidity and mortality. Cardiac regenerative therapy has progressed considerably from clinical and preclinical studies delivering simple suspensions of cells, macromolecule, and small molecules to more advanced delivery methods utilizing biomaterial scaffolds as depots for localized targeted delivery to the damaged and ischemic myocardium. Here, regenerative strategies for cardiac tissue engineering with a focus on advanced delivery strategies and the use of multimodal therapeutic strategies are reviewed.
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Affiliation(s)
- Hugh S O'Neill
- Tissue Engineering Research Group (TERG), Department of Anatomy, Royal College of Surgeons in Ireland (RSCI), 123, St. Stephens Green, Dublin 2, Dublin, D02 YN77, Ireland
- Trinity Center for Bioengineering (TCBE), Trinity College Dublin, Dublin 2, Dublin, Ireland
| | - Laura B Gallagher
- Tissue Engineering Research Group (TERG), Department of Anatomy, Royal College of Surgeons in Ireland (RSCI), 123, St. Stephens Green, Dublin 2, Dublin, D02 YN77, Ireland
- Trinity Center for Bioengineering (TCBE), Trinity College Dublin, Dublin 2, Dublin, Ireland
| | - Janice O'Sullivan
- Tissue Engineering Research Group (TERG), Department of Anatomy, Royal College of Surgeons in Ireland (RSCI), 123, St. Stephens Green, Dublin 2, Dublin, D02 YN77, Ireland
- Trinity Center for Bioengineering (TCBE), Trinity College Dublin, Dublin 2, Dublin, Ireland
| | - William Whyte
- Tissue Engineering Research Group (TERG), Department of Anatomy, Royal College of Surgeons in Ireland (RSCI), 123, St. Stephens Green, Dublin 2, Dublin, D02 YN77, Ireland
- Advanced Materials and Bioengineering Research Center (AMBER), RCSI and TCD, Dublin, Ireland
| | - Clive Curley
- Tissue Engineering Research Group (TERG), Department of Anatomy, Royal College of Surgeons in Ireland (RSCI), 123, St. Stephens Green, Dublin 2, Dublin, D02 YN77, Ireland
- Trinity Center for Bioengineering (TCBE), Trinity College Dublin, Dublin 2, Dublin, Ireland
| | - Eimear Dolan
- Tissue Engineering Research Group (TERG), Department of Anatomy, Royal College of Surgeons in Ireland (RSCI), 123, St. Stephens Green, Dublin 2, Dublin, D02 YN77, Ireland
- Trinity Center for Bioengineering (TCBE), Trinity College Dublin, Dublin 2, Dublin, Ireland
| | - Aamir Hameed
- Tissue Engineering Research Group (TERG), Department of Anatomy, Royal College of Surgeons in Ireland (RSCI), 123, St. Stephens Green, Dublin 2, Dublin, D02 YN77, Ireland
- Trinity Center for Bioengineering (TCBE), Trinity College Dublin, Dublin 2, Dublin, Ireland
| | - Joanne O'Dwyer
- Tissue Engineering Research Group (TERG), Department of Anatomy, Royal College of Surgeons in Ireland (RSCI), 123, St. Stephens Green, Dublin 2, Dublin, D02 YN77, Ireland
- Trinity Center for Bioengineering (TCBE), Trinity College Dublin, Dublin 2, Dublin, Ireland
- School of Pharmacy, Royal College of Surgeons in Ireland, 123, St. Stephens Green, Dublin 2, Dublin, Ireland
| | - Christina Payne
- Tissue Engineering Research Group (TERG), Department of Anatomy, Royal College of Surgeons in Ireland (RSCI), 123, St. Stephens Green, Dublin 2, Dublin, D02 YN77, Ireland
- School of Pharmacy, Royal College of Surgeons in Ireland, 123, St. Stephens Green, Dublin 2, Dublin, Ireland
| | - Daniel O'Reilly
- Tissue Engineering Research Group (TERG), Department of Anatomy, Royal College of Surgeons in Ireland (RSCI), 123, St. Stephens Green, Dublin 2, Dublin, D02 YN77, Ireland
| | - Eduardo Ruiz-Hernandez
- Tissue Engineering Research Group (TERG), Department of Anatomy, Royal College of Surgeons in Ireland (RSCI), 123, St. Stephens Green, Dublin 2, Dublin, D02 YN77, Ireland
- Trinity Center for Bioengineering (TCBE), Trinity College Dublin, Dublin 2, Dublin, Ireland
- Advanced Materials and Bioengineering Research Center (AMBER), RCSI and TCD, Dublin, Ireland
| | - Ellen T Roche
- Department of Biomedical Engineering, Eng-2053, Engineering Building, National University of Ireland, Galway, Ireland
| | - Fergal J O'Brien
- Tissue Engineering Research Group (TERG), Department of Anatomy, Royal College of Surgeons in Ireland (RSCI), 123, St. Stephens Green, Dublin 2, Dublin, D02 YN77, Ireland
- Advanced Materials and Bioengineering Research Center (AMBER), RCSI and TCD, Dublin, Ireland
| | - Sally Ann Cryan
- Tissue Engineering Research Group (TERG), Department of Anatomy, Royal College of Surgeons in Ireland (RSCI), 123, St. Stephens Green, Dublin 2, Dublin, D02 YN77, Ireland
- Trinity Center for Bioengineering (TCBE), Trinity College Dublin, Dublin 2, Dublin, Ireland
- School of Pharmacy, Royal College of Surgeons in Ireland, 123, St. Stephens Green, Dublin 2, Dublin, Ireland
| | - Helena Kelly
- Tissue Engineering Research Group (TERG), Department of Anatomy, Royal College of Surgeons in Ireland (RSCI), 123, St. Stephens Green, Dublin 2, Dublin, D02 YN77, Ireland
- School of Pharmacy, Royal College of Surgeons in Ireland, 123, St. Stephens Green, Dublin 2, Dublin, Ireland
| | - Bruce Murphy
- Trinity Center for Bioengineering (TCBE), Trinity College Dublin, Dublin 2, Dublin, Ireland
- Advanced Materials and Bioengineering Research Center (AMBER), RCSI and TCD, Dublin, Ireland
| | - Garry P Duffy
- Tissue Engineering Research Group (TERG), Department of Anatomy, Royal College of Surgeons in Ireland (RSCI), 123, St. Stephens Green, Dublin 2, Dublin, D02 YN77, Ireland
- Trinity Center for Bioengineering (TCBE), Trinity College Dublin, Dublin 2, Dublin, Ireland
- Advanced Materials and Bioengineering Research Center (AMBER), RCSI and TCD, Dublin, Ireland
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Wu J, Ye J, Zhu J, Xiao Z, He C, Shi H, Wang Y, Lin C, Zhang H, Zhao Y, Fu X, Chen H, Li X, Li L, Zheng J, Xiao J. Heparin-Based Coacervate of FGF2 Improves Dermal Regeneration by Asserting a Synergistic Role with Cell Proliferation and Endogenous Facilitated VEGF for Cutaneous Wound Healing. Biomacromolecules 2016; 17:2168-77. [PMID: 27196997 DOI: 10.1021/acs.biomac.6b00398] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Effective wound healing requires complicated, coordinated interactions and responses at protein, cellular, and tissue levels involving growth factor expression, cell proliferation, wound closure, granulation tissue formation, and vascularization. In this study, we develop a heparin-based coacervate consisting of poly(ethylene argininylaspartate digylceride) (PEAD) as a storage matrix, heparin as a bridge, and fibroblast growth factor-2 (FGF2) as a cargo (namely heparin-FGF2@PEAD) for wound healing. First, in vitro characterization demonstrates the loading efficiency and control release of FGF2 from the heparin-FGF2@PEAD coacervate. The following in vivo studies examine the wound healing efficiency of the heparin-FGF2@PEAD coacervate upon delivering FGF2 to full-thickness excisional skin wounds in vivo, in comparison with the other three control groups with saline, heparin@PEAD as vehicle, and free FGF2. Collective in vivo data show that controlled release of FGF2 to the wounds by the coacervate significantly accelerates the wound healing by promoting cell proliferation, stimulating the secretion of vascular endothelial growth factor (VEGF) for re-epithelization, collagen deposition, and granulation tissue formation, and enhancing the expression of platelet endothelial cell adhesion molecule (CD31) and alpha-smooth muscle actin (α-SMA) for blood vessel maturation. In parallel, no obvious wound healing effect is found for the control, vehicle, and free FGF2 groups, indicating the important role of the coavervate in the wound healing process. This work designs a suitable delivery system that can protect and release FGF2 in a sustained and controlled manner, which provides a promising therapeutic potential for topical treatment of wounds.
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Affiliation(s)
- Jiang Wu
- School of Pharmaceutical Sciences Key Laboratory of Biotechnology and Pharmaceutical Engineering, Wenzhou Medical University , Wenzhou, Zhejiang 325035, China
| | - Jingjing Ye
- School of Pharmaceutical Sciences Key Laboratory of Biotechnology and Pharmaceutical Engineering, Wenzhou Medical University , Wenzhou, Zhejiang 325035, China
| | - Jingjing Zhu
- School of Pharmaceutical Sciences Key Laboratory of Biotechnology and Pharmaceutical Engineering, Wenzhou Medical University , Wenzhou, Zhejiang 325035, China
| | - Zecong Xiao
- School of Pharmaceutical Sciences Key Laboratory of Biotechnology and Pharmaceutical Engineering, Wenzhou Medical University , Wenzhou, Zhejiang 325035, China
| | - Chaochao He
- School of Pharmaceutical Sciences Key Laboratory of Biotechnology and Pharmaceutical Engineering, Wenzhou Medical University , Wenzhou, Zhejiang 325035, China
| | - Hongxue Shi
- School of Pharmaceutical Sciences Key Laboratory of Biotechnology and Pharmaceutical Engineering, Wenzhou Medical University , Wenzhou, Zhejiang 325035, China
| | - Yadong Wang
- Department of Bioengineering and the McGowan Institute for Regenerative Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania 15219, United States
| | - Cai Lin
- The First Affiliate Hospital Wenzhou Medical University , Wenzhou, 325035, China
| | - Hongyu Zhang
- School of Pharmaceutical Sciences Key Laboratory of Biotechnology and Pharmaceutical Engineering, Wenzhou Medical University , Wenzhou, Zhejiang 325035, China
| | - Yingzheng Zhao
- School of Pharmaceutical Sciences Key Laboratory of Biotechnology and Pharmaceutical Engineering, Wenzhou Medical University , Wenzhou, Zhejiang 325035, China
| | - Xiaobing Fu
- Wound Healing and Cell Biology Laboratory Institute of Basic Medical Science, Chinese PLA General Hospital , Beijing 1008553, China
| | - Hong Chen
- Department of Chemical and Biomolecular Engineering, The University of Akron , Akron, Ohio 44325, United States
| | - Xiaokun Li
- School of Pharmaceutical Sciences Key Laboratory of Biotechnology and Pharmaceutical Engineering, Wenzhou Medical University , Wenzhou, Zhejiang 325035, China
| | - Lin Li
- School of Pharmaceutical Sciences Key Laboratory of Biotechnology and Pharmaceutical Engineering, Wenzhou Medical University , Wenzhou, Zhejiang 325035, China
| | - Jie Zheng
- School of Pharmaceutical Sciences Key Laboratory of Biotechnology and Pharmaceutical Engineering, Wenzhou Medical University , Wenzhou, Zhejiang 325035, China.,Department of Chemical and Biomolecular Engineering, The University of Akron , Akron, Ohio 44325, United States
| | - Jian Xiao
- School of Pharmaceutical Sciences Key Laboratory of Biotechnology and Pharmaceutical Engineering, Wenzhou Medical University , Wenzhou, Zhejiang 325035, China
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Kim SK, Lee J, Song M, Kim M, Hwang SJ, Jang H, Park Y. Combination of three angiogenic growth factors has synergistic effects on sprouting of endothelial cell/mesenchymal stem cell-based spheroids in a 3D matrix. J Biomed Mater Res B Appl Biomater 2015; 104:1535-1543. [PMID: 26268584 DOI: 10.1002/jbm.b.33498] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 07/22/2015] [Accepted: 07/27/2015] [Indexed: 12/22/2022]
Abstract
Combinations of angiogenic growth factors have been shown to have synergistic effects on angiogenesis and natural wound healing in various animal models. Each growth factor has unique roles during angiogenesis; vascular endothelial growth factor (VEGF) plays a key role during the initial step of angiogenesis, whereas PDGF functions in the maturation of blood vessels. We used a combination of three angiogenic growth factors to increase angiogenesis in vitro and in vivo. We chose VEGF as a basic factor and added platelet-derived growth factor (PDGF) and fibroblast growth factor (FGF) to induce angiogenesis in three in vitro and in vivo models: 3D angiogenesis assay, 3D co-culture, and matrigel plug implantation assay. Cell proliferation was significantly higher in co-cultured cells treated with PDGF + VEGF + FGF than in the control, single, or dual combination groups. mRNA expression of α-smooth muscle actin (α-SMA), von Willebrand factor (vWF), and CD105 was higher in the triple group (PDGF + VEGF + FGF) than in control, single, or dual combination groups. In the PDGF + VEGF + FGF group, the length and number of branches of spheroids was also significantly higher than in the control, single, or dual combination groups. Furthermore, in a nude mouse model, α-SMA expression was significantly higher in the PDGF + VEGF + FGF group than in other groups. In conclusion, the addition of PDGF and FGF to VEGF showed synergistic effects on angiogenesis in vitro and in vivo. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1535-1543, 2016.
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Affiliation(s)
- Sook Kyoung Kim
- Department of Biomedical Engineering, Medical College, Korea University, Seoul, Korea
| | - Jaeyeon Lee
- Department of Biomedical Engineering, Medical College, Korea University, Seoul, Korea
| | - Myeongjin Song
- Department of Biomedical Engineering, Medical College, Korea University, Seoul, Korea
| | - Mirim Kim
- Department of Biomedical Engineering, Medical College, Korea University, Seoul, Korea
| | - Soon Jung Hwang
- Department of Oral and Maxillofacial Surgery, Seoul National University Dental Hospital, School of Dentistry, Dental Research Institute, BK 21 Plus, Korea
| | - Hwanseok Jang
- Department of Biomedical Engineering, Medical College, Korea University, Seoul, Korea
| | - Yongdoo Park
- Department of Biomedical Engineering, Medical College, Korea University, Seoul, Korea.
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Collagen-glycosaminoglycan matrix implantation promotes angiogenesis following surgical brain trauma. BIOMED RESEARCH INTERNATIONAL 2014; 2014:672409. [PMID: 25309917 PMCID: PMC4182695 DOI: 10.1155/2014/672409] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2014] [Accepted: 07/25/2014] [Indexed: 12/29/2022]
Abstract
Surgical brain injury (SBI) is unavoidable during many neurosurgical procedures intrinsically linked to postoperative neurological deficits. We have previously demonstrated that implantation of collagen glycosaminoglycan (CG) following surgical brain injury could significantly promote functional recovery and neurogenesis. In this study we further hypothesized that this scaffold may provide a microenvironment by promoting angiogenesis to favor neurogenesis and subsequent functional recovery. Using the rodent model of surgical brain injury as we previously established, we divided Sprague-Dawley male rats (weighting 300-350 g) into three groups: (1) sham (2) surgical injury with a lesion (L), and (3) L with CG matrix implantation (L + CG). Our results demonstrated that L + CG group showed a statistically significant increase in the density of vascular endothelial cells and blood vessels over time. In addition, tissue concentrations of angiogenic growth factors (such as VEGF, FGF2, and PDGF) significantly increased in L + CG group. These results suggest that implantation of a CG scaffold can promote vascularization accompanied by neurogenesis. This opens prospects for use of CG scaffolds in conditions such as brain injury including trauma and ischemia.
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Yildirimer L, Thanh NT, Seifalian AM. Skin regeneration scaffolds: a multimodal bottom-up approach. Trends Biotechnol 2012; 30:638-48. [DOI: 10.1016/j.tibtech.2012.08.004] [Citation(s) in RCA: 202] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Revised: 08/17/2012] [Accepted: 08/17/2012] [Indexed: 01/07/2023]
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Zieris A, Chwalek K, Prokoph S, Levental K, Welzel P, Freudenberg U, Werner C. Dual independent delivery of pro-angiogenic growth factors from starPEG-heparin hydrogels. J Control Release 2011; 156:28-36. [DOI: 10.1016/j.jconrel.2011.06.042] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Revised: 06/23/2011] [Accepted: 06/28/2011] [Indexed: 10/18/2022]
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Chen L, He Z, Chen B, Yang M, Zhao Y, Sun W, Xiao Z, Zhang J, Dai J. Loading of VEGF to the heparin cross-linked demineralized bone matrix improves vascularization of the scaffold. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2010; 21:309-317. [PMID: 19634004 DOI: 10.1007/s10856-009-3827-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2009] [Accepted: 07/14/2009] [Indexed: 05/28/2023]
Abstract
Deficient vascularization is one of the prominent shortcomings of porous tissue-engineering scaffolds, which results in insufficient oxygen and nutrients transportation. Here, heparin cross-linked demineralized bone matrices (HC-DBM) pre-loaded with vascular endothelial growth factor (VEGF) were designed to promote cells and new microvessels invasion into the matrices. After being chemical crosslinked with heparin by N-hydroxysuccinimide and N-(3-di-methylaminopropyl)-N'-ethylcarbodiimide, the scaffold could bind more VEGF than the non-crosslinked one and achieve localized and sustained delivery. The biological activity of VEGF binding on heparinized collagen was demonstrated by promoting endothelial cells proliferation. Evaluation of the angiogenic potential of heparinized DBM loaded with VEGF was further investigated by subcutaneous implantation. Improved angiogenesis of heparinized DBM loaded with VEGF was observed from haematoxylin-eosin staining and immunohistochemistry examination. The results demonstrated that heparin cross-linked DBM binding VEGF could be a useful strategy to stimulate cells and blood vessels invasion into the scaffolds.
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Affiliation(s)
- Lei Chen
- Biotechnology Research Center, Hubei Province Key Laboratory of Natural Products Research and Development, China Three Gorges University, Yichang, People's Republic of China
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Young S, Kretlow JD, Nguyen C, Bashoura AG, Baggett LS, Jansen JA, Wong M, Mikos AG. Microcomputed tomography characterization of neovascularization in bone tissue engineering applications. TISSUE ENGINEERING PART B-REVIEWS 2009; 14:295-306. [PMID: 18657028 DOI: 10.1089/ten.teb.2008.0153] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Vasculogenesis and angiogenesis have been studied for decades using numerous in vitro and in vivo systems, fulfilling the need to elucidate the mechanisms involved in these processes and to test potential therapeutic agents that inhibit or promote neovascularization. Bone tissue engineering in particular has benefited from the application of proangiogenic strategies, considering the need for an adequate vascular supply during healing and the challenges associated with the vascularization of scaffolds implanted in vivo. Conventional methods of assessing the in vivo angiogenic response to tissue-engineered constructs tend to rely on a two-dimensional assessment of microvessel density within representative histological sections without elaboration of the true vascular tree. The introduction of microcomputed tomography (micro-CT) has recently allowed investigators to obtain a diverse range of high-resolution, three-dimensional characterization of structures, including renal, coronary, and hepatic vascular networks, as well as bone formation within healing defects. To date, few studies have utilized micro-CT to study the vascular response to an implanted tissue engineering scaffold. In this paper, conventional in vitro and in vivo models for studying angiogenesis will be discussed, followed by recent developments in the use of micro-CT for vessel imaging in bone tissue engineering research. A new study demonstrating the potential of contrast-enhanced micro-CT for the evaluation of in vivo neovascularization in bony defects is described, which offers significant potential in the evaluation of bone tissue engineering constructs.
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Affiliation(s)
- Simon Young
- Department of Bioengineering, Rice University, Houston, Texas, USA
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Komori M, Takada K, Tomizawa Y, Nishiyama K, Kondo I, Kawamata M, Ozaki M. Microcirculatory Responses to Acupuncture Stimulation and Phototherapy. Anesth Analg 2009; 108:635-40. [DOI: 10.1213/ane.0b013e31819317bc] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Komori M, Takada K, Tomizawa Y, Nishiyama K, Kawamata M, Ozaki M. Permissive range of hypercapnia for improved peripheral microcirculation and cardiac output in rabbits*. Crit Care Med 2007; 35:2171-5. [PMID: 17855833 DOI: 10.1097/01.ccm.0000281445.77223.31] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES Permissive hypercapnia improves outcomes in patients with respiratory failure, most likely because of a reduction in ventilator-induced lung injury. Because hypercapnia is a potent vasoactive stimulus, adequate tissue perfusion and oxygen delivery to dilated microvessels may be restored. We examined how Paco2 affects microvascular changes, hemodynamics, and cardiac output in rabbits. We evaluated the permissive range of Paco2 required for maintenance of the peripheral circulation. DESIGN Prospective experimental animal study. SETTING Animal research laboratory. SUBJECTS A total of 31 Japanese domestic white rabbits. INTERVENTIONS The animals were anesthetized with pentobarbital. An ear chamber was prepared to examine blood vessels by intravital microscopy. The rabbits were mechanically ventilated with air, oxygen, and CO2. The values of Paco2 were adjusted to about 20 (hypocapnia), 40 (normocapnia), 60, 80, 100, 125, 150, and >250 mm Hg (hypercapnia). After stabilization at each Paco2 level, microvascular changes were recorded with a microscope-closed video camera to permit analysis of arteriolar diameter and blood flow. MEASUREMENTS AND MAIN RESULTS The pH and heart rate decreased and mean blood pressure increased progressively as the Paco2 was increased. When Paco2 was increased from 20 to 80 mm Hg, vessel diameter, blood-flow velocity, and blood-flow rate increased markedly. Cardiac output increased slightly. When Paco2 exceeded 100 mm Hg, all of these variables decreased. When Paco2 exceeded 150 mm Hg, all variables were significantly lower than the control values (p < .01). CONCLUSION Intravital microscopic visualization of the rabbit ear microcirculation showed that 150 mm Hg is the permissive upper limit of acute hypercapnia with respect to maintenance of the peripheral microcirculation.
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Affiliation(s)
- Makiko Komori
- Department of Anesthesiology, Medical Center East, Tokyo Women's Medical University, Tokyo, Japan.
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Nillesen STM, Geutjes PJ, Wismans R, Schalkwijk J, Daamen WF, van Kuppevelt TH. Increased angiogenesis and blood vessel maturation in acellular collagen–heparin scaffolds containing both FGF2 and VEGF. Biomaterials 2007; 28:1123-31. [PMID: 17113636 DOI: 10.1016/j.biomaterials.2006.10.029] [Citation(s) in RCA: 301] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2006] [Accepted: 10/21/2006] [Indexed: 11/29/2022]
Abstract
An important issue in tissue engineering is the vascularisation of the implanted construct, which often takes several weeks. In vivo, the growth factors VEGF and FGF2 show a combined effect on both angiogenesis and maturation of blood vessels. Therefore, we hypothesise that the addition of these growth factors to an acellular construct increases blood vessel formation and maturation. To systematically evaluate the contribution of each scaffold component with respect to tissue response and in particular to blood vessel formation, five porous scaffolds were prepared and characterised, viz.: collagen, collagen with heparin, and collagen with heparin plus one or two growth factors (rrFGF2 and rrVEGF). Scaffolds were subcutaneously implanted in 3 months old Wistar rats. Of all scaffolds tested, the one with a combination of growth factors displayed the highest density of blood vessels (type IV collagen) and most mature blood vessels (smooth muscle actin). In addition, no hypoxic cells were found in this scaffold at day 7 and 21 (hypoxia inducible factor 1-alpha). These results indicate that the addition of both FGF2 and VEGF to an acellular construct enhances an early mature vasculature. This opens prospects for (acellular) tissue-engineered constructs in conditions as ischaemic heart disease or diabetic ulcers.
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Affiliation(s)
- Suzan T M Nillesen
- Department of Biochemistry 280, NCMLS, Radboud University Nijmegen Medical Centre, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
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